Agricultural intensification and climate effect on soil productivity in south-eastern Nigeria

Agricultural intensification and climate variability will affect future food security. Improved soil, land and water management strategies are desired to enable science-based land management interventions for improved soil productivity to achieve food security. Quantitative analyses of soil and 12 years (2000-2011) of rainfall/temperature data were analysed using standard schemes. The soils were variously classified: Typic Paleustults in Nsukka, Typic Haplustalfs in Umuahia South and Oxic Dystrusteps in Ikot Abasi. Soil degradation effects were most significant in Nsukka (SDR= 3.4; P<0.01) cultivated soils than those of Ikot Abasi (SDR= 2.6) and Umuahia South (SDR= 2.5; P<0.05). Anomalies and variations in rainfall and temperature over the 12 year period revealed rainfall decreases and temperature increases into the future, hence susceptibility of crop yields. Temperature changes had a much stronger impact on crop yields than rainfall changes. Rainfall decreased cassava (0.5139 kgha-1, P<0.05) and maize (0.1371 kgha-1, P<0.05) yields, while temperature decreased all crop yields: cassava (14.4556 kgha-1, P<0.001), maize (11.1758 kgha-1), cowpea (0.0538 kgha-1) and rice (8.1310 kgha-1) and accounted for 66 and 58 % significant (P<0.05) variation in cassava and maize yield, respectively. Land degradation also decreased cassava (6.6739 kgha-1) and cowpea (0.0359 kgha-1) yields. Continuous decrease of crop yields by unit (1oC) temperature increase and rainfall decrease negatively implicate food security in the future. Farmers ranked importance of soil properties to soil productivity. Combined green soil conservation measures: cover crops/live mulch; establishment of Vetiver system and early planting of diversified improved crop varieties are adaptation strategies recommended for action.