IV. ANALYSIS OF SECTOR-LEVEL MEASURES USED TO INTEGRATE ENVIRONMENTAL CONSIDERATIONS IN TERMS OF PERCEIVED EFFECTIVENESS IN ACHIEVING POLICY OBJECTIVES
A. Types of measures and intended impacts: ministries and agencies responsible
2. Loss of soil fertility through erosion, and its relationship to low productivity in the tea sector
The removal of fertile top soils as a result of erosion is one cause of land degradation. The other causes are depletion of soil nutrients, damage to physical and chemical properties of the soil, and the reduction in soil capacity to retain moisture. The loss of nutrients and the reduction in moisture retention capacity are associated with the loss of productive potential of soils. However, very little quantitative information is available in Sri Lanka on those areas.
It has been difficult to establish a relationship between land degradation because of soil erosion and productivity for perennial crops, such as tea, as a result of the lack of data on past soil characteristics (e.g., depth and nutrient content). There is also a dearth of time series data on other independent factors which influence crop yields. Furthermore, a drop in crop productivity and crop yields because of soil erosion and land degradation is an integrated response to several interacting factors such as soil fertility, prevalent climate, incidence of disease and pests, cultural practices, degree of past erosion and associated land degradation, and the current rate of erosion and land degradation.
Recent work carried out on land degradation and productivity in the case of rubber, and ongoing work on tea, suggest that the reduction in yields of perennial crops as a result of land degradation is relatively smaller than in the case of annual crops. However, the replanting of perennials like tea on degraded land is difficult and the related costs could be a prohibitive factor.