长期施肥下土壤性质变化及其对微生物生物量的影响

在对长期施用化肥以及与有机肥配施处理的红壤稻田土壤水分特征曲线研究的基础上，考察了土壤性质变化及各种孔隙分布特征，探讨了不同大小孔隙分布和有机碳含量以及微生物生物量的关系。结果表明：长期施用有机肥增加了土壤有机碳含量，提高了土壤保持水分的能力。相比于不施肥处理(通气孔隙度0.121 m3/m3)，施用有机肥增加了土壤的通气孔隙(通气孔隙度0.156 m3/m3)，施用化肥减少了土壤的通气孔隙(通气孔隙度分别为NK 0.11 m3/m3，NP 0.115 m3/m3，NPK 0.082 m3/m3，2NPK 0.113 m3/m3)，长期施用有机肥的土壤中大孔隙度和中孔隙度分别是施用化肥和不施肥处理的 1.45 ~ 1.68倍和1.22 ~ 1.43倍，小孔隙度在0.39 ~ 0.41 m3/m3之间，且所有施肥处理之间无显著差异。通过相关分析表明，土壤有机碳含量与土壤总孔隙度和中孔隙度均极显著相关(P<0.01)，与土壤大孔隙度显著相关(P<0.05)，土壤微生物生物量碳和呼吸强度与大孔隙度显著相关(P<0.05)，说明长期施用有机肥是通过提高土壤有机碳来改善土壤中、大孔隙比例，最终提高土壤总孔隙度，增加土壤大孔隙的数量，有利于土壤微生物的活动的。

Effects of Long-term Fertilization on Soil Property Changes and Soil Microbial Biomass

Based on analyzing the water retention curves in paddy soils of long-term fertilization, the relationship between soil properties and different pore size were explored. The results showed that soil organic carbon content and water-holding capacity increased with the application of organic manure. Compared to the no fertilizer treatment (aeration porosity 0.121 m3/m3), the organic manure application treatment increased aeration porosity (aeration porosity 0.156 m3/m3), whereas the chemical fertilizer application treatments decreased aeration porosity (NK 0.11 m3/m3, NP 0.115 m3/m3, NPK 0.082 m3/m3, 2NPK 0.113 m3/m3). The proportion of marcopores and mescopores were 1.45-1.68 and 1.22-1.43 times for organic manure application treatment to the no fertilizer treatment and the chemical fertilizer application treatments, the proportion of mircopores in 0.39 - 0.41 m3/ m3. Correlation analysis showed that the content of soil organic carbon exhibited significant correlates with total porosity and the proportion of mescopores (P<0.01) and significant correlates with the proportion of marcopores (P<0.05), but not significant with the proportion of mircopores; the proportion of macropores had significant correlates (P<0.05) with soil microbial biomass carbon and respiration intensity. These results suggested that long-term application of organic manure could improve the total porosity via the increase of the mescopores and marcopores, and the increased soil macropores could favor soil microbial activities.