During last year's growing season it was obvious that we had a number of mineral deficiencies in the vineyard evidenced by discolouring of the foliage. For example magnesium deficiency turns pinot leaves red and low levels of Iron result in yellow leaves on the Chardonnay. This was confirmed by soil analysis which identified low levels of Iron, Magnesium, Phosphorus, Manganese, Molybdenum and Sodium. Whilst Boron levels were adequate its availability will be restricted due to the high pH of the soil caused by high levels of Calcium.
The main concerns are the Magnesium deficiency and the need to maintain adequate Boron which has a very significant role in bud formation and pollen production and viability. Together with Calcium, Boron also helps form strong cell walls enabling the vine to withstand disease. It also enhances the uptake of Potassium and Magnesium and is a basic contributor in nucleic acid, carbohydrate and protein synthesis.
Being organic we have to be very careful about what we use on the vineyard, but we have obtained permission from our certification body Organic Farmers and Growers (OF&G) to use soil applied Boron, and Sulphur which will also help lower pH levels and improve Nitrogen assimilation. Our agronomist, John Buchan recommended 25kg/ha of Sulphur, 10kg/ha of Boron and 125kg/ha of Magnesium.
As the vineyard has been so wet we have had to apply everything manually by walking up and down the rows scattering the granules by hand!