Soil Temperature Effects on Root Growth and Phosphorus Uptake by Corn

Abstract

Temperature affects each of the mechanisms involved in P uptake by corn. The extent to which each reduces P uptake, however, has not been resolved. The objective of this study was to determine the effect of temperature on each of the parameters used in a mechanistic mathematical model that predicts P uptake and then to use the model in a sensitivity analysis to evaluate the temperature dependency of parameters critical for predicting P uptake by corn. The effect of soil temperature, 18 and 25°C, and soil P status on root growth and P uptake by corn (Zea mays L.) was investigated in a series of pot experiments in a controlled climate chamber. Total yield of corn was 4‐ to 6.4‐fold, root growth 2.6‐ to 5.1‐fold, and P uptake 2‐ to 4‐fold greater at 25°C than at 18°C. Increasing air temperature to 25°C while holding soil temperature at 18°C resulted in a 2.7‐fold increase in root growth and a 2.2‐fold increase in P uptake. Predicted P uptake calculated with a mechanistic mathematical model by corn grown for 8, 15, and 21 d agreed with observed P uptake at both 18°C (y = 0.97x + 3.64, r = 0.99**) and 25°C (y = 1.07 x − 1.86, r = 0.99**). In the sensitivity analysis the parameters used to calculate P uptake at 18°C were changed individually to those measured at 25°C and then P uptake was again predicted. Rate of root growth, which increased 4.97‐fold when temperature increased from 18 to 25°C, had the most pronounced effect on calculated P uptake, indicating that this was the primary reason low temperature reduced P uptake by corn. The parameters describing the movement of P to the root surface and P uptake at the root surface appear to play only a minor role in causing reduced P uptake by corn at low temperature.

Growth, phosphorus uptake, and water relations of safflower and wheat infected with an arbuscular mycorrhizal fungus

“…Mycorrhizal infection might be less beneficial under well watered than under drought conditions because P diffusion rates are much higher in moist soils (Koide, 1993). Mackay & Barber (1985) showed in corn that when soil moisture was raised from 22 to 27 "o total plant weight increased by 13-43 °o in soils of different P status. Corresponding increases in total P uptake by corn were 55-70"o, <ind corn root lengths increased 41-52 ^'Q.…”

Root mass distribution under conventional and conservation tillage

“…Corn root growth rates increase as temperature lncreases from lloC to 27oC (Barber and Kovar l99l) and reduced water and nutrient uptake at low soil temperatures have been attributed to poor root growth (Mackay and Barber 1984;Ma et al 1994). However, in much of the U.S. corn belt, temperatures are high enough that root growth rate is always 80% of the maximum potential rate (Barber and Kovar 1991).…”

Improving Phosphorus Nutrition of Corn

“…When planting early in high residue conditions, there is a greater risk of cool soil temperatures reducing root growth and nutrient uptake. Lower than optimum soil temperature can greatly affect root growth rate (Ching and Barber, 1979) and P uptake by roots (Mackay and Barber, 1984).…”