Long-term land-applications of poultry litter may results in
excessively high soil phosphorus (P). This
study examined the potential of common bermudagrass [Cynodon dactylon(L.) Pers.]
overseeded with annual ryegrass [Lolium multiflorum Lam.] and harvested for hay to reduce the
level of soil P that had accumulated in plots of Ruston soil (fine-loamy,
siliceous, thermic Typic Paleudult) from six previous applications of poultry litter
(0, 5, 10 and 20 Mg / ha; three replicates). Plots were fertilized with nitrogen or
potassium (as needed) without further addition of P. Across three years after the last litter
application and all previous litter rates, ryegrass
hay contained a higher percentage of P (0.51 % ryegrass vs. 0.35 % bermudagrass)
but ryegrass produced less dry matter (1.31 Mg / ha ryegrass vs. 1.56 Mg / ha bermudagrass).
Taken together, therefore, the data
suggest that ryegrass may have equal or greater potential for P uptake /
removal than bermudagrass. While soil
test P values (Bray 2) did decrease over all treatments, removal of residual P
did not correlate well to soil test P level.
Assuming four harvests each per year, summer bermudagrass overseeded with winter annual ryegrass may lower soil total
P by about 50 - 60 mg / ha annually.