Crop growth inhibited by over-liming in tea plantations

Abstract

Liming is a common strategy applied to attain optimal pH for tea growth in severely acidic soils. Tea however is a calciphobous plant, and the effects of liming on its growth and nutrient uptake remain poorly understand. Therefore, it is necessary to better understand the effects of liming on soil chemical properties and tea nutrient content. In this study, a tea plantation that had exhibited large variation in growth after liming was selected as a study site. We categorized plots into two growth condition groups: Plot 1 (poor growth) and Plot 2 (excellent growth). Tea nutrient levels, and soil chemical properties were then compared between the two groups. Normalized difference vegetation index (NDVI) and transformed vegetation index (TVI) values were significantly higher and lower, respectively, in Plot 2 than in Plot 1. Yield, number of buds per m2, and 100-bud weight were significantly higher in Plot 2. These results were attributed to higher N, K, and Al concentrations and lower Ca concentrations in leaves, and lower pH and available Ca and higher available Al in soil. Leaf concentrations of K and Al were significantly negatively correlated with leaf concentrations of Ca and soil pH. A positive relationship was observed between leaf concentrations of K and Al, indicating inhibited K and Al uptake due to over-liming, restricting tea growth. In conclusion, our results show that tea growth will be restricted by over-liming, as a result of the high soil pH and Ca concentration inhibiting the K and Al uptake.