Fertilizer application strategies
Fertilizer application strategies mainly include rate and time of application. Different amount (rate) and forms of fertilizers are applied using a number of methods according to specific needs of crop at a specific growth stage (time).
Dry fertilizer application: is either broadcast or more commonly banded underneath of the vine canopy. Higher nutrient rates are often used with dry application, because nutrient use efficiency is low due to nutrient ‘tie-up’ in the soil.
Fertigation: is supply of nutrients through irrigation directly to the active root zone with maximum nutrient use efficiency.
Application of nutrient into root zone through fertigation strategy ensures better application uniformity for every vine, delivering sufficient amount of nutrient at the right time to maximize nutrient uptake, growth, yield, and quality.
Foliar spray: is used to address an immediate nutritional need of crop where soil conditions restrict availability of specific nutrients. Micronutrients are commonly applied in this way.
Fruit spray: Potassium, calcium and micronutrients are sprayed on fruit during fruit development starting from berry fill growth stage to a few weeks before harvest to maximize berry quality. Complete coverage of the berry is essential, for example, when applying calcium to the bunch. Bunches can be dipped into nutrient solution, while they are on vine.
The following growth stages are critical for fertilizer application: bud burst (the leaves have separated at the tip, usually exposing the growth point); early flowering (the first flowers are open); fruit set (berries start to develop and are the size of small pellets); berry fill (berries expand in size); veraison (berries soften and change color as they begin to ripen); and post-harvest.
