What drives decline productivity in ageing tea plantation-soil physical properties or soil nutrient status?

Abstract

Over the years, the tea plantations in the Ribeira Valley, Brazil had been recording declining productivity and reduced tea quality. This had been associated with several factors including the age of the plantation, decling fertility, soil degradation among others factor. In this study, our objective was to identify the main driver of declining productivity in tea yield in the Ribeira Valley tea plantation in Brazil and to evaluate the effects of long-term tea cultivation on the physico-chemical changes and nutrient dynamics in the soil at 2 profile depths. Therefore, we evaluated the effects of long-term cultivation on changes in the physical and chemical properties of Acrisol Haplic planted to Tea in the Ribeira Valley region, Brazil. The soil samples were collected at two depths 0-10 cm and 10-20 cm in two representative plantations and analyzed for chemical, physical and mechanical soil properties. The selected sites; Thea Hills – TH1987 and Braço Preto – BP1972 presents different plantation ages on a similar cultivation practices. The harvested quantities of tea from the sites were monitored and their quality classified following international standards. We observed declining productivity in terms of harvested tea from both sites and the quality of harvested tea were better in TH1987 than BP1972. The soil nutrient study indicated an improvement in fertility parameters in the older plantation (BP1972). We observed degradation in the soil physical quality parament and all possible factors indicated that degradation of the soil structure through compaction was the main factor resulting in the observed declined productivity (quantitatively and qualitatively). Soil structure degradation adversely affects the soil functions including aeration, crop water use efficiency and soil nutrient conversion. We recommend appropriate soil tillage management in tea plantations too improve the productive cycle and capacities.