关键词: 紫色土, 坡地, 养分流失

Abstract: Purple soil is a main soil group,distributed on the slopeland in TGRA.The productivity of purple soil is influenced by soil erosion and degradation.By investigating typical regions and measuring the nutrients(N,P,K,or.m) of main soil profiles,assisted with rainfall simulation experiments on the plots(2×5m).this paper discusses the nutrient loss processes and nutrient conditions of purple soil.which is formed on the purple sandy-clay deposits of Jurassic Period.The results are as follow:1.The Contents of organic matter and nitrogen are quite low.about 15g/kg and 0.5g/kg respectively.The content of phosphorus is also low.about 0.4g/kg.But,potassium is not deficiency,which is from the parent materials.2.Sediment contains more nutrients than surface soils,which is the main way of nutrient losses.So it is suggested that the factors influence on soil losses are closely related to nutrient losses,such as the cover of plant.slope degree and rainfall intensity etc..3.Silt(0.02-0.002) and clay(less than 0.002) fractions have higher proportions in the sediments in the runoff from slope surface than that in surface soils.Silts and clays are the carriers of nutrients.4.Nutrient losses are related to soil losses.The concentration of available nutrients in the sediments are much higher at the beginning of runoff on slopeland than that at the later periods,but the tatol losses per unit area is lower due to low soil losses.

Key words: Nutrient losses, Purple soil, Slopeland