How Does N Mineral Fertilizer Influence the Crop Residue N Credit?

Abstract

In no-tillage systems, there is an accumulation of crop residues (CR), which plays an essential role in the availability of soil-N. A study was set up to provide information regarding the N credit and the influence of N mineral fertilizer. There was the addition of a similar rate of residue (10 Mg ha−1; sugarcane, soybean, and brachiaria) and N mineral fertilizer (urea; 120 kg N ha−1) in loam soil. After the stabilization of biological activity (73 days), soil and remaining residues were collected, and C and N monitored. The results showed that the N credit was positive with the application of soybean, sugarcane, and brachiaria. There was a positive balance of the soybean N credit in soil with a reduction from 2.49 to 0.90 g kg−1 of N in remaining residue, and a direct increase of 90% of soil-N. There is no need of N fertilizer to potentialize the soybean N credit, but it is required to potentialize N credit of brachiaria and sugarcane. The urea demonstrated to be an excellent enhancer of brachiaria N credit, but it was not adequate for sugarcane residues. Based on our result, the accumulation and incorporation of CR can be considered as N credit with a positive contribution in soil-N.