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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #302012
Title: Soil phosphorus dynamics under sprinkler and furrow irrigation

Author
item Ippolito, James
item Bjorneberg, David - Dave

Submitted to: Proceedings of the Idaho Nutrient Management Conference
Publication Type: Proceedings
Publication Acceptance Date: 3/6/2014
Publication Date: 3/6/2014
Citation: Ippolito, J.A., Bjorneberg, D.L. 2014. Soil phosphorus dynamics under sprinkler and furrow irrigation. Proceedings of the Idaho Nutrient Management Conference. 7:60-64.

Interpretive Summary:

Technical Abstract: Furrow irrigation detaches and transports soil particles and subsequently nutrients such as phosphorus. To reduce the risk of erosion and offsite phosphorus movement, producers can convert from furrow to sprinkler irrigation. We completed research on soil phosphorus dynamics in furrow versus sprinkler irrigated soils from four paired fields in south central Idaho. Surface soils (0-2.5 inches) were obtained from fields in the fall following harvest. Furrow irrigated soils contained 38 parts per million of plant-available phosphorus (i.e. Olsen-extractable) on average, as compared to 20 parts per million under sprinkler irrigation. These results are important as 20 parts per million Olsen-extractable phosphorus may be considered the concentration where soil phosphorus is considered low to medium in soil testing; extractable phosphorus values over 40 parts per million limit sites to phosphorus application based on crop uptake only, based on the Idaho One Plan. Soils were additionally analyzed using a sequential extraction to identify inorganic soil phosphorus pools, and an amorphous aluminum and iron technique was used to help further explain differences in extractable soil phosphorus under furrow and sprinkler irrigation. Soils under furrow irrigation had greater concentrations of inorganic phosphorus in the soluble/aluminum-bound/iron-bound and occluded iron phases (i.e. iron coated phosphorus), and in the amorphous iron phases. These findings suggest that iron reduction chemistry plays a large role in phosphorus availability under furrow irrigation, even in calcareous soil systems.