Pastures in crop sequencing (SFS 00022) Final report on trialling conducted through the project

Transcription

1 Pastures in crop sequencing (SFS 00022) Final report on trialling conducted through the project December

2 Contents Insights from trials using pastures and fodders in a crop rotation... 3 Dry matter production from fodders... 3 Grain production after fodders... 4 Soil nitrogen... 5 Weeds... 5 Changes to soil moisture... 6 Subsoil modification... 7 Trial 1: Duration, sowing rate and species for weed control, nitrogen accumulation and soil manipulation... 8 Trial 2: Best bet one year 'fix' with winter crops only Trial 3: Best bet one year 'fix' with winter crops or winter and summer crops Trial 4: The impact on weeds from altering the time of sowing and crop density Trial 5: Capturing the systems value of green and brown manuring Trial 6: Evaluating the effectiveness of spray grazing wild radish Trial 7: Evaluating the effectiveness of stubble burning on seed survival and dormancy with different stubble loads Trial 8: Hay making options to control annual ryegrass Trial 9: One year fodder rotation for weed control and nitrogen accumulation Trial 10: Two year fodder rotation for weed control and nitrogen accumulation Trial 11: Use of in-situ fodders for subsoil manuring

3 Insights from trials using pastures and fodders in a crop rotation A total of 14 trials and one demonstration were conducted through the Pastures in Crop Sequencing program in Victoria and South Australia. The Victorian trials were conducted by Southern Farming Systems and the South Australian trials by MacKillop Farm Management Group and Agriculture KI. The trials were to investigate the impact of pasture and fodder species and tactics on production, weeds, nitrogen and soil condition when incorporated as part of a crop rotation. This resulted in some short and long rotation trials. This report provides the measurements and observations from the trialling. Due to the diversity in species tried, rotation length, interventions used and seasonal challenges, there is no discussion for each trial. Instead trials that deal with a common theme such as weed control, nitrogen accumulation, fodder production and impact on following crop yield and soil condition have been grouped, discussed and referenced collectively. The insights from comparing and contrasting a number of results is arguably more powerful than discussing each trial in isolation. Background on each trial, the methods used and the results are presented if the reader wishes to investigate these further. Dry matter production from fodders A number of factors influenced the total amount of dry matter produced from the fodders sown. Seasonal conditions, species choice, time of sowing and perenniality all had an impact. A range of fodders were grown across three years (2012 to 2014). During this period the growing season rainfall varied from well above average (decile 8 & 9), to around average (decile 4 & 5) to well below average (decile 1 & 2). As a consequence dry matter production also fluctuated dramatically, with growth more affected by the drier rather than the wetter growing season. A typical year was 2012 (roughly average rainfall) and yields were commonly around 7 to 10 t/ha for grasses (oats and ryegrass) and 1.5 to 6 t/ha for the legumes (trials 1, 2, 3). Aerial seeding legumes (arrowleaf, balansa, Persian) were generally higher yielding than sub clover or lucerne. In 2013 (an above average season), yields for crop varieties sown as a fodder (peas, beans, oats, wheat, vetch) were typically between 10 and 14.5 t/ha (trials 1, 5, 10). Pasture grasses in the same year yielded between 3.3 & 11.1 t/ha, but typically around 5 to 8 t/ha (trials 1, 10) and legumes between 1.2 and 8 t/ha, typically around 5 to 6 t/ha (trials 1, 9, 10). Lucerne was commonly the lowest yielding legume even under favourable growing conditions. A much drier years was encountered in 2014, resulting in some species failing to establish and lower dry matter production (trials 1, 8, 10). Perennial grasses such as phalaris and soil seed burial legumes such as sub clover sown the previous year responded more favourably than the annual varieties that required resowing. Pasture grasses that established commonly yielded between 4 and 9 t/ha, with legumes between 1 and 6 t/ha. The higher legume dry matter yields were recorded with sub clover and the poorest with established lucerne. In one trial (trial 1) the weeds or nil treatment were allowed to grow (with seed set controlled) and were compare to the dry matter produced by sowing a dedicated species. In 2012, yields from the nil treatment were approximately one third to one half as productive as sown species, however in 2013 (decile 8 or 9) dry matter production was half of the grasses but equal to most legumes. 3

4 Summer fodders were only briefly examined in two trials and only in one year (trial 3). The 2012/2013 summer season was decile 1 rainfall, with low amounts of dry matter measured from the fodder rape, forage sorghum and millet (0.5 to 2.3 t/ha). Equivalent summer growth was achieved from the nil treatment where opportunistic weeds grew. Increasing sowing rate of fodders above common practice had minimal impact on total fodder production (trial 1). These results illustrate the range in dry matter production possible from species across different growing conditions. Therefore the choice of species will depending on the outcomes sought from the fodder phase. These can be summarised as follows; For maximum annual dry matter production and grazing consider annual grass species such as oats and annual ryegrass. If a longer fodder phase is sought, consider short lived perennial ryegrass or phalaris. If a legume is required then consider annual aerial seeding varieties such as arrowleaf, balansa or persian clover. If a longer fodder phase is sought, consider subclover however be prepared for lower growth in the first year. If maximum nitrogen fixation is required but no grazing, then consider peas or beans Avoid using lucerne in short term rotations as dry matter production was lower than other legume species (and does effect subsequent crop yields if rainfall is below average). Fodder quality was consistently high, with digestibility for the legumes throughout the growing season commonly above 75% (10.8 MJ ME/kg) and protein above 15%. Grain production after fodders An increase in grain production is a common objective from using a fodder phase. The likelihood of achieving this results is highly dependent on in season rainfall and the length of the fodder rotation. One year of fodder Results from only one year of winter legume (arrowleaf, balansa, Persian, sub clover, peas, beans) showed in most cases no difference in subsequent grain yield of canola or wheat (trials 1, 2, 3, 9), when the winter crop growing season was favourable (decile, 4, 8 or 9). The exceptions were higher yields at one site after balansa clover or peas. One year of grass fodder resulted in significantly lower yields (trial 1) and could be explained by lower soil nitrogen (refer to discussion on soil nitrogen). The second year of crop showed no significant different in yields from the one year of any species, with the exception of lower yields after oats (trial 1) and serradella (trial 1, 5, 9). There was no impact on yield of the third crop after the fodder (trial 1). Two years of fodder A two year fodder phase had an impact on grain yield with most grass fodders (+/- companion legumes) and unsown treatments (trials 1, 10). Yields were considerably lower compared to treatments that had been fallowed or were in a continuous crop rotation. The yield response if legumes were sown varied. There was no significant effect on 2014 crop yield (decile 2 year), but yields were lower after lucerne (signif at one site and close to signif at the other). Crops sown in 2015 after two years of legume fodder showed a significant reduction in grain yield at the location 4

5 with decile 1 growing season rainfall but no significant yield loss at the site receiving decile 5 rainfall. This would suggest yield decline following two years of annual legume may occur in very low rainfall years. The second year of crop after two years of fodder showed no significant difference in yield to any treatment (trial 1) but was a decile 1 rainfall year. Three years of fodder Three years of fodder followed by a crop was only tested with one trial and at two locations (trial 1). Decile 1 growing season rainfall prevented successful crop establishment at one site (Inverleigh). There were no differences in yield at the other site (Lake Bolac), however yields were well below expectations (~1.2 t/ha for canola). Soil nitrogen Measuring changes in soil nitrogen was challenging, especially given the dry conditions, failed establishment and some crops being ensiled to manage weeds. Most testing was undertaken on trial 1, with the two sites at Inverleigh and Lake Bolac showed marked differences in nitrogen accumulation under various legumes. Inverleigh responded largely in line with accepted rules. Total soil nitrogen was higher in the legume plots than the grasses and 17 kg/ha of N fixed by Persian clover per tonne of dry matter grown (trial 5). The accumulated nitrogen after two years of fodders resulted in marginally higher canola yields under legumes (except for lucerne) even though it was a decile 2 growing season rainfall. After 3 years of crop (only 1 year of fodder) there was no difference in barley yields or differences in grain protein, suggesting most of the accumulated nitrogen has been used or lost. In contrast Lake Bolac did not show increases in total soil nitrogen even after three years of legume fodder. Canola yields in the following year from fodder were not significantly different from the common annual legumes such as Arrowleaf, Persian and sub clover compared to the ryegrass. Balansa clover was the exception with significantly greater canola yields after one or two years of fodder. No plant N fixation work was conducted at this site and the fodders appeared visually OK, however there may be some nodulation issues at the Lake Bolac site that has prevented adequate N fixation. The dry conditions no doubt confounded some of the potential yield and therefore nitrogen response. While yield increases from the legume treatments were only recorded at one location (trial 10), most showed no significant improvement in yield after the fodder phase. Significant grain protein responses were recorded after one year of legume at several sites (trials 2, 5, 10) but not at others (trial 3), however screenings were commonly higher under the legume treatments, suggesting inadequate soil moisture limited potential yield. Weeds Annual ryegrass and wild radish were the two weeds studies in these trials. Initial weed counts were usually undertaken in July, however ongoing observations (trial 4) illustrates the problem with late germinating weeds, especially annual ryegrass. Mid-crop measurements were not providing an accurate understanding of carry over weeds. More recent observations were also taken in October and November to pick up very late germinating weeds that had not be controlled by knockdown or in crop herbicides. 5

