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SWEEP Report #58

Manure Management in Conservation Farming

Roger Samson, Anne Weill, Allison Arkinstall, and Jeff Quinn, Resource Efficient Agricultural Production (REAP) Canada, Ste. Anne de Bellevue, Quebec.

Executive Summary

Evaluation Summary (Tech. Transfer Report Summaries)

View/Download Final Report [267 KB pdf]

Associated SWEEP/LSP Research


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Completed: July, 1992

Key Words:

liquid manure, oilseed radish, rye cover crop, no-till, soybeans, winter wheat, manure compost, solid manure

Executive Summary

The agronomic use of manure was evaluated in four major field crops in southern Ontario (corn, soybeans, winter wheat and alfalfa) over a three year period (1989-91). The principle objective of the research was to identify manure management systems which result in good agronomic yields and minimize the potential for environmental pollution. Systems were developed which emphasized nutrient cycling and ground cover. Cover crops, crop rotation and reduced tillage were considered to be important components in the development of a more holistic manure management system. The experiments were conducted on farms with the active participation of four farmer cooperators.

The overall approach in the research trials was to:

  1. apply manure during a low runoff period (late summer), incorporate manure with surface tillage, seed a fast growing cover crop (to conserve nutrients and provide ground cover) and subsequently establish the main crop the following spring using a conservation tillage system;
  2. apply manure during a high runoff period (spring, early summer) directly to an established crop (providing high ground cover) and prior to a period of high biomass accumulation (minimizing nutrient leaching potential).
Individual findings from the experiments are summarized below.

Expt. 1. Effect of Oilseed Radish, Timing of Manure Application and Tillage System on Nutrient Cycling and Corn Performance (Within a Winter Wheat-Corn Sequence)

Seeding of an oilseed radish catch crop following a late summer liquid manure application improved nutrient cycling. Oilseed radish took up approximately 100 kg N, 15 kg P and 125 kg K from the soil in the fall. The potential for fall nitrate leaching was reduced by the oilseed radish as soil nitrate levels (at four sites) and soil moisture levels (at one site) were lowered. In 1990, oilseed radish caused a temporary immobilization of P at the silt loam site which was observed as lower tissue P levels in whole corn plants harvested at the 5 leaf stage. Potassium uptake was lowest in plots where corn was no-tilled into oilseed radish residue and highest where oilseed radish had been plowed in the previous fall. Use of oilseed radish generally increased fall soil cover but lowered soil cover in the spring. Minimum tillage systems (Aerway and zero-till) were the most effective systems for maintaining residue cover and reducing runoff and soil loss. Tillage reduction improved P nutrition at the 5 leaf stage but reduced N and K ear leaf tissue content in corn at silking. Corn yields under minimum tillage were generally equivalent to conventional tillage when sufficient levels of N were available. Spring liquid manure applications resulted in higher N availability in corn than manure applied during the late summer of the previous year. Using split applications of liquid manure (30,000-40,000 l/ha), the first in late summer (followed by seeding of oilseed radish) and the second the following spring is suggested as an alternative to one high rate application (75,000 l/ha) either in late summer or early spring.

Expt. 2. Effect of Manure and Rye Cover Crop on No-Till Soybean Production

Rye seeded late in the summer appeared to be a promising cover crop to reduce erosion and P surface loss potential following a late summer incorporation of manure. Seeding of winter rye (Aug. 30 or Sept. 1) after solid manure application provided high ground cover ratings in the fall (90-91%) and again the following spring after no-till soybean planting (96-100%). At the time of soybean planting, the winter rye provided a high biomass yielding surface mulch (> 5 t/ha) with a low P content (0.28-0.31%) which would further reduce potential for P surface loss. However, the winter rye appeared to be affecting soybean development and yield. This was examined more fully in the second year of the study. Late summer seeded rye cover crops took up approximately 40-50 kg N/ha in the spring which depleted soil nitrogen at the time of no-till soybean planting. Early season soybean dry matter accumulation, leaf tissue content (N and P) and yield appeared to be most affected by treatments which had the highest rye biomass at the time of soybean planting. The use of solid manure applied prior to rye seeding did not appear to relieve nutrient deficiency problems in the no-till soybeans. The solid manure in the present study contained large quantities of straw which may have retained manure nutrients. Use of liquid manure in conjunction with winter rye would probably have been a more effective system for no-till soybean production as a relatively high N:low C manure source would be used in conjunction with a low N:high C cover crop.

