引用本文:李 奕,房 焕,彭 显龙,周 虎.模拟搅浆对水稻土结构和有机氮矿化的影响[J].土壤学报,2019,56(5):1171-1179.
LI Yi,FANG Huan,PENG Xianlong,ZHOU Hu.Effects of Simulated Pudding on Structure of Paddy Soil and Organic Nitrogen Mineralization Therein[J].Acta Pedologica Sinica,2019,56(5):1171-1179
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模拟搅浆对水稻土结构和有机氮矿化的影响
李 奕1, 房 焕2, 彭 显龙1, 周 虎2
1.东北农业大学资源与环境学院;2.土壤与农业可持续发展国家重点实验室(中国科学院南京土壤研究所)
摘要:
搅浆(Puddling)是传统水稻种植过程中的重要环节,搅浆会改变土壤结构,进而影响氮转化过程。通过室内模拟试验,设置不搅动(CK)、低强度搅动(LIS)和高强度搅动(HIS)三个处理,研究搅浆引起的土壤结构变化,及其对土壤有机氮矿化的影响。首先利用湿筛法测定不同处理团聚体分布及稳定性,采用CT扫描和图像分析方法研究不同处理土壤孔隙结构,并通过室内培养法测定土壤有机氮矿化量,进一步分析土壤结构与有机氮矿化之间的关系。结果显示,与CK相比,LIS和HIS两处理中大于1 mm的水稳性团聚体含量和平均重量直径(MWD)均显著降低,LIS和HIS处理间无显著差异。CK、LIS和HIS的土壤孔隙度分别为3.3%、3.2%和3.3%,各处理间无显著差异;但三个处理的土壤孔隙形态有明显差异,CK大孔隙分布较多且连通性好,LIS和HIS处理孔隙多为球状孔隙,连通性较差。矿化培养第一周,LIS和HIS处理矿化量均快速增加,高于CK处理;但是培养2周后CK矿化氮高于搅动处理,培养试验结束时(4周)CK累积矿化氮量(N28)和氮矿化潜势(N0)显著高于LIS和HIS处理,说明搅拌降低了有机氮的累积矿化量。相关分析表明,土壤有机氮矿化与粒径大于0.25 mm的团聚体含量和当量直径为30~100 μm的孔隙数量具有显著正相关关系,其内在机制尚待进一步研究。
关键词:  搅浆  团聚体稳定性  孔隙结构  显微CT  有机氮矿化
DOI:10.11766/trxb201811050484
分类号:
基金项目:国家自然科学基金项目(41471183,41877022)和国家重点研发计划项目(2016YFD0300900)资助
Effects of Simulated Pudding on Structure of Paddy Soil and Organic Nitrogen Mineralization Therein
LI Yi1, FANG Huan2, PENG Xianlong1, ZHOU Hu2
1.College of Resources and Environment, Northeast Agricultural University;2.State Key Lab of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences
Abstract:
【Objective】Soil structure plays an important role in nitrogen transformation processes. Puddling, a key process of rice cultivation, generally conducted to level and prepare paddy fields for rice transplantation, greatly alters soil structure, which in turn affects soil nitrogen transformation. However, quantitative knowledge of the influence of puddling on nitrogen mineralization is still absent. 【Method】In this study, puddling practice was simulated in the lab by stirring the Hubai paddy soil in a PVC vessel and then incubated for four weeks, for investigation of effects of stirring on soil structure and organic nitrogen mineralization. The incubation experiment was designed to have three treatments in stirring intensity, i.e. no stirring (CK), a low intensity stirring (LIS) and a high intensity stirring (HIS). Soil aggregates were fractionated by particle size and their water stabilities determined with the wet-sieving method. The X-ray computed tomography and image processing technique was used to determine pore size distribution of the soil in each treatment. Mineralized nitrogen was measured with the organic nitrogen mineralization incubation method. 【Result】Compared with CK, both LIS and HIS significantly decreased the proportion of >1 mm aggregates and the mean weight diameter of water stable aggregates, but did not differ much between the two in the effect. Cumulative porosity of the soil in CK, LIS and HIS was 3.3%, 3.2% and 3.3%, respectively, showing no big difference between the treatments. However, the three treatments did show significant differences in soil pore morphology. In CK, numerous big channels high connectivity were found, while in LIS and HIS, spherical or ellipsoidal voids low connectivity were found. Organic nitrogen mineralization in LIS and HIS increased rapidly and exceeded that in CK for the first week after stirring, but declined down even below that in CK from the second week on. At the end of the incubation, CK was found to be higher than LIS and HIS in cumulative nitrogen mineralization and mineralized nitrogen potential. 【Conclusion】Results show that stirring or puddling increases nitrogen mineralization rate in the early stage, however decreases cumulative nitrogen mineralization in the end. Correlation analysis shows that soil organic nitrogen mineralization is significantly and positively related to macroaggregate content and 30~100 μm pores. However, more studies are needed to differentiate the effects of aggregate breaking down and pore restructuring on nitrogen mineralization as a result of puddling.
Key words:  Puddling  Aggregate stability  Pore structure  Micro-CT  Nitrogen mineralization