Nitrogen source effects on rabbiteye blueberry plant‐soil interactions

Abstract

The acidity of alfisols and ultisols may be unfavorably increased for blueberry production by the use of specific nitrogen (N) fertilizers. Several ammonium containing fertilizers were evaluated for their effects on rabbiteye blueberries (Vaccinium ashei Reade). Rooted ‘Tifblue’ cuttings were grown in a 1: 1 peat: Lilbert loamy fine sand mix for 90 days. After establishment, plants were moved into the glasshouse and fertilized four times at 90‐day intervals with one of six N sources at one of four rates. Nitrogen sources were (NH₄)₂SO₄ (AS), NH₄NO₃ (AN), urea, urea‐NH₄NO₃ (UAN), Nitro‐form (NF) and sulfur coated urea (SCU). Rates of N per application were equivalent to 0, 112, 224, or 336 kg/ha. The application of the high rate of each N source reduced plant growth. The 112 and 224 kg/ha N treatments increased growth compared to no nitrogen treatments. When comparing N sources, SCU treatments produced the greatest plant growth and AS treatments the lowest. Sulfur coated urea had less effect on soil pH and Al than other sources. Poor growth with AS was caused by the combined effects of decreased soil pH, increased soil electric conductivity (EC) and increased exchangeable aluminum. Plant leaf N increased with increasing N rate. Nitrogen sources which produced the greatest plant growth had the lowest N levels.

Key words:

• soil pH
• Vaccinium ashei Reade
• aluminum

Notes

Texas Agricultural Experiment Station Scientific Journal Article No. TA 22819.

Assistant Professor, Associate Professor, Research Technician II, Research Assistant and Research Associate, respectively.