Expt. 3. Effect of Tillage System, Manure Form and Rate on Winter Wheat

The combination of no-till or aerial seeding winter wheat in conjunction with low rate spring liquid manure applications appeared to be a promising low external input wheat production system that minimized surface runoff potential. Aerial, no-till and conventional seeding of winter wheat following soybeans resulted in equivalent wheat yields in both years when averaged over fertility treatments (compost, liquid manure, N fertilizer). All three tillage systems resulted in high ground cover ratings (> 50%) at the time fertility treatments were applied in late April. Ratings were highest on winter wheat established using a conservation tillage system. In both years, liquid swine manure applied at 40,000 l/ha to the winter wheat provided equivalent yields to nitrogen fertilizer. Mature compost applied on the surface at rates up to 15 t/ha did not increase yields compared to the control in 1989. Immature compost applied at rates of 40 t/ha increased wheat flag leaf N and P and wheat yield in 1990, but yields were lower than with liquid manure or fertilizer. In both years red clover was undersown in the winter wheat as a fall cover crop to further protect the soil after winter wheat harvest. Red clover biomass production was reduced and fall weed biomass increased in treatments where soluble N forms (liquid manure and fertilizer N) were used to fertilize the winter wheat. The main differences among the two conservation planting techniques was that aerial seeding resulted in greater ground cover (1990) and a higher flag leaf N content (1991) than no-till seeding. This was attributed to the earlier establishment of winter wheat in the aerial seeded plots.

Expt. 4. Effect of Solid Manure, Compost and Fertilizer on Established Forages

Overall, the risk of runoff and soil erosion from a perennial forage stand to which low rates of solid manure or compost had been applied appeared low. The annual application of low rates of solid manure (10 t/ha) or compost (7.5 t/ha) and fertilizer (0-30-135) moderately stimulated forage yields on an established alfalfa-timothy hay stand. All three fertilizer sources increased total forage yield but yields were highest when solid manure was applied. All three fertilizer sources increased alfalfa yield compared to the unfertilized control plot. As well, the solid manure treatment increased the grass yield of the forage stand which was responsible for the increase in total forage yield in this treatment. Throughout the course of the study, soil nutrient levels declined so that levels were very low at the end of the experiment. The fertility treatments did not maintain soil nutrient levels but delayed their decline. More frequent low rate applications of compost or solid manure would probably be more effective in reducing pollution risks while maintaining forage productivity and composition than one large annual manure application.

The four experiments indicate the potential for compatibility of conservation farming practices with manure management. According to the agricultural code of practice, manure should be incorporated within 24 hours of application. Experiments 1 and 2 indicate that this is compatible with reduced tillage systems if manure is surface incorporated, a cover crop seeded and the main crop subsequently established using a conservation tillage system. In Experiments 3 and 4, manure was applied to wheat and alfalfa which had very high ground cover ratings. In these experiments, no surface incorporation of manure occurred and relatively low manure application rates were applied to maintain crop productivity while minimizing pollution risks.

Evaluation Summary

(From Technology Transfer Report Summaries - A. Hayes, L. Cruickshank, Co-Chairs)
In Experiment 1, the efficiency of nutrient availability of late summer liquid swine manure application was compared with spring applied manure. The treatments consisted of summer applied manure with an oilseed radish cover crop, summer applied manure, and spring applied manure. The tillage treatments were: fall moldboard plowing, fall chisel plowing, spring Aerway, and zero-till. The subplot treatments were 0 kg N and 50 kg N added. The tillage systems in combination with manure management were evaluated as to the most efficient management approach for nutrient conservation, pollution control and corn performance. A randomized complete block design with split plots was used (12 plots, 2 subplots, 3 replications).

