Season-long Grazed Green Manure Systems Study

Transcription

1 Season-long Grazed Green Manure Systems Study Progress Report - April 2013 Martin Entz Research Leader Joanne Thiessen Martens and Keith Bamford - Technicians University of Manitoba Department of Plant Science INTRODUCTION Previous research has shown that grazing annual legume green manure crops can provide a valuable product to farmers (i.e. livestock forage) while contributing biologically fixed nitrogen (N) to following crops, thus reducing or eliminating the need for N fertilizer. The challenge presented by such systems is that most annual legume green manures have a rapid growth phase followed quickly by maturity, leaving only a small window of time between adequate biomass accumulation (and associated N fixation) and declining forage quality and palatability. For good utilization of such a grazed green manure, a farmer would require large numbers of livestock for only a few weeks of the summer. Thus, our goal is to develop a system that provides a continuous supply of forage throughout the season while still fixing ample amounts of N. In this way, we hope to design a system that maximizes the value of the green manure year, since no grain crop is harvested during that year. The objective of this study is evaluate the potential of various annual legume-based systems to provide forage during particular windows of time throughout the growing season, with the twin goals of providing adequate livestock nutrition and adequate N fixation (i.e. at least 100 kg N ha -1 ). This process begins with examination of various crops and crop combinations to fill specific niches and then combines the information from individual components to develop some flexible and practical options that can be implemented by farmers. DESIGNING A SEASON-LONG GRAZED GREEN MANURE SYSTEM Extending forage availability beyond the mid-summer when most annual green manures could typically be grazed requires consideration of other crop species and strategies for establishing and grazing them. We are considering three major strategies for extending the green manure grazing season: 1. Broadening the window of midsummer grazing through crop choice and staggered seeding date 2. Extending grazing into the late summer and fall by using crops that regrow after grazing 3. Gaining spring and early summer grazing potential through establishment of some crops in the previous year. These strategies, combined with multiple cropping approaches that allow for at least two grazing events on each plot of land, have the potential to meet the goals described above. Thus, we envision a system in which a green manure area could be divided into three or more plots of land, each with a different combination of crops, among which livestock could be rotated throughout the season. In Figure 1 and Table 1, we describe one potential system, including how the experiments we are conducting in this study help us reach this goal, using the three strategies described above. 1

2 Figure 1. Schematic description of biomass availability for grazing in a potential season-long grazed green manure system. Each coloured line represents one plot of land, each of which provides forage at specific times during the season. Table 1. Description of a potential season-long grazed green manure system including strategies for extending the grazing season and specific experiments and research questions in the current study. Field System Strategy Experiment Primary Research Question 1 Fall rye followed by annual green manure #3 #1 Exp 1 fall rye based systems Exp 1 fall rye based systems How much spring grazing potential does fall rye offer? How do green manures perform after grazed fall rye? 2 Overwintering legumes for early summer grazing 3 Spring-seeded annual green manure, underseeded to Italian ryegrass #3 #3 #1 #2 Exp 2 fall-seeded legumes Exp 5 establishment strategies for overwintering legumes Exp 4 green manure species and seeding dates Exp 3 spring-seeded Italian ryegrass systems How much spring grazing potential do fall-seeded legumes offer? What are the best establishment strategies for overwintering legumes? Can staggered seeding dates and different green manure crop choice broaden the mid-summer grazing window? How well can Italian ryegrass establish, persist, and regrow when grown with grazed annual legume green manures? 2

