Biological Sweet Corn Trial Lowood Q 2009

Transcription

1 Comparison of the agronomic and economic performance of Ausmin biological fertiliser programs versus a conventional program on a commercial sweet corn crop at Lowood in southern Queensland: Feb to June 2009 Grower: David, Matthew & Daniel Hood. The crop was grown under contract by Keller Farms at Lowood, Q. Researchers: Jules Guerassimoff (B. Ag Sc., M. Ag Sc.), David Hardwick (B. Eco. Ag., Dip. Ag.) Project description: This was a trial comparing a biological program using biological fertilisers and inoculants (Ausmin s BioBrew range, and a Platinum fertiliser) to a conventional program on an sweet corn crop in subtropical conditions. The key question was to look at whether bio-fertilisers can improve or maintain crop yields, plant vigour and enterprise gross margin. Parameters measured include cost of inputs, nutrient use efficiency, cob yield & quality and plant growth & health over one crop cycle. The effect of the addition of a silica mineral product, MaxSil with good levels of soluble silicon was also investigated. Farm description: Hood Farms run a number of farms along eastern Australia including some that are leased from other growers. They grow a range of summer and winter crops including sweet corn, beans and brassicas. This property is located just outside Lowood in Southern Queensland and is a leased farm with the local farmer, David Keller, growing the crop under contract to Hood Farms. The soil of the trial paddock is a loam and is located on flat alluvial plains to the north of Lowood, Q. Trial design: Plot layout: The trial design consisted of side by side comparative strips. There were two conventional strips and 1 strip each of the two Ausmin programs. Each strip consisted of at least 6 planted rows of corn approximately 400m long. C1 was rows A1 was rows A2 was rows C2 was from row 37 onwards. The crop was planted on the 23/2/09 and it was harvested on the 3/6/09 at night. The layout of strips is shown in Figure 1. Figure 1: Paddock layout of treatment strips in the Biological Sweet Corn Trial Lowood C1 A1 A2 C2 Rows 1-24 Rows Rows Rows 37 onwards Research Project Final Report: Biological Sweet Corn Trial Lowood Q June

2 Trial duration: One crop cycle. Corn planted on 23/2/08. Harvest occurred on 3/6/09. Soils: A soil sample of the trial site was taken by collecting 5 sub-samples of the top 15 cm of the soil and combining to make a composite sample. This was then sent to the Environmental Analysis Laboratory at Southern Cross University for analysis. The analysis included available and exchangeable reserves of nutrients as well as the total reserves of nutrients. Table 1 shows the key characteristics of the soil. The soil is a loam and contains high levels of nutrient cations. For a soil of this level of inherent fertility (high CEC) it has moderately low levels of organic matter. This may be expected after many years of continuous cropping. The ph, at 6.7 is in an optimal range and the Carbon to Nitrogen ratio is at 13.4:1. This indicates that the soil has a slight deficiency in overall nitrogen compared to carbon which may reduce soil biological activity and nutrient cycling. The available, exchangeable and total nutrient levels of all elements are in moderate to high amounts. The exception to this is the levels of available sulphur, the total reserves of boron and selenium and the level of organic matter and total nitrogen. Significant reserves of phosphorus, calcium, magnesium, potassium and many of the trace elements are present in the total pool. Table 1: Levels of selected chemical, physical and biological characteristics of the trial site soil. Available & Exchangeable Nutrient Unit Level Total Nutrients Unit Level Nitrate ppm 22 Phosphorus ppm 1294 P (Colwell) ppm 331 Calcium ppm 5038 Sulphates ppm 10 Magnesium ppm 5494 Calcium ppm 1547 Potassium ppm 1794 Potassium ppm 185 Zinc ppm 94 Boron ppm 8.9 CEC Cmol/kg 45 Organic Matter % 3.35 ph (water) 6.7 Ca:Mg ratio 1.3:1 Research Project Final Report: Biological Sweet Corn Trial Lowood Q June

