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 applied fertilizers are either broadcast, or more commonly banded underneath the vine canopy. Higher nutrient rates are often used with dry applied fertilizer programmes to cover inefficiencies and ‘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 the right fertilizer at the right time to maximize nutrient uptake, growth, yield, and quality. In this way, fertigation using low doses to suit the growth stage needs, can help overcome the apparent conflict of high nitrogen and potassium levels needed for yield, with the winery’s desire for low nitrogen and potassium levels in the grape and must.
Foliar application is used to address an immediate nutritional need and where soil conditions restrict availability of specific nutrients. Micronutrients are commonly applied in this way.
The following growth stages are critical time of 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.