Lucerne establishment in dryland conditions: effects of crop residues and wheat as a nurse crop

Abstract

Establishing lucerne (Medicago sativa) in dryland conditions poses challenges due to unpredictable rainy seasons and seedling vulnerability. A potential solution is adopting a nurse crop during the first year in the same field. This study aimed to assess the impact of wheat as a nurse crop and crop residue on lucerne establishment in South Africa’s Mediterranean climate region. The experiment employed a split-plot design with two treatment factors across six blocks. Half of the area received wheat straw, while the rest had low residue content with almost bare soil. The nurse crop combinations included wheat alone, lucerne alone, and a wheat-lucerne mixture. Results revealed competition between wheat and lucerne when planted together. When plant populations, total biomass, wheat grain yield and grain quality were considered, wheat performed better in pure stands, as did lucerne when grown without wheat. Germination of lucerne was significantly impacted by high crop residue levels. Wheat achieved superior grain yield without crop residue, despite producing less biomass. Results indicated that it is advisable to avoid using a nurse cropping system for lucerne in this Mediterranean climate region.