3 EXPERIMENTS CONDUCTED IN 2012 Field experiments were conducted at Carman MB at the Ian N. Morrison Research Farm, beginning in fall 2011 and continuing in the summer of Due to poor winter survival of some fallseeded crops, some experiments could not be conducted as planned. Therefore, one additional experiment was established in spring 2012 to help fill some of our knowledge gaps. The 2012 experiments represent Year 1 of a multi-year study. Some of these experiments will include a Year 2 phase in 2013, where wheat is grown on all plots to determine the effects of crop combinations and grazing on the performance of the following crop. Some of these experiments will also be repeated beginning with Year 1 in 2013; others will be modified based on what we have learned so far in order to more fully explore the systems that demonstrate the potential to meet the goals of the season-long grazed green manure system. EXPERIMENT 1: FALL RYE BASED SYSTEMS Materials and Methods The objective of this experiment was to investigate grazed green manure systems that begin with fall-seeded fall rye. Fall rye itself can be grazed by livestock in spring and, if not grazed, its early maturity allows for relay or double-cropping of green manure crops that provide N fixation and forage for late-season grazing. This allows for various potential combinations of crops and grazing events. Oat and soybean control crops, as well as ungrazed versions of grazing treatments, were included in order to compare grazing treatments to typical crop rotations in terms of their effect on the following crop. Treatments and seeding and grazing dates in this trial are summarized in Table 2. The experimental design was a randomized complete block with four replications. Individual plots were 2x9 m in size. Crops were seeded at typical to high seeding rates on the dates indicated in Table 2. The relaycropped Italian ryegrass and red clover mixture was direct seeded into the established fall rye using a plot-scale no-till disc drill. The pea-soy-oat mixtures seeded in June and August were seeded using a plot-scale air seeder equipped with hoe openers, after tilling the plots with a rotovator. All legumes were inoculated with the appropriate strain of Rhizobium bacteria prior to seeding. Grazing with sheep began at the end of May in treatments where fall rye was grazed; other crops were grazed during August and September. In all cases, sheep were preconditioned to their assigned crop before being placed in the trial to allow them to acquire a taste for the crop. Forage crop biomass was measured immediately before grazing by collecting above-ground biomass from two randomly placed quadrats in each plot. Residual biomass was collected in a similar fashion after grazing to determine how much biomass was consumed by the sheep. In some cases, extremely small amounts of biomass remained after grazing and so residual samples were not collected and forage utilization was assumed to be 100%. 3

4 Table 2. Description of treatments in Experiment 1 at Carman MB in First crop Second crop Treatment Seeding date Grazing date Seeding date Grazing date Oat control May Soybean control May Fall rye grain control (no grazing) Aug FR grain with stubble grazing Aug Sep FR grain with double cropped pea-soy-oat (no grazing) FR grain with double cropped pea-soy-oat (grazed) FR grain with relay cropped Italian ryegrass-red clover (no grazing) FR grain with relay cropped Italian ryegrass-red clover (grazed) FR grazed, then seeded to peasoy-oat mixture (not grazed) FR grazed, then seeded to peasoy-oat mixture (grazed) Aug Aug Aug Aug Sep Aug Apr Aug Apr Sep Aug May 30-Jun Aug May 30-Jun Jun Jun Aug Results Establishment of all crops was adequate to good, except for the soybean control crop which failed to establish as a result of equipment difficulties during seeding and the double-cropped pea-soyoat mixture which had poor emergence and growth due to extremely dry soil conditions at time of seeding. Fall rye was grazed later than intended and had already headed out at time of grazing, resulting in very poor utilization by the sheep (Table 3). Even so, termination of fall rye at this stage, followed by seeding of a pea-soy-oat green manure crop provided the highest amount of forage of all treatments in this experiment. Biomass of crops for late-season grazing was limited somewhat by poor moisture availability throughout the latter part of the summer. In fact, biomass produced by the double-cropping pea-soyoat mixture seeded after fall rye harvest was lower than the weed biomass in the fall rye stubble grazing treatment (Table 3). Of all grazing treatments where fall rye was harvested for grain, the relay-cropped ryegrass and red clover treatment provided the greatest amount of biomass. Forage utilization in stubble grazing, double cropping and relay cropping treatments was estimated to be equal to biomass availability, based on visual observation. 4

5 Table 3. Total biomass immediately prior to each grazing event and forage utilization by sheep in Experiment 1 at Carman MB in Treatment First crop graze Forage Biomass utilization kg ha Second crop graze Forage Biomass utilization -1 FR grain with stubble grazing FR grain with double cropped pea-soy-oat (grazed) FR grain with relay cropped Italian ryegrass-red clover (grazed) FR grazed, then seeded to peasoy-oat mixture (not grazed) FR grazed, then seeded to peasoy-oat mixture (grazed) * * * Negative values for forage utilization are likely a result of poor utilization of fall rye by sheep, along with some fall rye growth during the grazing period. Major Findings Next Steps Timing of fall rye grazing is critical to getting adequate forage utilization of the fall rye. Grazing should occur before fall rye heading. Earlier grazing of fall rye would also provide an opportunity to seed the following green manure crop earlier, potentially increasing the biomass yield potential of that crop. When soil conditions are very dry, seeding a second crop after fall rye harvest may result in poor establishment and growth. Relay-cropped red clover and Italian ryegrass established successfully in a fall rye crop and provided adequate late-season forage. In 2013, wheat will be grown on all plots in order to determine the effect of these grazing systems on the performance of the following crop. We also intend to repeat this experiment in

