Growth, yield and grain protein content of wheat (Triticum aestivum L.) in response to nitrogen fertiliser rates, crop rotation and soil tillage

Abstract

Soil tillage affects both the profitability and sustainability of cropping systems. Minimum- and no-tillage systems are promoted because research has shown that these systems may reduce production costs and improve biological sustainability when compared to conventional systems, in which mouldboard and disc ploughs are used. However, responses to different tillage systems may differ for different crops as well as different soil and climatic conditions. This long-term study, conducted under a Mediterranean-type climate, showed that no-tillage systems can be used successfully to produce spring-type wheat crops in sustainable crop rotation systems under rain-fed conditions in the Swartland wheat-producing area of the Western Cape province of South Africa. Higher wheat yields when wheat is grown in a crop rotation system compared to a monoculture system can be ascribed to improved soil organic carbon and nitrogen (N) contents, which result in more plant-available mineral N and hence more vigorous crop growth. Grain yields of wheat responded positively to increased N application rates and the results suggest that application rates of more than 100 kg ha–1 should be considered where minimum and no-tillage are practised. Higher N application rates resulted in higher grain protein and hence improved bread-making quality of the wheat.

Keywords: cropping systems, fertiliser applications, soil properties, soil tillage, Triticum aestivum

South African Journal of Plant and Soil 2012, 29(2): 73–79