据估算，全球每年所产生的动物有机肥 (畜禽粪便) 氮的总量约为100 Tg N 如果能够将这一部分有机肥氮有效地还田而替代部分化学氮肥施用，不仅能够减少化学氮肥施用所带来的一系列环境问题，而且能够进一步实现有机肥的资源化利用并能够提高土壤肥力，从而有利于作物产量的累积，但是同时也会对于土壤的温室气体排放产生影响。然而，目前关于有机肥还田部分替代化学氮肥施用对于粮食安全，活性氮以及温室气体排放的综合影响尚不清楚。
我室颜晓元课题组利用数据荟萃分析的方法，在全球范围内选取了141篇发表的文章，全面评价了有机肥还田部分替代化学氮肥施用对于 (谷粒作物和蔬菜) 作物生产力、活性氮损失以及土壤温室气体排放的影响。研究发现，与只施用化学氮肥的措施相比较，有机肥部分替代化学氮肥施用 (总施氮量保持一致) 显著提高了作物的籽粒产量4.4%，并显著提高了作物地上部的吸氮量 (7.8%) 和氮肥利用率 (10.3%)。与此同时，显著降低了NH3 挥发26.8%，降低了氮的淋溶损失28.9% 以及氮的径流损失26.2%。对于温室气体的净排放而言，有机肥部分替代化学氮肥施用提高了旱地土壤的碳汇，却同时提高了稻田土壤的碳源 (主要归因于对于稻田CH4排放的显著增加)。但是，通过采用合理的有机肥还田措施，例如采用发酵后的有机肥进行化学氮肥的替代施用，能够进一步降低对于稻田土壤温室气体排放的促进效应。
以上结果在美国化学学会期刊Environmental Science & Technology 上在线发表链接http://pubs.acs.org-doi-abs-10.1021-acs.est.6b06470。
Xia LL Shu Kee Lam Yan XY Chen DL. How does recycling of livestock manure in agroecosystems affect crop productivity reactive nitrogen losses and soil carbon balance? Environmental Science & Technology 2017 doi: 10.1021-acs.est.6b06470
Abstract
Recycling of livestock manure in agroecosystems to partially substitute synthetic fertilizer nitrogen (N) input is recommended to alleviate the environmental degradation associated with synthetic N fertilization which may also affect food security and soil greenhouse gas (GHG) emissions. However how substituting livestock manure for synthetic N fertilizer affects crop productivity (crop yield; crop N uptake; N use efficiency) reactive N (Nr) losses (ammonia (NH3) emission N leaching and runoff) GHG (methane CH4; and nitrous oxide N2O; carbon dioxide) emissions and soil organic carbon (SOC) sequestration in agroecosystems is not well understood. We conducted a global meta-analysis of 141 studies and found that substituting livestock manure for synthetic N fertilizer (with equivalent N rate) significantly increased crop yield by 4.4% and significantly decreased Nr losses via NH3 emission by 26.8% N leaching by 28.9% and N runoff by 26.2%. Moreover annual SOC sequestration was significantly increased by 699.6 and 401.4 kg C ha−1 yr−1 in upland and paddy fields respectively; CH4 emission from paddy field was significantly increased by 41.2% but no significant change of that was observed from upland field; N2O emission was not significantly affected by manure substitution in upland or paddy fields. In terms of net soil carbon balance substituting manure for fertilizer increased carbon sink in upland field but increased carbon source in paddy field. These results suggest that recycling of livestock manure in agroecosystems improves crop productivity reduces Nr pollution and increases SOC storage. To attenuate the enhanced carbon source in paddy field appropriate livestock manure management practices should be adopted.
