1.Key Laboratory of Arable Land Conservation Middle and Lower Reaches of Yangtze River,Ministry of Agriculture,Huazhong Agricultural University,P R China.;2.Scientific Observing and Experimental Station of Arable Land Conservation（Hunan），Ministry of Agriculture and Rural Affairs，Soil and Fertilizer Institute of Hunan Province
Supported by the National Natural Science Foundation of China（No.41977020） and China Agriculture Research System of MOF and MARA(No.CARS-22).
铁氧化物是土壤团聚体重要的胶结物质，其主要存在于土壤黏粒中。为探索紫云英还田并配施化肥下土壤团聚体中铁氧化物的变化规律及其在不同粒级黏粒组分中的富集特点，以湖南省南县长期紫云英还田的水稻土为研究对象，选择单施紫云英（MV）、单施化肥（F100）、紫云英配施全量化肥（MV+F100）和紫云英配施80%化肥（MV+F80）4个处理，通过湿筛和离心分离土壤团聚体（>250、53~250 和2~53 μm）和黏粒（<2 μm），测定不同处理土壤团聚体及其黏粒中铁氧化物的含量，并分析它们与团聚体稳定性的关系。结果表明：（1）与MV和F100相比，紫云英与全量化肥配施增加了>250 μm粒级团聚体的含量，降低了53~250 μm粒级团聚体含量，团聚体平均重量直径（MWD）和几何平均直径（GMD）分别提高了8.2%~20.5%和4.1%~8.5%。（2）与MV相比，紫云英与化肥配施显著提高了各粒级团聚体、2~53 μm团聚体黏粒和自由态黏粒非晶质铁的含量（12.7%~55.6%，52.4%~54.9%和45.9%~48.6%），降低了>250和53~250 μm团聚体非晶质铁的富集率（32.8%~36.8%和17.2%~28.4%）。而与F100相比，2~53 μm团聚体和团聚体黏粒非晶质铁的含量以及富集率均显著降低（3.5%~21.3%、29.2%~30.4%和10.9%~26.9%）。（3）>250 μm团聚体含量与团聚体黏粒的非晶质铁含量、铁的活化度呈极显著正相关，与团聚体黏粒的游离铁含量、非晶质铁的富集率呈显著正相关。团聚体的MWD和GMD与>250μm团聚体含量呈极显著正相关，而与<2 μm团聚体含量呈极显著负相关。>250、2~53 μm团聚体黏粒和自由态黏粒的游离铁是团聚体MWD和GMD最重要的影响因子。紫云英与化肥配施，能够提高团聚体黏粒铁氧化物的含量，促进>250 μm团聚体的形成，从而增强团聚体的稳定性。
【Objective】Iron oxides are important cementitious substances in soil aggregates, which mainly exist in soil clay particles. This study aimed to reveal the transformation of iron oxides in soil aggregates and their enrichment characteristics in clay fractions of different particle sizes under the conditions of returning Chinese milk vetch to the field and applying chemical fertilizers.【Method】Four treatments including a single application of Chinese milk vetch (MV), a single application of chemical fertilizer (F100), Chinese milk vetch applied with chemical fertilizer (MV+F100) and Chinese milk vetch combined with 80% of chemical fertilizer (MV+F80) were selected. Soil aggregates (>250, 53~250 and 2~53 μm) and clay particles (<2 μm) were separated by wet sieving and centrifugation, and the content of iron oxides in soil aggregates and their clay particles with different treatments was determined. Also, the relationship between iron oxides and the stability of aggregates was analyzed.【Result】(1) Compared with MV and F100, the content of >250 μm aggregate was increased and the content of 53-250 μm aggregate was decreased, and the mean weight diameter (MWD) and geometric mean diameter (GMD) were increased by 8.2% to 20.5% and 4.1% to 8.5%, respectively. (2) Compared with MV, the combined application of Chinese milk vetch and chemical fertilizer significantly increased the contents of amorphous iron (12.7%-55.6%, 52.4%-54.9% and 45.9%-48.6%) in aggregates of various sizes, clay particles of 2~53 μm and free clay particles. The enrichment rates of amorphous iron in >250 and 53~250 μm aggregates were decreased (32.8%~36.8% and 17.2%~28.4%). Compared with F100, the content and enrichment rate of amorphous iron in 2~53 μm aggregates and clay of aggregates were significantly reduced (3.5%~21.3%, 29.2%~30.4% and 10.9%~26.9%). (3) The content of >250 μm aggregates was positively correlated with the content of non-crystalline iron and activation degree of iron in the clay of aggregates, and positively correlated with the enrichment rate of amorphous iron and the content of free iron in aggregates. The MWD and GMD were significantly positively correlated with the content of >250μm aggregates, and significantly negatively correlated with the content of <2μm aggregate. The free iron in the clay of >250 and 2~53μm aggregates and free clays was the most important factor influencing the MWD and GMD.【Conclusion】Combined application of Chinese milk vetch with chemical fertilizer could increase the content of iron oxide in the clay of different aggregates and promote the formation of >250μm aggregates, thus, enhancing the stability of aggregates.
黄 丽,谢 坤,耿明建,聂 军,鲁艳红,廖育林.长期紫云英还田与化肥配施下水稻土团聚体中铁氧化物的演变规律[J].土壤学报,DOI:10.11766/trxb202111110611,[待发表]
HUANG Li, XIE Kun, GENG Mingjian, NIE Jun, LU Yanhong, LIAO Yulin. Evolution of Iron Oxides in Aggregates of Paddy Soil Under Long-term Returning of Chinese Milk Vetch and Combined Application of Chemical Fertilizers[J]. Acta Pedologica Sinica, DOI:10.11766/trxb202111110611,[In Press]