6 Annual ryegrass Results clearly show annual ryegrass populations can be dramatically reduced with only one year of a fodder, either a legume, grass or cereal fodder (trials 1, 2, 3, 10). Achieving adequate seed set control is the key. The only trial where annual ryegrass populations increased (trial 9) was the result of no spring intervention with the fodder treatments. To highlight the importance of seed set control, a canola treatment in the same trial that failed due to waterlogging was sprayed out in spring. This resulted in a dramatic reduction in annual ryegrass the next year compared to the untreated fodders. Increasing the fodder duration from one to two or three years generally had a continuing, albeit smaller benefit in lowering ryegrass populations (trials 1, 10) in the fodders. This also appears to provide greater time with lower plant numbers in subsequent crops 1 (trial 1). Other tactics such as increasing crop or fodder sowing rates above common practice (trials 1, 4) and stubble burning (trial 7) proved ineffective in enhancing annual ryegrass control. Delaying sowing time (trial 4) was effective in gaining improved mid-winter weed control however the delay resulted in lower grain yield and no difference in end of season ryegrass numbers because of the late germinating weeds described above. This confirms the issue of late germinating weeds that are beyond the effectiveness on in crop herbicides. Wild radish Control of wild radish was largely ineffective. While a decline in numbers was observed in the first year of one trial (trial 1), equivalent or even increased populations of wild radish were recorded (trials 2, 3, 6, 7) with different fodders or different treatments such as spraygrazing or stubble burning. In one trial (trial 1) the first year of canola after one year of fodder had to be abandoned (crop ensiled) because of very high wild radish numbers. This was irrespective of the treatment applied. Wild radish was still present in considerable numbers in the first year of crop after three years of fodder (trial 1). This is not surprising given the longevity of wild radish seed but does bring into question the long term effectiveness of a short term fodder phase as a tactic to control this weed. Other tactics such as increasing crop or fodder sowing rates above common practice (trials 1, 4), stubble burning (trial 6) and spray grazing (trial 7) proved ineffective in achieving long term weed control. Changes to soil moisture Apart from the lucerne treatment, most annual fodder species dried the soil profile a similar amount. With adequate winter rainfall in 2013, the soil profile was full (sometimes waterlogged) by the end of winter and the water used by various fodders in that year was similar (trial). Crops grown in 2013 year (trials 1, 2, 3) showed no yield difference that could be related to differences in starting soil moisture created by the previous fodder was a dry year and starting soil moisture after two years of fodder were the same between Persian clover, sown ryegrass and the nil treatment (% w/w of 39%, 38% and 42% respectively). There was no significant grain yield difference between treatments. The exception was in 2015 at Frances in South Australia, where there were differences in starting soil moisture due to the treatments and a strong correlation with grain yield (trial 10). In this trial 1 Weeds will be counted in 2016 as part of the Grain and Graze program to continue 6

7 the lowest soil moisture was under the lucerne, followed by the grasses (perennial ryegrass and phalaris). Highest soil moisture was under crop fodders (oats for hay, peas for green manuring) and a fallow treatment and this correlated with higher grain yield. Similar differences in soil moisture between fodder treatments were not measured at other sites. This data shows that perennial fodders such as lucerne, phalaris and perennial ryegrass are likely to deplete soil moisture from the profile more than any of the annual fodders (annual clovers, annual ryegrass) but less than crop species such as oats or peas sown for fodder or green manuring and then terminated before the end of the growing season. Adequate growing season rain is required to avoid compromising subsequent grain yield because of the extra moisture depletion. Subsoil modification One trial was undertaken to investigate the potential of placing organic material at depth (trial 11). From this limited work, and two extremely dry seasons, several issues can be identified that relate to the risks and requirements of subsoil modification with organic matter. The first is the enhanced dry matter production achieved when there is sufficient rainfall. This was illustrated by the greater early growth and vigour of plants under various subsoil treatments in This larger, healthier crop would have used larger amounts of soil water. With the dry finish, the bulkier crop ran out of water earlier. In 2015, the lack of soil moisture from sowing onwards did not result in the same visual difference as both the treated and untreated plots were moisture deficient. The second is the lack of moisture at flowering and grain fill curtailed any potential yield difference. This is supported by measurements of significantly higher protein and screenings in the treatments compared to the control in 2015, with a similar indication in The higher grain protein indicates plants were accessing an additional source on nitrogen (from the organic material) and the higher screenings indicate many grain aborted because of a lack of moisture. In other words the potential was there to grow a larger yielding crop if moisture had been available. Thirdly the work illustrates the need to compact the soil around the organic material. In a typical season we would expect enough rain to settle the soil, however this did not occur because of inadequate rainfall. The inability to expel many of the air pockets in the soils (because of the technique used), combined with a lack of winter rainfall meant there were cavities in the soil where roots were unable to access and draw moisture from. 7

8 Trial 1: Duration, sowing rate and species for weed control, nitrogen accumulation and soil manipulation Aim: To understand the interactions between species, sowing rate and length of time in the rotation to achieve weed, nitrogen and soil benefits. Duration: 4 years Location(s): Inverleigh (primarily for wild radish control), Lake Bolac (for annual ryegrass control) Trial design Factorial design: 10 x 3 x 3 = 90 treatments Replicates: 4 Species: 10 (as listed) Sowing rate: 3 (common, double rate, triple rate) Duration in rotation: 3 (one, two or three years) followed by annual crop in 2015 Time of sowing: May 2012, then April may for annual species Grazing: Cut with forage harvester when considered suitable for grazing Silage / hay Cut with forage harvester Key measurements Dry matter production, grain yield, weeds, soil nitrogen, soil water. Species and sowing rate Species Sowing rate (kg/ha) Times of Common Twice rate Triple rate sowing Arrowleaf clover cv Arrowtas Annual Persian clover cv Flash Annual Balansa clover cv Viper Annual Sub clover cv Riverina Once Peas cv Hayman Annual Lucerne cv Sardi Once Serredella cv Serratas Annual Grazing oats cv Targa Annual Ryegrass cv Winter star Annual NIL - just what weeds grow 8

9 Results Rainfall Seasonal rainfall was highly variable over the four years of the trial. Winter crop growing season rainfall (May to November) was above average for the first two years (decile 6 and 8-9), followed by two years of extremely low growing season rainfall (decile 2 and decile 1). Fodder and crop yields Location Period Inverleigh Lake Bolac (Winchelsea) May Nov 2012 (mm) 385 (decile 6) 374 (decile 6) Dec 2012 Apr 2013 (mm) 78 (decile 1) 76 (decile 1) May Nov 2013 (mm) 471 (decile 9) 420 (decile 8) Dec 2013 Apr 2014 (mm) 163 (decile 4) 144 (decile 3) May Nov 2014 (mm) 283 (decile 2) 254 (decile 2) Dec 2014 Apr 2015 (mm) 165 (decile 4) 132 (decile 2) May Nov 2015 (mm) 241 (decile1) 237 (decile 1) Practices were applied to the fodders depending on their suitability for grazing, ensiling, hay making or manuring. The practices applied varied depending on the season but reflected what would commonly done given the situation. Annual yield results for the common sowing rate are presented for Inverleigh (table 1) and Lake Bolac (table 2). Severe slug problems at Inverleigh prevented the successful establishment of the canola in The trial was resown in July but establishment was patchy and then followed extremely dry conditions. It was decided to not harvest the canola as results would be unreliable. The dry conditions in 2015 were reflected in the low yields and high screenings from the wheat and barley. Average barley yields at Inverleigh in 2015 were only 2.62 t/ha, with 14.3% screenings and 2.71 t/ha with 8.0% screenings. If yields of both the wheat and barley are compared by species at Inverleigh there was a significant difference between species, with lower yields measured after the lucerne (2.37 t/ha), serradella (2.54 t/ha), subclover (2.59 t/ha) and arrowleaf (2.60 t/ha) rotations compared to the ryegrass (2.93 t/ha) and balansa (2.86 t/ha) rotations (LSD p=0.05=0.25 t/ha). 9

10 Table 1: Fodder and crop yields from 2012 to 2015 at Inverleigh for common sowing rate Duration 1 year fodder Fodders Canola Species Arrowleaf Canola Fodders Wheat Barley Total fodder Persian Balansa Excessive Sub clover wild Peas radish Lucerne infestation Serradella so cut for Grazing oats silage Ryegrass Nil LSD P=0.05 NS 1.06 NS Duration 2 year fodder Species Fodders Fodders Crop Fodders Canola Wheat Total fodder Arrowleaf Persian Balansa Sub clover Peas Lucerne Serradella Grazing oats Ryegrass Nil LSD p= NS Duration 3 year fodder Species Arrowleaf Fodders Fodders 10 Crop Fodders Crop Canola Total fodder Persian Balansa N/A 12.5^ Sub clover Failed to Peas N/A 9.7^ establish Lucerne Serradella Grazing oats N/A 17.5^ Ryegrass Nil ^ = Data for 2012 and 2013 only sowing of some species failed to establish LSD p=0.05 NS

11 Table 2: Fodder and crop yields from 2012 to 2015 at Lake Bolac for common sowing rate. Duration 1 year fodder Species Fodders (kg/ha) Fodders (kg/ha) Canola Fodders (kg/ha) Wheat Barley Total fodder Arrowleaf Persian Balansa Sub clover Peas Lucerne Serradella Grazing oats Ryegrass Nil LSD p= NS Duration 2 year fodder Species Fodders (kg/ha) Fodders (kg/ha) Crop Fodders (kg/ha) Canola Wheat Total fodder Arrowleaf Persian Balansa Sub clover Peas Lucerne Serradella Grazing oats Ryegrass Nil LSD p= NS Duration 3 year fodder Species Fodders (kg/ha) Fodders (kg/ha) Crop Fodders (kg/ha) Crop Canola Total fodder Arrowleaf N/A ^ Persian N/A ^ Balansa N/A ^ Sub clover Peas N/A ^ Lucerne Serradella Grazing oats N/A Ryegrass N/A ^ Nil ^ = Data for 2012 and 2013 only sowing failed to establish LSD p=0.05 NS 11

