Project Details:

Evaluation of Soil Health Test to Determine Fertilizer Needs for Soybean in Kansas

Parent Project: This is the first year of this project.
Checkoff Organization:Kansas Soybean Commission
Categories:Soil fertility, Soil and tillage management
Organization Project Code:1751
Project Year:2017
Lead Principal Investigator:Dorivar Ruiz-Diaz (Kansas State University)
Co-Principal Investigators:
Charles Rice (Kansas State University)
Gretchen Sassenrath (Kansas State University)
Doug Shoup (Kansas State University)

Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

Recent emphasis on sustainable agriculture resulted in a renewed interest in soil health as key component for sustainable crop production. Chemical soil heath indicators are currently used to provide fertilizer recommendations to producers. In addition to chemical indicators, soil health test also include physical and biological assessment that in combination can potentially help improve overall recommendations. However, any soil test method requires appropriate correlation and calibration under local soils and production systems for accurate fertilizer recommendations. The Soil Science Society of America define soil test correlation as "The process of determining the relationship between plant nutrient uptake or yield and the amount of nutrient extracted by a particular soil test method". And soil test calibration as "The process of determining the fertilizer requirement at different soil test values". These two essential components are well established for currently used test in Kansas. However, newly developed soil health test will require appropriate correlation-calibration for Kansas.
It is critical to recognize the importance of correlation and calibration in developing fertilizer recommendations. When soil is sent to a laboratory for analysis, specific procedures and extractants are used to determine the estimated availability of nutrients. Different extracts and procedures typically result in different estimates of nutrient availability. The process of correlation helps determine the relationship between plant nutrient uptake or yield and the amount of nutrient extracted from the soil. A soil test is considered "correlated" when lower yield and plant growth can be predicted at lower soil test values, and higher yield and plant growth can be predicted at higher soil test values.

Project Objectives

1.Evaluate commercially available soil health tests for fertilizer management in soybean under Kansas soils and production practices; and compare to traditional soil test methods.
2. Determine the effect of long-term management practices (i.e. tillage system, cover crops, rotations) on fertilizer requirements/recommendations for optimum soybean yields.
3. Develop soil test interpretations for recently proposed soil health chemical indicators (Haney H3A and Cornell modified Morgan), and evaluate the effect of physical and biological factors/indicators on nutrient availability and plant uptake.

Project Deliverables

This project will be completed at 4-5 locations each year. Locations will be selected based on contrasting management history to include fields with multiple years under no-till, use of cover crops, and fields under conventional tillage system. Soil samples at the 0-6 inch depth will be collected from the study area and analyzed using commercially available soil health test with emphasis on chemical indicators for fertilizer recommendations. Two soil health test methods (Haney and Cornell) will be evaluated for soybean in Kansas. The extraction methods used by these test include the Haney H3A and Cornell modified Morgan. These analyses will be performed in cooperation with the KSU soil testing lab when possible to explore the possible value of alternative soil test methods for soybean in KS.
Soil samples will be also analyzed for routine soil fertility test recommended for Kansas. Analysis will include soil test phosphorus (Mehlich-3), soil test potassium (Ammonium acetate), and soil pH by standard methods. Key physical and biological soil health indicators will be evaluated in addition to chemical indicators.
Correlation and calibration of soil health tests methods will be completed for P and K. Fertilizer application treatments will include multiple rates of P and K to estimate the soil test critical concentration using soil health methods as well as current KSU recommended methods. Soil samples collected for this study will be handled and analyzed using two methods 1) traditional air-dry and ground samples, and 2) moist samples. The use of dry and moist soil samples as well as the use of soil health test (such as C02 burst) will be evaluated to help improve the accuracy of current fertilizer recommendations.
Total plant nutrient uptake will be evaluated during the growing season by tissue analysis for total N, P, and K. Soybean whole plant samples will be collected at the V3 stage and the uppermost trifoliate at the R2-R3 stage and analyzed for total N, P, and K. These measurements will be used to estimate nutrient uptake and nutrient use efficiency with fertilizer application and correlated to the soil tests evaluated in this study. At harvest, yield will be recorded for each plot and a seed sample will be collected and analyzed for seed quality, nutrient content and removal.
Collaboration with other studies: proposed collaboration with other projects include: "cover crop effect on soybean yield" (Shoup et al.); and "cover crops to control soil-borne pests and diseases" (Sassenrath et al.). These collaborations can provide an opportunity to evaluate soil heath test methods for fertilizer recommendations under cover crop management systems; in addition to other management, soils, and tillage system in KS.

Progress of Work

Update: field studies were established at 5 locations with a mix of contrasting management systems. Some locations included long term no-till and the use of cover crops as well as conventional tillage system with minimum use of soil health management tools. Treatments were established and intensive soil sampling was completed before planting and samples are currently under analysis.

Update: Soybean plant samples were collected from field studies and submitted for analysis. Lab analysis of soil samples for soil health test methods are ongoing.

Update: Soil and plant analysis was completed for most study locations. Data analysis for the 2017 season is ongoing. Preliminary results show that some soil health chemical methods show correlation to traditional soil test methods. Contrasting soybean management systems in 2017 showed differences in soil test parameters. Physical and biological soil parameters will be evaluated for correlation with soybean yield response.

Updated April 15, 2018:
Update: data analysis for the 2017 season was completed and the 2018 study locations identified. Field studies in 2018 will be established at 5 locations with contrasting management systems. Locations will include long term no-till and the use of cover crops as well as conventional tillage system with minimum use of soil health management tools. Treatments will be established and intensive soil sampling will be completed before planting.

Final Project Results

Benefit to Soybean Farmers

Currently available commercial soil health test provides general recommendations for crop production in Kansas. However, there are no published studies on correlation and calibration research conducted in Kansas for these tests. This study will contribute with new information and help develop guidelines for accurate interpretation of soil health test for fertilizer management in Kansas. Appropriate fertilizer management will contribute with increased productivity, cost savings, and to minimize the environmental impact.

Performance Metrics

Project Years