Uptake and balance of fertilizer nitrogen applied to sugarcane

During the 2000/2001 and 2001/2002 cropping seasons, a study was conducted at the Tanganyika Planting Company (TPC) estate in Tanzania, to investigate the uptake and balance of mineral N applied as urea (60 kg ha(-1)) and ammonium sulphate (AS) (40 kg ha(-1)) on a saline (pH 8.8) and a non-saline (pH 7.8) soil. Both fertilizers were labelled with 10 at.% N-15 excess. The results showed high recoveries (> 90%) in the sugarcane plant growing on a non-saline soil for N applied as both urea and ammonium sulphate. On a saline soil, recoveries were lower but depended on the form of N, being lower (similar to 34%) with urea than with ammonium sulphate (similar to 77%). These lower recoveries of N in the plant were also associated with lower recoveries in the soil-plant system and imply that there were significant losses of N to the environment in this soil. Possible causes for the losses were discussed. (c) 2005 Elsevier B.V. All rights reserved.