THE AVAILABILITY STATUS OF BORON IN THE CULTIVATED SOIL OF NEPAL

Abstract

Boron is available in nature in rocks and deposits and the availability is influenced by soil organic matter, soil pH, soil texture, and temperature and is taken up by plants in non-ionic form H3BO3 (boric acid) but this concentration account for only about 10% of total soil boron leading to boron deficiency. Also, boron toxicity may occur in low rainfall, extremely alkaline, and saline soils harming plants’ growth and development. Boron shortage and toxicity in plants have a fairly narrow range, and both are detrimental. Hence, it is needed to critically balance boron homeostasis in cropping soil. The concentration of boron in cultivated soil in different agroecological regions was found to be low to very low (1mg/kg of soil) in this review study, which was undertaken to familiarize the status of boron in Nepalese cultivated land. In separate micronutrient investigations, a few additional micronutrients were shown to be medium albeit, boron was found to be low even in the valley (>0.01ppm) including all three ecological regions. This shows boron deficiency is a universal problem in Nepal affecting 80-90% of agricultural soil. And this problem can be corrected by both foliar applications and by soil application of boron sources such as borate as per the recommended dose.