3 Treatments: 1. Conventional Program (C1 & C2): Biological Sweet Corn Trial Lowood Q 2009 a. Pre-plant - Incitec 350 kg/ ha. Applied on 23/2/09 b. Side dress 200kg/ha. Applied on 17/3/09 2. Ausmin 1 program (A1) a. Pre-plant Platinum kg /ha. Applied on 23/2/09 b. Side Dress Biocoated 150kg/ha. Applied on 17/3/09 c. Soil drench 100l/ha. + BioBrew 30l/ha. Applied after planting 3. Ausmin 2 program (A2) a. MaxSil seed coating 10kg/ha. b. Pre-plant Platinum kg /ha. Applied on 23/2/09 c. Side Dress Biocoated 150kg/ha. Applied on 17/3/09 d. Soil drench 100l/ha. + BioBrew 30l/ha. Applied after planting The biological programs had less major nutrients applied. The trial was designed to see if nutrient use efficiency (kg of yield per unit of nutrient applied) for the key nutrients of N, P and K could be achieved through the enhancement of biological activity. Table 2: Amount of nutrients applied per hectare for each treatment. Nutrient Kgs nutrient applied/ha Conventional Ausmin 1 Ausmin 2 Nitrogen Phosphorous Potassium Sulphur All treatments received an application of a pre-emergence herbicide (Dual Gold (metolochlor)). Conventional areas were also sprayed with an insecticide (chlorpyriphos) for insect pests. The biological plots were not treated with the insecticide to avoid potential impacts of the chemical on the applied biological inoculants and on plant immunity status. Methods: The parameters measured in this trial included Soil chemistry, Yield (# cobs /plant, number of cobs per planted meter), Plant characteristics (Brix, height, root biomass), cob characteristics (number kernels, size, nutrient levels), Input cost /ha. The crop was monitored on a periodic basis from planting through to harvest. Key sampling times, parameters and methods are shown in Table 3. Research Project Final Report: Biological Sweet Corn Trial Lowood Q June

4 Table 3: Monitoring activities and methods for the trial. Biological Sweet Corn Trial Lowood Q 2009 Date Parameter Methods 26/3/09 Leaf Brix (%) 1 sample leaf (3 rd leaf from the top) from 5 randomly selected plants in each treatment strip was collected. The sap was extracted manually with a hand held sap press and the % Total Dissolved Solids (Brix) was measured using a calibrated refractometer. The average of the 5 plants in each strip was recorded. The measurements on the two conventional strips were consolidated for one average. Root weight (g) 5 randomly selected plants in each treatment strip were collected. The plants were cut at 50mm above the stem base and the root mass was collected. The root balls were washed until all soil was removed. The root weights and 50mm of the stem in the first internode were then obtained using an electronic scale. The average root weights of each sample were then calculated. 21/4/09 Leaf #/plant 10 randomly selected plants in each treatment strip were nominated and the number of fully formed leaves per plant was counted. The average number of leaves per plant was then determined. Visible cobs/plant (#) 10 randomly selected plants in each treatment strip were nominated and the numbers of visible cobs per plant were counted. An average of the 10 plants was then calculated. Leaf Brix (%) 1 sample leaf (3 rd leaf from the top) from 5 randomly selected plants in each treatment strip were collected. The sap was extracted manually with a hand held sap press and the % Total Dissolved Solids (Brix) was measured using a calibrated refractometer. The average of the 5 plants in each strip was recorded. The measurements on the two conventional strips were consolidated for one average. Stem circumference (mm) Root weight (g) 23/5/09 Cob # per 10 linear metres 5 randomly selected plants in each treatment strip were collected. The stem circumference half way along the second internode was measured with string and a metric ruler. An average circumference was then calculated for each sample. 5 randomly selected plants in each treatment strip were collected. The plants were cut at 50mm above the stem base and the root mass was collected. The root balls were washed until all soil was removed. The root weights and 50mm of the stem in the first internode were then obtained using an electronic scale. 10 randomly selected 10 metre transects were chosen in each treatment strip. The number of cobs over 25cm in length in each transect was recorded and the average number of cobs per 10 linear meters for each treatment was then calculated. Research Project Final Report: Biological Sweet Corn Trial Lowood Q June

