Submitted to: International Symposium Agricultural Techniques in Cold Regions
Publication Type: Proceedings
Publication Acceptance Date: 8/14/2001
Publication Date: N/A
Interpretive Summary: Interior Alaska's long days promote rapid growth and N uptake. This paper presents the results of several studies, and relates the availability of various N sources to barley N uptake. Potential grain yields are about 300 kg ha -1 at spring planting; another 30 kg N ha-1 will mineralize from the soil organic matter by crop maturity. The crop must get 60 kg N -1 from external sources. Green manure will supply 30 kg N ha-1 to the barley cro Therefore, 30 kg N ha-1 must be applied as fertilizer following a green manure crop. Continued use of green manure in rotation with barley is expected to increase the rate of soil N mineralized, but it will take several years to meet the demands of barley crop.
Technical Abstract: Long summer days in interior Alaska promote rapid plant growth, but cool so slow the release on mineral Nitrogen from soil organic matter or green manu Therefore, crops such as barley require the addition of fertilizer nitrogen achieve maximum yields, even when green manure is used. Furthermore, this nitrogen needs to be available early in the growing season to avoid plant stress that will reduce yields. A normal barley crop requires about 60 po of nitrogen per acre above what the soil can supply. Green manure can supp up to 30 pounds of N per acre. Therefore, even with green manure, 30 pound of nitrogen per acre must be applied to maintain yields.