长期定位施肥下紫色土土壤微形态特征

Micro-morphological Features of A Purple Soil under Different Long-term Fertilizer Treatments

通过对紫色土长期定位施肥下不同施肥处理0～20cm耕层土壤微形态特征的研究,试图说明施肥对紫色土微形态的影响。用单偏光显微镜对不同处理的土壤微形态进行了观察与分析。结果表明:长期不施肥料的CK处理,土壤耕层结构致密,很少有孔隙发育,土壤微结构为结构较差的碎屑聚积状-沙粒聚积状;长期单施化学肥料,土壤颗粒未形成结构体,少孔隙,土壤微结构主要为斑晶胶凝状-细沙粒聚积状结构,土壤结构比CK处理优;长期施用有机肥或有机无机肥料配施的处理,土壤粗颗粒数量显著增加,结构疏松,孔隙量大,动、植物残体丰富,有铁锰结核和腐殖质的形成和微团聚体的发育,土壤微结构类型以MNPK处理最好,为胶凝紧实状-多孔状结构。有机无机肥料配施能显著改良紫色土的结构,培肥土壤,实现土壤可持续发展。

Through a study on the 0～20cm topsoil micro-morphological characteristics of a purple paddy soil in a long-term fertilizer experiment, it is intended to interpret effects of different fertilizer treatments on the soil micro-morphology. Soil micro-morphological features were observed and analyzed with the single polarizing microscope. Results showed that the topsoil structure of the CK （no fertilizer） treatment was dense with little porosity developed, and the soil microstructure was sandy granular fabric - granular fabric. In these treatments using chemical fertilizers only, the soil particles did not form soil structure with little porosity, and the soil microstructures in the N, NP or NPK treatment were observed as prophyropectic fabric-fine sand agglomerplasmic fabric, much better than the CK treatment. In those treatments receiving farm manure alone or farm manure plus chemical fertilizers, the quantity of groundmass increased obviously. The soil had a loosen structure, higher porosity, enriched animal and plant residua, iron-manganese nodules and humus, and more micro-aggregates developed. The soil microstructure of the MNPK treatment was pectized-compacted takyric fabric-intertextic fabric, the best microstructure observed among all the treatments. Thus, combined application of both organic and inorganic fertilizers could significantly improve the structure of purple paddy soil, enhance soil fertility and achieve soil sustainable development.