Zinc is the most widespread micronutrient deficiency for paddy rice, with deficiency observed on about half of the land area in Asia.  The redox chemistry associated with paddy rice reduces the availability of Zn.  Boron deficiency is the next most important, especially in high pH environments, but its occurrence is inadequately characterized.  Although addition of fertilizer to soil remains the preferred treatment for B deficiency, effective strategies for Zn include fertilization of rice nurseries and seed treatment.   Foliar application can increase Zn in seed and field trials have shown that micronutrient enriched seed can successfully address Zn and Mo deficiencies and can give higher yields than applying micronutrients to soil, probably because of root health benefits. 

An emerging issue in Bangladesh, India and Nepal is arsenic phyto-toxicity to rice, which is being driven by use of high arsenic containing irrigation water.  Yield of boro season rice under field conditions was reduced from 7 to 2 t/ha over a soil arsenic gradient from 68 to 12 mg/kg in Bangladesh.  Projections show that continued use of groundwater could have a negative effect on rice yield over much of the Southern half of Bangladesh.  Despite several possible mitigation strategies, managing arsenic in the environment presents a substantial challenge.

Rice is the main source of nutrients for humans whose diets depend highly on rice, such as South Asian countries.  Several approaches to increasing the Fe and Zn content of rice have been proposed.  One study has shown a positive effect on women's Fe status.  Dietary intake of Zn from Zn enriched rice (35 mg Zn/kg) should be sufficient to address prevalent Zn deficiency for both 2-4 and 5-10 year old children in Bangladesh.  On the other hand, rice represents a potentially significant route for human exposure to arsenic.