Influence of Residual Nitrogen and Tillage on White Lupin

Abstract

White lupin (Lupinus albus L.) yield and forage quality depend on the tillage and residual N from a previous crop. The objective of this study was to evaluate the response of winter white lupin seeded in two tillage systems [strip‐till (ST) and conventional (CT)] to four N rates applied to a previous cotton (Gossypium hirsutum L.) crop (0, 67, 134, and 202 kg ha−1). The experiment was conducted in 1995–1996 and 1996–1997 growing seasons. The influence of residual N from a previous cotton crop on white lupin dry matter and grain yields, and silage N concentration varied from year to year. Residual N did not influence silage in vitro organic matter digestion (IVOMD), neutral detergent fiber on a dry matter (DM) basis (NDFt), or neutral detergent fiber ash‐free (NDFaf). However, the weight of 1000 lupin seeds increased by 0.07 g for every 1 kg N applied to a previous cotton crop. Dry matter and grain lupin yields were 15 and 31% greater from ST than CT, respectively. Silage NDFt and NDFaf from ST were 6% greater than that from the CT system. However, the IVOMD, N, and P concentrations were 2, 11, and 27% greater from CT than ST, respectively. The results of this study indicate that greater dry matter and grain yields, NDFt, and NDFaf, and lesser IVOMD, N, and P concentration may be obtained from ST than CT. However, the influence of residual N on dry matter and grain yields of white lupin needs to be further defined.