The Shenandoah Valley of Virginia and some other regions produce more manure nutrients than local crops need. This manure has traditionally been applied to row crops and overapplication has led to soil-test phosphorus (P) being well above agronomic optimum in many cases. In 2008, it was estimated that nutrient-management regulations now require that approximately 85 percent of poultry litter be applied off poultry farms, as they do not have sufficient land to beneficially recycle their manure nutrients. There is a substantial area of nutrient-deficient forage production in the Shenandoah Valley that could benefit from this poultry litter. This publication summarizes two years of field research on fertilizing nutrient-deficient forages with poultry or commercial fertilizer. It also evaluates split versus single annual applications of nutrients and addresses a common misconception that poultry litter contains weed seeds.

Animal manures are a good source of nitrogen (N) and phosphorus (P) for agricultural crops, but they have an imbalance in their N to P ratio, so that if they are applied to meet crop N needs, then P is overapplied. For many years, manures have been applied to meet crop N needs, which has resulted in some soils containing more P than crops require, leading to environmental concerns. Regulations have been developed to limit P losses from manures and soils high in P by moving manure nutrient management from an N basis to a P basis.

One of the challenges of white potato production, as with any crop, is the efficient management of nitrogen
(N) fertilizer. Excessive N fertilizer applied at or before tuberization can extend the vegetative growth period and delay tuber development, resulting in a lower tuber yield. However, too much N applied later in the season can delay maturity of the tubers, reducing
yield and adversely affecting tuber quality and skin set. Conversely, under-application of N at any point in the season can result in lower tuber yields and reduced profits. Environmental considerations must also be taken into account in N fertilizer management. Nitrogen
is a mobile nutrient in the soil and any excess N has the potential to move off-site via leaching or surface runoff. This is particularly true on the coarse-textured, low-organic matter soils common to the Eastern Shore, the premier potato-producing region in Virginia. These factors make the appropriate N rate and N application timing critical for successful white potato production.