6 EXPERIMENT 2: FALL-SEEDED LEGUME SYSTEMS Experiment 2a: Fall-seeded legumes for early-season grazing Materials and Methods The objective of this experiment was to evaluate various fall-seeded legumes for their potential to provide early-season grazing the following year. While this experiment only tested the fall-seeded legumes themselves, the intent of including these crops is to provide N fixation and forage early in the season, while allowing time for another annual forage to be planted afterwards. Red clover and hairy vetch are examples of legumes that can be seeded in fall and grazed the following spring or early summer. An early-seeded pea-oat mix was also included in the experiment to determine whether fallseeded legumes allowed for earlier grazing than spring-seeded annual green manures. Once again, oat and soybean controls, a control with no green manure crop, and ungrazed versions of green manure treatments were included to allow us to compare the effects of grazing systems to typical crop rotations on the performance of the following crop. Fall-seeded crops were direct seeded into standing stubble on August 29, 2011 using a plot-scale no-till disc drill. After emergence, crop seedlings were counted in each plot to determine the establishment rate. In the spring of 2012, plants were counted again to determine winter survival. Results The winter survival of hairy vetch was extremely low and red clover plant stand in spring 2012 was very patchy, possibly due to poor snow cover in the winter of These poor crop stands, along with heavy pressure from perennial weeds such as dandelion, led us to terminate this experiment on May A new experiment (Experiment 5, described below) was conducted in order to learn more about effective ways to establish over-wintering legumes in order to provide early-season grazing and N fixation. Experiment 2b: Hairy vetch and Italian ryegrass systems Hairy vetch is a winter annual legume with the potential for very high biomass production and N fixation. Italian ryegrass is a high-energy grass that is highly tolerant of grazing, making it a popular forage among grass-finished beef producers. Since Italian ryegrass requires good soil fertility (especially N), planting Italian ryegrass after grazed hairy vetch may provide the ryegrass with the nutrients it needs to be productive. However, in this system, a balance must be struck between grazing the hairy vetch early enough to allow for good establishment and growth of the Italian ryegrass and allowing the hairy vetch to grow long enough to fix ample amounts of N. Thus, the objective of this experiment was to investigate the effect of hairy vetch grazing date and subsequent seeding date of Italian ryegrass on the productivity of the Italian ryegrass. The four treatments included: 1. Underseeding Italian ryegrass into hairy vetch in early spring, then grazing hairy vetch in late June. Ryegrass would regrow after grazing to provide continuous forage through the rest of the summer. 2. Grazing hairy vetch in late May, followed immediately by seeding of Italian ryegrass. 6

7 3. Grazing hairy vetch in mid-june, followed immediately by seeding of Italian ryegrass. 4. Grazing hairy vetch in late June, followed immediately by seeding of Italian ryegrass. Hairy vetch was direct seeded into standing stubble on August 29, Germination and establishment of hairy vetch was adequate, but winter survival was extremely poor. Nonetheless, we proceeded with the first seeding date of Italian ryegrass and achieved good establishment. However, the hairy vetch population was so low that we did not continue with the other treatments, and the experiment was terminated. Experiment 2c: Legume productivity trial for early-season grazing Materials and Methods The objective of this experiment was to compare three fall-seeded, overwintering legumes and a pea-oat mix seeded in early spring in terms of their ability to provide forage for early-season N fixation and grazing. The fall-seeded legumes included hairy vetch, red clover and cicer milkvetch, a non-bloating perennial forage legume. Hairy vetch, red clover and cicer milkvetch were direct seeded at relatively high seeding rates into standing stubble on August 29, 2011 using a no-till disc drill. Following emergence, plants were counted in two randomly selected locations within each plot. The fourth treatment, a pea-oat mixture, was seeded on April 29, In May 2012, plants were counted in all treatments to determine winter survival for the fall-seeded legumes and establishment rate of the pea-oat mix. Biomass samples were collected from surviving treatments at approximate 3-week intervals throughout the growing season to characterize the availability of forage in each treatment. Results Establishment of red clover was somewhat patchy, while establishment of pea-oat was very good. Hairy vetch winter survival and cicer milkvetch establishment were very poor; thus these treatments were not sampled in Total biomass of the early spring seeded pea-oat mixture exceeded that of fall seeded red clover at all sampling points during the growing season (Figure 2). However, biomass production of pea-oat peaked in early July when these crops reached maturity, whereas red clover continued to grow throughout the summer and fall. 7

