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Leaching losses of nitrogen and phosphorus from arable hillslope purple soils under different mulberry-crop combinations in Three Gorges Reservoir Region
Received:February 23, 2016  
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KeyWord:Three Georges Reservoir Region;upland soil;nitrogen;phosphorus;leaching loss
Author NameAffiliationE-mail
SHANG Er-feng College of Resources and Environment, Southwest University, Chongqing 400716, China  
SHI Shu College of Resources and Environment, Southwest University, Chongqing 400716, China  
LIN Xiao College of Resources and Environment, Southwest University, Chongqing 400716, China  
LUO Bai-lin College of Resources and Environment, Southwest University, Chongqing 400716, China  
WANG Fa College of Resources and Environment, Southwest University, Chongqing 400716, China  
MU Zhi-jian College of Resources and Environment, Southwest University, Chongqing 400716, China
Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three-Gorges Reservoir Area, Chongqing 400716, China
Key Laboratory of Eco-environment in Three Gorges Reservoir Region of Ministry of Education, Chongqing 400715, China 
muzj@swu.edu.Cn 
NI Jiu-pai College of Resources and Environment, Southwest University, Chongqing 400716, China
Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three-Gorges Reservoir Area, Chongqing 400716, China
Key Laboratory of Eco-environment in Three Gorges Reservoir Region of Ministry of Education, Chongqing 400715, China 
 
XIE De-ti College of Resources and Environment, Southwest University, Chongqing 400716, China
Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three-Gorges Reservoir Area, Chongqing 400716, China
Key Laboratory of Eco-environment in Three Gorges Reservoir Region of Ministry of Education, Chongqing 400715, China 
 
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Abstract:
      A field monitoring was carried out at the Wanjiagou catchment of Fuling District in the Three Gorges Reservoir Region, to quantify the vertical leaching losses of nitrogen(N) and phosphorus(P) from arable hillslope purple soils under different mulberry-crop systems by employing mixed ion exchangeable resin burying and adsorption method. The experiment consisted of four treatments, i.e., contour cultivation, contour cultivation with mulberry trees planted on the upper, middle and lower slopes, contour cultivation with mulberry trees planted on the four sides of the slope, and contour cultivation with mulberry trees planted on the four sides of the slope and the middle slope. All experimental plots received the same tillage and fertilization treatments and were subjected to a maize-mustard rotation system. Results showed that leaching rates of total N(TN) from soils under different treatments varied from 10.19 to 11.37 kg·hm-2 for the maize-cropping eason and from 11.06 to 12.23 kg·hm-2 for the mustard-cropping season. The loss of TN was not significantly different among different treatments during the same cropping seasons or between different cropping seasons for the same treatments(P>0.05). The contribution of nitrate-N and ammonium-N to the annual TN loss averaged 63.9% and 36.1%, respectively, indicating that nitrate dominated in the N leaching loss. For the same treatments, the leaching loss of nitrate-N was greater during the mustard season than during the maize season, and vice versa for the loss of ammonium-N. The annual leaching loss of total P(TP) from soils ranged from 0.19~0.21 kg·hm-2, and no significant differences were found among different treatments(P>0.05). The poor development of mulberry-root systems associated with the short planting duration may fail in differentiating the retention capacity of N and P leaching loss among different treatments.