Deep cultivation of a sandy clay loam II. Effects on soil hydraulic properties and on root growth, water extraction and water stress in 1977, especially of broad beans

Abstract

Increasing the depth of cultivation from 23 to 45 cm reduced the water extracted by potatoes ( Solanum tuberosum), broad beans ( Vicia faba var. major), summer cabbage ( Brassica oleracea var. capitata) and red beet ( Beta vulgaris var. rapacea f. rubra) from the 0–30 cm depth and increased extraction from the 30–70 cm depth. Deep cultivation lowered bulk density, increasing the water holding capacity (%, w/ w) and allowing more rapid drainage. Broad beans yielded 17% more total dry matter after deep cultivation, had deeper root systems and for a limited period showed less water stress and extracted more water than the same crop grown after minimum tillage. It is argued that the effect of the altered soil hydraulic properties on crop water extraction was small and theoretical calculations suggest that improved root distribution accounted for the beneficial effects on water use.