增施或减施有机物料对长期培肥红壤性水稻土团聚体组成的影响

利用一个长达30年且已进行适当变更的定位肥料试验,采用湿筛法进行土壤团聚体分级,测定并计算土壤容重、孔隙度与平均质量直径(MWD),探讨了长期施用高量有机肥、常量有机肥、化肥及当其施肥措施改变(化改常、常改高、高改化、常改化)3年后红壤性水稻土团聚体组成及结构的变化特征,以期为已培肥红壤性水稻土选择合理的后续施肥策略而促进水稻土可持续发展提供理论依据。结果表明,与施用化肥30年相比,长期施用有机肥(常量、高量)能显著降低土壤容重(10.38%~19.81%),并提高孔隙度(6.77%~13.13%)与MWD(46.84%~61.58%)。有机肥处理(常量、高量、化改常、常改高)下粗大团聚体(2 mm)所占比例最高,而化肥处理(高改化、常改化、化肥)下细大团聚体(2~0.25 mm)所占比例最高。在施肥措施改变3年后,如减少有机肥(高改化、常改化)的施入量将导致土壤容重增加(6.47%~14.34%),土壤孔隙度(3.63%~6.79%)或MWD(21.15%~31.43%)降低;而增加有机肥(化改常、常改高)的施入量将显著降低土壤容重(3.08%~9.02%)并增加土壤孔隙度(1.73%~6.01%)与MWD(5.45%~44.58%)。由此,为进一步维持或改善土壤结构,红壤性水稻土长期培肥后应继续或加大田间外源有机物料的投入量。

Effects of organic material on the aggregation in long term cultivited reddy paddy soils

A 30 years experiment was altered and soil aggregates,bulk density,porosity and mean weight diameter (MWD) were measured to determine the effects of following-up fertilization reforming on soil aggregation of reddy paddy soils cultivated under different seven fertilization treatment,i.e.high organic material (HOM),normal organic material (NOM),chemical fertilizer (CF),normal organic fertilization treatment changed from chemical fertilization treatment (C-N),chemical fertilization treatment changed from original normal organic fertilization treatment (N-C),chemical fertilization treatment changed from original high organic fertilization treatment (H-C),high organic fertilization treatment changed from original normal organic fertilization treatment (N-H),which in order to select a reasonable follow-up fertilization strategy for cultivited reddy paddy soils and provide theoretical basis for promoting the sustainable development of paddy soil.The results showed that organic fertilization (HOM,NOM) had greater ability to decrease soil bulk density by 10.38％ ～ 19.81％ and improve soil porosity by 6.77％ ～ 13.13％ and MWD by 46.84％ ～61.58％ compared with chemical fertilization (CF).It was the coarse macroaggregate (＞ 2 mm) which having the highest ratio among soil aggregates under organic fertilization treatments (HOM,NOM,C-N,N-H),while it was the fine macro aggregate (2 ～0.25 mm) under chemical fertilization (H-C、N-C、CF).After 3 years following-up fertilization alteration,reducing the input of organic fertilizer (H-C、N-C) would increase soil bulk density (6.47％ ～ 14.34％),decrease soil porosity (3.63％ ～ 6.79％) and MWD (21.15％ ～ 31.43％).while increasing input of organic fertilizer (C-N,N-H) would decrease soil bulk density (3.08％ ～ 9.02％),increase soil porosity (1.73％ ～ 6.01％) and MWD (5.45％ ～ 44.58％).As a conclusion,the following-up organic fertilization was necessary to maintain or improve soil aggregation in the long-term cultivited reddy paddy soils with high fertility.