Site-specific Manure Management for Improving Soil Quality

Site-specific Manure Management for Improving Soil Quality

Summary

Precision manure management is a multidimensional concept that converges the best manure management practices along with precision agricultural techniques. Our three years of project work indicates that the variable rate application of animal manure across productivity level management zones has potential to enhance grain yield of low producing areas of the spatially variable farm fields. There are also positive improvements in the soil quality parameters that are highly correlated to grain yield and productivity. Extension workshops and meetings indicate significant interest among farmers and practitioners in learning about precision manure management.

Objectives/Performance Targets

1. Demonstrate and compare five manure management strategies applied across site-specific management zones delineated on farmer’s fields to assess its impact on productivity and soil quality.

2. Demonstrate and compare the improvement in soil quality parameters (as measured by pH, bulk density, aggregate stability, water retention, organic matter content, electrical conductivity, and sodium adsorption ratio).

3. Demonstrate and make economic comparisons of site-specific management zone based manure management strategies to estimate differences in economic returns among the strategies.

4. Evaluate the impact of manure management strategy on water quality risk, through the use of P Index and the N Leaching Index.

5. Develop a network of farmers to conduct on-farm trials, provide hands-on training via field days, farm tours, and extension workshops in the design, implementation, and analysis of field-scale farm trials using innovative site-specific management zone techniques.

Accomplishments/Milestones

Accomplishment / milestones listed below are for the period of January 2009 through December 2009, i.e., third year of our project.

After the harvest of crop (second year) in late 2008, we started working on data analysis to compare the various manure management strategies for the second year of the project. Our second year data failed to differentiate grain yield response to applied variable rate manure across management zones. While this was not so encouraging, the overall grain yield of plots managed with variable rate manure out-performed plots managed with variable rate fertilizer across all management zones. This was an interesting observation. After much discussion among the team members, we concluded that with below normal precipitation in the first year of our study, manure failed to mineralize as one would normally expect. The non-mineralized manure from the first year and the new application of manure in the second year coupled with above normal precipitation must have boosted the mineralization of manure that translated into higher grain yield. (Objective 1).

Following harvest, soil samples were acquired to assess and monitor the changes in soil quality parameters across the manure management strategies (Objective 2), as outlined in the project proposal. Soil analyses for soil quality parameters were conducted in Dr. Jessica Davis’s (Co-PI of the project) laboratory at CSU. Soil analyses work for second year of soil samples was completed by late summer of 2009. We found positive trends occurring in the soil quality parameters, particularly in soil bulk density, organic matter, and water retention curves.

The Ph.D. graduate student working on this project (Mr. Edwin Moshia) worked on the economic analyses (Objective 3) of the project under the guidance of Dr. Khosla and Dr. Frasier (Co-PI). His economic analyses indicated that most or all manure management strategies were profitable when calculated at the corn prices of Sept 2008 ($7/bu). The graduate student also performed sensitivity analyses with reference to corn prices, and found that if economic analysis is performed at 5 year historical average price of corn (~ $3/bu) none of the strategies were profitable. He then calculated the break even point which was around $4.50/bu. One of the primary reasons attributed to such a finding is that the overall grain yields in this study were lower than with manure as the only source of crop nutrients.

Objective 4: we made progress on the P runoff index and N leaching index as well. Our preliminary analyses indicates only low to moderate level of risk associated with the amount of variable rate manure applications that were or are being applied in this study across management zones. Such a finding was a bit surprising for the team, since we are applying up to 30tons of manure/acre rate per year. This may primarily be attributed to relatively heavier textured soil on which this study is being conducted. We had a meeting with NRCS professionals as well and are looking deeper into P runoff and N leaching index.

Objective 5: Several presentations were made at extension workshops and scientific conferences. One oral paper presentation was made at the Joint International Agricultural Conference in Wageningen, Netherlands. Another oral paper presentation was made at the Western Nutrient Management Conference in Salt Lake City, UT. Another oral presentation was made by the graduate student at the Western Society of Soil Science annual meetings, in Fort Collins, CO. A field day was conducted in September.

Impacts and Contributions/Outcomes

It is too early to start estimating the impact of precision manure management strategies. We are in the process of educating the producers by sharing new knowledge that we are learning from the project. Precision manure management shows potential; however we are concerned about the peak nutritional requirement of the crop which may be compromised because on non-synchronous mineralization of manure. So we are cautiously excited about the potential and at the same time are contemplating strategy that may perhaps include addition of fertilizer at peak nutrient uptake of crop while manure may meet the nutritional need of the crop at other times and also aid in improving soil quality.

In 2009, we were able to impact over 40 individuals, who attended the workshops and fields days organized by our team. This includes farmers, crop advisors, extension agents, NRCS and EPA personnel and participants from USDA-ARS, university faculty and students. There continues to be significant interest among farmers who are enthusiastically participating in our project to find out the enhanced productivity and soil quality benefits associated with utilization of manure on their fields.

Publications:

Moshia, M.E., R. Khosla, D.G. Westfall, J.G. Davis, and R. Reich. 2009. Precision Manure Management across Site-Specific Management Zones in the Western Great Plains of the USA. In the CD-ROM Proceedings of the European Conference on Precision Agriculture, Wageningen, July 2009.

Khosla, R., W.M. Frasier, D.G. Westfall, B. Koch. 2009. Economics of Fertilization Under Site-Specific Management Zones. In the Proceedings of the 2009 Western Nutrient Management Conference. Salt Lake City, UT.

Moshia, M.E, R. Khosla, D.G. Westfall, J.G. Davis, and R. Reich. Precision Manure Management across Site-Specific Management Zones in the Western Great Plains of the USA. In proceedings of the Joint International Agriculture Conference, Waginengen, Netherlands. July 6th-8th, 2009.

Moshia, M.E., R. Khosla, D. Westdfall, J.G. Davis, and R. Reich. 2009. Precision Manure Management on Site-Specific Management Zones: Surface soil quality and environmental impact. In the abstract book of the Western Society of Soil Science Annual Meetings. Fort Collins, CO June 22-23rd, 2009.

Khosla, R., and J. Davis. 2009. Precision Manure Management: Enhancing Soil Quality and Productivity. Newsletter of the Colorado Livestock Association.

Khosla, R., and J. Davis. 2009. Precision Manure Management: It matters where you put your manure. Extension Newsletter From the Ground Up. Vol 28. Issue 3. pg 24-25.

Moshia, M.E., R. Khosla, D.G. Westfall, J.G. Davis, and R. Reich. 2008. Nitrogen Mineralization Rate of Animal Manure across Productivity Level Management Zones. In Proceedings of the 9th International Conference on Precision Agriculture, Denver, CO July 21-23, 2008.

Moshia, M.E., R. Khosla, D.G. Westfall, J.G. Davis, and R. Reich. 2008. Precision Manure Management Strategies across Site Specific Management Zones for Enhancing Corn (Zea Mays L) Grain Yield. In Proceedings of the 9th International Conference on Precision Agriculture, Denver, CO July 21-23, 2008.

Moshia, M.E., R. Khosla, D.G. Westfall, J. Davis, R. Reich. 2008. Nitrogen mineralization rate of animal manure across productivity level management zones. In Proceedings of the Great Plains Soil Fertility Meetings, March 4th – 5th, Denver, CO.

Collaborators: