Effects of straw returning and feeding on greenhouse gas emissions from integrated rice-crayfish farming in Jianghan Plain, China.

Abstract

Great efforts have been devoted to assessing the effects of straw managements on greenhouse gas (GHG) emissions, global warming potential (GWP), and net economic budget in rice monoculture (RM). However, few studies have evaluated the effects of straw managements on GHG emissions and net ecosystem economic budget (NEEB) in integrated rice-crayfish farming (RC). Here, a randomized block field experiment was performed to comprehensively evaluate the effects of aquatic breeding practices (feeding or no feeding of forage) and straw managements (rice straw returning or removal) on soil NH4+-N and NO-3-N contents, redox potential (Eh), CH4 and N2O emissions, GWP, and NEEB of fluvo-aquic paddy soil in a rice-crayfish co-culture system in Jianghan Plain of China. We also compared the differences in CH4 and N2O emissions, GWP, and NEEB between RM and RC. Straw returning significantly increased CH4 and N2O emissions by 34.9-46.1% and 6.2-23.1% respectively compared with straw removal. Feeding of forage decreased CH4 emissions by 13.9-18.7% but enhanced N2O emissions by 24.4-33.2% relative to no feeding. Compared with RM treatment, RC treatment decreased CH4 emissions by 18.1-19.6% but increased N2O emissions by 16.8-21.0%. Moreover, RC treatment decreased GWP by 16.8-22.0% while increased NEEB by 26.9-75.6% relative to RM treatment, suggesting that the RC model may be a promising option for mitigating GWP and increasing economic benefits of paddy fields. However, the RC model resulted in a lower grain yield compared with the RM model, indicating that more efforts are needed to simultaneously increase grain yield and NEEB and decrease GWP under RC model.