SOIL SOLUTION CHEMISTRY UNDER TEA GARDEN IN TAN CUONG COMMUNE OF THAI NGUYEN PROVINCE, VIETNAM

Abstract

The objective of this study is to investigate soil solution chemistry under tea gardens at the alluvial plain of Cong River in Tan Cuong commune, Thai Nguyen province, Vietnam. The study area is the core area for high-quality tea production. Four tea gardens in a transect line established perpendicularly with the river were selected as study sites. Soil solution samples were collected at the depth of 20 cm by using porous cups. The results of the present study are well agreed with those of our previous studies that the nitrification of ammonium fertilizers applied in tea cultivation still occur although the existence of strongly acidic condition and nitrification-derived NO₃^- is the dominant counter anion for leaching loss of base cations. The differences in precipitation between rainy and dry seasons and farming practices in terms of fertilization were responsible for the variation in the volume and chemical properties of the soil solution collected. Annually, soil nutrients have been added through fertilization at the end of dry season but rapidly solubilized and leached down by higher precipitation in the rainy season, especially in coarse-texture soil with high content of kaolin clay mineral adjacent to the river.