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.