Chapter 9 Environmental aspects of boron

Abstract

This chapter discusses the environmental aspects of boron. Boron is an essential micronutrient for higher plants, but the range between deficient and toxic concentration is smaller than for any other nutrient elements. Boron deficiency is mostly found in soils of humid regions. Therefore, boron deficiency can be triggered by liming of acid soils because of increased boron adsorption at high soil pH. Soil solution pH is one of the most important factors affecting the availability of boron in soils. Acidic soils may result in boron deficiency symptoms in plants. Boron deficiency decreases as soil temperature increases. This can be because of an interactive effect of soil temperature with soil moisture. The highest naturally occurring concentrations of boron have been found in soils derived from marine evaporates and marine argillaceous sediments. Various anthropogenic sources of boron excess may increase soil boron to toxic levels for plants. The most important source is irrigation water, as well as other sources such as surface mining, flying ash, and industrial chemicals.