旱地施有机肥对土壤有机质和水稳性团聚体的影响

通过渭北旱塬2007-2010年田间定位试验，研究了有机肥不同施用量(低量7500 kg·hm^-2、中量15000 kg·hm^-2、高量22500 kg·hm^-2)对连作玉米地土壤有机质、团聚体各层粒径分布和稳定性的影响.结果表明：0～20 cm土层，高量有机肥处理土壤有机质含量较低量有机肥处理提高4.1%～4.6%，高、中量有机肥处理较对照提高4.6%～11.2%,低量有机肥处理在施肥第4年（2010年）较CK提高4.7%～6.3%.0～30 cm土层，所有有机肥处理>5 mm水稳性团聚体的增幅最大，其含量随有机肥用量的增加而显著升高；有机肥处理显著提高了土壤>0.25 mm水稳性团聚体含量、团聚体平均质量直径和团聚体稳定率，且随有机肥用量的增加而显著增加；中、高量有机肥处理比单施化肥处理增加效果显著.

Effects of organic manure application on dry land soil organic matter and water stable aggregates

A four-year (2007-2010) field experiment was conducted to study the effects of applying different amounts (7500, 15000, and 22500 kg x hm(-2)) of organic manure on the organic matter content, aggregate particle size distribution, and aggregate stability in different soil layers in a continuously cropped maize field on the Weibei Dry Land, Shaanxi Province of Northwest China. In 0-20 cm soil layer, the organic matter content in treatment 22500 kg x hm(-2) of organic manure was 4.1%-4.6% higher than that in treatment 7500 kg x hm(-2) of organic manure (P < 0.05), and the organic matter content in treatments 15000 and 22500 kg x hm(-2) of organic manure was 4.6%-11.2% higher than that in CK (chemical fertilization) (P < 0.05). In the fourth year (2010) of applying 7500 kg x hm(-2) of organic manure, the organic matter content in 0-20 cm soil layer was 4.7%-6.3% higher than that of CK (P < 0.05). In 0-30 cm soil layer, all treatments with organic manure application had an increased amount of soil water stable aggregates (> 5 mm), and the amount of the aggregates increased significantly with the increasing application rate of organic manure. Applying organic manure increased the amount of soil water stable aggregates (> 0.25 mm), aggregate mean mass diameter, and aggregate stability in 0-30 cm soil layer, as compared with CK, and these three indices increased significantly with increasing organic manure application rate.