Soil-Chemical Properties as Affected by Yam/Cassava/Landrace Legumes Intercropping Systems in Owerri Ultisols Southeastern Nigeria

摘要

Soils with low N when planted with legumes or legumes in association with tuber/root crops helped to increase N-fixation. Biological nitrogen fixation may be the only means by which N supply to plants can be increased in tropical farm lands since yam/cassava based intercropping with landrace legumes left behind substantial amounts of N after a cropping season especially when initial soil N is low. Intercropping and even sole cropping resulted in increased organic matter content of the soil and higher quantities are expected when the litters are incorporated into the soil and there is total decay. There is Phosphorous (P) decline in plots with tuber/root crops as they take up large quantities of P from the soil. Also, there was a decline in soil basic cations calcium (Ca) magnesium (Mg) and potassium (K) in tuber/legume crop mixture. This is viewed as being temporary since the decay of litters and roots of these crops thereafter will boost the soil reserve as a result of humus complexes, which will release most of the lost nutrients back to the soil. Tuber/legume crop mixture increased soil pH . Soil chemical properties in terms of macro, meso and micro nutrients after a cropping period depends on the type of crops planted and cropping systems used.