title: Reducing phosphorus release from paddy soils by a fly ash-gypsum mixture.
abstract: A mixture of fly ash and phospho-gypsum (50:50, wtwt(-1)) was selected to study its potential to supply Ca and Si to rice while reducing B toxicity. We expected that the high Ca content in this mixture might convert water-soluble P to less soluble forms and thereby reduce the loss of soil P to surface runoff. The mixture was applied at rates of 0, 20, 40, and 60 Mgha(-1) in two paddy soils of contrasting textures (silt loam in Yehari and loamy sand in Daegok). The mixture significantly reduced water-soluble phosphate (W-P) in the surface soils by shifting from W-P and iron bound-P (Fe-P) to calcium bound-P (Ca-P) and aluminum bound-P (Al-P) during rice cultivation in both soils. Lancaster and Mehlich 3 extractable P increased significantly with application rate due to high contents of P and Si in the mixture. Mixtures of fly ash and phospho-gypsum should reduce P loss from rice paddy soils and increase soil fertility.
authors.affiliation: Division of Applied Life Science, Gyeongsang National University, Kaswa-dong, Jinju, 660-701, South Korea.
authors.forename: Chang Hoon
authors.initials: CH
authors.lastname: Lee
authors.forename: Yong Bok
authors.initials: YB
authors.lastname: Lee
authors.forename: Hyup
authors.initials: H
authors.lastname: Lee
authors.forename: Pil Joo
authors.initials: PJ
authors.lastname: Kim
mesh_terms: D002118:Calcium / Q000378:metabolism; D002133:Calcium Sulfate / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D060729:Coal Ash; D004787:Environmental Pollution / Q000517:prevention & control*; D005618:Fresh Water / Q000737:chemistry; D012275:Oryza / Q000254:growth & development* / Q000378:metabolism; D052638:Particulate Matter / Q000737:chemistry*; D010758:Phosphorus / Q000032:analysis* / Q000737:chemistry; D012825:Silicon / Q000378:metabolism; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D012995:Solubility
chemical_list: D060729:Coal Ash; D052638:Particulate Matter; D012987:Soil; D012989:Soil Pollutants; D010758:Phosphorus; D002244:Carbon; D002118:Calcium; D002133:Calcium Sulfate; D012825:Silicon