5 3/6/09 Average cob weight 3/6/09 Kernel Brix (%) 3/6/09 Number of kernels along cob length 3/6/09 Number of kernels around cob circumference 3/6/09 Cob nutrient levels After harvest a sample of 40 randomly selected cobs from each treatment strip were collected. The weight of these 40 cobs was weighed. A total weight per 40 cobs was determined and then an average weight per cob was calculated. For each treatment strip after harvest a sample of 40 randomly selected cobs was collected and taken to the Ausmin office. For each treatment strip a randomly selected sub-sample of 5 cobs was then taken. The sap of randomly selected kernels from these 5 cobs was extracted manually with a hand held sap press and the % Total Dissolved Solids (Brix) was measured using a calibrated refractometer. The average of the 5 readings in each strip was calculated. For each treatment strip after harvest a sample of 40 randomly selected cobs was collected and taken to the Ausmin office. For each treatment strip a randomly selected sub-sample of 5 cobs was then taken. The number of kernels per length of cob (from base to tip) was counted for the 5 samples and an average number of kernels per cob length was then calculated. For each treatment strip after harvest a sample of 40 randomly selected cobs was collected and taken to the Ausmin office. For each treatment strip a randomly selected sub-sample of 5 cobs was then taken. The number of kernels per circumference of cob (measurement taken 2.5 cm from base of cob) was counted for the 5 samples and an average number of kernels per cob circumference was calculated. For each treatment strip after harvest a sample of 40 randomly selected cobs was collected and taken to the Ausmin office. For each treatment strip a randomly selected sub-sample of 5 cobs was then taken. This sub-sample was then sent to the Environmental Analysis Laboratory (EAL) to test the total level of nutrients per cob. EAL combined the 5 samples to form a composite sample before analysis was done. The crop was severely lodged some 14 days before harvest by a heavy storm event. This resulted in a reduction in harvested cobs due to many being missed by the mechanical harvester as the plants were flattened. Complete yield data as measured from the harvester was not obtainable. Hand counting of harvestable cobs per 10 meter transect was then used to obtain number of cobs per planted row meter. Yield data was then derived by calculating a potential per hectare yield based on a planting row width of 50cm and using the cobs per planted meter data. The storm also caused severe waterlogging in the soil. Final root biomass weights were not able to be obtained as the wet heavy clay soil broke off root mass as the root balls were being extracted from the field. Research Project Final Report: Biological Sweet Corn Trial Lowood Q June

6 Results: The results of the measurements for the trial parameters are presented below. Table 4 shows the average % Brix recoded for the corn in the various treatments at three stages of the crop cycle. The Ausmin treatments had slightly higher brix leaf levels at the mid-crop stage (21/4/09). The cob brix levels were higher in both biological treatments than the conventional ones. Table 4: Average Total Dissolved Solids in leaf and cob through crop cycle (% Brix) Date Parameter Conventional a Ausmin 1 Ausmin 2 26/3/09 Leaf Brix (%) /4/09 Leaf Brix (%) /6/09 Cob Brix (%) 15.3 b a Combined average of the two conventional strips (C1 & C2) only was measured. b The averages for the each of the two conventional strips were taken. They were combined for ease of presentation in the table. The average of each of the conventional strips was 15.2 & Table 5 shows the average weight of root biomass for the corn plants. Both biological treatments had higher average root weights than the conventional treatments. At mid-crop (21/4/09) the biological root weights were over 150% greater than the average weight of the conventional corn plants. Table 5: Average root weights through crop cycle (g) Date Parameter Conventional a Ausmin 1 Ausmin 2 23/3/09 Root weight (g) /4/09 Root weight (g) a Combined average of the two conventional strips (C1 & C2) only was measured. The results of various crop physical characteristics are presented in Table 6. The results show that the biological treatments had a greater number of visible cobs at this stage. The average stem circumference was approximately 7% greater in the biological corn plants as compared to the conventional corn plants. Table 6: Average measurements of various corn physical characteristics at the mid-crop stage. Date Parameter Conventional a Ausmin 1 Ausmin 2 21/4 Leaf #/plant (#) Visible cobs/plant (#) Stem circumference (mm) a Combined average of the two conventional strips (C1 & C2) only was measured. Research Project Final Report: Biological Sweet Corn Trial Lowood Q June

7 The productivity measurements including average number of cobs per 10 meters, weight of 40 cobs and mean weight of cobs are shown in Table 7. No large differences between the means were noticed. A slight increase in number of cobs per linear 10 metre was observed. Table 7: Average measurements of productivity parameters for the corn crop Date Parameter Con 1 Con 2 Ausmin 1 Ausmin 2 23/5/09 Average # of cobs/ 10 linear metres 3/6/09 Weight of 40 cobs (kg) 3/6/09 Average weight per cob (kg) The corn cob characteristics measured included the average number of corn kernels pre cob length and per cob circumference. These figures are shown in Table 8. No differences were observed. Table 8: Average measurements of corn cob characteristics. Date Parameter Con 1 Con 2 Ausmin 1 Ausmin 2 3/6/09 # of kernels per cob length 3/6/09 # of kernels per cob circumference The level of nutrients in cob tissue was measured by EAL and the results for selected elements are in Table 9. Some variations did occur in nutrient levels between treatments for a few nutrient elements. For others no differences were observed. More K was found in the tissue for the A2 treatment. At least 50% more Cu occurred in the A1 treatment compared to the other treatments. The level of Zn in the A1 treatment was around 80% of that found in the other treatments. The level of Si was between 30 and 90% higher in the A1 treatment as compared to the other treatments. Table 9: Total nutrient levels of selected nutrients in the corn cobs at harvest. Nutrient Unit Con 1 Con 2 Ausmin 1 Ausmin 2 N % P % K % S % C % Research Project Final Report: Biological Sweet Corn Trial Lowood Q June

