Utilisation of cover crops: implications for conservation agriculture systems in a mediterranean climate region of South Africa

Abstract

Cover crops can provide multiple agroecosystem services to crops produced in conservation agriculture systems. South African grain producers in the Mediterranean climate region are reluctant to integrate cover crops in rainfed systems since cover crops replace cash crops leading to nancial losses. Using cover crops as fodder can help cover input costs, while providing a range of advantageous services to the cropping system. The aim of this study was to investigate how cover crop mixtures and the utilisation of cover crops affect soil quality, the quality and quantity of the mulch as well as wheat (Triticum aestivum L.) produced in the subsequent year. Methods A two-year study was conducted in the Western Cape Province of South Africa. In Year 1, diverse legume and cerealbased cover crop mixtures were partially grazed, cut and material removed for haymaking, or left unutilised as a mulch. In Year 2, spring wheat (Triticum aestivum L.) was planted to investigate the effects of cover crop mixtures and utilisation method on subsequent spring wheat yield. Results Cover crops used as hay or for grazing did not affect (P < 0.05) grain yield of wheat that followed in rotation. Legumebased cover crop mixtures increased (P < 0.05) wheat grain protein content regardless of utilisation method. Soil quality and nitrogen content improved (P < 0.05) when cover crops were grazed. Conclusions Cover cropping can be used by South African grain producers as an important agronomic tactic to improve system productivity and support sustainable intensi cation of rainfed cropping systems.

Views and perspectives of local farmers on crop diversification in the North-Western Free State, South Africa

“…This corresponds to the current surge in soya bean production where the area planted under soya beans in South Africa has increased by 64% since 2016/ 2017 with the North-Western Free State being a major contributor (Department of Agriculture, Land Reform and Rural Development (DALRRD), 2020; Farmer's Weekly, 2021). Few farmers in the area rotated maize with cover crop, which is a cash crop substitute that should be considered to improve rotational system's productivity (Smit et al, 2021). By introducing cover crops, with the already included soya beans in rotation with maize, soil nutrients could be further replenished, decreasing the R 2 Linear = 0.17 y = -0.10 + 0.13*x Total average relevance Crop Density Index amount of costly fertilizer required (Nortjè and Laker, 2021).…”

“…Crop rotation systems are normally made up of shallow and deep-rooted crops alternating with leguminous crops (Indoria et al, 2017). Studies suggest that by diversifying crops, farmers prevent nutrient losses and have the potential to maintain high production levels with less fertilizer (Rovers and Kroonen, 1999;Nevens and Reheul, 2001;Smit et al, 2021). These benefits improve soil structure and moisture holding capacity which in turn improves root growth and root vigour, resulting in a healthy, high yielding plant (Nickel et al, 1995;Weisskopf et al, 1995).…”

“…Sustainable rotational systems differ according to climate and soil conditions; what works for one area does not necessarily work in another (Nortjè and Laker, 2021;Smit et al, 2021). Often farming systems proven successful in developed countries are attempted elsewhere with disappointing results, especially in developing countries (Nortjè and Laker, 2021).…”

Effects of Long-Term (44-years) Tillage Sequences on Wheat Grain Yield in a Dryland Farming System in South Africa

“…In addition, the substantial increase in wheat grain yield across all tillage treatments could also be attributed to the positive effects of growing cover crops for three consecutive years within this trial site. Smit et al (2021) noted that the use of cover crop mixtures can increase soil available nitrogen and can lead to increased productivity of the following crops.…”

Regenerative agriculture v. conservation agriculture: potential effects on soil quality, crop productivity and whole-farm economics in Mediterranean-climate regions

“…These limitations warrant investigating the option of using nutrient-rich cover crops as a mulch following termination. Mulched winter cover crops have been shown to increase soil nitrogen and organic carbon in numerous long-term studies (Vincent-Caboud et al 2019;Smit et al 2021). However, more research is needed to better understand the link between cover crop composition, in terms of the C-to-nitrogen (N) ratio, decomposition and mineralisation dynamics in the context of hot, dry Mediterranean summers.…”