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Legacy Phosphorus in Alabama Hartsells Soil after Long-Term Amendment with Broiler Litter.

Heidi M WaldripTerra N CampbellJacek A KozielDexter B WattsH Allen Torbert
Published in: Journal of environmental quality (2023)
Numerous studies have investigated effects of long-term manure application on total phosphorus (P) and inorganic P (P i ), but few have evaluated soil organic P (P o ). Little is known about crop management effects on P o in soils with varying minerology. In this study, sequential fractionation was used to characterize specific P forms after 25 y of broiler litter (BL) or ammonium nitrate (Con) applications to an Alabama Hartsells soil. Crops (corn [Zea mays L.], soybean [ Glycine  Willd .], corn or soybean with a wheat [Triticum aestivum L.] cover crop) were under conventional till (CT) or no-tillage (NT). Regardless of crop, tillage or fertilizer type, the proportion of extractable P i was relatively stable at 21-49% at 0-5 cm and 25-45% at 5-10 cm. Extractable P i ranged from 0.69 to 2.4 mg g -1 . BL increased total extractable P i (P ≤ 0.001) at 0-5 cm and 5-10 cm. Total extractable P was influenced at 0-5 cm (P ≤ 0.006) by both tillage and fertilization type, but not at 5-10 cm or at either depth in soybean plots. Long-term BL application increased total extractable soil P at 0-5 cm. In corn systems, CT did not reduce P loading to topsoil or result in P leaching to lower soil depths, compared to NT. Soybean and soybean-wheat reduced P loading in BL plots, compared to corn and corn-wheat. Soil P o was classed in the order of monoesters > phytate and polyphosphates, where most was extractable with NaOH. BL increased extractable P o in all fractions. Care should be taken when applying BL to highly weathered soils to avoid legacy P o accumulation. Soybean rotations and cover crops could help remediate P-laden soils after repeated BL application. This article is protected by copyright. All rights reserved.
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