Interaction of Biochar with Chemical, Green and Biological Nitrogen Fertilizers on Nitrogen Use Efficiency Indices

Abstract

Chemical nitrogen (N) fertilizers are regarded as one of the environmental contaminants in addition to the necessity for fossil sources for their production. Conversely, it is impossible to neglect the supply of nitrogen needed as one of the essential ingredients for plant function. For organic agriculture, it is crucial to use alternative fertilizer management to reduce the harmful impacts and production costs of chemical fertilizers. In a one-year pot experiment, nitrate (NO−3) leaching and nitrogen efficiency of wheat were examined in relation to biochar (B) mixed with urea (U), legume residues (L), and azocompost (A), which represent chemical, green, and biological sources of N-fertilizers, respectively. Control (no biochar, no fertilizer), U (46 kg ha−1), A (5 t ha−1), L (5 t ha−1), B (10 t ha−1), UB, AB, and LB were the experimental treatments. Grain yield of wheat was enhanced by 337% and 312% with UB and UL, respectively. The LB produced the highest grain N yield, with a rise of 8.8 times over the control. L had the highest N-use efficiency, with an increase of 149% over the control. The highest N-harvest index and N-recovery efficiency were obtained by using LB, with values of 91 and 70 %, respectively. Nitrate leaching occurred in the following order: U > Control ≥ A ≥ L > UB > AB ≥ LB > B. Nitrogen is retained for the plant in the extensive specific surface of biochar when N-fertilizers are used in conjunction with them. This not only improves N-efficiency but also minimizes nitrogen loss through leaching. Additionally, the soil can benefit from the addition of leguminous organic fertilizer in a similar way as to urea fertilizer in terms of increasing wheat grain yield, particularly when combined with biochar.