On-farm Assessment of Cover Crop Management Effects on Plant Tissue Nutrients and Soil pH in the Western Cape Province

 Abstract — The choice of cover crop (CC) species and their growth termination stage is crucial to optimize their benefits. Field experiments were carried out at two sites (Nietvoorbij and Bien donne) in the Western Cape, from 2017 to 2018. This study examined the: (i) Effect of two termination stages (vegetative and flowering) on the chemical composition (C, N and C:N) of four CCs (oats, rye, pea, vetch) and (ii) Short-term impacts of living CCs and residues on soil pH. The experiment was conducted in a randomized block design with three replicates. Plants were sampled at kill while soil was sampled at kill and one year after. Delaying termination from vegetative till flowering increased the total C and C:N ratios of vetch, pea, oats and rye, respectively, while their tissue N decreased, at both sites. CC presence also decreased soil pH at both sites. Results of this study showed that CC tissue and soil C, N, C:N ratios may be manipulated through appropriate species selection and termination stage. However, longer-term studies are needed to evaluate the long-term effects of CC species on soil pH which have the potential to affect microbial activities and nutrient release