Root Characteristics and Phosphorus Uptake of Maize Seedlings in a Bilayered Soil

Abstract

Under temperate climates, no‐tillage results in cooler and denser topsoils than conventional tillage (CT) and in surface accumulation of immobile nutrients. Hence, early growth and functioning of maize ( Zea mays L.) roots may be adversely affected. These field conditions were simulated in a controlled environment system, allowing gradients in soil properties between topsoil (0–10 cm) and subsoil (10–50 cm). Combinations of topsoil temperature (Temp top ), bulk density (BD top ), and P concentration (P top ) were applied on maize seedlings grown until the three‐leaf stage. Topsoil bulk density and Temp top acted independently on shoot and root parameters but showed some interactions with P top An increase in BD top caused a linear decrease in root length, root mass, and the root/shoot ratio; an increase in root diameters in both topsoil and subsoil; and a concentration of roots in the topsoil. This resulted in a greater contribution of the topsoil roots to the nutrient supply of the shoot, as shown by 15 N labeling. Decreasing Temp top reduced shoot and root growth to a similar extent. High P top increased length, diameter, and topsoil fraction of roots, particularly at high BD top There was possibly a trade‐off between the adverse effects of low Temp top and the positive impacts of high P top on root growth. Shoot P concentration (P c ) was increased by high P top and, to a lesser degree, by increasing BD top The temperature of the topsoil had no effect on P c . It is concluded that in dense, cool soils, particular attention needs to be paid to the P supply of maize seedlings.