Soil and water loss has been a major environmental problem in the Danjiangkou Reservoir Region.A study of 14°sloping farmland was performed on impact of different contour hedgerows on runoff,losses of soil and nu...Soil and water loss has been a major environmental problem in the Danjiangkou Reservoir Region.A study of 14°sloping farmland was performed on impact of different contour hedgerows on runoff,losses of soil and nutrients during 2008 and 2011,with five treatments and three replications.The winter wheat and summer maize were used as the test crops.Treatments consisted of four hedgerows:Amorpha(Amorpha fruticosa L.),Honeysuckle(Lonicera japonica Thunb.),Day-lily flower(Hemerocallis citrina Baroni.),and Sabaigrass(Eulaliopsis binata),and a control without hedgerow.Result showed that the runoff under the control treatment was much higher than that of hedgerows.Amorpha could reduce the runoff by 35.2%compared with the control.Soil losses in four hedgerows showed significant reduction in four years(e.g.,Amorpha:78.3%;Honeysuckle:77.1%).Nutrient losses in winter were much higher than that in summer,especially total nitrogen,total phosphorus and total potassium,even though there was an abundant precipitation in summer.Hedgerows greatly affected the soil and nutrient losses on slopping farmland compared with the control treatment,especially Amorpha treatment.The present study found that the Amorpha could be used as the hedgerow species for reducing soil and water loss in the Danjiangkou Reservoir Region.展开更多
A litterbag experiment of 12 weeks was conducted to study nitrogen mineralization process of prunings of six nitrogen-fixing hedgerow species in a dry valley of the Jinsha River. Prunings were incorporated into soil o...A litterbag experiment of 12 weeks was conducted to study nitrogen mineralization process of prunings of six nitrogen-fixing hedgerow species in a dry valley of the Jinsha River. Prunings were incorporated into soil or used as mulch. The results indicated that pruning N of the six hedgerow species was mineralized fast in the first week and then decreased slowly in the rest of the study period. When prunings were incorporated into soil, the amount of nitrogen mineralized by the end of the first week accounted for 69.9%, 58.2%, 54.5%, 43.0%, 29.6% and 20.6% of the total N in prunings of Desmodium rensonii, Tephrosia Candida, Leucaena leucocephala, Albizia yunnanensis, Acacia dealbata, and Acacia mearnsii, respectively. When prunings of L. leucocephala were used as mulch materials, the amount of nitrogen mineralized in the first week was 16.2% less than that of prunings incorporated into soil. The mineralization pattern of pruning N could be simulated by an exponent model Nt% = N01% (1 ?exp(梜1t))+ No2% (1 ?exp(梜2t) where Nt% is cumulative mineralized N in time t, N01 % and No2 % are readily and less readily mineralizable N in prunings, respectively, and k1 and k2 are rate constants. A half-life period of pruning nitrogen mineralization could also be determined by this model. The nitrogen content in the pruning residues decreased quickly in the first week but fluctuated thereafter. The initial C/N ratio was negatively related to the mineralization rate of prunings.展开更多
文摘Soil and water loss has been a major environmental problem in the Danjiangkou Reservoir Region.A study of 14°sloping farmland was performed on impact of different contour hedgerows on runoff,losses of soil and nutrients during 2008 and 2011,with five treatments and three replications.The winter wheat and summer maize were used as the test crops.Treatments consisted of four hedgerows:Amorpha(Amorpha fruticosa L.),Honeysuckle(Lonicera japonica Thunb.),Day-lily flower(Hemerocallis citrina Baroni.),and Sabaigrass(Eulaliopsis binata),and a control without hedgerow.Result showed that the runoff under the control treatment was much higher than that of hedgerows.Amorpha could reduce the runoff by 35.2%compared with the control.Soil losses in four hedgerows showed significant reduction in four years(e.g.,Amorpha:78.3%;Honeysuckle:77.1%).Nutrient losses in winter were much higher than that in summer,especially total nitrogen,total phosphorus and total potassium,even though there was an abundant precipitation in summer.Hedgerows greatly affected the soil and nutrient losses on slopping farmland compared with the control treatment,especially Amorpha treatment.The present study found that the Amorpha could be used as the hedgerow species for reducing soil and water loss in the Danjiangkou Reservoir Region.
基金Project supported jointly by the Chengdu Di Ao Science Foundation and the Sichuan Provincial Science Foundation for Young Scient
文摘A litterbag experiment of 12 weeks was conducted to study nitrogen mineralization process of prunings of six nitrogen-fixing hedgerow species in a dry valley of the Jinsha River. Prunings were incorporated into soil or used as mulch. The results indicated that pruning N of the six hedgerow species was mineralized fast in the first week and then decreased slowly in the rest of the study period. When prunings were incorporated into soil, the amount of nitrogen mineralized by the end of the first week accounted for 69.9%, 58.2%, 54.5%, 43.0%, 29.6% and 20.6% of the total N in prunings of Desmodium rensonii, Tephrosia Candida, Leucaena leucocephala, Albizia yunnanensis, Acacia dealbata, and Acacia mearnsii, respectively. When prunings of L. leucocephala were used as mulch materials, the amount of nitrogen mineralized in the first week was 16.2% less than that of prunings incorporated into soil. The mineralization pattern of pruning N could be simulated by an exponent model Nt% = N01% (1 ?exp(梜1t))+ No2% (1 ?exp(梜2t) where Nt% is cumulative mineralized N in time t, N01 % and No2 % are readily and less readily mineralizable N in prunings, respectively, and k1 and k2 are rate constants. A half-life period of pruning nitrogen mineralization could also be determined by this model. The nitrogen content in the pruning residues decreased quickly in the first week but fluctuated thereafter. The initial C/N ratio was negatively related to the mineralization rate of prunings.