12 Increasing the sowing rate made a significant difference to the annual amount of dry matter produced in 2012 at Inverleigh, but no difference at either site in 2013 (table 3). Table 3: Annual average dry matter production from all species at different sowing rates Location Inverleigh Lake Bolac Sowing rate Dry matter Common Double Triple LSD p= NS Common Double Triple LSD p=0.05 NS NS Further examination of individual species only showed a significant increase in dry matter production for Balansa clover, peas and Serradella at Inverleigh in 2012 and Arrowleaf clover at Lake Bolac in There were no species responses in 2013 at either site. Weeds Weed populations were monitored from 2012 to Control of these weeds were based on a combination of herbicides, silage, hay and mulching. Different species enabled different herbicide groups to be applied. Annual forage legumes (Sub, Balansa, Arrowleaf, Persian) - Group A, I, F, G herbicides Annual forage legumes (Serradella) - Group A, B, G herbicides Perennial forage legumes (Lucerne) - Group A, B, C, L herbicides Annual grain legumes (Peas) - Group A, B, G herbicides Grass forages (Ryegrass, forage oats) - Group I, F herbicides Weed counts were taken annually six to eight weeks after sowing. Counts in the crop were after initial knock down and early post sowing herbicides. For the remaining fodder species no herbicides had been applied. Further strategic weed counts were taken in late spring of 2015 because of emerging evidence of very late germinating weeds. There was a dramatic decline in weed species after only 1 year of fodder for the major problem weed species. After 3 years there was a further decline in wild radish at Inverleigh and annual ryegrass at Lake Bolac (figure 1 and 2). The first year decline was 77% for wild radish at Inverleigh after only 1 year and 61% after 3 years. At Lake Bolac the first year decline in annual ryegrass was 83% and 94% after 3 years. This is likely to be caused by a combination of different competition effects between species, the ability to use different herbicide groups and late season interventions to control seed set. Wild radish population at Inverleigh appears to have increased in 2015, the first year out of fodder and sown to canola, irrespective of the treatment. The same effect was not recorded for annual ryegrass at Lake Bolac. This different response from wild radish and annual ryegrass is likely to be a result of weed seed longevity. 12

13 Wild radish (pl/m2) Arrowleaf clover Persian clover Balansa clover Sub clover Peas Lucerne Serradella Grazing oats Ryegrass Nothing sown Figure 1: Change in wild radish numbers (pl/m2) after three years of different fodder break crops at Inverleigh (weeds counted in June 2012, 2013, 2014) and in following canola crop (July 2015). All sowing rates Annual ryegrass (pl/m2) Arrowleaf clover Persian clover Balansa clover Sub clover Peas Lucerne Serradella Grazing oats Ryegrass Nothing sown Figure 2: The change in annual ryegrass numbers (pl/m2) after three years of different fodder break crops at Lake Bolac (weeds counted in June 2012, 2013, 2014) and in following canola crop (2015). All sowing rates 13

14 The less dominant weeds at both Inverleigh and Lake Bolac did not increase either (figure 3 & 4). Annual ryegrass numbers increased slightly at Inverleigh (where wild radish was the dominant weed) but wild radish declined slightly at Lake Bolac (where annual ryegrass was the dominant weed), although both comparisons are from a low starting population. Controlling annual ryegrass in the serradella treatment proved difficult (figure 3). 300 Annual ryegrass (pl/m2) Figure 3: Change in annual ryegrass numbers (pl/m2) after three years of different fodder break crops at Inverleigh (weeds counted in June 2012, 2013, 2014) and in following canola crop (July 2015) Wild radish (pl/m2) Arrowleaf clover Persian clover Balansa clover Sub clover Peas Lucerne Serradella Grazing oats Ryegrass Nothing sown Figure 4: Change in wild radish numbers (pl/m2) after three years of different fodder break crops at Lake Bolac (weeds counted in June 2012, 2013, 2014) and in following canola crop (July 2015). 14

15 Further examination of the length in the fodder revealed some interesting results. Firstly the weed populations in fodder treatments that were only sown for one year, followed by a rotation of canola (2013), wheat (2014) and barley (2015) appear at least as effective than the two or three year fodders. This is illustrated by the plant population counts in late November 2015 (figure 5). Figure 5: Annual ryegrass population (Lake Bolac - left) and wild radish population (Inverleigh right) in crop late November 2015 after one, two or three years of a sub clover fodder phase. Seven different fodder legumes were used as fodder options. Most were as effective as each other, with the exception of serradella which proved problematic because of challenges with establishment and herbicide options. Two grass fodders were also included (grazing oats and annual ryegrass), which were used for grazing and fodder conservation. Despite the difference herbicide approaches, both grass fodders were similarly effective as the fodder legumes (figure 6). Figure 6: Annual ryegrass population (Lake Bolac - left) and wild radish population (Inverleigh right) in crop late November 2015 after one, two or three years of a legume or grass fodder phase. Nitrogen Nitrogen measurements were taken on a limited number of treatments. Trials started with an average total soil N (0 60 cm) of 106 kg/ha at Inverleigh and 109 kg/ha at Lake Bolac. At the end of the first fodder season (December 2012) there was a measurable decline in soil nitrogen which remained relatively unchanged to May 2013 (figure 7). This is not surprising given December 2012 to April 2013 was less than 80 mm (decile 1 rainfall). 15

16 Figure 7: Total soil nitrogen (Lake Bolac - left) and (Inverleigh right) during the trial (0-60 cm) After two years of fodder production, and more favourable summer moisture (approximately double the amount from the previous year), there was a consistent increase in soil nitrogen at Lake Bolac across all species, including the non-legumes. At Inverleigh the response was less pronounced except for the Persian clover. After three years of fodder and one year of crop there was not obvious difference in total soil nitrogen at Lake Bolac between the Persian clover and the ryegrass. In contrast there was significantly more total soil N at Inverleigh by May 2016 compared to two years earlier. The total soil nitrogen accumulated under the Persian clover treatment was higher than the ryegrass or Nil treatments. The difference in total soil N is striking. From figure 7 it would appear there has been no additional change in the soil nitrogen pool from the Persian clover compared to the ryegrass at Lake Bolac. The combined fodder production from the Persian clover in 2012 and 2013 was 12.0 t/ha, the lucerne 5.4 t/ha, ryegrass 15.3 t/ha and the Nil, which just grew weeds 10.5 t/ha. The third year of the fodder phase was extremely dry and both the Persian clover and ryegrass failed to establish. The lucerne only grew 0.61 t/ha and the Nil 1.05 t/ha (refer to table 2). At Inverleigh there was a large increase in total soil N from the Persian clover treatment compared to other species. Persian clover had yielded 11.9 t/ha after 2 years and a further 1.0 t/ha in In comparison the ryegrass grew 11.6 t/ha after 2 years and a further 0.9 t/ha in 2014 (refer to table 1). Unfortunately there was no canola harvested in 2015 due to slug damage at establishment and an extremely dry finish. Total soil nitrogen was compared in May 2016 after either one year of fodder followed by 3 years of crop or three years of fodder and one year of crop. At Inverleigh there was more total soil nitrogen after three years of fodder compared to one year and a difference between the treatments (figure 8). The 2015 crop was sown with MAP at 100 kg/ha. After one year of crop the Persian clover treatment was noticeably higher in total soil N than the ryegrass or Nil treatment, although all treatments had increased. However after three years of crop, not only had the total soil N declined, but the differences between treatments had dissipated, suggesting the previous crops had used the nitrogen accumulated after 1 year of fodder. In contrast at Lake Bolac there was no similar increase in soil N after three years of fodder and no difference between the Persian clover and the ryegrass or Nil treatment. The three years of fodder was similar to only one year. 16

17 Figure 8: Total soil nitrogen (Lake Bolac - left) and (Inverleigh right) after one or three years of fodder and one or three years of crop (0-60 cm) A comparison was made of total soil N under each treatment after one year of fodder. The results indicate only a small amount of N accumulation at Lake Bolac compared to the ryegrass. At Inverleigh the contrast in N accumulation between legumes and the ryegrass was greater, with more than double the soil N under some legumes compared to the ryegrass (figure 9). Figure 9: Total soil nitrogen under different species (Lake Bolac - left) and (Inverleigh right) after one years of fodder (0-60 cm) Nitrogen fixation tests (using N 15 ) were conducted in 2012 on Persian clover, lucerne and peas grown at Inverleigh. The fixation rates are presented (table 4). Table 4: Nitrogen fixed (kg/ha) per tonne of dry matter grown Species Shoot N fixed (kg N/t DM) Dry matter grown Anticipated soil N added (kg/ha) Soil N above ryegrass (kg N /ha) Persian clover Lucerne Peas This would suggest more nitrogen should have been added to the soil than measured through soil testing. 17

18 Soil water Soil water was measured at the same time nitrogen cores were taken. Soil moisture in May 2013 (before sowing), indicates most species had similar soil moisture. The lowest soil moisture was recorded under the lucerne (figure 10). Figure 10: Total soil water under different species (Lake Bolac - left) and (Inverleigh right) in May 2013 after one years of fodder (0-60 cm) Moisture tracked across seasons showed little difference except for the lucerne. However the extremely dry conditions would have prevented any major changes from different growing season length from being exhibited. 18

19 Trial 2: Best bet one year 'fix' with winter crops only Aim: To test the effectiveness of five current (2012) best bet treatments to control target weeds and contribute to the nitrogen pool for the subsequent crop. Duration: 1 year Location(s): Inverleigh (primarily for wild radish control), Lake Bolac (for annual ryegrass control) Trial design Randomised block: 5 treatments Replicates: 4 Treatments Nil (to use as a comparison) Autumn herbicide, autumn sown arrowleaf clover, spraytop Autumn herbicide, autumn sown (persian Inverleigh, Balansa Lake Bolac), fodder removal Autumn tickle, autumn herbicide, fallow, spring herbicide, peas, green manure Autumn tickle, autumn herbicide, fallow, spring herbicide, peas, harvest Grazing: Cut with forage harvester when considered suitable for grazing Silage / hay Cut with forage harvester Key measurements Dry matter production, grain yield, weeds. Results Rainfall Location May Nov 2012 (mm) Inverleigh 385 (Winchelsea) (decile 6) Lake Bolac 374 (decile 6) Fodder and crop yields There were differences in dry matter production at Inverleigh and Lake Bolac in 2012 as a result of the treatments. This is to be expected given alternative species and approaches applied (table 1). 19

