Impact of long-term production management practices on wheat grai yield and quality components under a semi-arid climate

摘要

Wheat production in South Africa has declined significantly over the past three decades making the country a nett importer of wheat. Proper production management practices are needed to counter this trend. The aim of the study was therefore to determine the effect of different production management practices on wheat grain yield and quality components after 37 years. The treatments included two residue management methods (burning and no burning), three tillage methods (no tillage, stubble mulch and ploughing), two weed control methods (chemical and mechanical) and three levels of nitrogen application (20, 30 and 40 kg N ha 1 until 2003, thereafter 20, 40 and 60 kg N ha-1). Grain protein content (GPC) was affected to a larger extent than hectolitre mass and falling number. Both grain yield and GPC varied over the long-term, probably due to annual rainfall variation and distribution. Grain yield was significantly higher with residue burning and GPC was lower compared to no residue burning. However, grain yield and GPC increased significantly with tillage intensity. Yield and GPC differences between the two weed control methods were negligible. Grain yield increased slightly with higher nitrogen application while GPC increased significantly. Incorporating crop rotation can probably improve the results with conservation agriculture practices, and requires further investigation.