Conservation agriculture effects on plant nutrients and maize grain yield after four years of maize–winter cover crop rotations

Abstract

The effects of maize rotation with oat (Avena sativa cv. Sederberg) and grazing vetch (Vicia dasycarpa cv. Max) winter cover crops on nutrient availability, maize grain yield and maize grain nutrient concentration were investigated. Soil samples were collected from the 0–5 and 5–20 cm depths of experimental plots after four years of continuous maize–winter cover crop rotations. Winter cover crops caused small increases of extractable soil Cu, Mn, P and Zn, but not Ca and K, concentrations. A small dose of fertiliser applied to maize (60, 30, 40 and 1.5 kg ha−1 of N, P, K and Zn, respectively) also caused a significant increase in P and Zn, as well as mineral N, concentrations but only in the vetch–maize rotations. Stratification of Mn, K and Zn in the 0–5 cm soil depth occurred in all treatments. Vetch additionally increased maize grain yield, grain N concentration and soil acidity more than either oat or fallow. Non-fertilisation of maize reduced maize grain yield on oat and fallow–maize rotations more than it did on vetch–maize rotations. A combined application of vetch winter cover crops and small doses of fertiliser could significantly improve sustainability of low input maize-based conservation agriculture systems.