| Popis: |
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 (P0.05), 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) (P0.05). 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 (P0.05). 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. |
