Infl uence of Short-duration Legume Fallow on N Availability and Performance of Tomato in a Tropical Rainforest Zone of Nigeria

Th e incorporation of plant biomass (litter/prunned residues) into the soil constitutes an important pathway for nutrient cycling in ecosystems. Th e feasibility of meeting N needs of tomato (Lycopersicon esculentum Mill) with short-duration pigeon pea fallow was studied in the fi eld in Akure, a humid zone of Nigeria. Th e trials were set up on site where late season pigeon pea – maize intercrop was previously assessed between August and December in years 1999 and 2000. Fallows were allowed to grow during the fi ve months of dry season and were cleared before planting tomato in the following rainy season. Treatments consisted of 3 x 2 factorial combinations of tomato macroplots established following the previous years layout on fallows of pigeon pea alone, pigeon pea interplanted with maize and non-fallow land at two levels of inorganic N fertilizer (0 and 150 kg N ha-1) with three replications per treatment. In both seasons, preseason topsoil inorganic N correlated with tomato fruit yield (r2 = 0.45; P < 0.001). Accumulation of N in the aboveground biomass related weakly to initial soil N contents (r2 = 0.32; P<0.001) while fruit yields of tomato signifi cantly correlated with N concentration in aboveground biomass (r2 = 0.97; P < 0.01). Th e status of soil nitrogen, plant N uptake and yields of biomass and fruits of tomato under pigeon pea biomass incorporation following legume fallow were similar to those obtained under mineral fertilizer application. Th erefore, N requirement of tomato can be partly substituted by short-duration legume fallow.