Response of rice to nitrogen and phosphorus applied on typical soils of Dakawa Irrigation Scheme, Morogoro, Tanzania

Abstract

A screen-house pot experiment was conducted at Sokoine University of Agriculture, Morogoro, Tanzania to assess response of rice variety TXD 306 growth parameters to nitrogen and phosphorus applied to the dominant soil type at Dakawa Irrigation Scheme (DIS) Morogoro, Tanzania. The study was prompted by low rice yields and the need to find out the soil constraints to high rice production at the scheme. Based on physical, chemical and biological properties of composite soil sample, the soil had low total N, OC, exchangeable Ca and Mg, hence rated as marginally to moderately suitable for rice production. N and P rates adopted were 0, 50,100, 150, 200 kg N ha-1 and 0, 40, 80, 120, 160 kg P ha-1, respectively. Sources of N and P were (NH4)2SO4 and Ca(H2PO4)2, respectively applied in a 52 factorial in CRBD. Number of tillers increased significantly (p < 0.05) with N and P levels from P0N0 kg ha-1 to P80N200 kg ha-1. Biomass weight (g) increased significantly (p<0.05) from 10.99 g pot-1 to 93.04 g pot-1 at P0N0 kg ha-1 and P160N200 kg ha-1, respectively. Grain yield (g) increased significantly (p<0.05) from 2.24 g pot-1 to 33.06 g pot-1 for the absolute control and P160N200 kg ha-1, respectively. Thus, for optimum grain yield of TXD 306 on Cambisols at DIS, 80 kg P ha-1 should be applied as basal and N in two splits i.e. 100 kg N ha-1 close to tillering and 100 kg N ha-1 at panicle initiation. For appropriate N and P recommendations, field studies should be conducted to take onboard integrated soil fertility management strategies, principles and practices in rice cultivation based on soil types to allow extrapolation of the results to other similar soils and areas.