20 Table 1: Total DM production and crop yields. Treatment in 2012 Inverleigh Lake Bolac Total DM Crop yield Protein (%) Total DM Crop yield Protein (%) Nil herbicide fallow only Autumn herbicides, autumn sown arrowleaf clover, spraytop in spring Autumn herbicides, autumn sown balansa clover, hay Autumn tickle, autumn and spring herbicides, spring sown peas, green manure in December Autumn tickle, autumn and spring herbicides, spring sown peas, harvested LSD p=0.05 N/A 1.02 NS (p=0.07) N/A NS 1.40 The crop yields in the year after the fodder were significantly higher across all treatments compared to the nil treatment (chemical fallow only) at Inverleigh and also higher but not significant at Lake Bolac. Grain protein was also higher (almost significant at Inverleigh, significant at Lake Bolac), suggesting the yield increase is a result of additional nitrogen from the fodder. Higher protein levels corresponded to greater fodder production the previous year. Weeds There were no significant difference in weed populations between treatments one and two years after the fodder phase. This would indicate all treatments were equally as effective on weed control. However there was a large reduction in annual ryegrass in the crop immediately after the treatment (from 2012 to 2013). A further measurement of annual ryegrass in 2014 at Inverleigh would suggest the large reduction in weed numbers is reversed in the next year, with small increases in annual ryegrass across all treatments (table 2). Table 2: Population of annual ryegrass (pl/m 2 ) at Inverleigh and Lake Bolac (2012 to 2014). Treatment in 2012 Inverleigh Lake Bolac Nil herbicide fallow only Autumn herbicides, autumn sown arrowleaf clover, spraytop in spring Autumn herbicides, autumn sown balansa clover, hay Autumn tickle, autumn and spring herbicides, spring sown peas, green manure in December Autumn tickle, autumn and spring herbicides, spring sown peas, harvested LSD p=0.05 NS NS NS NS NS 20

21 The population of wild radish showed a similar trend as annual ryegrass at Inverleigh, with a decline the year after treatment but then an increase in the next year. At Lake Bolac there was an increase across all treatments (table 3). Table 3: Population of wild radish (pl/m 2 ) at Inverleigh and Lake Bolac (2012 to 2014). Treatment in 2012 Inverleigh Lake Bolac Nil herbicide fallow only Autumn herbicides, autumn sown arrowleaf clover, spraytop in spring Autumn herbicides, autumn sown balansa clover, hay Autumn tickle, autumn and spring herbicides, spring sown peas, green manure in December Autumn tickle, autumn and spring herbicides, spring sown peas, harvested LSD p=0.05 NS NS NS NS NS 21

22 Trial 3: Best bet one year 'fix' with winter crops or winter and summer crops Aim: To measure the effectiveness of a combined winter or winter and summer fodder approach on problem weeds and subsequent crop performance. Duration: 1 year Location(s): Inverleigh (primarily for wild radish control), Lake Bolac (for annual ryegrass control) Trial design Factorial: 3 x 4 = 12 treatments Replicates: 4 Treatments 3 winter legumes (Short season persian clover, balansa clover and peas) 4 summer fodder species (Nil, Winfred rape, Forage sorghum, millet) Crop Wheat in 2013 Grazing: Cut with forage harvester when considered suitable for grazing Silage / hay Cut with forage harvester Key measurements Dry matter production, grain yield, weeds. Results Rainfall Location May Nov 2012 (mm) Inverleigh 385 (Winchelsea) (decile 6) Lake Bolac 374 (decile 6) Dec 2012 Apr 2013 (mm) 78 (decile 1) 76 (decile 1) Fodder and crop yields Winter fodder yields varied between species and at different sites. Peas produced significantly more dry matter in winter than either Balansa or Persian clover at Inverleigh, however Persian clover was the highest yielding at Lake Bolac. Despite the differences in dry matter production, none of the winter treatments had an effect on subsequent grain yields (table 1). Table 1: Total DM production and crop yields for winter legume component. Winter Inverleigh Lake Bolac treatment 2012 Winter DM Crop yield Winter DM Crop yield Persian Balansa Peas LSD p= NS 0.35 NS 2 Not all treatments sampled to calculate results 22

23 Summer fodder production was below expectations, although forage sorghum out yielded the forage rape, millet or the Nil treatment at Inverleigh (table 2). At Lake Bolac the Nil treatment grew significantly more dry matter than any of the sown species. Growth on the Nil treatment, was from the aftermath of the residual winter crop that survived spraying and summer weeds. Table 2: Total DM production and crop yields for summer fodder component. Summer Inverleigh Lake Bolac treatment Summer DM Crop yield Summer DM Crop yield Nil Forage rape Forage sorghum Millet LSD p= NS 0.55 NS The combination of peas, followed by forage sorghum or fodder rape produced the greatest total dry matter at both Inverleigh and Lake Bolac, if the Nil dry matter production is excluded (table 3). Interestingly the summer dry matter production from the Nil treatment was similar to the sown species. Crop yields were not affected by either winter, summer or a combination of both fodder crops. Table 3: Total DM production and crop yields. Treatment in 2012 Inverleigh Lake Bolac Winter DM Summer DM Total DM Crop yield Winter DM Summer DM Total DM Crop yield Persian, no summer crop (Nil) Balansa, no summer crop (Nil) Peas, no summer crop (Nil) Persian, fodder rape Balansa, fodder rape Peas, fodder rape Persian, forage sorghum Balansa, forage sorghum Peas, forage sorghum Persian, millet Balansa, millet Peas, millet LSD p=0.05 NS 0.45 Grain protein was similar across the four summer treatments suggesting the small amount of nitrogen that may have been used over summer was not large enough to deplete soil nitrogen in the subsequent grain crop to any large effect. 23

24 Weeds Weed populations generally declined from June 2012 to June This was especially the case for annual ryegrass at Lake Bolac. There were no significant difference in weed populations from the various winter or summer options at either site (tables 4 to 7). While the Inverleigh site had a greater infestation of wild radish than Lake Bolac, measurements at Inverleigh would indicate surprisingly low starting population of wild radish for this trial. Given the low starting population responses to different treatments needs to be viewed with caution (as the starting population was also significantly different between treatments). Table 4: Population of annual ryegrass (pl/m 2 ) at Inverleigh and Lake Bolac after the winter fodders Winter Inverleigh Lake Bolac treatment (pl/m 2 ) 2013 (pl/m 2 ) (pl/m 2 ) (pl/m 2 ) Persian Balansa Peas LSD p= NS NS NS Table 5: Population of wild radish (pl/m 2 ) at Inverleigh and Lake Bolac after the winter fodders Winter Inverleigh Lake Bolac treatment (pl/m 2 ) 2013 (pl/m 2 ) (pl/m 2 ) (pl/m 2 ) Persian Balansa Peas LSD p= NS NS NS Table 6: Population of annual ryegrass (pl/m 2 ) at Inverleigh and Lake Bolac after the summer fodders Summer Inverleigh Lake Bolac treatment (pl/m 2 ) 2013 (pl/m 2 ) 2012 (pl/m 2 ) (pl/m 2 ) Nil Forage rape Forage sorghum Millet LSD p=0.05 NS NS NS NS Table 7: Population of wild radish (pl/m 2 ) at Inverleigh and Lake Bolac after the summer fodders Summer Inverleigh Lake Bolac treatment (pl/m 2 ) 2013 (pl/m 2 ) 2012 (pl/m 2 ) (pl/m 2 ) Nil Forage rape Forage sorghum Millet LSD p=0.05 NS NS NS NS 24

25 Trial 4: The impact on weeds from altering the time of sowing and crop density Aim: To determine to what extent early competition is able to control annual ryegrass and wild radish in a wheat crop. Duration: 1 year Location(s): Inverleigh (primarily for wild radish control) and Lake Bolac (for annual ryegrass control). Trial design Factorial design: 3 (times of sowing) x 3 (seeding rates) = 9 treatments Replicates: 4 Species: Wheat cv Revenue Sowing dates: Early (8/04/2013, Inv. 17/04/2013, LB) Early (10/05/2013, Inv. 30/05/2013 LB) Late (12/06/2013, Inv. 28/06/2013 LB) Target sowing rates: 100 pl/m pl/m pl/m 2 Key measurements Establishment, weeds, grain yield and quality. Results Rainfall Seasonal rainfall was well above average for 2013 with 471 mm from the start of May to the end of November at Inverleigh (decile 9 season) and 420 mm at Lake Bolac (decile 8 season). Establishment Crop establishment was close to the desired plant population except at Inverleigh, where the highest sowing rate was not significantly different from the middle sowing rate (table 1). There was no significant different in plant populations with different times of sowing. Table 1: Desired and actual plant population Desired plant Actual plant population (pl/m 2 ) population Inverleigh Lake Bolac 100 pl/m pl/m pl/m LSD p= Crop yield and grain quality Crop yields were not affected by seeding rate but were by the time of sowing. The optimum time of sowing was in May, with yields at least 1 t/ha better than the late sowing. The early sowing difference was more than 2 t/ha at Inverleigh (sown 08/04) but much less at Lake Bolac, where the early sowing was 17/04 and the mid sowing 30/05 (table 2). 25

