Minimize Phosphorus Loss By Leaching With Coal Fly-ash From Phosphorus-rich Soils

It was essential for optimum crop growth and profitable agriculture that supply enough phosphate to meet crop remands for phosphorus. While applied phosphorus fertilizer is higher than the requirement of crop, phosphorus would built up in soils. And it also would stimulate the phosphorus loss by leaching. Now phosphorus come from crop land had been identified as one of major causes of decreased surface water quality. It had widespread concern about how to decrease phosphorus losses from phosphorus rich soils. The paper delivered a research about the potential of coal fly-ash to mitigate phosphorus leaching, it also evaluated the different impaction of fly-ash, gypsum, limestone, ferric chloride and aluminum sulfate to decrease phosphorus losses. The results indicated:1. Fly-ash had high potential to fix phosphorus from solution. With increasing of phosphate concentration, the amount of phosphate be fixed was increasing too. The relationship of phosphate concentration and adsorbed phosphate amount could fitted with Langmuir equation(R=0.9915**). pH had no remarkable impaction to the capability of fly-ash to fix phosphate. The accompanying and competitive icon had less impacte too.2. The effective of fly-ash for controlling phosphorus losses was between gypsum, limestone, ferric chloride and aluminum sulfate. The concentration of total phosphorus in leaching solution coming from Al₂(SO₃)₄ and FeCl₃ treatment were between 0.03⁰.50 mg·l^-1. It was 0.6 mg l^-1 in fly-ash treatment. During 60 day period, the total phosphorus loss mount was 77.1 mg m^-2. It had been reduce about 60.5 %, 82.3 %, 35.6 %, 14.1 %, 22.2 % with fly-ash, gypsum, limestone, ferric chloride and aluminum sulfate treatment respectively.3. The results of soil phosphorus pool indicated that fly-ash could decreased the proportion of Ca²-P, Ca⁸-P, it also decreased the amount of Olsen extractable phosphorus, but it did not decreasing the bio-available phosphorus. In summary, fly-ash had high power to fix phosphorus in soil solution, and it could decrease phosphorus loss effectively, and the impaction of fly-ash to bio-available phosphorus was miner.