ISHS Acta Horticulturae 810: IX International Vaccinium Symposium
MINERAL NUTRITION OF CRANBERRY: WHAT WE KNOW AND WHAT WE THOUGHT WE KNEW |
| Author: | T.R. Roper |
| Keywords: | Vaccinium macrocarpon, nitrogen, phosphorus, potassium, tissue sufficiency |
| Abstract:
The objective of cranberry fertility programs is to achieve and maintain tissue sufficiency, thus eliminating mineral nutrition as a yield limitation. There is much disagreement in older work about fertilizer requirements; with regional, soil, genetic, and technical variables contributing to the disagreement. Nitrogen is the most important mineral nutrient; NH4 is the preferred form of N. Adding nitrogen to N deficient vines increased total upright number, flowering upright number, flower number and total berry weight. Although the essentiality of NH4 for cranberry has been dogma, growers note increased vegetative growth when irrigating with high nitrate water. Nitrate use may be mediated by ericoid mycorrhizal fungi, which are ubiquitous in cultivated cranberry. Small plot research showed that tissue P increased with increasing P application, but not yields. Even after 6 years with no P application, zero P plots were still in the tissue sufficiency range. We have no research-based data that can justify the use of P rates greater than 22.4 kg/ha in beds with tissue P in the sufficient range. Plot work varying potassium application from 0 to 896 kg/ha K2O showed no response of yield, fruit size, or fruit color to increasing K applications. At the rates tested, KCl and K2SO4 were equally effective and did not show toxicity. In column studies K did not overly exchange other cations from the soil. Progress has been made in understanding cranberry fertility, but much more work remains to be done. | |
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