Soil testing is used for vineyards to evaluate the chemical status of the soil before and after planting. A soil test before planting can determine if there are any nutrient deficiencies or toxicities that may affect the growth of young vines. There are many fertilizer amendments that are much more effective when incorporated into the soil profile and this is best accomplished during the soil preparation period prior to planting. This is why a pre-planting soil sample is used. This sample consists of a random composite sample from the 18-24” soil profile. Generally, the number of samples necessary is based on soil types present and the acreage. A good general rule is to take one sample per 5 acres. A good soil sample consists of at least one liter of soil.
Water testing is used to determine the suitability of a water source for irrigation purposes and also to determine the nutrients present in the fertigation solution. Some ground water can have toxic levels of sodium, chloride, or boron. Water that is determined to be very alkaline with high bicarbonate alkalinity may lead to an increase in the soil pH and may also create potential clogging problems with drip irrigation systems. The alkalinity of the water will also determine its effectiveness when using certain pesticides and the need for water treatment in the pest control program. It is also very important when determining the best fertigation or liquid fertilizer program. Samples should be collected in a clean one-liter bottle, filled to the top and sent in for analysis. Samples can be refrigerated if not sent promptly.
Plant Tissue Analysis
Once a vineyard is established, generally after the third year, it is best to determine the fertility status of the vines with the use of petiole analysis.
Due to the rooting depth of vines, it is sometimes more effective to analyze the current nutrient levels within the plant rather than the soil fertility levels around the roots.
A good petiole sample consists of a random composite sample of the petioles opposite the flower cluster at mid-bloom stage of the vineyard. A sample should contain 30–50 petioles. Small leaf varieties should have at least 50 petioles and larger leaf varieties 30 petioles per sample. The petioles are then placed in paper bags, labeled and sent in for testing promptly. If shipping is delayed, lightly rinse samples in clean water and place in a paper bag, kept open in a warm, dry well-ventilated area to prevent molding and decay of the tissue.