Prediction of Phosphorus and Potassium Uptake by Soybeans with a Mechanistic Mathematical Model
1983
Silberbush, M. | Barber, S. A.
Mechanistic mathematical models have been used to predict P and K uptake by corn (Zea mays L.) but not soybeans (Glycine max L. Merr). A model developed by Cushman to account for root competition has not been tested. The objective of this research was to evaluate the Cushman mathematical model for predicting P and K uptake by soybeans. Three soybean cultivars, ‘Century’, ‘Williams-79’, and ‘Elf’, were grown on two soils in a controlled climate chamber and harvested at intervals from 12 to 28 d. The soils were Raub, an Aquic Argiudoll, and Chalmers, a Typic Haplaquoll, silt loams. The Cushman model was used to simulate P and K uptake from soil by soybeans. Predicted P uptake (y) agreed closely with observed P uptake (y = 1.08x −0.06, r= 0.96) for uptake by all cultivars on both soils. Predicted K uptake was overestimated on Raub soil (y = 1.53x − 0.84, r = 0.97) but was closer for the Chalmers soil (y = 0.95x − 0.43, r = 0.95). The Cushman model was as satisfactory for prediction of P as the Claassen-Barber model, but predicted K uptake more accurately because root-to-root competition for soil K is a factor in K supply to the root.
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