Fertilizer Management for Grapevines
Timing of Applications
Early in the season vines have only developed a small proportion of their total leaf area and this combined with low evaporation limits fertilizer uptake. If possible apply smaller amounts of fertilizer more frequently in the periods of maximum vine demand. Smaller applications will give the vines an opportunity to take up all the applied fertilizer before the next irrigation or rainfall leaches the soil.
Fertilizer placement is an integral part of efficient vineyard management. Correct placement often improves efficiency by which vines take up nutrients and consequently encourages acceptable yields and the production of marketable fruit. Many placement techniques are available for growers.
Broadcasting spreads fertilizer across the soil surface. Broadcast fertilizer can be left on the soil surface or incorporated by a tillage operation after application. With incorporation, these nutrients are mixed into the surface layer of the soil where root interception is more likely to occur. Broadcasting is generally the fastest and least costly fertilizer application method.
Narrow bands of fertilizer are applied on or below the soil surface adjacent to the vine row. Banding is one way to satisfy the phosphorus needs of vines as the roots develop.
Fertigation refers to injecting fertilizer into an irrigation system. This is accomplished in drip (trickle) by using some type of injector to meter the concentrated fertilizer solution into the irrigation water. In addition to greater flexibility in application timing and optimal placement, fertigation increases the rate of nutrient uptake and predictability of vine response to fertilization compared to broadcast and band applications
Fertilizers can also be applied directly to the vine foliage where nutrients are taken up by the leaves. Nutrient foliar sprays are most commonly used to correct micronutrient deficiencies. Foliar application of micronutrients is preferred for three reasons: 1) micronutrients such as zinc, boron, manganese, and iron are required in relatively small quantities by vines, 2) many micronutrients are readily fixed by most soils, so they soon become unavailable to the vine with soil fertilization, and 3) the elements form insoluble precipitates at neutral to alkaline pH.
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