8 Biomass (kg ha -1 ) Red clover Pea/oat Jun 11-Jul 30-Jul Figure 2. Total biomass (crop + weeds) of fall-seeded red clover and early spring-seed pea oat green manures over the growing season in Experiment 2c at Carman in Major Findings Pea-oat is a highly productive crop with very rapid biomass accumulation, making it superior at providing early to mid-summer biomass for grazing. However, the window of time during which pea-oat can be grazed may be small due to its rapid maturity after peak biomass production. Red clover biomass accumulation is not as rapid in the early summer, but continues throughout the summer and fall, providing a continual supply of forage throughout the season. 8

9 EXPERIMENT 3: SPRING-SEEDED ITALIAN RYEGRASS SYSTEMS Materials and Methods Italian ryegrass is a high quality forage with very good grazing tolerance, which allows it to be grazed repeatedly throughout the summer and fall. By intercropping the ryegrass with N-fixing legumes, it may be possible to provide the ryegrass with the high soil N levels it requires without requiring N fertilizer. The objective of this experiment was to evaluate various legumes as potential intercrop components with Italian ryegrass, with the goals of allowing for successful ryegrass establishment and persistence and high forage production and N-fixation by the legume. Treatments included Italian ryegrass grown alone, or in combination with a pea-oat mix, a hairy vetch-oat mix, or in alternate rows with red clover. Oat and soybean control crops were also included. Plots were 2x9 m in size. All treatments were seeded on May using a plot-scale air seeder equipped with hoe openers, except the soybean control which was seeded May 24. After emergence, plants were counted to determine plant stand and establishment rate. Grazing treatments were initiated at an appropriate plant stage for each treatment and were repeated throughout the season as permitted by plant growth. A late summer graze was not possible in the ryegrass-pea-oat treatment due to poor regrowth of the ryegrass following the midsummer graze. Grazing dates and effective stocking rates are summarized in Table 4. Effective stocking rates were calculated based on the number of sheep per plot and the time spent in each plot. Where sheep spent less than 24 hours in a treatment, stocking rates were calculated based on a 16 hour grazing day. Biomass samples were collected before and after each grazing event in order to determine forage availability and utilization by sheep. In cases where there was virtually no biomass left after grazing, utilization was assumed to be 100%. Table 4. Grazing dates and effective stocking rates in Experiment 3 at Carman MB in Crop Ryegrass (RG) alone RG and red clover RG and peaoat Midsummer graze Late summer graze Fall graze Stocking rate* Stocking rate* Stocking rate* Date (ewes/ha/day) Date (ewes/ha/day) Date (ewes/ha/day) July Aug Sept July Aug Sept July Sept RG and hairy vetch-oat July Aug Sept * Stocking rates were calculated on a per hectare basis from actual numbers of sheep per plot and time spent in each plot. Results Establishment of all crops was acceptable, except for the soybean control crop which failed to establish as a result of equipment difficulties during seeding. 9

