2012 22.2 Cover Crop Calculator

OSU to launch online tool in April 2012

The Cover Crop Calculator was developed by Nick Andrews, Dan Sullivan, Kristin Pool and Jim Julian from Oregon State University Extension. Contact Nick at or (503) 678-1264 x149 for more information.

Oregon State University (OSU) will launch its new Cover Crop Calculator, an expanded version of the existing Excel-based Organic Fertilizer Calculator, as a free online tool in early April 2012. The new Cover Crop Calculator will estimate plantavailable nitrogen (PAN) contributions from cover crops, organic fertilizers and compost – helping farmers determine the most costeffective and well-balanced nutrient management programs. The
Cover Crop Calculator will be available on the OSU Small Farms website (http://smallfarms.oregonstate.edu), along with detailed instructions on how to take cover crop samples from the field and simple lab tests required for calculations.

Organic amendments contain organic nitrogen that must be mineralized into inorganic forms (nitrate or ammonium) to be available for plant uptake. The mineralization process is difficult to predict, making it complicated to determine accurate rates for organic fertilizers and to estimate cover crop plant-available nitrogen (PAN) contributions. In Oregon, university researches have validated three computer models that predict nitrogen release from 1) cover crops, 2) organic fertilizers, and 3) compost. These models are integrated into the Cover Crop Calculator and provide an estimate of the timing and amount of plant-available nitrogen released.

The Cover Crop Calculator includes an economic component that estimates the cost of managing cover crops and applying fertilizers. Costs include seed, irrigation, labor, fuel, and equipment depreciation. Users can customize these numbers to estimate the real cost of managing cover crops and applying fertilizers. The Cover Crop Calculator also allows users to compare the costs of cover crops and various fertilizers to determine the most cost effective nutrient management program for their farm.

Online instructions will be available to help users navigate the Cover Crop Calculator. These will include a records sheet with necessary information for calculations, such as fertilizer labels and prices, an estimate of percent dry matter in the fertilizers, and fertilizer recommendation. Quick Guides (figure 1) with instructions for sampling and analyzing cover crops will also be available.

Tags: Cover Crop, Cover Crop Calculator, Nitrogen, Nitrogen Cover Crop Calculator, Oregon State University, OSU