26 Table 2: Grain yield at different times of sowing Time of Grain yield sowing Inverleigh Lake Bolac April May June LSD p= Grain protein was significantly lower at Inverleigh with the higher yielding May sown crop, suggesting a possible limitation of nitrogen (9.8% compared to 10.9 % and 11% for the early and late sowing). Screenings were also significantly higher in the early and late sown crops (4.3% and 3.5% respectively) compared to the May sowing at 2.6%. Lake Bolac grain quality was surprisingly low, indicating inadequate nitrogen applied to the crop. Grain protein were 7.4%, 7.9% and 8.2% for the early, mid and late season sowing respectively (LSD p0.05 = 0.3%). Screening were also much higher than Inverleigh at 10.3%, 16.2% and 14.8% for the early mid and late season sowing respectively (LSD p0.05 = 2.8%). Weeds Annual ryegrass seed counts were also taken approximately 1 month after the June crop sowing at Lake Bolac. This measurement was useful in indicating the effectiveness of the pre sowing and early in crop herbicides (table 3). Table 3: ARG plants on the 26 July at different times of sowing Time of sowing Herbicide applications ARG (pl/m 2 ) 17 April No herbicide no weeds germinated at time of sowing May 29/05 Roundup l/ha, 188g/ha, Avadex 2.0 l/ha / ml/ha, LVE MCPA 200 ml/ha 28 June 27/06 Roundup l/ha, 188g/ha 4.1 LSD p= Annual ryegrass (ARG) seed heads were measured just before harvest. This gave an indication of the likely seed load that would be carried forward in the next year. Large populations of annual ryegrass were recorded at both sites. Despite a significantly lower ARG population in late July on the later sown crop (table 3), the ryegrass seed heads were still at very high numbers by the end of the season (tables 4 & 5). Increasing sowing rate had no impact on the number of ARG seed heads at either site (table 4) nor did time of sowing at Inverleigh (table 5). However the earlier time of sowing did significantly increase the number of ARG seed heads at Lake Bolac. There were no interaction effects at either site. 26

27 Table 4: ARG seed heads at different sowing rates Desired plant ARG tillers (tillers/m 2 ) population Inverleigh Lake Bolac 100 pl/m pl/m pl/m LSD p=0.05 NS NS (p=0.08) Table 5: ARG seed heads at different times of sowing Time of ARG tillers (tillers/m 2 ) sowing Inverleigh Lake Bolac April May June LSD p=0.05 NS 47 These results would suggest annual ryegrass germination beyond the effective life of the in crop applied herbicides, even with late sowing. Additional observations on time of sowing were made on two blocks (un-replicated) to observe the effect of multile herbicide application and sowing. A heavy wheat stubble sprayed in May was burnt late (Sept 2013) following herbicide desiccation (figure 1), then either sown or treated with another herbicide applications before a later sowing. Figure 1: Wheat stubble before first Spring spraying. Note new germination and dead ryegrass from typical May knockdown Annual ryegrass was measured in December before harvest. Despite the late application of herbicide, there were a large population of annual ryegrass at harvest (table 6). 27

28 Table 6: Annual ryegrass population on 11/12/2013 after a September 6 (single knock down herbicide) or September 6 and September 29 (double knock down) herbicide application. Treatment One knockdown spray on 29/08/2013, then burnt, sown 06/09/2013 One knockdown spray on 29/08/2013, then burnt, followed by a second knock down spray on 29/09 sown 30/09/2013 Annual ryegrass pl/m 2 Std Dev

29 Trial 5: Capturing the systems value of green and brown manuring Aim: To capture the value that a one year green or brown manuring has on weeds, nitrogen and future crop yields in a rotation. Duration: 2 years Location(s): Inverleigh (primarily for wild radish control) and Lake Bolac (for annual ryegrass control). Trial design Factorial design: 5 (varieties) x 2 (manuring treatments) = 10 treatments Replicates: 4 Sown: 29/05/2013, Inv. 23/05/2013, LB Wheat cv Beaufort sown 26/06/2014 Inv. 11/06/2014 LB Barley cv Oxford, sown 13/05/2015 Inv. 15/05/2015 LB. Varieties Wheat cv 94 kg/ha Clover cv 6 kg/ha Peas cv 100 kg/ha Beans cv 150 kg/ha Vetch cv 50Kg/ha Manuring treatment Green manuring on 23/10/2013 Brown manuring on 23/10/2013 (Roundup 2 l/ha) Key measurements Soil N, weeds, crop establishment, dry matter, grain yield & quality. Results Rainfall Seasonal rainfall was well above average for the 2013 with 471 mm from the start of May to the end of November at Inverleigh (decile 9 season) and 420 mm at Lake Bolac (decile 8 season). In contrast 2014 was well below average, with decile 2 growing season rainfall at both sites (283 mm at Inverleigh and 254 mm at Lake Bolac) was even drier with decile 1 rainfall at both sites (241 mm at Inverleigh and 237 mm at Lake Bolac). Fodder establishment and production All fodders established successfully at both sites except for the clover where there was no germination at first sowing. This was resown on the 5/08/13 at Inverleigh but establishment and production were again poor, effectively resulting in a fallow type treatment. Favourable growing conditions resulting in a large amount of dry matter being produced for manuring (table 1). 29

30 Table 1: Dry matter available for manuring Variety Dry matter Inverleigh Lake Bolac Wheat Clover N/A N/A Peas Beans Vetch Nitrogen The large quantity of dry matter grown in 2013 resulting in a large accumulation of nitrogen under each of the legume treatments, especially the vetch (figure 1). Total nitrogen - kg/ha (0-60 cm) Peas Beans Vetch Figure 1: Accumulation of nitrogen from one year of legumes at Inverleigh (left) and Lake Bolac (right). Error bars represent 1 std dev. Nitrogen fixation tests (using N 15 ) were conducted on peas, beans and vetch at Inverleigh. The fixation rates are presented (table 2). Table 2: Nitrogen fixed (kg/ha) per tonne of dry matter grown Species Shoot N fixed (kg N/t DM) Dry matter grown Anticipated soil N added (kg/ha) Calculated soil N added compared to peas = 0 (kg /ha) Change in soil N compared to peas = 0 (kg N/ha) Peas Beans Vetch The results calculated from soil testing broadly match the changes measured through soil testing. Grain yield and quality Grain yield and quality was measured in 2014 and There was no significant increase in grain yield at Inverleigh across either year from the different species, although grain protein was significantly higher with the legume treatments in 2014 (table 3). There was no protein response in 2015 and no screening difference in either year. 30

31 Table 3: Grain yield, protein and screenings at Inverleigh in 2014 and 2015 following different legume species Species Yield Protein (%) Screenings (%) Wheat Clover N/A N/A N/A N/A N/A N/A Peas Beans Vetch LSD p=0.05 NS NS 0.6 NS NS NS A similar response was recoded at Lake Bolac in 2015 (table 4). There was no yield response Table 4: Grain yield, protein and screenings at Lake Bolac in 2015 following different legume species Species Yield Protein (%) Screenings (%) Wheat Clover N/A N/A N/A Not Not Not Peas recorded recorded recorded Beans Vetch LSD p=0.05 NS NS (p=0.11) NS (p=0.06) Weeds Weeds were monitored in late August of 2014 at the Inverleigh site only. There were no significant differences in annual ryegrass (ARG) or wild radish due to the manuring treatment (table 5). Table 5: In crop weeds the season after manuring treatments (2014) Treatment ARG (pl/m 2 ) Wild radish (pl/m 2 ) Green manuring Brown manuring LSD p=0.05 NS NS 31

32 Trial 6: Evaluating the effectiveness of spray grazing wild radish Aim: To evaluate whether spray grazing wild radish using different chemicals and application rates improves weed control by grazing. Duration: 2 years Location(s): Inverleigh Trial design Factorial design: 3 (herbicides) x 2 (rates) x 2 (+/- grazing) = 12 treatments Replicates: 4 Species: Barley cv Westminster Herbicides: MCPA (1.1 l/ha, 2.2 l/ha) Tigrex (0.5 l/ha, 1.0 l/ha) Precept (0.5 l/ha, 1.0 l/ha) Time of sowing: May 2012 Grazing: Grazed with sheep for 11 days (30/08/2013 to 10/09/2013) Key measurements Establishment, dry matter production, grain yield, weeds. Results Rainfall Seasonal rainfall was well above average for the 2013 with 471 mm from the start of May to the end of November (decile 9 year) was significantly drier recording only 283 mm in the corresponding May to November period (decile 2). Establishment and fodder production The barley established well (above 200 pl/m 2 ) with no significant difference between any treatments. With the very favourable growing conditions, 2600 kg/ha of dry matter was available for grazing (grazed at GS 32). This was high quality feed (DMD 81.9%, CP 21.7%). Grazing opened up the canopy, to an extent that enabled the wild radish to also be grazed (see photos). Weed control Initial wild radish population before treatment was 5.8 pl/m 2 (no difference between treatments). Plant populations after herbicide treatment decreased by 72% to 1.6 pl/m 2 on average. There was no significant difference between the herbicides used. The rate of chemical used also did not have a significant effect on wild radish population. The average of using the half rate was 1.8 pl/m 2 and 1.5 pl/m 2 for the full rate. Grazing resulted in a reduction in wild radish population. The average population of the ungrazed treatment (but treated with herbicides) was 2.3 pl/m 2 and 0.9 pl/m 2 where both grazing and herbicide had been applied. However this was not significant (P 0.05 = 0.11). 32

