Evaluation of Trends in Integration of Organic Farming System into Potato Farming: Soil Fertility and Productivity

Abstract

Application of chemical fertilizers is the general fertilization practice in the potato (Solanum tuberosum L.) farming system. Present trend is application of animal manure along with reduced rates of chemical fertilizers in potato farming. Precise impacts of incorporation of organic farming system into conventional farming system was evaluated by means of potato productivity and soil fertility using major potato growing fields in Sri Lanka. Three clusters were selected on the basis of different fertilizations, and physical and chemical properties of soils were analyzed. Productivity and production costs of potato were also assessed in all clusters from 2003 to 2005. Major nutrient levels were higher than the required amounts for potatoes in all clusters in both manure amended systems (MASs) and manure unamended systems (MUSs), but there was no significant difference in major nutrient levels between MASs and MUSs. However, the tuber yield was not affected by incorporation of organic farming system and showed a strong positive linear correlation with sand : clay ratio of soil. Animal manure amended systems reduced the potato production costs by 3.0-7.2% without affecting the tuber yield, and thereby increasing the benefit to cost ratio.