Effects of Urea Fertilizer on Yield and Water Productivity of Amaranthus viridis in the Tropical Rainforest and the Derived Savanna of Nigeria

Abstract

The experiment was conducted using a lysimeter in June, 2014 in Saki (Derived Savanna) and Ile-Ife (Tropical Rainforest) to determine the crop coefficients and the effects of Urea fertilizer on the yield and water productivity of Amaranthus viridis in Nigeria. The loamy sandy soil in the top 15 cm was sampled, air-dried and analysed. Eighteen (18) kg of the air-dried and sieved soils were weighed into the thirty-two (32) lysimeters. Drill method was used for the sowing and the seeds were spread within 2 cm in the lysimeter. Urea fertilizer was applied at 0, 40, 80 and 160 kg N/ha twice during the growing season. The crop coefficients at the initial, mid, and late stages ranged from 0.15 to 0.41 in Ile-Ife, while in Saki, they ranged from 0.29 to 1.15 under Urea fertilizer. In Saki, the peak crop evapotranspiration was 1.21 mm/day for 0 kg N/ha of Urea while in the Ile-Ife, the crop evapotranspiration was 1.83 mm/day for 160 Kg N/ha of Urea. Water productivity in Saki and Ile-Ife were 45.47 kg/ha mm and 18.58 kg/ha mm respectively for 160 kg N/ha. This implies that Amaranthus viridis required more water during canopy expansion and flowering in Ile-Ife than in Saki.