Effects of improved pigeonpea fallows on biological and physical soil properties and their relationship with maize yield

Declining soil properties have triggered lower maize yields among smallholder famers in South Africa. Legume trees such as pigeonpea can be used as improved fallows to replenish degraded soils. The objectives of the study were to: (1) examine the effects of improved pigeonpea fallows on enhancing biological, physical soil properties and maize yield responses and (2), analyze the relationship of maize grain yield to biological and physical soil properties after improved pigeonpea fallows at Wartburg, South Africa. Pigeonpea fallows were established in 2015/16 season and terminated in 2017 and subsequently maize was planted. A randomized complete block design replicated three times was used with five treatments: continuous sole maize without fertilizer (T1), natural fallow then maize (T2), pigeonpea + grass-pigeonpea then maize (T3), maize + pigeonpea-pigeonpea then maize (T4), two-year pigeonpea fallow then maize (T5). Improved pigeonpea fallows increased maize yields through improvement in soil macrofauna species abundance, richness and diversity, aggregate stability, infiltration rate. Pigeonpea fallows increased maize yield by 3.2 times than continuous maize without fertilizer. The maize grain yield (3787 kg ha(-1)), was the highest on two-year pigeonpea fallows while continuous maize without fertilizer had the least (993 kg ha(-1)). There was a significant positive correlation between soil macrofauna indices and physical soil properties to maize yields. Smallholders who have limited access to fertilizers can sustainably use improved fallows to restore degraded soils to achieve higher maize yields in South Africa.