Abstract
Two trials were conducted on a clay soil and one on a loam soil in the wet season in Trinidad. No-tillage did not significantly reduce the plant parameters of plant height, leaf area, stem dry matter (OM), leaf DM, root OM, nodule DM, seeds pod-1, yellow pod yield, and dry seed yield compared to conventional tillage on the clay and loam soils. Although conventional tillage decreased soil moisture content (SMC), it did not significantly increase crop performance. Application of N fertilizer or rhizobium on the clay soil was beneficial to cowpea especially under high moisture conditions and no-tillage. Nitrogen fertilizer did not significantly affect plant height but it significantly increased leaf area, stem and leaf DM, and pod yield. Nitrogen at 40 kg ha-1 significantly increased cowpea yield especially under high moisture conditions and no-tillage on the clay soil. It would appear that N can compensate for the adverse soil conditions caused by high moisture and no-tillage. On the clay soil rhizobium inoculation was not as effective as 40 kg N ha-1 but on the loam 40 kg N ha-1 depressed yields and only rhizobium was effective in significantly increasing crop performance.