8 Ca % Cu ppm Zn ppm Si ppm Due to lodging of the crop by a storm just prior to harvest, an estimate of the yield per hectare was obtained by determining the number of cobs per linear meter. Assuming a planting width of 50cm and a strip length of 100m there would be 200 planted rows per hectare. This equates to linear metres. The yield was then calculated as estimated number of cobs per hectare. Using the mean weight data collected per cob, a tonnage per hectare was also calculated. These figures are shown in Table 10. Table 10: Yield calculations. Parameter Con 1 Con 2 Ausmin 1 Ausmin 2 Mean # of cobs/ linear metre Mean # of cobs/ hectare Tonnes of cobs per hectare The amount of fertiliser nutrients applied per tonne of corn grown was calculated to show the nutrient use efficiency (NUE) achieved under the different treatments. This efficiency was determined by calculating the kilograms of nutrient applied per tonne corn grown per hectare. The conventional treatments used three times as much P fertiliser per tonne of corn grown as compared to the biological treatments. The conventional treatments used over twice the amount of S and K fertiliser per tonne of corn grown when compared to the biological treatments. Nitrogen required per tonne of corn grown was a quarter less in the biological treatments when compared to the conventional ones. Table 11 shows the NUE figures for the four key nutrients N, P, K and S. Table 11: Nutrient use efficiency (NUE) figures for N, P, K and S (kg/tonne/hectare) Nutrient Con 1 Con 2 Ausmin 1 Ausmin 2 Nitrogen (N) Phosphorus (P) Potassium (K) Sulphur (S) Research Project Final Report: Biological Sweet Corn Trial Lowood Q June

9 Economic performance indicators for the crop were calculated. The Gross Income was calculated from a unit priced per cob multiplied by the number of cobs grown per hectare. The Gross Margin for each treatment was then calculated by deducting the cost of fertilisers applied as well as the agrichemicals applied to each treatment. An assumption that the labour, machinery, spraying and harvest costs were identical for all treatments was made. The biological and conventional treatments had one spray application each. Table 12 shows the results of Gross Income, Fertiliser costs and Gross Margin calculations for the crop. Table 12: Estimated Gross Income, Fertiliser costs and Gross Margin per hectare for the three treatments. Gross Income ($/ha.) Fertiliser costs ($/ha.) Gross Margin a ($/ha.) Con 1 Con 2 Ausmin 1 Ausmin 2 $ $ $ $ $980 $980 $783 $798 $ $ $ $ a Calculated by subtracting fertiliser costs from Gross Income. Application labour costs of MaxSil have been excluded. b Unit price of $0.45 per cob sale price. Gross Income is unit price multiplied by number of cobs/hectare. Fig 2: Corn at 59 days: Biological treatment A2 is on the left. C2 is on the right. 21/4/09 (D.Hardwick) Research Project Final Report: Biological Sweet Corn Trial Lowood Q June

10 Fig 3: Height comparison. Biological treatments are in the centre 21/4/09 (D.Hardwick) Fig 4: Crop comparison Biological treatment A1 is on the right. Conventional C1 is on the left 21/4/09 (D.Hardwick) Fig 5:Root biomass comparison. 21/4/09 (J Guerassimoff) Fig 6: Root biomass comparison. 21/4/09 (J Guerassimoff) Fig 7: Cob comparison. 3/6/09 (J Guerassimoff) Research Project Final Report: Biological Sweet Corn Trial Lowood Q June

