Long-Term Application of Organic Manure and Mineral Fertilizer on N2O and CO2 Emissions in a Red Soil from Cultivated Maize-Wheat Rotation in China

A long-term field experiment was established to determine the influence of mineral fertilizer and organic manure on soil fertility. A tract of red soil (Ferralic Cambisol) in Qiyang Red Soil Experimental Station (Qiyang County, Hunan Province, China) was fertilized beginning in 1990 and N2O and CO2 were examined during the maize and wheat growth season of 2007–2008. The study involved five treatments: organic manure (NPKM), fertilizer NPK (NPK), fertilizer NP (NP), fertilizer NK (NK), and control (CK). Manured soils had higher crop biomass, organic C, and pH than soils receiving the various mineralized fertilizers indicating that long-term application of manures could efficiently prevent red soil acidification and increase crop productivity. The application of manures and fertilizers at a rate of 300 kg N ha−1 yr−1 obviously increased N2O and CO2 emissions from 0.58 kg N2O-N ha−1 yr−1 and 10 565 kg C ha−1 yr−1 in the CK treatment soil to 3.01 kg N2O-N ha−1 yr−1 and 28 663 kg C ha−1 yr−1 in the NPKM treatment. There were also obvious different effects on N2O and CO2 emissions between applying fertilizer and manure. More N2O and CO2 released during the 184-d maize growing season than the 125-d wheat growth season in the manure fertilized soils but not in mineral fertilizer treatments. N2O emission was significantly affected by soil moisture only during the wheat growing season, and CO2 emission was affected by soil temperature only in CK and NP treatment during the wheat and maize growing season. In sum, this study indicates the application of organic manure may be a preferred strategy for maintaining red soil productivity, but may result in greater N2O and CO2 emissions than treatments only with mineral fertilizer.