In Experiment 2, the effect of manure and rye cover crops on no-till soybean production was evaluated. The treatments included: rye seeded in August and September, manure application with rye seeded in August and September, manure alone and a control. Subtreatment plots consisted of weed control: either chemical or hand pulled or no weed control.

Experiment 3 was conducted to determine the potential of various manure sources and rates for no-till winter wheat production. Various N rates were evaluated to determine the N requirements of no-till winter wheat seeding systems following soybeans. The treatments included: aerial seeding at leaf yellowing in soybeans, no-till drilled (after soybean harvest), conventional (one cultivation after soybean harvest). Subtreatment plots included the use of chemical fertilizer, liquid swine manure, mature swine and beef compost. The swine and beef compost was used one year and replaced with immature dairy compost the following year.

Experiment 4 was conducted to determine the effect of low rates of summer-applied solid manure and compost on forage yield and composition. It was believed that compost would reduce manure clumping which smothers alfalfa plants and the risk of manure being present in the hay at time of harvest. The treatments were solid beef manure, mature beef compost, fertilizer (0-30-135) and no fertilizer or manure.


The researchers took a systems approach when conducting the study. However, when evaluating the effect of the different parameters, it is difficult to determine which parameter is causing the observed result. Generally, it is questionable whether two years is long enough to draw some of the conclusions that appear in this report. However, rather interesting observations have been noted. A number of issues were not commented on in the report.

In Experiment 1, no comment was made on the release of nutrients from the cover crop once it had died. It is not known if these nutrients were released and whether timing was appropriate for crop growth.

The study commented on the increased infiltration rate created by a no-till system. The potential for groundwater contamination by nitrates and bacteria was not explored.

The rotation used was winter wheat/corn with swine manure. Because of the tendency of fusarium in corn, with a winter wheat/corn rotation, swine farmers are tending to move away from this rotation. Therefore, this type of rotation may not be appropriate for a liquid hog manure management system.

Appendix to Experiment 1, which involved looking at the effect of manure application, tillage and fall cover crops on erosion, was located on a separate site; this eliminated the opportunity for direct comparison.

In Experiment 2, variability occurred within the trial when the source of manure was changed from beef manure to dairy manure and the application rate was increased by 50 t/ha. The reason for the change was given as the diary manure was believed to be richer. Test results to prove this belief are not provided in the report or no mention that any analysis was conducted. Straw from the applied manure was counted in the residue measurements of the plots and therefore the manured plots had a higher residue count. Results of the study indicated that the timing of rye planting early versus late had a greater effect on rye biomass than did manure application. This is widely known. The longer a plant has to grow before killing should be able to produce greater amounts of biomass than a plant seeded later and killed at the same time.

In Experiment 3 there seemed to be little consistency from year to year within the same trial. After the first year the mature compost was changed to immature compost. Also the compost application rate was increased over that of the first year. Biodynamic compost was used in the second year of the trial. The maturity and C:N ratio of the compost are not stated. The significant increase of the winter wheat was attributed to the biodynamic compost. No credit was attributed to the compost from the previous year. The speculation that a superior compost (one with more nitrogen) could produce yields comparable to those obtained from the soluble N, chemical fertilizer plots is suspect.

At the end of Experiment 4, the researchers recommended incorporating high rates of manure before forage establishment to ensure medium to high soil nutrient levels. They neglected to determine or establish several items: the desirable nutrient levels for forage establishment, the fate of nutrients before establishment, and the impact on water quality.

Associated SWEEP/LSP Research:

  • SWEEP Report #66 - Volume V. Economic Assessment of the Technology Evaluation and Development (TED) Program

Future Research: ( ) indicates reviewers suggestion for priority, A - high, C - low.

(A) A comprehensive research program is required to determine the fate of nutrients from several sources (commercial manure, urban) in various tillage and cropping systems over time. Site-specific recommendations for rates, combinations of materials, timing of operations and cultural practices then could be developed to ensure cost-effective production with minimal environmental impact.




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Created: 05-28-1996
Last Revised: Thursday, May 19, 2011 04:17:03 PM