N2O emission from soil associated to nitrogen fertilized application methods in sugarcane ratoon

Abstract

The effectiveness of N from fertilizer by sugarcane usually it is lower than 50%, affecting crop yield and increasing the risks of nitrous oxide emission. Further, previous data showed that sugarcane root system it is located near of ratoon, indicating gains in sugarcane yield when nitrogen fertilizer was applied in those region with high roots concentration. In spite of this subject (nitrogen fertilization) is highly evaluated in Brazilian field condition, the nitrogen fertilization has few attention relating to application forms in sugarcane crop, excepting for urea application (needs to incorporate urea in soil to avoid losses of NH3 by volatilization). Likewise, our hypothesis it is that every nitrogen fertilizer will have better performance for plant nutrition when it is incorporated in the soil. If our hypothesis would be true, will be easy to transfer this technology for growers, because, there is equipment available to be bought for that. Then, our project is aiming to evaluate the N2O emission relating to nitrogen use efficiency (NUE) by sugarcane cultivated under different N fertilizer application forms. For this, it has been performing a field experiment located in Iracemapolis-SP, where N-fertilizers application forms has been tested. The treatments are: 1) Control (without N); 2) superficial banded application (over the trash); 3) below trash banded application; 4) banded application with incorporation in the soil (10 cm of deep). All treatments with N-fertilizer application the banded is around 20 cm far from ratoon. During the 2015/2016 crop season will be evaluated N2O emission from soil. Physical, chemical (mineral N content) and microbiological (functional genes) soil analysis will be done. Moreover, isotopic technique will be adopted to analyze 15N-fertilizer soil-plant balance. At the end of first crop season evaluated (2014/2015) was verified better crop yield when the N-fertilizer was incorporated to the soil. Therein, the evaluation of the second crop season using outstanding soil science techniques to explain the crop performance and N from fertilizer turnover will ensure the adoption of the best practices of nitrogen fertilizer management for sugarcane under green cane harvesting system. This is very important to guarantee a positive balance of carbon mitigation from renewable biofuels. (AU)