Soil moisture dynamics under rainfed sorghum and soybean on contrasting tillage–mulch seedbeds in a mineral sandy loam at derived savanna of south-eastern Nigeria
2012
Obalum, Sunday Ewele | Igwe, Charles Arizechukwu | Obi, Martin Eze
Rainfall variability, often accompanied by high temperatures and soil drought, is a common problem of grain crop production by resource-poor farmers in Nsukka Agroecological Zone of Nigeria. The effects of no-till (NT), conventional tillage (CT), bare-fallow (B) and mulch (M) (combinations of which gave NTB, NTM, CTB and CTM) on moisture status of a sandy loam sole-cropped to sorghum and soybean at Nsukka were evaluated during the 2006 and 2007 growing seasons. Sampling was carried out from 0–10, 10–20, 20–30 and 30–50 cm soil layers at 10±1-day intervals. Rainfall was more favourable in the first season than in the second. The effects of the tillage–mulch treatments were generally less distinct under sorghum than soybean. The profile moisture storage followed the order, NTM ≤ CTB ≤ CTM ≤ NTB under sorghum and NTB ≤ CTB ≤ NTM ≤ CTM under soybean. Moisture content tended to be higher with CT within the 0–20 cm layers, but with NT in the 30–50 cm soil layer under soybean. Higher moisture status due to mulch was evident under both crops. The soybean field maintained a higher soil moisture status than the sorghum field during the second season. The differing effects of the crops should be considered in years of erratic rainfall, especially when the next crop can benefit from the residual soil moisture.
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