Combinations of in-field moisture conservation and soil fertility management reduce effect of intra-seasonal dry spells on maize under semi-arid conditions

Abstract

Abstract The high frequency of prolonged intra-season dry spells since the turn of the 21st century continues to heighten risk of crop failure in rainfed cropping systems of Southern Africa including Zimbabwe. This study explored the effects of combining in-field moisture conservation techniques and soil fertility management on maize (Zea mays L.) productivity under rainfed conditions in semi-arid eastern Zimbabwe. Treatment combinations were co-designed with farmers through participatory approaches, and tested on-farm on sandy and clayey soils over three consecutive seasons (2015/16–2017/18). Two tillage practices namely conventional (CT) and reduced tillage (RT), with 30 % mulch cover of dried thatching grass (Hyparrhenia filipendula (L.) Stapf) applied either at planting or tasseling or at both stages, were combined with low (35 kg N ha−1, 14 kg P ha−1and 3 t ha−1 of manure) and high (90 kg N ha−1, 26 kg P ha−1 and 7 t ha−1 of manure) fertilizer application rates in a split-split plot design. Intra-seasonal dry spells were more frequent during the first two seasons (i.e. 2015/16 and 2016/17), while the 2017/18 season was rather wet with well-distributed rains. Soil water content varied significantly (p