Soil analysis is esssential before planting and then should be repeated every 2 – 3 years. The most crucial part is getting a representative sample:

• Divide the vineyard into blocks according to different types of soil
• Don’t sample areas that have had recent fertiliser applications or very wet soils
• At least 25 samples/block. Use a zigzag shape
• Depth 20 – 60 cm, but useful to take surface ones as well.
• The larger the sample the better
• Mix samples in a bucket, then send about 500 g

Nitrogen is not usually measured in a soil analysis, as its levels are particularly dependent on seasonal factors such as soil moisture, aeration, temperature and the activity of soil organisms. Interpretation of the results is not easy, but can use ADAS figures as a rough guide.

Leaf and petiole analysis can be useful for:

• Confirming visual symptoms of nutrient deficiency
• Comparing good vine areas with bad
• Assessing the effectiveness of fertiliser applications or changes in practices such as irrigation and weed control

In terms of sampling method, remove 100 leaves from the nodes opposite the lower bunches at veraison or full bloom (or both). In dry areas, samples should be taken early in the day (before stress), but not directly after overhead irrigation. Wash leaves to remove pesticides, dry, and then send off leaves or petioles for analysis. Unfortunately leaf and petiole analysis does not tell you how much to add.

It is important to be able to visually recognise deficiency symptoms in the grapevine, but:

• If symptoms are sporadic, they are probably due to something else, such as root or bark damage, girdling with ties, viral diseases
• Deficiencies might affect vine performance without showing symptoms (‘hidden hunger’) e.g. Magnesium & zinc
• Multiple deficiencies are difficult to diagnose