Effects of oats and grazing vetch cover crops and fertilisation on microbial biomass and activity after five years of rotation with maize

Abstract

Degraded soil quality could be improved by cover crops. This study determined effects of maize–oats and maize–vetch rotations with or without fertilisation on soil microbial biomass and activity. Winter treatments were oats, vetch and weedy fallow, in rotation with summer maize. Fertilisation strategies were: fertilised cover crop and maize (F1), fertilised cover crops only (F2), fertilised maize only (F3) and no fertiliser (F4). The 2 × 4 factorial (plus control) was laid out in a randomised complete block design with three replications. After five years, soils were sampled from the 0–5 and 5–20 cm depths and analysed for microbial biomass carbon (MBC), dehydrogenase, β-glucosidase, urease and phosphatase activities. Cover crops resulted in higher MBC and enzyme activities than the weedy fallow. Fertilisation of cover crop (F2) and maize (F3) resulted in similar MBC. The F4 in cover crops and F3 under weedy fallow had similar dehydrogenase activities, whereas F4 under vetch was similar to F3 under oats. The F4 for vetch had similar β-glucosidase activity to F1, and urease activity to F1, F2 and F3, of oats. Phosphatase activities in F1 and F2 were similar. The use of vetch and fertilisation of cover crops stimulated soil biological activity compared with the control.

Keywords: cover crops, fertiliser, soil enzymes