Effect of nitrification inhibitor DMPP on nitrogen leaching, nitrifying organisms, and enzyme activities in a rice-oilseed rape cropping system

Hua LI, Xinqiang LIANG, Yingxu CHEN, Yanfeng LIAN, Guangming TIAN, Wuzhong NI
2008 Journal of Environmental Sciences(China)  
DMPP (3,4-dimethylpyrazole phosphate) has been used to reduce nitrogen (N) loss from leaching or denitrification and to improve N supply in agricultural land. However, its impact on soil nitrifying organisms and enzyme activities involved in N cycling is largely unknown. Therefore, an on-farm experiment, for two years, has been conducted, to elucidate the effects of DMPP on mineral N (NH 4 + -N and NO 3 − -N) leaching, nitrifying organisms, and denitrifying enzymes in a rice-oilseed rape
more » ... g system. Three treatments including urea alone (UA), urea + 1% DMPP (DP), and no fertilizer (CK), have been carried out. The results showed that DP enhanced the mean NH 4 + -N concentrations by 19.1%-24.3%, but reduced the mean NO 3 − -N concentrations by 44.9%-56.6% in the leachate, under a two-year rice-rape rotation, compared to the UA treatment. The population of ammonia oxidizing bacteria, the activity of nitrate reductase, and nitrite reductase in the DP treatment decreased about 24.5%-30.9%, 14.9%-43.5%, and 14.7%-31.6%, respectively, as compared to the UA treatment. However, nitrite oxidizing bacteria and hydroxylamine reductase remained almost unaffected by DMPP. It is proposed that DMPP has the potential to either reduce NO 3 − -N leaching by inhibiting ammonia oxidization or N losses from denitrification, which is in favor of the N conversations in the rice-oilseed rape cropping system.
doi:10.1016/s1001-0742(08)60023-6 pmid:18574953 fatcat:aodnuc7ff5f2hlfjpewfxoek6e