有机肥等氮替代化肥对稻田CH4和N2O排放的影响

Effects of Partial Organic Substitution for Chemical Fertilizer on CH4 and N2O Emissions in Paddy Field

自2015年中国实施化肥施用量零增长行动以来,有机肥部分替代化肥的研究越来越受到关注。该试验,采用静态箱-色谱法对宁波地区稻麦轮作系统CH4和N2O排放进行了田间原位观测,研究两种有机肥分别以不同比例等氮替代化肥对稻田CH4和N2O排放及水稻产量的影响。试验设置不施氮肥(CK)、全量化肥(U)、25%城市污泥堆肥(25%S)、25%猪粪堆肥(25%P)、50%城市污泥堆肥(50%S)、50%猪粪堆肥(50%P)6个处理。结果表明,与U处理相比,有机肥替代处理的CH4排放量增加18%-51%,其中50%S和50%P处理显著增加稻田CH4排放量34%-51%(P<0.05),CH4排放量随有机肥替代比例的增加而增加,相同替代比例的城市污泥堆肥处理和猪粪堆肥处理的CH4排放量无明显差异(P>0.05)。相对于U处理,有机肥替代处理显著降低了36%-51%的N2O排放量(P<0.05,25%P处理除外),各有机肥处理间N2O排放量无显著性差异(P>0.05)。稻田排放CH4和N2O的全球增温潜势(GWP)为:50%P>50%S>25%P>25%S>CK>U,其中50%P处理与U处理之间差异显著(P<0.05)。有机肥替代处理的水稻产量、有效穗数和穗实粒数分别比U处理高0.2%-3.8%、0.8%-4.1%、0.6%-1.4%(P>0.05)。等氮替代条件下,相对于猪粪堆肥,稻田中施用25%城市污泥堆肥替代化学氮肥是一种值得推荐的施肥模式,而其对稻米品质的影响仍需进一步研究。

Since 2015,China’s Ministry of Agriculture and Rural Affairs implemented a regulation of zero growth in chemical fertilizer application,researches on partial organic substitution for chemical fertilizer have attracted more and more attention.A field experiment was carried out to investigate the effects of two kinds of organic compost partially substituting for chemical fertilizer on growing-season CH4 and N2O emissions and components of grain yield under a rice-wheat rotation system in Ningbo.Seasonal variation of CH4 and N2O fluxes were monitored using the static black chamber-gas chromatography method.The experiment had six treatments:No nitrogen fertilizer(CK),Conventional chemical fertilizer(U),25%sewage sludge compost substitution(25%S),25%pig manure compost substitution(25%P),50%sewage sludge compost substitution(50%S),50%pig manure compost substitution(50%P).The total nitrogen rates of all fertilizer treatments were kept the same.Results showed that compared with treatment U,CH4 emissions in organic substitution treatments increased by 18%–51%;particularly,treatments 50%S and 50%P significantly enhanced CH4 emissions by 34%–51%(P<0.05).CH4 emissions increased with the increase of organic manure application ratio,and there was no significant difference between sewage sludge compost substitution treatment and pig manure compost substitution treatment of the same substitution ratio.Compared with treatment U,treatments with partial organic substitution significantly decreased N2O emissions by 36%–51%(P<0.05,except for treatment 25%P).However,no significant difference was observed among organic substitution treatments(P>0.05).The GWP of CH4 and N2O emitted from the paddy field was greatest in treatment 50%P,followed by treatments 50%S,25%P,25%S,CK and U,the difference between treatment 50%P and U reached significant level(P<0.05).Rice grain yield,productive spikes numbers and grain numbers per spike of organic manure substitution treatments increased by 0.2%–3.8%,0.8%-4.1%,0.6%–1.4%(P>0.05)compared to treatment U,respectively.Based on these results,at the same nitrogen substitution rate,25%sewage sludge compost substitution is recommended over the pig manure compost for paddy field,but its impact on rice quality still needs further investigation.