Comparison of Three Different Fertigation Strategies for Drip Irrigated Table Grapes – Part II. Soil and Grapevine Nutrient Status

A field trial was carried out in a drip irrigated Dan-ben-Hannah/Ramsey table grape vineyard near Paarlin the Berg River Valley region of South Africa to compare three fertigation strategies. Fertilisers wereapplied (i) two weeks after bud break, fruit set and post-harvest (LF), (ii) weekly from two weeks afterbud break until ten weeks after harvest, except during berry ripening (WF), and (iii) in daily fertigationpulses (DF). Grapevines of all treatments received c. 116 kg/ha N, 22 kg/ha P and 92 kg/ha K per season.Grapevines of all the fertigation strategies were thinned to obtain a normal and high crop load, whichis 26 and 36 bunches per grapevine respectively for Dan-ben-Hannah under the given conditions. In thecase of DF, the soil directly beneath the drippers became acidic after three years. Salt also accumulated onthe perimeter of the wetted soil volumes. Petiole P of the DF grapevines was 77% higher than that of theLF and WF grapevines. Daily fertigated grapevines bearing normal crop loads had 20% to 30% higherleaf blade P than the LF or WF grapevines. Leaf blade K of the WF grapevines was lower than in thegrapevines bearing a normal crop load of the LF and DF strategies. Grapevines bearing high crop loadstended to have lower juice N than grapevines with a normal crop load. Juice P of the DF grapevines washigher than that of the LF and WF grapevines, regardless of crop load. Daily pulse fertigation promotedthe accumulation of N, P and K in the berry skins