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
Converting from conventional tillage to no-tillage influences the soil aggregate-size distribution and thus soil organic carbon(SOC)stabilization.However,the dynamics of soil aggregation and the straw-derived carbon(C...Converting from conventional tillage to no-tillage influences the soil aggregate-size distribution and thus soil organic carbon(SOC)stabilization.However,the dynamics of soil aggregation and the straw-derived carbon(C)incorporation within aggregate fractions are not well understood.An experiment was established in 2004 to test the effects of two treatments,no-tillage with residue(NT)and conventional tillage without residue(CT),on the soil aggregate-size distribution and SOC stabilization in a continuous maize(Zea mays L.)cropping system located in the semiarid region of northern China.Soil samples were collected from the 0-10 cm layer in 2008,2010 and 2015,and were separated into four aggregate-size classes(〉2,0.25-2,0.053-0.25,and〈0.053 mm)by wet-sieving.In each year,NT soil had a higher proportion of macroaggregates(i.e.,〉2 and 0.25-2 mm)and associated SOC concentration compared with CT.Additionally,to compare straw-derived C incorporation within NT and CT aggregate fractions,^13C-labeled straw was incubated with intact NT and CT soils.After 90 days,the highest proportion of 13C-labeled straw-derived C was observed in the〉2 mm fraction,and this proportion was lower in NT than that in CT soil.Overall,we conclude that long-term continuous NT increased the proportion of macroaggregates and the C concentration within macroaggregates,and the physical protection provided by NT is beneficial for soil C sequestration in the continuous maize cropping system in semiarid regions of northern China.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supported by the National Natural Science Foundation of China(31171512)the Central Publicinterest Scientific Institution Basal Research Fund,China(Y2017PT26)
文摘Converting from conventional tillage to no-tillage influences the soil aggregate-size distribution and thus soil organic carbon(SOC)stabilization.However,the dynamics of soil aggregation and the straw-derived carbon(C)incorporation within aggregate fractions are not well understood.An experiment was established in 2004 to test the effects of two treatments,no-tillage with residue(NT)and conventional tillage without residue(CT),on the soil aggregate-size distribution and SOC stabilization in a continuous maize(Zea mays L.)cropping system located in the semiarid region of northern China.Soil samples were collected from the 0-10 cm layer in 2008,2010 and 2015,and were separated into four aggregate-size classes(〉2,0.25-2,0.053-0.25,and〈0.053 mm)by wet-sieving.In each year,NT soil had a higher proportion of macroaggregates(i.e.,〉2 and 0.25-2 mm)and associated SOC concentration compared with CT.Additionally,to compare straw-derived C incorporation within NT and CT aggregate fractions,^13C-labeled straw was incubated with intact NT and CT soils.After 90 days,the highest proportion of 13C-labeled straw-derived C was observed in the〉2 mm fraction,and this proportion was lower in NT than that in CT soil.Overall,we conclude that long-term continuous NT increased the proportion of macroaggregates and the C concentration within macroaggregates,and the physical protection provided by NT is beneficial for soil C sequestration in the continuous maize cropping system in semiarid regions of northern China.
