Nutrient Recovery By Warm and Cool Season Forages from Litter Amended Soils.

Large volumes of litter are a by-product of the Virginia poultry industry and land application including on pasture is the main mode of disposal. In this study, we compared nutrient recovery from litter-amended soils by Bermuda grass (Cynodon dactylon), switchgrass (Panicum virgatum), stinging nettle (Urtica dioica) and native fallow vegetation.

Bermuda grass recorded significantly higher dry matter yield while U. dioica had the lowest. In terms of nutrient removal, U. dioica had more than double the P recovery rate observed for the grasses but C. dactylon had the highest cumulative P removal in large part due to higher than average dry matter yield. Stinging nettle was relatively more efficient in the recovery of K, Mg, Ca, and particularly Fe.

Nitrate levels in soil water sampled from different depths were highest in P. virgatum, and in fertilized fallow plots. These treatments represent the greatest risk for nutrient flow into ground water mainly because switch grass has upright growth (slow spreading), while fallow growth is seasonal with limited cover during the winter months.

Results from soil analyses suggest that depending on treatment, P accumulation in soil after litter application can still be a problem and future plans include modeling P dynamics for each species. The data presented is from the first year of study and it is likely that more variation in nutrient removal, biomass yield, and forage quality will emerge as the three species become better established.