214-6 Risks of Phosphorus Leaching Associated With Long-Term Repeated and Single Applications of Animal Manure.

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Nutrients and Environmental Quality General Session: I

Tuesday, November 5, 2013: 2:35 PM
Tampa Convention Center, Room 39

Jian Liu1, Helena Aronsson2, Lars Bergström2, Barbro Ulén2, Karin Blombäck2 and Andrew N. Sharpley3, (1)Department of Plant Science, Pennsylvania State University, State College, PA
(2)Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden
(3)115 Plant Sciences Bldg., University of Arkansas, Fayetteville, AR
Abstract:
Phosphorus (P) leaching from arable lands contributes to eutrophication of adjacent water bodies. To assess risks of P leaching from a sandy soil associated with long-term manure applications, patterns of total-P leaching from separately tile-drained field plots during 1989-2003 were analyzed and simulated with the ICECREAM model. The plots were annually applied with pig slurry at high (56 kg P ha-1 yr-1) and low (28 kg P ha-1 yr-1) rates, and only mineral P (24 kg P ha-1 yr-1). Intact topsoil columns from the plots were used to study potential of P leaching resulting from such long-term slurry applications and after incorporation of single dose of slurry (22 kg P ha-1). In addition, effects of different slurry application methods, i.e. surface application and incorporation of 30 kg P ha-1, on potential of P leaching were studied with columns from a similar sandy soil with relatively low degree of P saturation (DPS) and from a clay soil. We found that moderate rate of pig slurry (20-30 kg P ha-1) could be applied to low-DPS sandy soils without increasing potential of total-P leaching. However, long-term repeated applications of slurry at high rates increased the leaching potential. Concentration of dissolved reactive P, the dominant form in total-P, was positively correlated with soil DPS (R2=0.95, p<0.0001). Surprisingly, measured total-P leaching in drain tiles was low (0.17 kg ha-1 yr-1), due to a high sorption of P especially in the subsoil. In contrast to a sandy soil, moderate slurry application to the clay soil constituted a high risk of total-P leaching, most likely due to presence of macropore flow pathways. This risk was reduced by 50% when the slurry was incorporated, but it was still high. Therefore, manure applications to this type of soil during wet periods should be followed by incorporation or avoided.

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Nutrients and Environmental Quality General Session: I