Boron Speciation in Soils Irrigated with Fresh and Effluent Municipal Waters

Boron (B) excess/toxicity is an important disorder that can limit plant growth on soils of arid and semiarid environments. Although of considerable agronomic and environmental importance, our understanding of B biogeochemical behavior and fate is rather fragmented and limited (Gupta et al., 1985; Yermiyahu et al., 2001). Irrigation water is one of the main sources of high B levels resulting in toxicity in the field. Various fractionation/speciation techniques have been developed for soil B to distinguish its forms (Jin et al., 1987; Tsadilas et al., 1994; Hou et al., 1996) utilizing methods originally developed for selective extraction of different soil fractions. Surprisingly, only a few works have considered the necessity to include B-organic matter-bound forms in their schemes: synthetic soils were tested for Borganic fractions by Hou et al. (1996), and Yermiyahu et al. (2001) studied the effect of composted organic matter on B uptake by plants. The objectives of the presented work were: (1) approach to detailed B speciation within principal humus and inorganic soil components, and (2) to evaluate B behaviour/ potential mobility of soils irrigated with fresh and effluent waters.