Simulating corn yields over 16 years on three soils under inorganic fertilizer and hog manure fertility regimes
1995
Parsons, R.L. | Pease, J.W. | Martens, D.C.
Corn yields (Zea mays L.) on control treatments with inorganic fertilizer and on copper-enriched hog manure treatments with annual rates up to 168 mt/ha from a 16-year study were modelled with the Erosion Productivity Impact Calculator (EPIC) simulation model. The field research study was conducted on three diverse soils, a Guemsey silt loam, a Bertie fine sandy loam, and a Starr-Dyke clay loam. Results indicated that EPIC simulated the manure and fertilizer treatments equally well. EPIC produced simulated yield means that were not different from measured yield means for all treatments (p less than or equal to 0.05). Goodness of fit tests indicate that simulated yields did not differ from measured yields for all simulation models except the Bertie manure treatment (p less than or equal to 0.05). For control and manure treatments, simulated yields explained 78% and 89% of variation in measured yields for the Guernsey soil, 55% and 42% for the Bertie soil, and 76% and 70% for the Starr-Dyke soil, respectively. Overall, these are reasonable yields estimates, but site-specific soil and other model parameter respecification is critical. Yield modeling with heavy applications of animal manure or inorganic fertilizer is feasible and useful.
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