Journal list menu

Volume 35, Issue 6 p. 2321-2332
Waste Management

Estimating Plant-Available Nitrogen Release from Manures, Composts, and Specialty Products

Eric S. Gale

Eric S. Gale

Dep. of Crop and Soil Science, Oregon State Univ., Corvallis, OR, 97331

Search for more papers by this author
Dan M. Sullivan

Corresponding Author

Dan M. Sullivan

Dep. of Crop and Soil Science, Oregon State Univ., Corvallis, OR, 97331

Corresponding author ([email protected])Search for more papers by this author
Craig G. Cogger

Craig G. Cogger

Dep. Crop and Soil Sciences, Washington State Univ., 7612 Pioneer Way E., Puyallup, WA, 98371

Search for more papers by this author
Andy I. Bary

Andy I. Bary

Dep. Crop and Soil Sciences, Washington State Univ., 7612 Pioneer Way E., Puyallup, WA, 98371

Search for more papers by this author
Delbert D. Hemphill

Delbert D. Hemphill

Dep. Horticulture, Oregon State Univ. North Willamette Research and Extension Center, Aurora, OR, 97002

Search for more papers by this author
Elizabeth A. Myhre

Elizabeth A. Myhre

Dep. Crop and Soil Sciences, Washington State Univ., 7612 Pioneer Way E., Puyallup, WA, 98371

Search for more papers by this author
First published: 01 November 2006
Citations: 138

ABSTRACT

Recent adoption of national rules for organic crop production have stimulated greater interest in meeting crop N needs using manures, composts, and other organic materials. This study was designed to provide data to support Extension recommendations for organic amendments. Specifically, our objectives were to (i) measure decomposition and N released from fresh and composted amendments and (ii) evaluate the performance of the model DECOMPOSITION, a relatively simple N mineralization/immobilization model, as a predictor of N availability. Amendment samples were aerobically incubated in moist soil in the laboratory at 22°C for 70 d to determine decomposition and plant-available nitrogen (PAN) (n = 44), and they were applied preplant to a sweet corn crop to determine PAN via fertilizer N equivalency (n = 37). Well-composted materials (n = 14) had a single decomposition rate, averaging 0.003 d−1 For uncomposted materials, decomposition was rapid (>0.01 d−1) for the first 10 to 30 d. The laboratory incubation and the full-season PAN determination in the field gave similar estimates of PAN across amendments. The linear regression equation for lab PAN vs. field PAN had a slope not different from one and a y-intercept not different than zero. Much of the PAN released from amendments was recovered in the first 30 d. Field and laboratory measurements of PAN were strongly related to PAN estimated by DECOMPOSITION (r2 > 0.7). Modeled PAN values were typically higher than observed PAN, particularly for amendments exhibiting high initial NH4–N concentrations or rapid decomposition. Based on our findings, we recommend that guidance publications for manure and compost utilization include short-term (28-d) decomposition and PAN estimates that can be useful to both modelers and growers.