Decomposition and nutrient release pattern of wheat (Triticum aestivum) residues under different treatments in desert field conditions of Sudan

Background Recycling of crop residues is essential tosustain soil fertility and crop production. Therefore, it is ofcrucial importance to study the decomposition of cropresidues particularly in the arid tropics. The decompositionand nutrient release pattern from crop residues incorporatedin the soil have rarely been investigated under semiaridclimatic conditions in Sudan. Decomposition andnutrient release pattern from wheat residue were investigatedin a 12 week litter bag experiment under field condition.Litter bags contain 50 g wheat residue were buriedin plots cultivated with guar and treated with followingtreatments: crop residue (CR), recommended fertilizer? crop residue (RF ? CR), sewage sludge (SS) andnon treated control (C). In each plot of each block, 12 litterbags were buried. Four bags from each treatment wereretrieved at 2, 4, 6, 8, 10 and 12 weeks of decomposition.The decomposed residue was analysed for remaining drymatter (DM), nitrogen (N), phosphorus (P), potassium(K) calcium (Ca), and magnesium (Mg) contents. Mass lossand nutrients released from wheat residue followed theexponential model, Wt = W0 9 e-kt from which the specificdecay rate constants (k) and t0.5 and t0.95 werecalculated.Results The result show that the mineral fertilizationcombined with crop residues (RF ? CR) resulted in themaximum decomposition and nutrient release compared tothe other treatments. The half-life (t0.5) values of thetreatments were in the following order: RF ? CR(6.70 weeks)SS (8.0 weeks)CR (9.60 weeks)C(11.91 weeks). The percentage remaining DM in the litterbags followed the order C (73.25 %)[CR (66.45%)[SS (59.85 %)[RF ? CR (53.85 %). A 50 % lossof residue N was found after 8.88 weeks in the C treatmentand 5.04 weeks in RF ? CR treatment. Generally,nutrient loss from all treatments in the order ofMg[K = N[Ca[P.Conclusions Application of mineral fertilizer or sewagesludge enhances the decomposition of low-quality residue(wheat). Therefore, it is essential to apply fertilizer indegraded soil before incorporation of crop residue withhigh carbon to nitrogen ratio.