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Details van artikel 17 van 21 gevonden artikelen
| Titel: |
Quantities of potassium fertilizer required to raise soil test value |
| Auteur: |
Johnston, Michael A. Miles, Neil Thibaud, Guy R. Hughes, Jeffrey C. |
| Verschenen in: |
Communications in soil science and plant analysis |
| Paginering: | Jaargang 30 (1999) nr. 17-18 pagina's 2485-2487 |
| Jaar: |
1999-10 |
| Inhoud: |
In order to calculate the potassium (K) fertilizer requirement, it is necessary to know how much of this nutrient element must be applied in order to overcome any buffering effects and raise the soil test value to a desired level. A glasshouse study was conducted on a wide range of KwaZulu-Natal (South Africa) soils to establish this information. The topsoil (0-200 mm) at 51 sites was sampled. Soils varied greatly in texture (4-83% clay), organic carbon (0.2-9.2%), and clay mineralogy (kaolinitic-sesquioxic through to illitic and smectitic). Soil from each site was treated with four levels of K and taken through three wetting and drying cycles over a six-week period. Analysis for K using the “Ambic”; [ammonium bicarbonate (NH4HCO3)/ammonium fluoride (NH4F)/EDTA] extractant showed that the quantity of applied K (kg ha-1) required to raise the soil test value by a unit (1 mg L-1), i.e., the K requirement factor, varied between 1.5 and 8.8. Therefore, on soils that display the highest K fixation, the calculated fertilizer K requirement, which is currently based on a factor of 2.5, could be underestimated by as much as 70%. Clay mineral analysis showed that the higher levels of K fixation tended to be associated with the presence of vermiculite. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 17 van 21 gevonden artikelen
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