VARIATIONS OF CHEMICAL CHARACTERS AND IONIC CONTENT ALONG THE CATENA UNDER INTENSIVE VEGETABLE CULTIVATION IN UP COUNTRY WET ZONE

Abstract

Deterioration of soil quality and pollution of water bodies through the accumulation of nutrient elements and heavy metals due to the heavy application of chemical fertilizers and organic manure are the major concerns in the intensive vegetable cultivation system of upcountry Sri Lanka. Therefore, this research was conducted to study the variation of ionic contents (nutrient elements and heavy metals) and some soil chemical parameters along the soil catena. Hulankapolla and katumanna provided a representative catena to represent Badulla and Nuwara eliya district respectively. Along the catena from prescribed distances surface soil samples were collected from 30 cm depth from both locations. There were five sampling locations along the catena and each location had three sampling points. Soil sampling was done monthly for the duration of three months period. Soil samples were analyzed for pH,EC,Cation Exchange Capacity [CEC], organic C,Total N, available P and S, exchangeable K,,Mn,Zn, and Cu. The accumulation of plant nutrients and heavy metals is evident toward the bottom valley of the catena in both locations in the upcountry. Some soil chemical parameters such as EC were also increased in the bottom valley of the catena. This nutrients build up is associated with excessive application of fertilizer, for intensive vegetable cultivation. Continuous use of fertilizers and manure therefore may negatively affect to soil quality as well as to the water quality.