10 Crop biomass and forage utilization for each grazing event is presented in Table 5. Italian ryegrass, red clover and pea-oat appeared to be highly palatable to the sheep; conversely, they did not appear to find hairy vetch palatable and selectively grazed other crops and weeds in the mixture, resulting in very low forage utilization for the hairy vetch treatment. Negative values are likely a result of highly variable biomass within plots due to hairy vetch s viney growth habit, leading to poor estimation of pre-grazing and residual biomass. Total forage utilization over the growing season was highest for the ryegrass-pea-oat system, due to high levels of forage produced by the pea-oat mixture. Of the systems tested in this experiment, the ryegrass-pea-oat system appears to hold the greatest potential to meet the twin goals of forage availability and N fixation. Table 5. Total biomass immediately prior to each grazing event and forage utilization by sheep in Experiment 3 at Carman MB in Midsummer graze Late summer graze Fall graze Total Forage Forage Forage Forage Crop Biomass utilization Biomass utilization Biomass utilization utilization -1 kg ha Ryegrass (RG) alone RG and red clover RG and pea-oat RG and hairy vetch-oat * * ** * Negative values for forage utilization are likely a result of high variability within the plot, combined with poor utilization of hairy vetch by sheep. ** Total forage utilization for this treatment was calculated using a forage utilization value of 0 for the first two grazing events. One of the goals of this experiment was to extend grazing into the late summer and fall through use of Italian ryegrass; therefore we compared the fall productivity of the ryegrass in each of the four treatments (Figure 3). Statistical analysis indicates that ryegrass biomass was not significantly different among treatments. Weed biomass was numerically greater in the ryegrass-only and ryegrass-hairy vetch treatments, but these differences were not statistically significant. 10

11 Biomass (kg ha -1 ) Weeds Other crop Ryegrass Ryegrass - red clover Ryegrass - pea - oat Ryegrass - hairy vetch Ryegrass only Figure 3. Biomass present in Experiment 3 on Sept , immediately prior to the final grazing treatment. Major Findings A pea-oat green manure crop underseeded with Italian ryegrass provided the greatest biomass and forage, as well as the greatest potential for N fixation. Grazing the ryegrass-pea-oat mixture very intensively during hot, dry weather resulted in poor ryegrass persistence. However, those plants that remained appeared to have better N nutrition than ryegrass in other treatments. Spring-seeded red clover intercropped with Italian ryegrass produced very little biomass and thus can be expected to provide very little N to the system. Next Steps Wheat will be grown on all plots in 2013 to assess the impact of these systems on the following crop. Further research on this system will explore management strategies for the ryegrass-pea-oat system that achieve a balance of biomass production by the pea-oat component and ryegrass persistence for late summer and fall grazing. 11

12 EXPERIMENT 4: GREEN MANURE SEEDING DATES FOR CONTINUOUS FORAGE SUPPLY Materials and Methods Annual green manure crops typically have a rapid growth phase followed quickly by flowering and seed maturation. This may limit the window of time available for grazing these crops while maximizing biomass production and N fixation. Staggered seeding dates may allow farmers to lengthen the grazing season on annual legume green manure mixtures. At later seeding dates, warm-season crops may perform better than cool season crops. Therefore, the objective of this experiment was to characterize the growth of two green manure mixtures seeded on several dates in order to understand the effect of seeding date and crop choice on biomass production and forage availability. Two annual green manure crop mixtures were tested in this experiment. Both contained a cool season and a warm season legume (pea and soybean, respectively). One mixture contained a cool season cereal (oat) and the other contained a warm season cereal (millet). Both mixtures were seeded at three week intervals, beginning May 2 and ending July 5. Plots were 2x9 m in size. For the last seeding date, a different variety of millet was used because of poor millet emergence in the first three dates. Biomass samples were collected weekly in each treatment beginning 6 weeks after seeding and continuing until the crop was mature (12-13 weeks after seeding). Samples collected at 6, 9 and 12 weeks after seeding were sorted into the mixture components (i.e. pea, soybean, oat/millet) and weeds, in order to assess the contribution of each crop to the total biomass of the mix. Results Total plant population in the green manure mixtures was adequate in most cases; however, millet emergence was poor in the first three seeding dates due to poor seed vigour and soybean emergence was poor in the first two seeding dates, possible due to cool soil temperatures. Total biomass for the two mixtures was plotted according to date, in order to describe the forage availability throughout the season (Figure 4). Peak growth generally occurred between 6 and 10 weeks after seeding, except for the first seeding date, where growth appeared to continue until 13 weeks after seeding. Total biomass production was highest for early seeding dates and declined with later seeding dates. The mixture containing oat produced higher biomass for the first three seeding dates (where poor millet seed was used); for the last seeding date, the millet mixture produced more biomass than the oat mixture. By using the best-performing mixture at each of the four seeding dates, a steady supply of forage would be available for grazing from the middle of July until the middle of September. The legume component of the green manure mixtures was dominated by peas, especially for mixtures seeded in May (Figure 5). Soybean contributed somewhat more biomass in later seeded mixtures than early seeded ones, but still produced less biomass than pea. Oat was more productive than millet for the first three seeding dates, due to poor millet seed vigour. Mixtures seeded on July 5, however, were dominated by millet. Early-seeded green manures suppressed weeds better than the June-seeded mixtures. In the July 5 mixtures, which included better quality millet seed, millet outperformed oat. 12

