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 two years of project work indicates that the variable rate application of animal manure across productivity level management zones is potentially a good strategy for enhancing grain yield of low producing areas of the spatially variable farm fields. However the potential is not conclusive. Improvements in soil quality (as hypothesized) are yet to be observed since it is time related. However, there is significant interest among farmers in learning “how to enhance the value of manure and its utilization for production and soil quality purposes.”

Objectives/Performance Targets

1. Demonstrate and compare five manure management strategies applied across site-specific management zones delineated on farmers’ 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 October 2007 through December 2008, i.e., second year of our project.

Crops from the demonstration fields were harvested at maturity in October/November of 2007. Data collected from crop harvest were analyzed to compare the various manure management strategies for the first year of the project. Our first year data indicated that application of manure in higher amounts on low productive areas of the field has potential to enhance 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 first year soil samples was completed by late summer of 2008.

Likewise the N mineralization study (i.e., to evaluate soil N mineralization potential of manure applied on soil across productivity potential management zones that was initiated by graduate student, Edwin Moshia in summer of 2007) was completed by early spring of 2008. And as per our expectation, this additional laboratory work is helping us in understanding the reasons behind soil N-mineralization under different manure application rates across management zones [Note: soil N mineralization study was not a part of this project].

Based on the lessons learned from 2007 and to avoid the failure (as that happened in spring 2007 due to weather conditions), the project team decided to select the demonstration fields at the cooperating farmer’s farm in fall of 2007. Soil sampling was performed, management zones delineated, and manure was “fall-applied” instead of “spring-applied.” The cooperating farmers were more enthused about such a manure application strategy in fall versus spring time. In 2008 growing season we successfully conducted our project on five locations (Objective 1 and 5). Three locations were on farmers field and two locations (one dryland and one irrigated) were at the CSU Agricultural Research Development and Education Center (ARDEC).

The crop growing season had a natural stress on the crop. At the Fort Collins location (ARDEC) there was a tornado that went through ARDEC followed by a severe hailstorm. The occurrence of a tornado in this region (foothills) of Colorado is very rare. The last reported tornado was 37 years prior to this one. While the tornado did not pass through the crop fields, the hailstorm did adversely impact the leaf area index of the crop. The crops were harvested in late November and early December because of unpredictable snowfall in the region that delayed harvesting. We are currently in the process of analyzing the yield data to estimate the yield losses due to the hailstorm.

Based on the soil and crop data collected over the past 2 years of the project, the responsible team members of our project started working on the impact of manure management strategy on water quality risk, through the use of P Index and the N Leaching Index (objective 4). Ms. Addy Elliot, research associate of Dr. J. Davis, is currently working on that aspect of the project. Likewise, Edwin (graduate student) who is working on his Ph.D. research by virtue of this project initiated working on the economic comparisons of site-specific management zone based manure management strategies (objective 3) under the guidance of Dr. Marshall Frazier (Ag Economist and Co-PI of the project).

Preliminary findings of the project were presented at several conferences. We presented the first-year findings of this work at the Great Plains Soil Fertility Meetings in Denver, CO in March of 2008. Two papers (one oral and one poster) were presented at the 9th International Conference on Precision Agriculture in Denver, CO, July 2008. Likewise, one oral paper presentation was made at the American Society of Agronomy and Soil Science Society of America Meetings in Houston, TX in October 2008.

Impacts and Contributions/Outcomes

In 2007, based on the summary of evaluations from the two “hands-on workshops” and two “field-days” conducted in 2007, we impacted over 65 individuals who attended the workshops and fields days. Total acres impacted as reported by the participants were 108,450 acres,. out of which 55,450 acres were farmer-owned and 53,000 were consulted upon. The crops impacted were forages, alfalfa, corn, wheat, sugar beets, barley, sunflower, pinto beans, safflower, and vegetables. The weighted average value of our workshop as reported by the participants was about $2.33/ac which would translate into an economic impact of over $250,000.

In 2008, we were able to impact 31 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 is significant interest among farmers who are enthusiastically participating in our project to find out the soil quality benefits associated with utilization of manure on their fields and consequential increase in the yield of the low productive areas of the field. We received new requests from consultants, producers, and extension agents to organize workshops to share the findings of our work.

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