Soil nutrients

I found a website with recommendations for fertilization of vineyards. Their recommendation regards growing conditions in various countries, including Italy, Spain, South Africa and India, which I imagine would apply to us as well. 

• Plant population: 2,000-10,000 vines/Ha.
• Soil type: light to medium.
• Expected yield: 15-30 T/Ha.

Soil level		Suggested correction method
Low P	10-25 ppm	Band 1250-600 (resp.) Kg/Ha superphosphate
Medium P	25-40 ppm	Band 600-350 (resp.) Kg/Ha superphosphate
High P	40 ppm and above	Band 350-200 (resp.) Kg/Ha superphosphate
Low K	<200 ppm	360 Kg/Ha SOP
High K	>200 ppm	No correction required

Our soil analysis showed very low concentrations of both Potassium (K) and Phosphorus (P).  The analysis also confirmed the pH readings we got using our gauge. 

That may explain our low yield in year one. As we have now placed seaweed at the base of the first ten plants, I am hopeful that we can correct that over the course of the winter. I'd like to maintain an organic approach to the management of the vines. 

Happy winter solstice!

Soil Analysis

A soil pH in the range of 5.5 to 6.5 is considered optimum for grapes and generally has a better nutrient balance for plant growth than soils that are more acidic or alkaline. Vines will grow from pH 4.0 to 8.5, but a pH below 5.5 and above 8 will depress yields and create problems for the vines. The ideal soil pH depends on the type of grapevine. French American (hybrid) grapevines that are grown for wine prefer a 6.0 soil pH; Vinifera grapevines grown for wine and direct consumption prefer a pH of 6.5. The amount of material needed to adjust the soil pH will depend on the soil texture (the amount of sand, silt and clay in the soil) and the type of grapevine. Our pH readings were good. Consistently reading just under 6.0. The official analysis showed 6.5. That's a good start. 

Alex sent soil samples off for analysis and, as expected, we have silty clay soil. The composition is:

It's not the best but it ain't bad according to several sources consulted. In fact, it's great that there's no indication of loam as loam is too rich for grapevines. They like poor soil best. We've got that in spades. 

We also had Phosphorus (P) and Potassium (K) results reported; they were in the very low index. When I find out what that means for grapevines, I will share it here.