Evaluating the impact of soil pH and fertiliser use on tea yields and smallholder resilience in Landuyaya and Ihalagalagama, Sri Lanka

Abstract

Sri Lanka’s economy relies heavily on tea cultivation, which necessitates sustainable soil management to ensure long-term productivity. Using questionnaire surveys, this study investigated sustainable practices and soil pH regulation among 58 smallholder tea farmers in the Landuyaya and Ihalagalagama Gramaniladhari Divisions who were chosen at random. Regression models, correlation analysis, and descriptive statistics were used in IBM SPSS to analyse the data. Typically, 10,000–12,500 bushes were planted per hectare in tea estates, and 53% of smallholders used dolomite to adjust the pH. The pH range of the soil was 4 to 6.2 (mean = 5.11), which falls within the ideal range of 4.5 to 5.5 for tea cultivation. The amount of U709 fertilizer, which primarily consisted of nitrogen, phosphorus, and potassium, ranged from 250 to 500 kg/ha/year. Productivity was highly impacted by seasonal variations, with peak yields (∼1250 kg/ha) occurring during periods of regular rainfall and decreases during periods of drought or excessive rainfall. In the heavy-rain season, fertilizer application and yield showed significant positive correlations (r = 0.377, p < 0.01), indicating that management practices have a direct impact on output. Strong relationships were also discovered between crop production and other important variables, including chemical practices (r = 0.494, p < 0.01) and maintenance inputs (r = 0.442, p < 0.01). Fertiliser application was found to be the most significant predictor of yield (β =0.356, p=0.002) by regression analysis, which also explained 21.9% of the variability in yield (R2 = 0.219). These results highlight the importance of targeted input management and soil amendments in maintaining productivity, specifically under climatic variability. The study emphasises the requirement of government involvement and community-based soil management methods to assist smallholders. Farmers in Landuyaya and Ihalagalagama can improve soil pH regulation, maximise fertiliser use, and strengthen the long-term resilience of tea cultivation by combining scientific data with traditional knowledge.