33 Wild radish populations were measured in 2014 post sowing (27/08/2014). There was no significant difference in wild radish population as result of the previous treatment in Wild radish in the ungrazed treatment was 6.3 pl/m 2 compared to 4.5 pl/m 2 on the grazed treatments. The product used or the rate applied also made no difference; Product: Precept = 4.7 pl/m 2, MCPA 5.6 pl/m 2, Tigrex 6.0 pl/m 2 Rate: Half rate = 1.8 pl/m 2, full rate = 1.5 pl/m 2 Annual ryegrass (ARG) was also monitored in the trial (although the focus of the experiment was on wild radish). ARG populations were low after crop establishment (measured on 27/06/2013) at an average of 1.9 pl/m 2. Measurements of seed heads (tillers) taken immediately before grain harvest (31/12/2013) shows a significant negative effect due to grazing. Tiller numbers were more than double in the grazed treatments compared to the ungrazed treatments (13.8 pl/m 2 ungrazed, 32.4 pl/m 2 grazed, LSD p=0.05 = 11.1 pl/m 2 ). There was no significant effect due to rate of application although there was a significant difference on ryegrass heads from using Precept compared to MCPA (28.0 pl/m 2 compared to 15.5 pl/m 2 ). No explanation can be made for this measured difference. There was no significant treatment differences when ARG populations were measured in late August However the population was much higher than the plant numbers recorded in 2013 (average 1.9 pl/m 2 in late June 2013 and 8.5 pl/m 2 in late August 2014). Grain yield and quality Grain yield was significantly affected by grazing, despite the favourable growing conditions after grazing. Average grain yields in the ungrazed treatment were 5.95 t/ha and 3.54 t/ha for the grazed treatments (LSD p=0.05 = 0.63 t/ha). The effect of grazing was also reflected in higher test weight (58.8 kg/hl compared to 53.6 kg/hl), higher grain protein (8.9% compared to 8.5%) and lower screenings (1.7% compared to 4.9%). Pre grazing (Sept 2) Post grazing (Sept 12) 33

34 Post grazing recovery (29 Oct) 34

35 Trial 7: Evaluating the effectiveness of stubble burning on seed survival and dormancy with different stubble loads Aim: To assess the stubble load required to reach necessary temperature thresholds required for weed control (i.e. to measure the effect of burning different stubble loads on weed populations). Duration: 1 year Location(s): Lake Bolac (for annual ryegrass) Trial design Factorial design: Randomised block design (5 treatments) Replicates: 4 Species: Wheat cv Trojan (in 2014) Treatments 2 t/ha stubble 4 t/ha stubble 6 t/ha stubble 8 t/ha stubble 10 t/ha stubble Stubble loads manipulated using cutting height to achieve indicative loads. Key measurements Stubble load pre-burning, weeds in subsequent crop Results Stubble loads & burning The wheat crop was harvested at different heights to provide differences in stubble load. These stubbles were then measured and stubble either added or removed to achieve a range in stubble loads (figure 1). The amount of stubble at the heavier loads were reduced because when created they appeared unrealistic for typical stubbles in the district. Figure 1: Stubble loads for various treatments Stubbles were burnt at pm on the 22 May 2014 (late burn). Wind was westerly, 25 km/hr, 19 0 C. The amount of heat generated for 10 seconds in each treatment was measured using a hand held 35

36 temperature sensor (refer to associated video footage). However temperatures dropped rapidly after 10 seconds irrespective of stubble load and typically were at only C after 30 seconds. The temperatures reached for each stubble load are shown in figure 2 and indicate temperatures around C with loads of 4 t/ha and above (which is common for this area). There was a significant correlation between stubble load and temperature reached (r=0.66, p=0.001). Figure 2: Temperature reached for 10 seconds under different stubble loads (error bars represent 1 std dev). Weeds The population of annual ryegrass and wild radish were measured on 22/07/2014. There was no significant impact from burning on either annual ryegrass (figure 3) or wild radish (although there was less than 2 pl/m 2 wild radish plants recorded in any of the treatments). Figure 3: Annual ryegrass population under different treatments (error bars represent 1 std dev). 36

37 Additional weed observations were made on a grazing crop trial run at Inverleigh through the Grain and Graze program that was also burnt. Grazing has been proven to reduce residual stubble which theoretically should mean different stubble loads. This trial also had different species (wheat, oats, barley) and cultivars which produced different biomass. This provided another opportunity to observe the effect of burning on weed populations. No stubble mass or burning temperature measurements were taken so the results need to be viewed with some caution. There was no influence on weed populations from grazing on either annual ryegrass (grazed = 2.5 pl/m 2 ungrazed = 2.3 pl/m 2 ) or wild radish (grazed = 4.7 pl/m 2 ungrazed = 4.3 pl/m 2 ). There was also no influence from different crop types. 37

38 Trial 8: Hay making options to control annual ryegrass Aim: To demonstrate the hay making options available to control herbicide resistant annual ryegrass. Duration: 1 year Location(s): Inverleigh Trial design Trial design: Demonstration strips Replicates: 1 Species: AGF mix (83% ryegrass, 13% Shaftal & Balansa clover SPS mix (40% Knight Ryegrass, 32% Nourish ryegrass, 16% Shaftal balansa clover, 12% Viper Balansa clover) Landmark (80% Vortex ryegrass, 10% Shaftal Persian Clover, 10% Paradana Balansa Clover) Heritage Seeds (40% Hulk Ryegrass, 15% Maximus Ryegrass, 15% Laser Persian Clover, 10% Bolta Balansa Clover) Wheat cv. Scenario Oats cv. Forrester Sowing rate All pasture mixes at 25 kg/ha, wheat at 94 kg/ha, oats at 120 kg/ha Herbicides: Determined after herbicide resistance testing Spraytopping on half of each strip 350 ml/ha) Time of sowing: 22 April 2014 Key measurements Herbicide resistance, dry matter production, hay quality Results Rainfall Seasonal rainfall was well above below average, with only 283 mm of rain falling between May and November (decile 2). Herbicide resistance Herbicide testing indicates the annual ryegrass present was resistant to four commonly used chemicals (table 1). Table 1: Annual ryegrass resistance rating to commonly used herbicides Herbicide Product Rate Herbicide Group Annual ryegrass (ml/ha) Survival (%) Resistance rating Axial + 0.5% Adigor 300 A-Den 90 RRR Select + 1% Hasten 500 A-Dims 35 RR Hussar OD + 1% Hasten 100 B-Sulfonylureas 30 RR Intervix + 1% Hasten 750 B-Imidazolinones 35 RR Atrazine + 1% Hasten 2000 C-Group C 15 R Glyphosate 1500 M-Group M 0 S Resistance-rating: RRR - indicates plants tested have strong resistance RR- indicates medium-level resistance R - indicates low-level but detectable resistance S - indicates no detection of resistance 38

39 Fodder production Despite the low growing season rainfall a significant amount of fodder was produced across the growing season (table 2). Hay was baled on the 28/11/2014, showing considerable late season growth from the cereals. Table 2: Dry matter production before hay cutting (cut 24/10/2014) and after cutting (28/11/2014) Mix Late season (kg/ha) Hay production (kg/ha) Landmark mix SPS mix AGF mix Oats Wheat Half of each fodder mix was spraytopped to prevent weed seed set before hay cutting. The effect on fodder quality was minimal, with a small improvement in protein and digestibility with the grass and clover mixes but possibly a small decline with the cereals (figures 1 & 2). Figures 1 & 2: Protein and Digestibility for hay from five fodders (+/- spraytopping) 39

40 Trial 9: One year fodder rotation for weed control and nitrogen accumulation Aim: To understand the impact of a one year fodder or legume crop on subsequent crop yields, weeds and nitrogen. Duration: 3 years Location: Kangaroo Island Trial design Random block design: 4 treatments Replicates: 4 Species: 3 (as listed) Rotation: One year fodder followed by annual crop in 2014 & 2015 (as listed) Sowing rate: Fodders: Sub clover 30 kg/ha, Balansa 8 kg/ha Grain: Beans 180 kg/ha, Canola 4 kg/ha, wheat Time of sowing: June 4, 2013, May , May 14, 2015 Fertiliser: Sown with 90 kg/ha DAP in 2013, Grazing: Cut when considered suitable for grazing Herbicides: Variable in 2013 (as listed). Herbicides the same in subsequent years Key measurements Dry matter production, fodder quality. grain yield and quality, weeds Species & rotation Treatment Name Year 1 (2013) Year 2 (2014) Year 3 (2015) Typical KI crop Canola cv Crusher Wheat Canola rotation 4 kg/ha KI rotation plus fodder Balansa clover cv Canola Wheat 8 kg/ha KI rotation plus regenerated pasture Regenerating sub clover cv Canola Wheat KI Rotation plus Broad Beans 30 3 kg/ha Beans cv 180 kg/ha Canola Wheat Herbicides Treatment Name Year 1 (2013) Typical KI crop Glyphosate knock down, P rotation Presowing Treflan and Dual Gold. In crop Verdict, In crop Select Spray out in Spring due to crop failure KI Rotation plus Broad Glyphosate knock down, P Beans Presowing Treflan and Dual Gold. 3 The sub clover was sown at a high rate with the intention to simulate a regenerating pasture, where only 30 kg/ha of seed germinates each year. 40

41 Results KI rotation plus regenerated pasture In crop Verdict, In crop Select Glyphosate knock down, P Presowing Treflan and Dual Gold. Rainfall Seasonal rainfall has been highly variable over the three years of the trial. Rainfall was well above average in 2013, resulting in severe waterlogging. In contrast 2014 was a typical year, with as slightly drier finish was drier again, with only 63 mm of rain in September and October. Establishment Period Period Annual Winter 2013 (mm) (decile 9) 2014 (mm) (decile 4) 2015 (mm) (decile 1) Long term average All crops and fodders established satisfactorily. The high sowing rates for the fodder legumes resulted in many plants establishing (table 1). Surprisingly the wheat establishment was lower in both years that expected. Table 1: Fodder and grain establishment 2013 to Species rotation Fodders (pl/m 2 ) Grain (pl/m 2 ) Grain (pl/m 2 ) Grain (pl/m 2 ) Balansa, canola, wheat Sub clover, canola, wheat Beans, canola, wheat Canola, wheat, canola Fodder and crop yields Fodder from the balansa clover and sub clover was harvested twice during 2013, despite the late sowing. This resulted in yields above 5 t/ha (table 1). There was no grain yield from the canola in 2013 because the crop failed due to severe winter waterlogging. However the beans did yield although there was very high variability between replicates (CV of 101%) (table 2). 4 Severe waterlogging encountered 41

