Comparison of several slow-released nitrogen fertilizers in ammonia volatilization and nitrogen utilization in summer maize field

ObjectivesSlow-release processing technologies have been used in urea production to reduce ammonia volatilization and de-nitrification of nitrate in soil, so to improve crop N uptake and eventually improve nitrogen utilization. Here the ammonia volatilization characteristics of different control-released urea were compared to provide references for their practical application.

MethodsA in-situ field experiment was conducted in a sandy soil in two years in North China plain. The treatments included no nitrogen fertilization control (CK), calcium nitrate (CN), common urea (CU), polymer-coated urea (CRF), release-controlled urea (LCU), polymer gel urea (CLP) and urea formaldehyde (UF). The ammonia volatilization loss, maize yield and nitrogen utilization were determined during the summer maize growing seasons.

Results1) The ammonia volatilization mainly occurred in the first week after applied into soil, the cumulative ammonia volatilization accounted for 81.6% of the whole growing period for CU, and 62.2%-82.2% for CLP, LCU, CRF and UF. 2) In 2014, the cumulative ammonia volatilization in CU was N 14.9 kg/hm²; those were significantly decreased by 21.7%-64.6% from CLP, LCU, CRF and UF. In 2015, that of the CU was N 17.3 kg/hm², the decreases were by 17.3%-57.2%. 3) The ammonia volatilization loss ratios of the CU, CRF and LCU were higher than 60.0% in the two monitoring years, and that of CU reached to 76.0% in average, while the ratio of the UF was 37.6%. 4) The yearly average yields of the UF, CLP, LCU and CRF were increased significantly by 6.3%-18.8%, compared with the CU. 5) The nitrogen use efficiency with UF was up to 57.9%, and those with CLP, LCU, CRF, CN and CU were 42.4%, 38.3%, 38.3%, 23.5% and 20.8%, respectively.

ConclusionsThe urea formaldehyde, polymer gel urea, lost-controlled urea and polymer-coated urea can significantly reduce the ammonia volatilization loss, improve the maize yield and nitrogen use efficiency. Among the tested controlreleased nitrogen fertilizers, urea formaldehyde and polymer gel urea perform better for the high-yield, highefficiency and less N loss.