PO 45: Determine crop nutrient needs by using:

Field history, such as the sod, manure, and fertilizer background, also influence nutrient levels. Nitrogen from sods becomes available through mineralization and nitrification. N availability from crop residues varies depending on sod composition and year since plowdown. For example, in NY, the following credits from sods are applied to corn following sod:

• Year 1 since plowdown: 55%
• Year 2: 12%
• Year 3: 5%

To calculate the total amount, multiply the decay series value by the estimated total N pool in the sod:

<40% legume pasture (image source)