42 Table 2: Fodder and grain yields 2013 to Species Fodders Grain Canola Wheat Canola Wheat Balansa Sub clover Beans Canola LSD p=0.05 NS NS NS NS Fodder quality Grain quality results were not replicated however there appears to be no obvious difference in grain protein with the different legumes (table 3). The canola sown in 2013 received 105 kg/ha of urea and a further 100 kg/ha of ammonium sulphate. Table 3: Fodder and grain protein 2013 to Species Fodders (%) Grain (%) Canola (%) Wheat (%) Canola (%) Wheat (%) Balansa Sub clover Beans No measure Canola No harvest Fodder quality was high (as expected) with balansa clover measured at 11.5 MJ ME/kg and sub clover at 11.0 MJ ME/kg. Weeds Annual ryegrass measured on 31/07/2013 was similar for all plot. All had received a combination of Glyphosate and Treflan and Dual Gold pre sowing. The canola crop received two in crop herbicides whereas no herbicides we applied to the two fodder and bean crops. Due to the poor crop vigour after a long period of waterlogging and high ryegrass population, the canola crop was sprayed out in spring This prevented ryegrass seed set. The result was a significant decrease in annual ryegrass the next year compared to the other treatments, which carried over into The increase in annual ryegrass was worse in the sub clover plots (figure 1). 42

43 Annual ryegrass (pl/m2) Balansa, canola, wheat Sub clover, canola, wheat Beans, canola, wheat Canola, wheat, canola Figure 1: Change in annual ryegrass population under different fodder and herbicide treatments Nitrogen Only one shallow nitrogen test was taken after the first year of the fodder rotation (figure 2). This would indicate adequate soil nitrogen, especially in the failed canola treatment. The high addition of N in late 2013 to try and save the crop, which wasn t captured in the grain was the likely cause of the increased nitrogen at sowing. Nitrogen (kg/ha) Broad beans Balansa Clover Sub Clover Canola Ammonium Nitrogen Nitrate Nitrogen Figure 2: Total soil nitrogen (kg/ha) in 0 10 cm in May 2014 before sowing for previous crops Gross margin A gross margin was calculated for the three years of the rotation. While assumptions needed to be made for the grazing value of the fodder, the failed canola crop in and different subsequent rotations taken into account there are differences financial returns (figure 3). 43

44 Gross margin $/ha Typical KI crop rotation KI rotation plus fodder KI rotation plus regenerated pasture Rotation treatment KI Rotation plus Broad Beans 2013 GM 2014 GM 2015 GM 3 year av GM Figure 3: Comparison of gross margin of the different rotations over three years and average. 44

45 Trial 10: Two year fodder rotation for weed control and nitrogen accumulation Aim: To understand the impact of a two years fodder or legume crop on subsequent crop yields, weeds and nitrogen. Duration: 3 years Location: Frances and Conmurra (South Australia) Trial design Soil type: o Frances Duplex o Conmurra - black cracking clay soil over limestone Random SP design: 11 treatments Replicates: 4 Species: 11 (as listed) Rotation: Two years fodder followed by annual crop in 2015 (as listed) Sowing rate: Fodders: Sub clover 12 kg/ha alone, 9 kg/ha mix, lucerne 15 kg/ha, phalaris 4 kg/ha, Perennial ryegrass 18 kg/ha, annual ryegrass 17 kg/ha Grains: Beans 180 kg/ha, Canola 4 kg/ha, Oat 90 kg/ha, wheat 90 kg/ha Time of sowing: June 18 & 19, 2013, June for peas and beans, May 27, 2015, Frances, June 17, 2015 Conmurra Fertiliser: Sown with 90 kg/ha DAP in 2013, Nitrogen on fodder 50 kg/ha N in Aug on fodders Grazing: Cut when considered suitable for grazing Herbicides: Variable in 2013 (as listed). Herbicides the same in subsequent years Key measurements Dry matter production, fodder quality, grain yield and quality, weeds, soil nitrogen. Species & rotation Trt Year 1 (2013) Year 2 (2014) Year 3 (2015) 1 Sub clover^ 2 Hybrid ryegrass^ + nitrogen 3 Hybrid ryegrass / sub clover^ 4 Barley Peas (green manure) 5 Phalaris / clover^ Wheat 6 Lucerne^ (var Trojan) 7 Oats (for hay) Sub clover 8 Perennial ryegrass / clover^ + N 9 Perennial ryegrass / clover^ 10 Wheat Beans 11 Wheat Fallow * ^ = Based on regeneration in 2014 * = Was intended for Canola but late break followed by wet period resulted in failed crop so was left as fallow 45

46 Herbicides Results Treatment Name Year 1 (2013) Typical KI crop Glyphosate knock down, P rotation Presowing Treflan and Dual Gold. In crop Verdict, In crop Select Spray out in Spring due to crop failure KI Rotation plus Broad Glyphosate knock down, P Beans Presowing Treflan and Dual Gold. In crop Verdict, In crop Select KI rotation plus Glyphosate knock down, P regenerated pasture Presowing Treflan and Dual Gold. Rainfall Seasonal rainfall has been highly variable over the three years of the trial. The growing conditions at both locations were extremely wet in 2013 and this suppressed growth of most species. In both 2014 and 2015 the season was very dry at Frances, especially from august to November but average or slightly below average at Conmurra (table 1). However spring was very dry at Conmurra, especially in Table 1: Rainfall at Frances and Conmurra Period Frances Conmurra Annual Growing season Annual Growing season 2013 (mm) (decile 8) (decile 8) 2014 (mm) (decile 1) (decile 4) 2015 (mm) (decile 1) (decile 5) Long term average Establishment There was no crop establishment data for Conmurra or Frances in In 2014 the peas established at 10 pl/m 2 and 9 pl/m 2 and the beans 8 pl/m 2 and 9 pl/m 2 at Frances and Conmurra respectively. Establishment of wheat in 2015 was generally poorer after two years of fodders, than after a crop or fallow (table 2). Table 2: Wheat establishment at Frances and Conmurra in 2015 after various fodders. Plants (pl/m 2 ) Species Frances Conmurra Sub clover 184abc 155a 46

47 Hybrid ryegrass/sub clover + nitrogen 5 173abc 162ab Hybrid ryegrass / sub clover 193a 133b Barley, peas (green manure) 193a 178a Phalaris / clover 164bc 70c Lucerne - 149ab Oats (for hay), sub clover 189ab 178a Perennial ryegrass / clover + N 5 171bc 128b Perennial ryegrass / clover 163c 130b Wheat, beans 179abc 150ab Wheat, fallow 185ab 168a LSD p= Fodder and crop yields Dry matter from the grass fodder mixes in 2013 was significantly higher than the sub clover or lucerne only (tables 3 & 4). Dry matter increased for most fodders in 2014 as plants because more established. This was despite lower than average rainfall. Wheat yields in 2015 were significantly higher after a crop / fallow or crop green manured peas than any of the two year fodders at Frances. The impact on wheat yield was not as great at Conmurra in 2015, although close to average rainfall was received. Grain yields after phalaris were noticeable poorer at both sites and may be partly explained by the poorer establishment after phalaris. Table 3: Fodder and grain yields 2013 to 2015 at Frances Species Fodders Grain Fodders Grain Wheat Sub clover c Hybrid ryegrass/sub clover 1.8c + nitrogen Hybrid ryegrass / sub 1.9c clover Barley, peas (green a manure) 3.56 (incorporated) Phalaris / clover c Lucerne No 2.0c estab 6 Not measured Oats (for hay), sub clover 3.46 Not measured 3.5ab Perennial ryegrass / clover 1.8c + N Perennial ryegrass / clover c Wheat, beans b Wheat, fallow?? 3.8a LSD p= NS N/A kg/ha of N in august 6 Failed to establish in autumn due to wet conditions. Spring resowing failed also. 47

48 Table 4: Fodder and grain yields 2013 to 2015 at Conmurra Species Fodders Grain Fodders Grain Wheat Sub clover ab Hybrid ryegrass/sub clover + 4.1b nitrogen Hybrid ryegrass / sub clover b Barley, peas (green manure) ab 7.15 (incorporated) Phalaris / clover c Lucerne ab Oats (for hay), sub clover Not measured 5.8a Perennial ryegrass / clover + 3.9cd N Perennial ryegrass / clover ab Wheat, beans ab Wheat, fallow?? 5.5ab LSD p=0.05 NS NS NS N/A 1.3 The addition of 50 kg/ha of nitrogen to the ryegrass and sub clover fodders in August grew more than 1 t/ha of additional fodder in 2013 at Frances but not Conmurra. The opposite results was recorded in 2014, with no yield increase at Frances but 0.7 to 2.2 t/ha at Conmurra. Seasonal conditions may explain the responses. Grain and fodder quality Fodder quality results were consistent with historic data on the fodder species. Most species treatments were around 11 MJ ME/kg, with variable protein in early spring and declined as species began flowering (table 5). Table 5: Fodder quality at Frances and Conmurra in Protein (%) Frances Energy (MJ ME/kg) Protein (%) Conmurra Energy (MJ ME/kg) Species 2 Sept 30 Oct 2 Sept 30 Oct 2 Sept 30 Oct 2 Sept 30 Oct Sub clover Hybrid ryegrass/sub clover + nitrogen Hybrid ryegrass / sub clover Phalaris / clover Lucerne N/A N/A N/A N/A Perennial ryegrass / clover + N

