秸秆还田与化肥配施对汉中盆地稻麦轮作农田土壤固碳及经济效益的影响

为汉中盆地秸秆还田技术和合理化肥减量技术提供科学依据,2015—2017年小麦和水稻生长季,设置秸秆不还田+常规施肥(SN+NPK);秸秆常规还田+常规施肥(S+NPK);秸秆促腐还田+常规施肥(SD+NPK);秸秆促腐还田+化肥减量15%(SD+85%NPK);秸秆促腐还田+化肥减量30%(SD+70%NPK),共5个处理,研究其对土壤总有机碳(TOC)、活性有机碳(LOC)、碳储量(SCS)、作物产量及经济效益的影响。结果表明与秸秆不还田配施常规施肥处理(SN+NPK)相比,秸秆还田配施不同比例化肥处理显著提高了稻田0～15cm土层的TOC和LOC,增幅分别为3.62%～25.07%和23.01%～46.79%; S+NPK和SD+NPK处理提高了0～30 cm碳储量,增幅分别为4.67%和18.20%。而SD+85%NPK和SD+70%NPK分别降低8.31%和9.83%。S+NPK和SD+NPK处理显著增加了小麦和水稻籽粒产量,而SD+85%NPK和SD+70%NPK处理均降低了小麦和水稻产量,周年产量2年平均增幅分别为3.47%、8.70%、-3.65%、-8.12%。与SN...

Effect of straw returning combined with NPK fertilization on soil carbon sequestration and economic benefits under rice-wheat rotation in Hanzhong basin

A two-year field experiment was conducted to investigate the response of soil carbon sequestration, crop yield and economic benefit to rates of NPK application and straw returning under rice-wheat rotation from 2015 to 2017. The experiment included five treatments: application of NPK without straw returning (SN+NPK), application of NPK with straw returning (S+NPK), application of NPK with decayed straw returning (SD+NPK), application of NPK with 15% reduction plus decayed straw returning (SD+85%NPK) and application of NPK with 15% reduction plus decayed straw returning (SD+70%NPK). Compared with SN+NPK, total organic carbon (TOC) and active organic carbon (LOC) in 0-15 cm depth increased by 3.62%-25.07% and 23.01%-46.79% in the treatments of straw returning plus different returned NPK application, respectively. Both S+NPK and SD+NPK treatments increased organic carbon storage (SCS) in 0-30 cm soil layer by 4.67% and 18.20%, but SD+85%NPK and SD+70%NPK decreased the SCS by 8.31% and 9.83%, respectively. Compared with SN+NPK, both S+NPK and SD+NPK increased grain yields for wheat and rice. However, SD+85%NPK and SD+70%NPK treatments significantly reduced grain yields for wheat and rice. Compared with SN+NPK treatment, the increase in annual average yield was 3.47% for S+NPK, 8.70% for SD+NPK, -3.65% for SD+85%NPK, and -8.12% for SD+70%NPK, while the increase of annual net profit in two years was 16.91%, 23.56%, 6.02%, and 1.06%, respectively. Soil organic carbon, crop yield and efficiency were the highest in the SD+NPK treatment, but lowest in SD+70%NPK. Compared with SD+70%NPK treatment, SD+85%NPK did not affect the annual average yield, but slightly increased the annual net profit due to a cost reduction caused by less fertilizer application with a total reduction of 80 kg ha ^-1. In conclusion, the combination of straw returning with NPK fertilization is an effective farming practice to improve soil carbon sequestration, crop yield and economic benefits in Hanzhong basin. Considering the environment and economic effects, decayed straw returning with 15% reduction in NPK application is more suitable to achieve the fertilizer reduction and green production.