The LTAR Cropland Common Experiment in the Upper Chesapeake Bay.

Dairy production is a key agricultural enterprise in the Upper Chesapeake Bay (UCB) basin, where phosphorous (P) and nitrogen (N) loading contribute to eutrophication. Import of forages and grains and application of mineral fertilizers contribute to nutrient imbalances in the basin. The UCB Long-Term Agroecosystem Research Cropland Common Experiment aims to evaluate diverse crop rotations that minimize the need for imported feed, maximize year-round living cover, and reduce nutrient losses.

The LTAR Common Experiment at Upper Chesapeake Bay: Integrated.

Corn (Zea mays) crops harvested as grain in autumn do not provide opportunity for cover crop establishment, which may be remedied by interseeding cover crops into growing corn. Grazing cover crops after corn grain harvest could provide added revenues and increase nutrient cycling in the system while providing additional ecosystem services. However, tradeoffs between cash crop productivity and cover crop inclusion, and use as grazed forage, are not fully understood.

Investigation of the inorganic and organic phosphorus forms in animal manure.

The most viable way to beneficially use animal manure on most farms is land application. Over the past few decades, repeated manure application has shown adverse effects on environmental quality due to phosphorus (P) runoff with rainwater, leading to eutrophication of aquatic ecosystems. Improved understanding of manure P chemistry may reduce this risk.

Manure composition and incorporation effects on phosphorus in runoff following corn biomass removal.

Greater demand for corn ( L.) stover for bioenergy use may lead to increased corn production acreage with minimal surface residue cover, resulting in greater risk for soil erosion and phosphorus (P) losses in runoff. A rainfall simulation study was conducted to determine the effects of spring-applied dairy cow () manure (none, in-barn composted, and exterior walled-enclosure pit) with >200 g kg organic solids content following fall corn biomass removal with and without incorporation (chisel plow [CP] and no-till [NT]) on sediment and P in runoff.

Sorption of inorganic and total phosphorus from dairy and swine slurries to soil.

Understanding P sorption from animal manures is essential to formulate best management practices with regard to land application of manure from the standpoint of crop production and environmental quality. Little research has focused on the construction of P sorption isotherms where the P source is manure. The objectives of this study were to: (i) develop a procedure to characterize how inorganic P (P(i)) and total P (P(t)) from dairy slurry and swine slurry sorbs to soil; and (ii) compare the sorption characteristics of P(i) and P(t) where the P source was dairy slurry, swine slurry, or potassium phosphate (KH2PO4).