49 Perennial ryegrass / clover Grain protein and screenings were measured in While grain protein varied between treatments, it was difficult to determine how much of this effect was due to the previous nitrogen build up from the fodder species, and how much was influenced by the dilution effect of different grain yields. It appears there is a grain protein dilution effect with yield evident at both sites (figure 1). Figure 1: Grain yield and protein for wheat grown in Treatments circled had a cereal in 2013 followed by one year of fodder in The treatments that showed the lowest grain and highest yields all had a cereal in 2013 followed by one year of a fodder. All the lower yielding but higher grain protein results were following 2 years of fodder. A similar trend was seen with screenings in the 2015 wheat. Lower screenings were measured in crops with higher yields and these again corresponded to those treatments with only one year of fodder (figure 2). 49

50 Figure 2: Grain yield and screenings for wheat grown in Soil moisture Soil moisture was measured on three treatments across 2013, 2014 and At Frances there was similar soil moisture (0-70cm) at the end of 2013, reflecting the above average season (figure 3). At the end of 2014 (below average rainfall) there was a difference between the two years of fodder, the peas that were manured and the fallow. This appears to have continue through into 2015 (another very dry year). Figure 3: Soil moisture at the end of 2013, 2014 and 2015 at Frances for three contrasting rotations. At Conmurra samples were only possible to 30 cm (before reaching limestone) but showed a similar trend, with lower soil moisture after two years of the fodder compared to a fallow or crop followed by green manured peas (figure 4). Figure 3: Soil moisture at the end of 2013, 2014 and 2015 at Conmurra for three contrasting rotations. It could be inferred from this data that the treatments had different soil moisture at the start of the 2015 crop season (as was probably even less with the perennial ryegrass treatment because of likely additional water use in late summer and early autumn). This would help explain the measured yield difference, especially given the finish to the season at Frances (figure 4). 50

51 Figure 4: Soil moisture at the end of 2014 and 2015 grain yield at Frances. Soil nitrogen Soil nitrogen was measured under each treatment (0 60 cm) at the end of the season. There was no obvious trends in the data, with some legume fodders (with or without a companion grass species) recording high levels of mineral N at the end of 2013 and other similar treatments recording much lower soil N (table 6). Similar variability was recorded at the end of Measurements at the end of 2015, after all treatments had been cropped with wheat showed similar residual N. Table 6: Soil nitrogen at the end of season (0 60 cm) at Frances in 2013, 2014 and Treatment Soil nitrogen (kg N/ha) Sub clover Hybrid ryegrass/sub clover + nitrogen Hybrid ryegrass / sub clover Barley, peas (green manure) Phalaris / clover Oats (for hay), sub clover Perennial ryegrass / clover + N Perennial ryegrass / clover Wheat, fallow The N results from Conmurra are even more difficult to interpret (table 7). Taking into account the shallower sampling (0 30 cm), the amount of soil N under the wheat and oats in 2013 is surprising high and similar to the legume fodders. Table 7: Soil nitrogen at the end of season (0 60 cm) at Conmurra in 2013, 2014 and Treatment Soil nitrogen (kg N/ha) Sub clover Hybrid ryegrass/sub clover + nitrogen Hybrid ryegrass / sub clover N/A

52 Barley, peas (green manure) Phalaris / clover Lucerne Oats (for hay), sub clover Perennial ryegrass / clover + N Perennial ryegrass / clover Wheat, fallow At the end of 2014 soil N rose in the oats / sub clover treatment but declined with two years of sub clover. Unlike Frances, the finishing soil N at the end of 2015 harvest was highly variable, with the most residual N measured on plots that yielded at least 5 t/ha. However with the more favourable growing conditions at Conmurra in 2015, there was a clear trend in increased grain yield and nitrogen (figure 5). Figure 5: Soil soil nitrogen at the end of 2014 and 2015 grain yield at Frances. Weeds Annual ryegrass was measured in October 2014, June/July and October The Frances data from 2014 shows a significant decline in annual ryegrass with the various fodder options used in 2013 compared to the barley/peas or wheat/fallow treatment (figure 6). By 2015 most of the two year fodder treatments were significantly lower in annual ryegrass than a crop-fodder (barley then peas green manured) treatment, which was in turn significantly lower than the two year crop (wheat then fallow). 52

53 Figure 6: Annual ryegrass at Frances in October 2014 (LSD p=0.05 = 22.4), June 2015 (NS) and October 2015 (LSD p=0.05 = 3.2) with different treatments. At Conmurra there was difficulty identifying annual ryegrass from perennial ryegrass, however Figure 7 indicates the high population of annual ryegrass after one year in wheat (Oct 2014) but significantly less annual ryegrass in the other non ryegrass fodder treatments. Figure 7: Annual ryegrass at Conmurra in October 2014 (LSD p=0.05 = 42) July 2015 (NS) and October 2015 (LSD p=0.05 = 3.9) with different treatments. The use of Sukura herbicide in the 2015 wheat crop was effective in reduce total annual ryegrass numbers, although the remaining ryegrass in the wheat then beans (two crops) was significantly higher than any other treatment. 53

54 Trial 11: Use of in-situ fodders for subsoil manuring Aim: To examine the effect of incorporating organic material grown in situ to improve subsoil condition. Duration: 2 years Location: Inverleigh Trial design Random block design: 4 treatments Replicates: 4 Treatments Mixture of peas and wheat at 8t/ha DM (incorporated at early head emergence on wheat) Mixture of peas and wheat at 16t/ha DM (incorporated at early head emergence on wheat) Lucerne pellets at 10t/ha Control Rotation: Wheat cv Derrimut in 2015, barley cv Navigator in 2015 Sowing rate: 100 kg/ha in both years Time of sowing: June 6, 2014, June Fertiliser: Sown with 90 kg/ha DAP Herbicides: l/ha on 02/06/ ml/ha on 06/08/2014 l/ha, Boxer 2.5l/ha, Amicide 500 ml/ha on 10/06/ l/ha, 500 ml/ha on 21/08/2015 Key measurements Establishment, dry matter production, grain yield and quality 2014 results Rainfall & temperature The season started well but became hot and dry by the end of the year. Growing season rainfall was 98 mm below the long term average (decile 2 year), at 310 mm compared to the long term average of 408 mm. Mean monthly maximum temperatures were also several degrees higher in September, October and November. Yields There was no significant difference in plant establishment, the number of tillers per plant, tiller weight or dry matter during early grain fill (table 1), despite all the subsoil manure treatments appearing greener and thicker than the control (figure 1). Table 1: Establishment, tillers per plant, tiller weight and dry matter at early grain fill Treatment Estab (pl/m2) Tillers (tillers/pl) Tiller wgt (gm/tiller) Dry matter 8 t/ha DM (peas & wheat) t/ha DM (peas & wheat) t/ha lucerne pellets Nil (control) LSD (p=0.05) NS NS NS NS 54

55 Figure 1: Treated plot (lucerne 10 t/ha) left compared to Nil (control) right. There was no significant difference in grain yield between treatments, however grain quality was increased by the subsoil treatments (table 2). Table 2: Grain yield, protein, test weight and screenings Treatment Yield Protein (%) Test weight Screenings (%) (kg/hl) 8 t/ha DM (peas & wheat) b a 16 t/ha DM (peas & wheat) a a 10 t/ha lucerne pellets a a Nil (control) c b LSD (p=0.05) NS 0.4 NS 1.2 The addition of organic material at depth did not affect crop yields, despite their appearing a visual difference in the bulk of crop at grain fill (although the DM cuts do not support this visual observation). However the grain protein were significantly higher in the treatments, with the highest recorded at the 16 t/ha peas and wheat and the 10 t/ha lucerne pellets. In addition the screenings in the treatments were also significantly higher, suggesting the crop was compromised by a lack of moisture results l/ha, Boxer 2.5l/ha, Amicide 500 ml/ha on 10/06/2015 Barley cv Navigator sown at 100 kg/ha on 26/06/ l/ha, 500 ml/ha on 21/08/2015 Dry matter cuts for biomass 23/11/2015 Harvested 12/12/2015 Rainfall & temperature Below average rainfall was recorded for all months of the growing season, making 2015 a decile 1 growing season year. Total growing season rainfall was 241 mm compared to the long term average of 408 mm. Mean monthly maximum temperatures were also several degrees higher in October and November. 55

56 Yields There was no significant difference in plant establishment although the untreated plots appeared slightly better than the treatments (table 3). Total dry matter production in November was lower than expected, reflecting a combination of low rainfall and additional moisture stress encountered by the plots where treatment was applied. It was visually evident the plants over the subsoil manured area showed less vigour than the outer rows where no soil disturbance occurred (figures 2 & 3). Table 3: Establishment, tillers per plant, tiller weight and dry matter at early grain fill Treatment Estab (pl/m2) Dry matter 8 t/ha DM (peas & wheat) t/ha DM (peas & wheat) t/ha lucerne pellets Nil (control) LSD (p=0.05) NS NS Figures 2 & 3: Treated plot (lucerne 10 t/ha) showing poor vigour in the middle of the plots where slotting occurred. Grain yield was extremely poor, a reflection of the seasonal conditions (table 4). There was no significant difference in grain yield between treatments, although several plots had insufficient grain to harvest. Despite not being significant, the yield of the Nil treatment (control) was higher than the other treatments. Grain protein was significantly higher in the treatments compared to the control and screenings were lower in the control. Table 4: Grain yield, protein, test weight and screenings Treatment Yield Protein (%) Screenings (%) 8 t/ha DM (peas & wheat) a t/ha DM (peas & wheat) 0.17 Insufficient grain to test 10 t/ha lucerne pellets a 10.2 Nil (control) b 7.8 LSD (p=0.05) NS 2.5 NS 56

57 Figure 5: Organic material two years after incorporation in the slot, with barley roots migrating towards the organic material. Note the lack of breakdown of the organic material because of very dry conditions. 57