Rational Application of Coal Fly Ash Enhances Plant Growth and Improves Phosphorus Nutrition of Erect Milkvetch Grown on a Loess Soil

Abstract

ABSTRACT Application of coal fly ash (CFA) as a soil amendment has produced great agronomic benefits. However, there are potential risks of using CFA for soil amelioration, due to the abundance of some elements, both essential and non-essential in plants, which can cause phytotoxicity and it even may cause health problems for humans through the food chain. A pot experiment was conducted to investigate the effects of various CFA application rates (5%, 10%, 20%, 40%, and 80%) on plant growth, accumulation of essential nutrient elements and potentially toxic trace elements in erect milkvetch grown on a loess soil. The results showed that plant growth was significantly enhanced by the 5%, 10%, and 20% CFA treatments, while a CFA application rate ≥ 40% did not benefit plant growth, or even considerably inhibited plant growth. Plant phosphorus nutrition was improved by CFA application, but concentrations of potassium, copper, and zinc in plants declined when CFA was applied. Concentrations of molybdenum, boron, and selenium in plants generally increased with CFA application rate. A 5% CFA application rate is appropriate for the loess soil, a higher rate will cause phytotoxicity in erect milkvetch. CFA is a promising source of nutrients such as phosphorus, rational application of CFA to soil can enhance plant growth and improve plant phosphorus nutrition.