长期秸秆配施化肥下土壤团聚体碳氮分布、微生物量与小麦产量的协同效应

【目的】研究秸秆配施化肥对暗棕壤团聚体组成、团聚体碳氮含量、土壤微生物量特征及小麦产量的影响，揭示长期秸秆配施化肥下土壤肥力和生产力的协同提升机制。【方法】依托长期定位40年施肥试验，选取4个处理：单施化肥(NP)、秸秆配施化肥(S+NP)、秸秆配施1/2化肥(S+1/2NP)、秸秆配施1/4化肥(S+1/4NP)，其中秸秆为麦秸隔年还田，用量为3 000 kg·hm^-2，氮磷化肥用量为150 kg N·hm^-2、150 kg P₂O₅·hm^-2。采集0—20 cm土层土样，利用湿筛法得到不同粒级的水稳性团聚体，测定团聚体中有机碳(SOC)、氮含量及土壤微生物量碳(SMBC)、微生物量氮(SMBN)含量。【结果】(1)长期秸秆配施化肥显著降低土壤容重并提高了团聚体稳定性，和NP相比，S+NP处理土壤容重降低4.7%,>2 mm团聚体含量、平均重量直径(MWD)和几何重量直径(GWD)分别提升254.4%、76.5%和91.3%。(2)S+NP、S+1/2NP处理>2...

Synergistic Effects of Organic Carbon and Nitrogen Content in Water-Stable Aggregates as well as Microbial Biomass on Crop Yield Under Long-Term Straw Combined Chemical Fertilizers Application

【Objective】The effects of long-term straw combined application of chemical fertilizers on the content of aggregates, distributions of aggregate-associated organic carbon and nitrogen, and soil microbial biomass were studied to reveal the promotion of soil fertility and productivity. 【Method】Soil samples were collected from a 40-year long-term experiment. The research was conducted with 4 treatments: pure chemical fertilizer (NP), straw with chemical fertilizer (S+NP), straw with 1/2 chemical fertilizer (S+1/2NP), and straw with 1/4 chemical fertilizer (S+1/4NP), and the straw was returned with the amount of 3 000 kg·hm^-2, chemical fertilizer NP was pure N 150 kg·hm^-2 and P₂O₅ 150 kg·hm^-2 conducted. All soils samples were separated into four aggregate-size classes (>2 mm, 0.25-2 mm, 0.053-0.25 mm, and <0.053 mm) by wet sieving. Organic carbon and total nitrogen content of aggregates and soil microbial biomass content were measured. 【Result】(1) Long-term application of chemical fertilizers with straw reduced soil bulk density, while improved the stability of aggregates. Compared with NP, the bulk density of S+NP decreased by 4.7%, while the proportion of aggregates >2 mm in size, the average weight diameter (MWD) and geometric weight diameter (GWD) increased by 254.4%, 76.5% and 91.3%, respectively. (2) In the three chemical fertilizers combined with straw return, the percentage of aggregates >2 mm, MWD and GWD under S+NP and S+1/2NP were significantly increased by 49.1%-52.4%, 19.43%-22.4% and 24.2%-33.3%, compared with S+1/4NP, respectively. (3) Compared with NP, S+NP, S+1/2NP and S+1/4NP increased the contribution rate of aggregates >2 mm and >0.25 mm to SOC and total nitrogen, and significantly improved the SOC, SMBC and SMBN content in bulk soil. Among them, the SOC content was the highest under S+NP, which was 6.3% and 12.6% higher than that under S+1/2NP and S+1/4NP, respectively. (4) The yield was showed that S+NP>NP>S+1/2NP>S+1/4NP, and S+NP increased wheat yield by 5.83%-83.6% compared with other treatments. (5) Positive correlation was revealed between soil aggregate stability, carbon and nitrogen content and crop yield, and >2 mm aggregate content, while MWD and GWD were significantly or extremely significant with the total soil SOC, SMBC content and wheat yield, respectively.【Conclusion】In the dark brown soil area, the long-term straw returning and fertilizer application of 150 kg N·hm^-2 and 150 kg P₂O₅·hm^-2 could improve aggregate stability, soil organic carbon content, microbial biomass and yield, and achieve the synergistic effect of soil structure improvement, fertility improvement and crop yield increase.