ISSN:
1573-5036
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary A study of results from experiments comparing several application rates of N showed that crop uptake of total and fertilizer N tended to increase linearly with amount applied over rather wide ranges, if factors other than N did not limit growth. Three types of N-uptake response curves were characterized on the basis of the deviation of the observed check uptake from that estimated by linear regression. Different conclusions result from percentage recoveries estimated by the usual difference method for each type. Evidence is presented that this commonly used difference method of determining N-recovery by crops is oversimplified and often does not effectively characterize the efficiency of applied N. A portion of the fertilizer N retained in the soil was independent of application rate. This caused check uptake values calculated by regression to be lower than the observed values. As a result, the usual isotopic dilution method of calculating recovery of applied fertilizer N was found to be subject to the same limitations as occur in estimated recoveries of unlabeled N by the difference method. For most routine N efficiency experiments, labeling techniques may have little advantage over methods with unlabeled N if multiple rates are compared.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01393911
