Assessment of soil fertility and nutrient management in betel (Piper Betle) cultivations in the Kurunagala district

Abstract

Betel plant (Piper betle) leaves, harvested at frequent intervals, result in the permanent depletion of soil nutrients. Farmers often complain that the amount of fertilizer recommended by the Department of Export Agriculture (DEA) is insufficient and there is a tendency to overuse fertilizers. The study aimed to assess the variability of soil fertility in betel cultivations in the Kurunagala district. It investigated the relationship between fertilizer amounts and betel yield, along with relationship of farm scale on soil fertility characteristics. Thirty farmer fields were surveyed, measuring soil fertility traits such as Nitrogen, Phosphorus, Potassium, and soil pH. Of the selected fields, 84% betel poles were cultivated between 2 to 3 years, while 16% were less than 2 years old. The survey found that 61% of farmers used cow dung and 39% used green manure as organic fertilizer. Harvesting was done every three weeks by 68% of farmers and every two weeks by 32%. Chemical fertilizers applied, biweekly by 72%, while the remaining 28% did so every three weeks. All farmers surveyed the used bed method and the same chemical fertilizers mixture. The soil analysis revealed that Wariyapola had the higher nitrogen (2.48±0.8 mg/g), Phosphorus (0.13±0.01 mg/g), Potassium (0.06±0.01 mg/g) and soil pH (5.63) values than Panduwasnuwara and Bingiriya areas. There is a negative relationship between amount of fertilizer applied and yield, but the ratio of leaf length to leaf width had a positive relationship. However, none of these differences or relationship between farm scale and soil fertility traits were statistically significant. The results indicate that over-dosing with fertilizer has no significant impact on betel yield improvement, besides excessive use of chemical fertilizers may increase cost and leads to nutrient loss by leaching, runoff, and evaporation.