The inlfuences of tillage systems on soil carbon （C） stocks have been studied extensively, but the distribution of soil C within aggregate fractions is not well understood. The objective of this study was to determi...The inlfuences of tillage systems on soil carbon （C） stocks have been studied extensively, but the distribution of soil C within aggregate fractions is not well understood. The objective of this study was to determine the inlfuences of various tillage systems on soil aggregation and aggregate-associated C under wheat （Triticum aestivum L.） and corn （Zea mays L.） double cropping systems in the North China Plain. The experiment was established in 2001, including four treatments：moldboard plow （MP） with residue （MP＋R） and without residue （MP-R）, rotary tillage with residue （RT）, and no-till with residue （NT）. In 2007 soil samples were collected from the 0-5, 5-10, and 10-20 cm depths, and were separated into four aggregate-size classes （〉2 000, 250-2 000, 53-250, and〈53 μm） by wet-sieving method. Aggregate-associated C was determined, and the relationships between total soil C concentration and aggregation-size fractions were examined. The results showed that NT and RT treatments signiifcantly increased the proportion of macroaggregate fractions （〉2 000 and 250-2 000 μm） compared with the MP-R and MP＋R treatments. Averaged across all depths, mean weight diameters of aggregates （MWD） in NT and RT were 47 and 20% higher than that in MP＋R. The concentration of bulk soil organic C was positively correlated with MWD （r=0.98; P=0.024） and macroaggregate fraction （r=0.96; P=0.036） in the 0-5 cm depth. In the 0-20 cm depth, comparing with MP＋R, total C occluded in the〉2 000 μm fraction was increased by 9 and 6%under NT and RT, respectively. We conclude that adoption of conservation tillage system, especially no-till, can increase soil macro-aggregation and total C accumulation in macroaggregates, which may improve soil C sequestration in the intensive agricultural region of the North China Plain.展开更多
The North China Plain（NCP） is one of major breadbaskets in China. Crop growth and grain yield differ significantly with spatial variations of soil properties. This study aims to identify the key soil properties in r...The North China Plain（NCP） is one of major breadbaskets in China. Crop growth and grain yield differ significantly with spatial variations of soil properties. This study aims to identify the key soil properties in relation to the grain yield for the winter wheat（Triticum aestivum L.）-maize（Zea mays L.） cropping system in a high-productivity farmland of the NCP. The field trials were conducted in three fields with different grain yield levels in Tai＇an City, Shandong Province, China, during the 2009–2012 period. Consistent field management strategies were applied in the three fields. Fifty-one physical and chemical indicators of the soil profile as related to grain yield were evaluated. An approximate maximum of 17.8% annual average grain yield difference was observed in the fields during the period of 2009–2012. The soil indicators were classified into three clusters with specific functions using cluster analysis, and three key indicators were extracted from each cluster to characterize the different soil properties of three fields. The first cluster represented soil water retention capacity, and the key indicator was available soil water（ASW）, which ranged from 153 to 187 mm in the 1.2 m profile and was correlated positively with grain yield. The second cluster represented soil water conductivity, as measured by saturated hydraulic conductivity（K s）. The higher yield field had a greater capacity to retain topsoil water for its lower K s（1.9 cm d^–1） in the 30–70 cm soil layer as compared to the lower yield field. The third cluster represented nutrient storage and supply, as indicated by the ratio of nutrient content to silt＋clay content of the top soil layer. The ratio of soil organic matter（OM）, total nitrogen（TN）, available P, exchangeable K＋ to silt＋clay content in the 0–20 cm soil layer were 19.0 g kg^–1, 1.6 g kg^–1, 94.7 mg kg^–1, 174.3 mg kg^–1 in the higher yield field, respectively, and correlated positively with the grain yield. By characterizing the differences in soil properties among fields with different yield levels, this study offers the scientific basis for increasing grain yield potential by improving the soil conditions in the NCP.展开更多
基金funded by the National Natural Science Foundation of China(31000250)the National 973 Program of China(2009CB118607)
文摘The inlfuences of tillage systems on soil carbon （C） stocks have been studied extensively, but the distribution of soil C within aggregate fractions is not well understood. The objective of this study was to determine the inlfuences of various tillage systems on soil aggregation and aggregate-associated C under wheat （Triticum aestivum L.） and corn （Zea mays L.） double cropping systems in the North China Plain. The experiment was established in 2001, including four treatments：moldboard plow （MP） with residue （MP＋R） and without residue （MP-R）, rotary tillage with residue （RT）, and no-till with residue （NT）. In 2007 soil samples were collected from the 0-5, 5-10, and 10-20 cm depths, and were separated into four aggregate-size classes （〉2 000, 250-2 000, 53-250, and〈53 μm） by wet-sieving method. Aggregate-associated C was determined, and the relationships between total soil C concentration and aggregation-size fractions were examined. The results showed that NT and RT treatments signiifcantly increased the proportion of macroaggregate fractions （〉2 000 and 250-2 000 μm） compared with the MP-R and MP＋R treatments. Averaged across all depths, mean weight diameters of aggregates （MWD） in NT and RT were 47 and 20% higher than that in MP＋R. The concentration of bulk soil organic C was positively correlated with MWD （r=0.98; P=0.024） and macroaggregate fraction （r=0.96; P=0.036） in the 0-5 cm depth. In the 0-20 cm depth, comparing with MP＋R, total C occluded in the〉2 000 μm fraction was increased by 9 and 6%under NT and RT, respectively. We conclude that adoption of conservation tillage system, especially no-till, can increase soil macro-aggregation and total C accumulation in macroaggregates, which may improve soil C sequestration in the intensive agricultural region of the North China Plain.
基金financially supported by the National Basic Research Program of China (2015CB150403)
文摘The North China Plain（NCP） is one of major breadbaskets in China. Crop growth and grain yield differ significantly with spatial variations of soil properties. This study aims to identify the key soil properties in relation to the grain yield for the winter wheat（Triticum aestivum L.）-maize（Zea mays L.） cropping system in a high-productivity farmland of the NCP. The field trials were conducted in three fields with different grain yield levels in Tai＇an City, Shandong Province, China, during the 2009–2012 period. Consistent field management strategies were applied in the three fields. Fifty-one physical and chemical indicators of the soil profile as related to grain yield were evaluated. An approximate maximum of 17.8% annual average grain yield difference was observed in the fields during the period of 2009–2012. The soil indicators were classified into three clusters with specific functions using cluster analysis, and three key indicators were extracted from each cluster to characterize the different soil properties of three fields. The first cluster represented soil water retention capacity, and the key indicator was available soil water（ASW）, which ranged from 153 to 187 mm in the 1.2 m profile and was correlated positively with grain yield. The second cluster represented soil water conductivity, as measured by saturated hydraulic conductivity（K s）. The higher yield field had a greater capacity to retain topsoil water for its lower K s（1.9 cm d^–1） in the 30–70 cm soil layer as compared to the lower yield field. The third cluster represented nutrient storage and supply, as indicated by the ratio of nutrient content to silt＋clay content of the top soil layer. The ratio of soil organic matter（OM）, total nitrogen（TN）, available P, exchangeable K＋ to silt＋clay content in the 0–20 cm soil layer were 19.0 g kg^–1, 1.6 g kg^–1, 94.7 mg kg^–1, 174.3 mg kg^–1 in the higher yield field, respectively, and correlated positively with the grain yield. By characterizing the differences in soil properties among fields with different yield levels, this study offers the scientific basis for increasing grain yield potential by improving the soil conditions in the NCP.
