PT  - JOURNAL ARTICLE
AU  - W. J. Conradie
AU  - D. Saayman
TI  - Effects of Long-Term Nitrogen, Phosphorus, and Potassium Fertilization on Chenin blanc Vines. I. Nutrient Demand and Vine Performance
AID  - 10.5344/ajev.1989.40.2.85
DP  - 1989 Jan 01
TA  - American Journal of Enology and Viticulture
PG  - 85--90
VI  - 40
IP  - 2
4099  - http://www.ajevonline.org/content/40/2/85.short
4100  - http://www.ajevonline.org/content/40/2/85.full
SO  - Am J Enol Vitic.1989 Jan 01; 40
AB  - The effects of nitrogen (N), phosphorus (P), and potassium (K) fertilization were investigated in a field trial with Vitis vinifera L. var. Chenin blanc over a period of 11 years. Three levels of N (16, 56, and 96 kg N/ha/yr), P (0, 9, and 18 kg P/ha/yr), and K (0, 45, and 90 kg K/ha/yr) were tested in a 3 x 3 x 3 factorial layout on a gravelly sandy loam soil containing 1.1% organic material, 12.7 mg P/kg, and 38 mg K/kg. Nitrogen fertilization increased yield and shoot growth slightly but reduced the pH of the topsoil. It was concluded that the N-supplying capacity of the soil was nearly sufficient to satisfy the N demand of the vines, which had an average yield of 13t/ha, and that an additional fertilization of only 40 kg N/ha was justified in this case. Phosphorus fertilization increased P levels in both topsoil and subsoil and also had a positive effect on yield and shoot growth. Evidence of a P/K antagonism was encountered. Apparently, little P fixation occurred, and it was found that less than 9 kg P/ha/yr was needed on this P-deficient soil to ensure optimum yield and growth. Potassium fertilization increased K levels in the soil as well as yield and shoot mass. A fertilization level of less than 45 kg K/ha/yr was needed on this soil with its marginal initial K content and a soil norm of 50 mg/kg seemed appropriate for K.