A study carried out for two cropping seasons at Nsukka, southeastern Nigeria, to determine the minimum rate of straw mulch for optimising the physical conditions of the topsoil (0–20 cm depth) of a fragile ultisol and maize (Zea mays L) and cowpea (Vigna unguiculata L Walp) yields, found that soil water sorptivity, transmissivity, steady state infiltration rate, cumulative infiltration after 90 min and time to attain steady state infiltration were optimal at the 2.0 t ha−1 mulch rate. Also, at this rate of mulching, water retention and per cent water-stable aggregates > 0.5 mm were maximal whereas soil compaction (measured by dry bulk density) was minimal. Between 2 and 10 days after saturation the surface soil had reductions of 11, 6, 6 and 6% in volumetric water content, respectively, on the control (0), 2.0, 4.0 and 8.0 t ha−1 mulched plots, mainly due to evaporation. Supra-optimal soil temperatures (> 30°) were observed only on the bare plots whereas no significant differences in maximum soil temperature among the mulched plots were noticed. Maize and cowpea yields were optimal at the 4.0 t ha−1 rate with respective increases over the bare plots of 80 and 67% at this rate.
Journal of the Science of Food and Agriculture 01/1991; 57(4):517 – 526. DOI:10.1002/jsfa.2740570405