水旱轮作条件下土壤有机无机复合状况的研究

STUDY ON THE STATE OF ORGANO-MINERAL COMPLEX IN SOILS UNDER THE ROTATION OF PADDY AND UPLAND CROPS

在黄棕壤和灰潮土上进行水旱轮作条件下土壤有机无机复合状况变化的研究表明:1.水改旱有利于促进土壤有机质与土壤矿质部分的复合,增加土壤有机无机复合量,旱改水则使游离态有机质增多。2.水改旱后,土壤所复合的腐殖质中紧结态的相对较多,同时松结态和紧结态腐殖质的易氧化部分增多,能促使结合态腐殖质的氧化更新;旱改水后,松结态腐殖质相对增多,以及松结态和紧结态腐殖质的难氧化部分增多。3.水改旱后可导致土壤腐殖质组分上的差异,即HA-B/FA-B的比值升高;HA-A/FA-A的比值下降。4.水改旱后土壤碳、氮含量除细粘粒复合体中有增加外,其他粒径复合体中的都减少了,而磷、硫含量在粗粘粒和细粘粒复合体中均有明显增加,说明水改旱有利于缩短土壤有机质以及氮、磷、硫养分的循环周期,促进其易矿化性。

The state of organo-mineral complex in soils under the rotation of paddy and upland crops was studied. Soils used in experiment were yellow brown earth derived from siashu loess and grey fluro aquic soil as well as their corresponding paddy soils. Results obtained are described as follows: 1. A change from paddy field to dryland was advantageous to promote the complexing process and increase the amount of organomineral complex in soils. However, a change from dryland to paddy field could increase the quantity of free organic matter and was advantageous to the accumulation of soil organic matter. The rotation of paddy and upland crops could improve the state of organomineral complex of soils by accelerating the transformation of organic matter. 2. After a change from paddy field to dryland, the content of tightly combined humus was comparatively increased, it was favorable to improve soil structure. Simultaneously, the liable oxidizing parts of loosely combined and tightly combined humus were increased and it could promote the oxidation and regeneration of combined humus. While a change from dryland to paddy field, the content of loosely combined humus was comparatively increased, it was advantageous to activation of soil humus. 3. The rotation of paddy and upland crops could caused the difference in fractionation and composition of soil humus. The increase of ratio HA-B/FA-B and the decrease of ratio HA-A/FA-A after the change from paddy field to dryland indicate that the laible mineralizable fraction of soil humus was increased and it might be promote to release soll nutrients. 4. The contents of C, N, P and S in soil complexes were enhanced with the reduce of soil complex particle sizes except silty complexes. The change of C, N, P and S contents in soil complexes of different particle sizes under the rotation of paddy and upland crops showed that a change from paddy filed to dryland was favourable to shorten the cycle period of C, N, P and S in soils and make them to be mineralizaed easily.