Predicting the Most Efficient Phosphorus Placement for Corn1
- I. Anghinoni and
- S. A. Barber2
Yield increase from P fertilizer application depends on the efficiency of utilization of the added P. Placing added P in part of the soil volume rather than mixing it with all the soil may increase P uptake because of less tie-up of P by the soil, however, the degree of benefit from P placement has been difficult to predict. The objective of this paper is to use data from P placement experiments with corn (Zea mays L.) together with a simulation model to develop a procedure for estimating the P placement that will maximize P recovery and plant yield. The Claassen-Barber simulation model gave predicted P uptake by corn that compared favorably with observed P uptake and hence was used in this study. The model uses parameters describing root growth and morphology, kinetics of P uptake, and kinetics of P supply by the soil. Measurements of corn root growth as affected by P placement, of P influx into corn roots as influenced by P concentration, and of soil P supply as affected by rate of P addition to three soils were used to provide data to use in the simulation model. Predicted P uptake by corn was calculated for a range of fractions of the soil volume treated with five rates of added P per pot for two soils and with one P rate on an additional soil. Uptake of P from P-treated soil was added to uptake from untreated soil to get total P uptake. As the volume fraction of P treated soil increased from zero, calculated P uptake increased to a maximum then decreased with further dilution of added P with soil. The optimum fraction of the soil that had to be P-treated to get the greatest predicted P uptake increased with rate of application. Where one rate was applied to three soils, the greater the adsorption of P by the soil, the lower the fraction of P-treated soil needed to maximize P uptake. The principles illustrated in this paper may be useful for developing the most efficient fertilizer placement for crops grown in the field.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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