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Details van artikel 138 van 164 gevonden artikelen
| Titel: |
The effect of soil sample handling between collection and drying on nitrate concentration |
| Auteur: |
Westfall, D. G. Henson, M. A. Evans, E. P. |
| Verschenen in: |
Communications in soil science and plant analysis |
| Paginering: | Jaargang 9 (1978) nr. 2 pagina's 169-185 |
| Jaar: |
1978 |
| Inhoud: |
The residual soil NO3-N concentration is used in determining the N fertilizer recommendation for many crops in the arid United States. Accurate representation of the field levels of residual NO3-N is complicated by the fact that the NO3 concentration in a soil sample can change significantly if the sample is not handled properly after collection. This will result in erroneous N fertilizer recommendations. Soil samples were retained in their field moist state after collection and subjected to various conditions that would be encountered under normal soil sample handling situations before they were dried and analyzed. Subsamples were removed periodically to determine the change in NO3-N as influenced by the various handling conditions. Samples with an original NO3-N concentration of 26 ppm increased by 30.4, 12.8, 27.5 and 36.4 ppm when incubated (30 C), refrigerated, kept at room temperature or placed in a window where they were exposed to the sun 7 hours/day over a 7 day period, respectively. These changes would result in N fertilizer errors ranging from 52 to 147 kg N/ha (based on a 0-30 cm sample depth). During the first 48 hours after collection the same treatments resulted in changes in NO3-N concentration that would cause N fertilizer errors in the range of 24.3 to 57.3 kg N/ha. Seven different soils were used in these investigations and only one showed a significant change in NO3-N concentration upon freezing or air drying for 7 days. Although these changes were statistically significant they were so small that the error in the resultant N fertilizer recommendation would be meaningless. Based on the results obtained, soil samples should be dried immediately after collection. Since “immediate”; drying is not always logistically possible, samples should be placed in a dryer within 12 hours after collection recognizing that changes in NO3-N will occur but the magnitudes of these changes will be relatively small when translated to N fertilizer recommendations. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 138 van 164 gevonden artikelen
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