The objective of this study was to determine the efficiency of different plant systems in capturing deep soil nitrate （NO3-） to reduce NO3- leaching in a field plot experiment using 15N labelling. The study was cond...The objective of this study was to determine the efficiency of different plant systems in capturing deep soil nitrate （NO3-） to reduce NO3- leaching in a field plot experiment using 15N labelling. The study was conducted on a calcareous alluvial soil on the North China Plains and the plant systems evaluated included alfalfa （Medicago sativa）, American black poplar （Populus nigra） and cocksfoot （Dactylis）. ^15N-labelled N fertilizer was injected to 90 cm depth to determine the recovery of ^15N by the plants. With conventional water and nutrient management, the total recovery of ^15N-labeled NO3--N was 23.4% by alfalfa after two consecutive growth years. The recovery was significantly higher than those by American black poplar （12.3%） and cocksfoot （11.4%）. The highest proportion of soil residual ~SN from the labeled fertilizer N （%Ndff） was detected around 90 cm soil depth at the time of the 1st year harvest and at 110-130 cm soil depth at time of the 2nd year harvest. Soil %Ndff in 0-80 cm depth was significantly higher in the alfalfa treatment than those in all the other treatments. The soil %Ndff below 100 cm depth was much lower in the alfalfa than those in all the other treatments. These results indicated that ^15N leaching losses in the alfalfa treatment were significantly lower than by those in the black poplar and cocksfoot treatments, due to the higher root density located in nitrate labeling zone of soil profile. In conclusion, alfalfa may be used as a plant to capture deep soil NO3- left from previous crops to reduce NO3- leaching in high intensity crop cultivation systems of North China Plain.展开更多
Background:The persistence of summer‐active perennial species is critical for pasture‐fed meat production in the temperate,uniform rainfall environment of south‐eastern Australia.Methods:To investigate the limitati...Background:The persistence of summer‐active perennial species is critical for pasture‐fed meat production in the temperate,uniform rainfall environment of south‐eastern Australia.Methods:To investigate the limitations of important pasture species under contrasting levels of drought and soil acidity stress,we monitored replicated field plots for persistence and productivity at three sites on the Southern Tablelands over 2–3 years.Results:All sites experienced a period of severe drought.At one site,persistence was ranked lucerne>phalaris>Porto cocksfoot>Savvy cocksfoot,tall fescue,chicory>plantain,red clover.Bromes survived via recruitment.Lucerne and chicory were the most productive immediately post‐drought in summer and phalaris and chicory in autumn.Cocksfoot outyielded tall fescue.At a higher‐elevation site,less drought‐tolerant species were more persistent and productive.At a site with deep soil acidity,lucerne failed to persist;chicory performed better but declined with overgrazing during drought.Tall fescue declined severely during drought.Conclusions:Lucerne remains the most productive summer option if soil conditions allow its growth,with chicory a potential replacement on acidic soils.Good productivity combined with acid soil tolerance favours cocksfoot over tall fescue.The ability to survive occasional severe drought is an important factor in species choice.展开更多
基金financially supported by the Provincial Natural Science Foundation of Hebei Province in China(C2006000491)the financial support from the National Natural Science Foundation of China(30571110,31172033)the National 863 Program of China(2012AA101403-3)
文摘The objective of this study was to determine the efficiency of different plant systems in capturing deep soil nitrate （NO3-） to reduce NO3- leaching in a field plot experiment using 15N labelling. The study was conducted on a calcareous alluvial soil on the North China Plains and the plant systems evaluated included alfalfa （Medicago sativa）, American black poplar （Populus nigra） and cocksfoot （Dactylis）. ^15N-labelled N fertilizer was injected to 90 cm depth to determine the recovery of ^15N by the plants. With conventional water and nutrient management, the total recovery of ^15N-labeled NO3--N was 23.4% by alfalfa after two consecutive growth years. The recovery was significantly higher than those by American black poplar （12.3%） and cocksfoot （11.4%）. The highest proportion of soil residual ~SN from the labeled fertilizer N （%Ndff） was detected around 90 cm soil depth at the time of the 1st year harvest and at 110-130 cm soil depth at time of the 2nd year harvest. Soil %Ndff in 0-80 cm depth was significantly higher in the alfalfa treatment than those in all the other treatments. The soil %Ndff below 100 cm depth was much lower in the alfalfa than those in all the other treatments. These results indicated that ^15N leaching losses in the alfalfa treatment were significantly lower than by those in the black poplar and cocksfoot treatments, due to the higher root density located in nitrate labeling zone of soil profile. In conclusion, alfalfa may be used as a plant to capture deep soil NO3- left from previous crops to reduce NO3- leaching in high intensity crop cultivation systems of North China Plain.
基金Meat and Livestock Australia,Grant/Award Number:P.PSH.1048。
文摘Background:The persistence of summer‐active perennial species is critical for pasture‐fed meat production in the temperate,uniform rainfall environment of south‐eastern Australia.Methods:To investigate the limitations of important pasture species under contrasting levels of drought and soil acidity stress,we monitored replicated field plots for persistence and productivity at three sites on the Southern Tablelands over 2–3 years.Results:All sites experienced a period of severe drought.At one site,persistence was ranked lucerne>phalaris>Porto cocksfoot>Savvy cocksfoot,tall fescue,chicory>plantain,red clover.Bromes survived via recruitment.Lucerne and chicory were the most productive immediately post‐drought in summer and phalaris and chicory in autumn.Cocksfoot outyielded tall fescue.At a higher‐elevation site,less drought‐tolerant species were more persistent and productive.At a site with deep soil acidity,lucerne failed to persist;chicory performed better but declined with overgrazing during drought.Tall fescue declined severely during drought.Conclusions:Lucerne remains the most productive summer option if soil conditions allow its growth,with chicory a potential replacement on acidic soils.Good productivity combined with acid soil tolerance favours cocksfoot over tall fescue.The ability to survive occasional severe drought is an important factor in species choice.
