AimsWe studied the effects of mixing rice straw and hairy vetch plant residues in a subtropical paddy soil, on subsequent carbon (C) and nitrogen (N) dynamics.MethodsUsing a theoretical framework, we designed two groups of experiments (involving equal amounts of residual C or N addition, referred to as either C or N treatments). Each experiment included mixed residues of rice straw and hairy vetch at different mixing ratios. Soils together with residues were incubated at 25 degrees C under waterlogged conditions for 100days. Greenhouse gas (GHG) emissions and soil C and N fractions were measured continuously.ResultsBoth C and N treatments affected soil C and N dynamics, and these dynamics were quantitatively dependent on residue C/N ratios. The effect of residue mixtures on C and N dynamics could not be predicted from single residues, since there were non-additive effects of residue mixtures. Synergistic effects were generally more frequent than antagonistic effects. Residue mixtures tended to enhance CO2 and CH4 emissions in both C and N treatments but decreased N2O emissions in the N treatment. In the N treatment, dissolved organic C (DOC), dissolved organic N (DON), and microbial biomass C (MBC) concentrations increased. DOC and DON concentrations decreased in the C treatment. Residue mixtures enhanced the global warming potentials (GWP) of greenhouse gases (GHG) emitted from soil by non-additive synergistic effects. The C/N ratio of residue mixtures affected the non-additive responses of soil C and N dynamics, for example mixtures with a C/N ratio of 25 had higher CO2 emissions and DOC concentrations than those with a C/N ratio of 35 as a consequence of non-additive effects, however, CH4 emissions and MBC concentrations were higher in mixtures with a C/N ratio of 35 than in mixtures with a C/N ration of 25.ConclusionsThese results indicated that non-additive effects can impact soil C and N dynamics and that residue C/N ratios play an important role in influencing non-additive effects. Applying a single residue to paddy soils may be better than residue mixtures from a GWP mitigation perspective.
1.Chinese Acad Agr Sci, Key Lab Plant Nutr & Fertilizer, Minist Agr, Inst Agr Resources & Reg Planning, Beijing 100081, Peoples R China 2.Nanjing Agr Univ, Coll Resources & Environm Sci, Nanjing 210095, Jiangsu, Peoples R China 3.Jiangxi Acad Agr Sci, Inst Soil&Fertilizer & Resource&Environm, Nanchang 330200, Jiangxi, Peoples R China 4.Scotlands Rural Coll SRUC, West Mains Rd, Edinburgh EH9 3JG, Midlothian, Scotland
Recommended Citation:
Zhou, Guopeng,Cao, Weidong,Bai, Jinshun,et al. Non-additive responses of soil C and N to rice straw and hairy vetch (Vicia villosa Roth L.) mixtures in a paddy soil[J]. PLANT AND SOIL,2019-01-01,436(1-2):229-244