PLANT AND SOIL ANALYSES AS GUIDELINES FOR THE FERTILIZATION OF TABLE GRAPES IN SOUTH AFRICA

W.J. Conradie
Fertilization trials, using cv. Barlinka grafted onto Ramsey, were carried out on three soils in the Hex River Valley. The 0 - 600 mm layer of the first soil (S1) contained 1.15% C and 6.7% clay, in comparison to 0.59% C and 2,8% clay for the second (S2), while the third (S3) contained 0,43% C and 4,1% clay. Annual N and K applications ranged from 0-180 kg ha-1 and 0-120 kg. ha-1, respectively. All soils showed NO3-N contents of less than 3 mg. kg-1 at budbreak. From this stage up to flowering, active mineralization occurred for S1 and S2, resulting in NO3-N contents of approximately 8 mg. kg-1 in the control treatments. Due to grapevines having a relatively large N - demand after flowering, NO3--N content for these treatments was reduced to 7 mg. kg-1 at véraison. Even though N fertilization increased NO3-N content in S1 and S2, cane mass and grape yield were not affected. The NO3+-N content of S3 never exceeded 5 mg. kg-1, even at the highest N application rate, pointing to a low N - supplying capacity and the necessity for N fertilization. Potassium accumulated in the soil with the highest clay content (S1. Leaching of K from the sandlier soils (S2 and S3) necessitated annual fertilization. Leaf analyses (total N, NO3-N and K) differed between the three soils. For each individual soil, however, leaf analyses were fairly constant, in spite of large differences in N and K applications. Soil analyses appeared to be a better guideline for N and K fertilization than leaf analyses.
Conradie, W.J. (1997). PLANT AND SOIL ANALYSES AS GUIDELINES FOR THE FERTILIZATION OF TABLE GRAPES IN SOUTH AFRICA. Acta Hortic. 448, 509-509
DOI: 10.17660/ActaHortic.1997.448.90
https://doi.org/10.17660/ActaHortic.1997.448.90

Acta Horticulturae