13 Oat mix May 2 Millet mix May 2 Oat mix May 24 Millet mix May 24 Oat mix June 14 Millet mix June 14 Oat mix July 5 Millet mix July 5 Oat mix May 2 Millet mix May 2 Oat mix May 24 Millet mix May 24 Oat mix June 14 Millet mix June 14 Oat mix July 5 Millet mix July 5 Oat mix May 2 Millet mix May 2 Oat mix May 24 Millet mix May 24 Oat mix June 14 Millet mix June 14 Oat mix July 5 Millet mix July Oat mix May 2 Millet mix May 2 Oat mix May 24 Millet mix May 24 Oat mix June 14 Millet mix June 14 Oat mix July 5 Millet mix July 5 Figure 4. Total biomass production of two green manure mixtures (Oat mix = pea-soy-oat; millet mix = pea-soy-millet) seeded on four dates (May 2, May 24, June 14 and July 5). Initial points for each line correspond to the seeding date for that treatment Biomass at 6 weeks after seeding Biomass at 9 weeks after seeding Biomass at 12 weeks after seeding Weeds Oat/millet Soybean Peas Figure 5. Biomass of green manure mixture components and weeds at 6, 9 and 12 weeks after seeding. (Oat mix = pea-soy-oat; millet mix = pea-soy-millet; dates indicate seeding dates May 2, May 24, June 14 and July 5.) 13

14 Major Findings Staggered seeding dates offer the potential to extend the mid-summer window of grazing for spring-seeded green manure mixtures. Peas produced more biomass than soybeans in the mixtures in almost all cases, suggesting that soybean is not a competitive component in a crop mixture, even at mid-summer seeding dates. A competitive cereal in the mixture can suppress legume growth; thus care should be taken to choose appropriate seeding rates for the cereal component of the mixture. Next Steps Further examination of the data collected in this experiment will be informative in developing appropriate green manure mixtures for seeding at various dates. Late-seeded green manure mixtures are a good fit in systems where fall rye is grazed in spring. We are interested in assessing the performance of green manure mixtures grown after grazed fall rye compared to those grown without a preceding cover crop. 14

15 EXPERIMENT 5: STRATEGIES TO ESTABLISH OVERWINTERING LEGUMES FOR EARLY-SEASON N FIXATION AND GRAZING Materials and Methods This experiment was conducted as a result of the poor overwintering of hairy vetch and red clover in Experiment 2. The objective of this experiment was to evaluate four approaches to establishment of overwintering legumes with the potential to provide early-season N fixation and forage. The legumes tested included hairy vetch, red clover, alfalfa, sweet clover, and a mixture of sweet clover and perennial ryegrass. The establishment methods included: 1. interseeding with oats, with oats cut for silage at the dough stage 2. interseeding with oats, with oats harvested for grain 3. seeding after oats cut for silage 4. seeding after oats harvested as grain The experiment was a factorial design in a split-plot arrangement with four replications. Main plots were legume establishment method and subplots were legume species. Subplots were 2x8 m in size. Seeding dates and oat removal dates are summarized in Table 6. Oats and legumes (where applicable) were seeded on May 31 using a plot-scale air seeder equipped with hoe openers. All legumes were inoculated with the appropriate strain of Rhizobium bacteria prior to seeding. After emergence, plants were counted in two locations in each plot in order to evaluate crop establishment. The locations of plant counts were marked so that counts could be repeated in the same locations later in the season. In Treatments 1 and 3, oats were cut on July 31 using a plot-scale swather and biomass was baled off the plots the next day. Legumes were seeded in Treatment 3 on August 7, using the same procedure as in spring. In Treatments 2 and 4, oats were swathed on Sept 7 and combined on Sept 13. Legumes were seeded in Treatment 4 on Sept 20, using the same procedure as in spring. Plants were counted in all plots just prior to the first snowfall, on November Table 6. Dates of oat and legume seeding and oat removal by silage or combining in Experiment 5 at Carman MB in Establishment Method Oat seeding date Oat removal date (silage / combining) Legume seeding date 1. Interseeded with oat (silage) May 31 July 31 May Interseeded with oat (grain) May 31 Sept 13 May Seeded after oat (silage) May 31 July 31 August 7 4. Seeded after oat (grain) May 31 Sept 13 Sept 20 Results Legume emergence in interseeded treatments was somewhat variable but was generally adequate to good (data not shown). Legume emergence in Treatment 3, after oat silage, was also variable due to poor soil moisture conditions. Legumes seeded after oat grain harvest failed to establish due to extremely dry soil conditions throughout the fall. 15

