Long-term application of organic manure and nitrogen fertilizer on N 2O emissions, soil quality and crop production in a sandy loam soil

Abstract

A long-term field experiment was established to determine the influence of mineral fertilizer (NPK) or organic manure (composed of wheat straw, oil cake and cottonseed cake) on soil fertility. A tract of calcareous fluvo-aquic soil (aquic inceptisol) in the Fengqiu State Key Experimental Station for Ecological Agriculture (Fengqiu county, Henan province, China) was fertilized beginning in September 1989 and N 2O emissions were examined during the maize and wheat growth seasons of 2002–2003. The study involved seven treatments: organic manure (OM), half-organic manure plus half-fertilizer N (1/2 OMN), fertilizer NPK (NPK), fertilizer NP (NP), fertilizer NK (NK), fertilizer PK (PK) and control (CK). Manured soils had higher organic C and N contents, but lower pH and bulk densities than soils receiving the various mineralized fertilizers especially those lacking P, indicating that long-term application of manures could efficiently prevent the leaching of applied N from and increase N content in the plowed layer. The application of manures and fertilizers at a rate of 300 kg N ha −1 year −1 significantly increased N 2O emissions from 150 g N 2O-N ha −1 year −1 in the CK treatment soil to 856 g N 2O-N ha −1 year −1 in the OM treatment soil; however, there was no significant difference between the effect of fertilizer and manure on N 2O emission. More N 2O was released during the 102-day maize growth season than during the 236-day wheat growth season in the N-fertilized soils but not in N-unfertilized soils. N 2O emission was significantly affected by soil moisture during the maize growth season and by soil temperature during the wheat growth season. In sum, this study showed that manure added to a soil tested did not result in greater N 2O emission than treatment with a N-containing fertilizer, but did confer greater benefits for soil fertility and the environment.