摘要
【目的】研究不同施肥处理对红壤水稻土水稳性团聚体组成、不同粒级团聚体中有机碳、氮含量与分布及土壤微生物生物量碳氮含量的影响,为揭示施肥对土壤肥力形成演变的影响机制提供重要理论依据。【方法】依托鹰潭农田生态系统国家野外科学观测研究站已进行了20年的长期定位试验,试验包括9个处理:对照(不施肥,CK)、有机质循环(C)、化学氮肥(N)、氮肥+有机质循环(NC)、化学氮磷肥(NP)、化学氮磷钾肥(NPK)、化学氮磷钾肥+有机质循环(NPKC)、化学氮磷肥(NK)和化学氮磷钾肥+1/2秸秆回田(NPKS)。采集各小区耕层土壤,利用湿筛法得到不同粒级水稳性团聚体,测定团聚体中有机碳、氮含量及土壤微生物量碳、氮含量。【结果】长期不同施肥处理对>2 mm团聚体含量影响最大,与对照相比,施用有机肥的处理(NC、NPKC、C)该粒级团聚体含量分别提高了37.0%、22.6%和33.2%。各施肥处理下,有机碳、氮在1—2 mm团聚体中含量最高,在0.053—0.25 mm团聚体中含量最低,>0.25 mm大团聚体比<0.25 mm微团聚体含有更多的有机碳、氮。有机肥的施用显著提高了各粒级团聚体中有机碳、氮的含量,NC处理各粒级团聚体中有机碳、氮含量均最高,与对照相比,各粒级有机碳提高了17.0%—34.6%,全氮提高了25.8%—48.3%。0.25—1 mm和>2 mm粒级团聚体对全土有机碳和全氮的贡献率最大,前者贡献率分别为22.1%—30.3%和23.3%—33.7%,后者贡献率分别为24.7%—37.3%和25.5%—38.0%。不同施肥处理间土壤微生物量碳、氮含量也有显著差异,与对照相比,NC、NPKC和C处理微生物量碳提高了122.1%、127.0%、94.0%,微生物量氮提高了92.0%、43.1%、91.1%。>2 mm团聚体含量与全土有机碳、全氮、微生物量碳、微生物量氮含量及水稻产量呈显著或极显著正相关,<0.053 mm团聚体则与之呈显著或极显著负相关。【结论】水稳性大团聚体是土壤有机碳、氮的主要载体;有机肥的施用显著提高了水稳性大团聚体及其中有机碳、氮的含量,是改善土壤团粒结构,提高红壤生物功能和生产力的有效措施。
[Objective] The effects of different fertilizer applications on contents of water-stable aggregates and distributions of aggregate-associated organic carbon and nitrogen as well as soil microbial biomass carbon and nitrogen contents in paddy soil of subtropical China were studied. [Method] Soil samples were collected from a 20-year long-term field experiment, which wasestablished in 1990 in the Farmland Ecosystem of Yingtan National Field Observation and Research Station. The experiment included 9 treatments： CK （without fertilization）, C （organic cycling）, N （N fertilizer）, NC （N plus organic cycling）, NP （N, P fertilizers）, NPK （N, P, K fertilizers）, NPKC （NPK plus organic cycling）, NK （N, K fertilizers）, NPKS （NPK plus 1/2 rice straw）. All soils were separated into five aggregate-size classes （〉2 ram, 1-2 mm, 0.25-1 mm, 0.053-0.25 mm and 〈0.053 mm） by wet sieving. Organic carbon and nitrogen contents of aggregates and soil microbial biomass content were determined： [Result] Compared with CK, application of fertilizers increased the proportion of aggregate 〉 2 mm in size, and organic manures application （NC, NPKC, C） increased the amounts of 〉2 mm aggregate by 37.0%, 22.6% and 33.2%, respectively. Among all the aggregates, the contents of organic carbon and nitrogen in 1-2 mm size fraction were the highest, while the lowest were in aggregate 0.053-0.25 mm in size. Moreover, the macro-aggregates （〉0.25 mm） concentrated more organic carbon and nitrogen than micro-aggregates （〈0.25 mm）. Application of organic manures significantly increased the contents of organic carbon and nitrogen in fractions of different sizes.The contents of organic carbon and nitrogen in aggregates of treatment NC both reached the highest, with organic carbon 17.0%-34.6% and nitrogen 25.8%-48.3% higher than CK. As for the contributing rates of aggregates to bulk soil organic carbon and total nitrogen, aggregates 0.25-1 mm and 〉2 mm in size were greater than other aggregate size fractions and the former one were 22.1%-30.3% and 23.3%-33.7%, and the latter one were 24.7%-37.3% and 25.5%-38.0%, respectively. Fertilization obviously affected soil microbial biomass carbon and nitrogen contents. Treatments NC, NPKC and C increased microbial biomass carbon by 122.1%, 127.0% and 94.0% and microbial biomass nitrogen increased by 92.0%, 43.1% and 91.1% compared with CK. The results of correlation analysis showed that there existed a significant positive correlation between the percentage of aggregate〉2 mm in size and the contents of soil organic carbon, total nitrogen and microbial biomass carbon and nitrogen. However, the content of aggregate 〈0.053 mm in size revealed a significant negative relationship with the contents of the indexes mentioned above. [Conclusion] Macro-aggregates were the main carrier of soil organic carbon and total nitrogen in the paddy soil. After application of organic manures （NC, NPKC, C）, the contents of macro-aggregates and organic carbon and nitrogen in them increased significantly, being beneficial to the improvement of soil structure and the increase of soil biological function and fertility.
出处
《中国农业科学》
CAS
CSCD
北大核心
2013年第5期950-960,共11页
Scientia Agricultura Sinica
基金
国家自然科学基金项目(41171233
41001143)
关键词
施肥
红壤水稻土
水稳性团聚体
有机碳
全氮
微生物生物量
fertilization
red paddy soil
water-stable aggregate
organic carbon
total nitrogen
microbial biomass
