| Abstrakt: |
In tests with sources of N, (NH)SO, when banded in the soil, usually resulted in highest tuber yield. Yields with Nitroform and sulfur-coated urea were similar to each other, and somewhat less than those from urea. Application of Aqua Humus, a humic acid derivative, in addition to several sources of N, had no significant effect on yields. Nitrogen absorption was highest from (NH)SO, as measured by NO content of the petioles or total N absorption by the entire plant. There was little difference in N absorption from Nitroform and sulfurcoated urea. These materials did not result in increased N absorption by plants during late growth. In Kern County experiments, about 80% of the N from (NH)SO and urea had nitrified and leached from the fertilizer band by 40 days after application. At 80 days after application, half of the N from Nitroform was still in place. In an experiment at Davis on a heavier soil, Nitroform had a slower rate of N release than sulfur-coated urea, followed in order by (NH)SO and urea. [ABSTRACT FROM AUTHOR] |
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