Oklahoma State University

Contact Info


Hailin Zhang
Nutrient Management Specialist
Dept. of Plant and Soil Sciences
Oklahoma State University
368 AG Hall
Stillwater, Oklahoma 74078

Phone: (405)-744-9566

(405) 744-0354


Nutrient Availability

Nutrient Availability

Chickens in Barn Picture



Nutrients in animal manure cannot be substituted for those in commercial fertilizers on a pound-for-pound basis because not all the nutrients reported on a manure analysis are readily available to a crop in the year of application.


Availability of Nitrogen

Nitrogen in the organic form must be converted (mineralized) into inorganic forms (ammonium and nitrate) before it can be taken up by roots. In general, about 50% of the organic N may become available the year of application. Organic N released during the 2nd and 3rd cropping years after application is usually about 15% and 6% of the original N content, respectively. Nitrogen availability may be higher if the manure is incorporated shortly after application, e.g., 65%. Nitrogen availability varies with the type of manure, read the following publications for more information on different types of manure:

Availability of Phosphorus and Potassium

Nearly all of the P and K in manure are available for plant use the year of application compared with commercial P and K fertilizers. In general, a 90% availability factor is used for K and P in the manure.

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