Soil pH and Phosphorus and Potassium Uptake by Maize Evaluated with an Uptake Model

Abstract Plant growth and nutrient uptake by plants have been shown to be affected by soil pH. However, the effects have not been evaluated with a mechanistic uptake model that can evaluate the relative influence of soil pH changes on changes in soil supply parameters that influence predicted P uptake. The objectives of this research were to verify the Barber‐Cushman nutrient‐uptake model under a range of soil pH conditions and to use the model to evaluate the influence of soil pH on the model parameters supplying P and K to maize ( Zea mays L.) roots. A pot experiment was conducted to evaluate the accuracy of the model for predicting P and K uptake at soil pH levels of 3.8, 4.7, 5.7, 6.5, 7.6, and 8.3 in Chalmers silt loam (fine‐silty, mixed, mesic Typic Haplaquoll). This study showed that the nutrient‐uptake model accurately predicted the effect of the soil pH on P uptake ( Y = 0.44 + 0.93 X , r 2 = 0.99) when the change of P from H 2 PO 4 to HPO 4 at the higher pH values was accounted for, and predicted K uptake ( Y = 67 + 0.94 X , r 2 = 0.99) without modification for pH.