Location: Livestock Nutrient Management ResearchTitle: Legacy phosphorus in Alabama Hartsells soil after long-term amendment with broiler litter
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2023
Publication Date: 2/9/2023
Citation: Waldrip, H., Thompson, T.N., Koziel, J.A., Watts, D.B., Torbert III, H.A. 2023. Legacy phosphorus in Alabama Hartsells soil after long-term amendment with broiler litter. Journal of Environmental Quality. 52(4):897-906. https://doi.org/10.1002/jeq2.20462.
Interpretive Summary: The application of animal manure and inorganic fertilizer often causes accumulation of stable, legacy phosphorus in soils. This legacy phosphorus can disrupt normal phosphorus cycling and may present environmental risks to surface and groundwater water sources. ARS researchers from Bushland, Texas, and Auburn, Alabama, evaluated how long-term, repeated broiler litter applications to a soil in Alabama affected concentrations of specific fractions of inorganic and organic phosphorus under different crops (corn, soybean, corn or soybean with a wheat cover crop) and types of tillage (conventional tillage and no-tillage). These researchers found that repeated broiler litter application increased concentrations of all forms of soil phosphorus, and this was evident down to a depth of 10 cm. These results showed that broiler litter application significantly increased levels of mineral-associated organic phosphorus, but these effects could be reduced somewhat by including soybean rotations and wheat cover cropping, compared to corn monoculture.
Technical Abstract: Numerous studies have investigated effects of long-term manure application on totalphosphorus (P) and inorganic P (Pi), but few have evaluated soil organic P (Po). Littleis known about crop management effects on Poin soils with varying minerology. Inthis study, sequential fractionation was used to characterize specific P forms after25 years of broiler litter (BL) or ammonium nitrate (Con) applications to an AlabamaHartsells soil. Crops (corn [Zea maysL.], soybean [GlycineWilld.], and corn orsoybean with a wheat [Triticum aestivumL.] cover crop) were under conventionaltillage (CT) or no-tillage (NT). Regardless of crop, tillage, or fertilizer type, theproportion of extractable Piwas relatively stable at 21%–49% at 0–5 cm and 25%–45% at 5–10 cm. Extractable Piranged from 0.69 to 2.4 mg g-1. BL increased totalextractable Pi(p=0.001) at 0–5 cm and 5–10 cm. Total extractable P was influencedat 0–5 cm (p=0.006) by both tillage and fertilization type, but not at 5–10 cm or ateither depth in soybean plots. Long-term BL application increased total extractablesoil P at 0–5 cm. In corn systems, CT did not reduce P loading to topsoil or result in Pleaching to lower soil depths, compared to NT. Soybean and soybean–wheat reducedP loading in BL plots, compared to corn and corn–wheat. Soil Powas classed in theorder of monoesters>phytate and polyphosphates, where most was extractable withNaOH. BL increased extractable Poin all fractions. Care should be taken when apply-ing BL to highly weathered soils to avoid legacy Poaccumulation. Soybean rotationsand cover crops could help remediate P-laden soils after repeated BL application.