11 Fig 8: Comparison between conventional and Ausmin 1. 3/6/09 (J Guerassimoff) Discussion: The aim of this trial was to evaluate the effect of biological fertilisers on crop growth and yield as compared to a program based on high levels of soluble chemical fertilisers. Biofertilisers are designed to enhance rhizosphere activity and therefore improve the supply of nutrients to the crop without the need for high levels of soluble nutrients. Key indicators that may demonstrate improved soil rhizosphere and nutrient cycling processes include nutrient use efficiency and root biomass. The key characteristics of the biological program used are the spectrum of nutrients included in the products (trace elements along with major nutrients), the labile carbon included that stimulates biological digestion of the fertiliser granule as well as providing an energy source for rhizosphere microbes in the early crop establishment stage, and the lower level of soluble nutrients provided. The liquid inoculum includes living microbial organisms and signal molecules which are designed to enhance soil microbial populations. General observations over a range of crops and conditions has shown that by reducing soluble nutrient applications and by stimulating soil biological function, root vigour can be significantly improved. This can lead to a greater potential for the crop to access nutrients from the soil reserves. Agronomic performance Unit applications per hectare of phosphorus, potassium and sulphur were significantly lower (by at least 50%) than those in the conventional treatments. Nitrogen applications were 25% lower. Despite this yield reductions were not seen in the biological treatments. Indeed based on the yield calculations in Table 10 a slight increase in yield was determined. There was a yield increase of around 7% in the biological treatments as compared to the conventional ones. This meant that the Nutrient Use Efficiency (NUE) of the biological programs was in the order of at least 50% greater for P, K and S. For nitrogen it was 25% greater. Research Project Final Report: Biological Sweet Corn Trial Lowood Q June

12 This increase in NUE is likely due to the significant increase in root biomass which probably led to more effective nutrient assimilation by the crop from soil reserves. The root biomass of the biological treatments was at least 150% greater than the root biomass of the conventionally treated programs. The soil analysis shows that there were significant reserves of exchangeable and total P and K. Therefore these nutrients may not have been limiting factors in this situation. S and N however were limited and despite the significantly lower levels of these two nutrients being applied in the biological programs, no yield reduction was observed when compared to the conventional treatments. Furthermore the results of the comparison of the nutrient levels in the corn cobs (Table 9) show that the levels of N, P, K and S were almost identical across all treatments for most nutrients. In general nutrient uptake into plant tissue was equal for most nutrients across all treatments. A minor reduction in Total Nitrogen (less than 5%) was present in the A1 corn cobs as compared to the other treatments. A significantly greater level of silicon in the A1 was also observed. Visual observations of the crop as well as measurements of root biomass, cob numbers and leaf numbers tend to correlate with the yield and nutrient level data. The biological treatments had much larger root weights, greater stem circumferences and similar numbers of cobs and leaves when those measurements were taken. Informal observation of leaf width, colour and vigour along with cob quality led the researchers to agree that these characteristics were noticeably improved in the biological treatments as compared to the conventional treatments. Figure 4 provides a visual confirmation of some of these observations. One researcher also commented that their observation was that the percentage of corn that had severely lodged after the storm event was lower in the biological treatments. Certainly silicon (an important element in plant cell strength) levels in the A1 treatment were marked higher than those found in all other treatments. Other observations to consider includes the apparent lack of adverse impacts that the preemergent herbicide had on root dynamics and activity. Despite the application of this chemical to the biological treatments, root activity was still significantly enhanced by the biological fertiliser program. A final point is that the biological treatments did not experience a decrease in yield due to the non-application of the insecticide that was applied to the conventional treatments. The application of the silica treatment (MaxSil) to the biological treatment (A2) showed a slight increase in final yield over the other biological treatment (A1). Interestingly the A1 treatment had higher levels of silicon in the cob tissue than the A2 treatment despite the A2 treatment having the MaxSil applied to the seed as a seed coating. The biological corn not treated with silicon took up more silicon but the MaxSil treatment seemed to confer greater overall production to the corn. It may be that the silicon treatment enhanced plant growth promoting processes in the rhizosphere. Other observations show very little difference between the two biological treatments. Research Project Final Report: Biological Sweet Corn Trial Lowood Q June

13 Economic performance The improvement in NUE in the biological treatments meant that significantly lower levels of soluble nutrient fertilisers were applied. The result was a reduction in fertiliser input costs by $200 per hectare. The slight increase in yield (around 7%) of the biological treatments improved the Gross Income. Assuming all else remained equal (the costs of application of the insecticide are excluded), the biological treatments had a higher Gross Income and a lower total fertiliser costs. This led to a higher Gross Margin of over $1000 per hectare for the biological treatments over the conventional strips. Summary: The results of this trial indicate the potential that the enhancement of soil biological fertility through the use of biological fertilisers has for improving nutrient use efficiency and lowering production costs in intensive horticulture and field crop enterprises. In particular the improvement in potential for roots to take up nutrients and water due to a larger root biomass and associated rhizosphere was evident in the biological treatments. The comparison of programs in this trial showed an increase in yield and Gross Margin in the biological treatments over the conventional treatments with the treatment that included a silicon seed coating (MaxSil) showing the highest Gross Margin. Research Project Final Report: Biological Sweet Corn Trial Lowood Q June