UTILIZING PHOSPHORUS BUDGETS AND ISOTOPIC TRACERS TO EVALUATE PHOSPHORUS FATE IN SOILS WITH LONG TERM POULTRY LITTER APPLICATION

Description

<p>Converting a nutrient management
plan from commercial fertilizers to poultry litter helps effectively utilize
waste from the nearly 10 billion broiler birds across the United States. Nine
field scale watersheds from the USDA ARS Grassland, Soil and Water Research
Laboratory near Riesel, TX were evaluated for P inputs and P outputs to
determine phosphorus budgets for 15 years of annual application of poultry
litter ranging from 75 – 219 kg P ha^-1 yr^-1 on cultivated
and pasture/grazed fields. The cumulative net P continued to increase
regardless of the application rate and had a positive relationship with soil
level P (Mehlich-3 P) and flow weighted mean concentration (FWMC) for dissolved
reactive P for both cultivated and pasture managed fields. We assessed
hydrological connectivity within two nested watersheds by using the
before-after-control-impact (BACI) design. Results showed hydrological
connectivity during high rainfall years whereas low rainfall years had minimal
connectivity compared to the controls. These results suggest the P
contributions from upstream fields receiving poultry litter, even at high
application rates, did not exhibit a treatment effect during the low rainfall
years at downslope monitoring stations. </p><p><br></p>

<p>As nutrient source variability
increases in nutrient management plans, improving our ability to differentiate
P sources and their fate in soils is critical. We evaluated soils with unique P
inputs: inorganic P, poultry litter, and cattle grazing for isotopic signatures
by forming silver phosphate and determining the δ¹⁸O_P. Isotopic
signatures of the oxygen molecules which are strongly bound to P, provided
signatures of 17.09‰,
18.00‰, and 17.20‰ for fields receiving commercial fertilizer, poultry manure,
and cattle grazed, respectively. Significant effort was made to determine
critical steps in the method to successfully precipitate Ag₃PO₄for analysis. Results show adding a cation removal step as well as monitoring
and adjusting pH throughout the method increases probability of successful Ag₃PO₄precipitation. Findings from this study provide a valuable framework for
future analysis to confirm unique δ¹⁸O_P signatures
which can be used to differentiate the fate of different phosphorus sources in
agricultural systems.</p>

Links & Downloads

1. 10.25394/pgs.12689309.v1

Tags

Agronomy

Phosphorus Isotopes

Phosphorus Budget

Phosphorus

Poultry Litter

LTAR

Nested Watershed

Edge of Field

Nutrient Management

Additional Fields

Identifer	oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/12689309
Date	24 July 2020
Creators	Janae H Bos (9153470)
Source Sets	Purdue University
Detected Language	English
Type	Text, Thesis
Rights	CC BY 4.0
Relation	https://figshare.com/articles/thesis/UTILIZING_PHOSPHORUS_BUDGETS_AND_ISOTOPIC_TRACERS_TO_EVALUATE_PHOSPHORUS_FATE_IN_SOILS_WITH_LONG_TERM_POULTRY_LITTER_APPLICATION/12689309