ISHS Acta Horticulturae 868: VI International Symposium on Mineral Nutrition of Fruit Crops
EFFECTS OF METHOD AND LEVEL OF NITROGEN FERTILIZER APPLICATION ON SOIL PH, ELECTRICAL CONDUCTIVITY, AND AVAILABILITY OF AMMONIUM AND NITRATE IN BLUEBERRY |
| Authors: | D.R. Bryla, A.D. Shireman, R.M.A. Machado |
| Keywords: | Vaccinium corymbosum, ammonium, electrical conductivity, nitrate, soil pH |
| DOI: | 10.17660/ActaHortic.2010.868.8 |
| Abstract:
Blueberries (Vaccinium spp.) require low soil pH and prefer N primarily as NH4+ for optimum production. Nitrogen fertilizer methods and rates were evaluated in a new field of ‘Bluecrop’ blueberry (Vaccinium corymbosum L.) to determine their effects on soil pH and availability of NH4+ and NO3- in soil solution. Treatments included four application methods (split fertigation, continuous fertigation, and two non-fertigated controls) and four rates of N application (0, 50, 100, and 150 kg•ha-1 N). Fertigation treatments were irrigated by drip and injected with liquid urea fertilizer; split fertigation was applied as a triple-split from April to June while continuous fertigation was applied weekly from leaf emergence to ≈2 months prior to the end of the growing season. Non-fertigated controls were fertilized with a triple-split of granular ammonium sulfate and irrigated by drip or microsprays. Soil pH was usually lower with microsprays than with drip, even when no N fertilizer was applied; however, soil pH was also reduced with higher N applications and, in fact, was similar between continuous fertigation and granular fertilizer (microspray) treatments when 150 kg•ha-1 N was added. Nitrogen application with granular fertilizer, whether irrigated by microspray or drip, maintained much higher NH4+ concentrations than continuous or split fertigation but often increased electrical conductivity (salinity) of the soil solution (ECw) to >2 dS•m-1. By comparison, ECw was always <1.5 dS•m-1 with either fertigation method. Granular N application coupled with microsprays also resulted in higher NO3- concentrations than any other treatment, which may lead to more N leaching since the ability of blueberry to acquire NO3--N is limited. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
