Tropentag, September 19 - 21, 2012 in Göttingen "Resilience of agricultural systems against crises"

Fate of Fertiliser N Applied to A Guar-Wheat Rotation System as Influenced by Crop Residue Incorporation in A Semi-Arid Vertisol

¹University of Al-Neelain, Fac. Agricultural Technology and Fish Science, Sudan
²University of Khartoum, Desertification and Desert Cultivation Studies Institute, Sudan

Abstract

Guar or cluster bean (Cyamopsis tetragonoloba) is an interesting crop adapted to the semi-arid tropics. Nitrogen recovery from inorganic fertiliser in the crop/soil systems was monitored for six seasons in a guar-wheat (Triticum aestivum) crop rotation using 10% 15N atom excess urea (12,72 kg ha^-1). N15 recoveries in wheat straw, wheat head and total recovery were 22.46%, 15.55% and 38.01% , respectively on plots without crop residue removal and 21.16%, 15.55%, and 36.71%, respectively, on plots with crop residue removal. It was observed that continuous incorporation of fertiliser without crop residue removal improved the N recovery with 20.46% as compared to the application of inorganic fertiliser with crop residue removal. In the 2^nd, 3^rd, 4^th, 5^th and 6^th crop cycle, incorporation of inorganic fertiliser without crop residue removal increased N retention of the topsoil by 4.6, 10.1, 3.4, 11.9 and 1.6%, respectively, as compared to the inorganic fertiliser application with crop residue removal.
N derived from fertiliser (Ndff) in the seeds or pods through all seasons, except the 2^nd season, was higher on plots with crop residue left and the application of inorganic fertiliser then on plots without crop residues and the application of inorganic fertiliser, by 8.98%, 7.77%, 33.33% and 1.37% for the 3^rd, 4^th, 5^th and 6^th season, respectively. It could be concluded that continuous application of crop residues along with fertilisers improved N recoveries in a guar-wheat rotation.

Keywords: Crop residues, crop rotation, guar, N15, semi arid, wheat

Contact Address: Nazar Omer Hassan Salih, University of Al-Neelain, Fac. Agricultural Technology and Fish Science, Khartoum, Sudan, e-mail: nazarmnayahoo.com