3Folmer E C R,Geurts P M H,Francisco J R.Assessment of soil fertility depletion in Mozambique[J].Agriculture,Ecosystems and the Environment,1998,71:159-167.
4Harris F M A.Farm-level assessment of the nutrient balance in northern Nigeria[J].Agriculture,Ecosystems and the Environment,1998,71:201-204.
5Shepherd K D,Soule M J.Soil fertility management in west Kenya:dynamic simulation of productivity and sustainability at different resource endowment levels[J].Agriculture,Ecosystems and the Environment,1998,71:131-145.
6Stocking M.Soil erosion:breaking new ground.In:Leach,M.,Mearns,R.(Eds.),the Lie of the Land:Challenging Received Wisdom on the African Environment[M].1996:141-154.
7Smaling E M A,Stoorvogel J J,Windmeyer P N.Calculating soil nutrient balances in Africa at different scales.Ⅱ.district scale[J].Fertilizer Research,1993,35:237-250.
8Hashim G M,Coughlan K J,Syers J K.On-site nutrient depletion:an effect and a cause of soil erosion.In:Kerr,J.(Eds.),Soil Erosion at Multiple Scales:principles and methods for assessing causes and impacts[M].CAB International,1998:207-221.
9Scoones I,Toulmin C.Soil nutrient balances:what use for policy[J].Agriculture,Ecosystems and the Environment,1998,71:255-267.