Effects of different cultivating patterns and nitrogen fertilizer application on soil aggregates
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DOI:10.7606/j.issn.1000-7601.2013.03.16
Key Words: cultivating patterns  nitrogen fertilizer  soil aggregate composition  geometric mean diameter (GMD)  mean weight diameter (MWD)
Author NameAffiliation
ZHOU Congcong Collage of Resource and Environment, Northuest A&F Uniersity, Yangling, Shaanxi 712100, China
 
CHEN Zhujun Collage of Resource and Environment, Northuest A&F Uniersity, Yangling, Shaanxi 712100, China
Key Laboratory of Plant Nutrition and the Agro-environment in Northuest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China 
ZHAO Shixiang Collage of Resource and Environment, Northuest A&F Uniersity, Yangling, Shaanxi 712100, China
 
ZHOU Jianbin Collage of Resource and Environment, Northuest A&F Uniersity, Yangling, Shaanxi 712100, China
Key Laboratory of Plant Nutrition and the Agro-environment in Northuest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China 
ZHANG Xiaomin Collage of Resource and Environment, Northuest A&F Uniersity, Yangling, Shaanxi 712100, China
 
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Abstract:
      The composition, distribution and stability of aggregate, and its relationships with soil organie carbon, soil moisture and yield were studied in a long-term fixed-location experiment. Different cultivating patters(F,CC,SC,RF+SC)and different nitrogen fertilizer amount(N0,N120,N240)were tested to investigate their effects on soil aggre-gates in dryland of northwest China.The results showed that:ridge furrow+straw mulching pattem(RF+SC)planting significantly reduced the 0.25~10 mm dry-sieving aggregate content while significantly increased aggregate that is bigger than 10 mm, in comparison with conventional and straw mulching(SC) patterns. RF+SC pattern planting also promoted formation of bigger size aggregate from 0.5~5 mm one. Content of 0.25~10 mm aggregate by dry-sieving method was significantly higher in N240 treatment than in NO treatment. Compared to conventional pattemn, straw mulching signifi-cantly increased content of water stable aggregate with diameters greater than 0.25 mm.There were no significant differences in water stable aggregate with diameters greater than 0.25 mm among the different nitrogen fertilization treatments. Mean weight diameter(MWD)and geometric mean diameter(GMD)of soil aggregate by dry-sieving method were signifi- cantly higher in RF+SC pattem than in SC and conventional patterns. MWD of water-stable aggregate in SC pattern was significantly greater than in conventional patterns, and its GMD was also significantly greater than in RF+SC pattem. NO treatment significantly improved GMD of water stable aggregate than N120 and N240 treatment; however, there was no significant difference in MWD among the three different N fertilizer treatments. Straw mulching and RF+SC patterns improved soil aggregate stability. There was no significan difference in aggregate stability among different nitrogen treatments. A significant positive correlation was observed between the average of water storage in 2 m soil profile over the 7 years and GMD of water stable aggregate, indicating that diffferent planting patterns affect soil aggregation through its in fluence on soil water and that soil water condition is the determent factor affected soil water stable aggregatte in the region. The correlation between average yield and GMD of water stability aggregate was significantly negative, indicating that small aggregate is benefit for crop yield.