16 Legume plant populations at the end of the growing season are presented in Table 7. In general, the establishment method resulting in the highest plant populations at the end of the season was interseeding legumes with oat and removing the oat crop as silage at the dough stage. Seeding after oat harvest resulted In the poorest establishment. Hairy vetch and alfalfa were able to establish quite successfully in all three of the other treatments. Table 7. Plant populations of various legumes with various establishment methods In Experiment 5 at Carman in Establishment method Legume Interseeded with oat (silage) Interseeded with oat (grain) Seeded after oat (silage) Seeded after oat (grain) -2 plants m Hairy vetch Red clover Alfalfa Sweet clover Sweet clover with perennial ryegrass Major Findings Next Steps Establishment of small-seeded legumes in late summer and fall was less successful than underseeding with a companion crop, due to extremely dry soil moisture conditions in the latter part of the summer. When legumes were underseeded to an oat companion crop, early removal of the companion crop by cutting as silage resulted in better legume persistence into the fall. Hairy vetch and alfalfa appeared to be most widely adapted to a range of establishment practices. Winter survival of all crops will be assessed in spring Biomass production of all crops will be assessed during the 2013 growing season, with the specific goal of seeing whether these legumes can provide early-summer N fixation and grazing. We are interested in exploring season-long management options for these legumes in order to maximize their value. These could include grazing strategies to maximize N fixation, production of a seed crop, or others. 16

17 PRELIMINARY CONCLUSIONS AND FUTURE RESEARCH Research trials conducted in 2012 have provided us with a good indication of the potential of season-long grazed green manure systems and have also presented new research questions that we would like to explore. Preliminary Conclusion In fall rye grain systems, there is considerable potential to produce relay or double cropped green manures for fall grazing, depending on soil moisture conditions. In grazed fall rye systems, it is possible to establish a legume green manure mixture after grazing fall rye, for late summer grazing. Fall rye grazing management will require better optimization of biomass production and forage palatability. Fall-seeded legumes did not overwinter well, possibly due to poor snow cover in Further testing of legume establishment strategies indicates that interseeding with a companion crop which is then removed as silage results in the best legume establishment. A pea-oat green manure with Italian ryegrass underseeded can provide high levels of biomass and N fixation, with the potential to graze ryegrass throughout late summer and fall. However, highly intensive grazing in mid-summer can adversely affect ryegrass regrowth. Staggered seeding dates of pea-soy-cereal mixtures can extend the availability of forage over the mid- to latesummer period. Next Steps This experiment (Exp 1) will be repeated in This experiment (Exp 1) will be repeated in In addition, we want to compare green manures seeded after grazed fall rye to those seeded without a preceding crop. We plan to establish a small trial to determine the optimum timing of fall rye grazing. Legumes will be monitored in Exp 5 for their winter survival and early summer biomass production, as well as potential season-long uses of these crops. Since the pea-oat system exhibited the greatest potential for forage production and N fixation, we hope to establish a new experiment to examine grazing management strategies that can optimize this system. Further analysis of data (Exp 4) will help us to determine the best interval between seeding dates as well as the best crop choice for particular dates. We are also interested in conducting a new experiment to determine the effect of green manure maturity on palatability to livestock. 17