25 Oct Post-Harvest: Irrigation & Fertility
Post-Harvest: Irrigation & Fertility
The Vineyard Team just released an article describing “The Importance of Post-Harvest Irrigation and Fertilization” written by Craig MacMillan. It starts off by calling out the best time of the season to apply Nitrogen and Potassium, taking place just after harvest but prior to leaf fall. The table below shows the amount of time required for vines to restore their nutrient reserves varying by crop load.
Replacing the crops’ nutrients during this time is vital. All those nutrients were taken away (in the harvested fruit) and not recycled back into the soil like the leaves or canes. Every situation is different, but below are the believable ranges of nutrients removed from the vineyard.
The article explains that “a combination of soil analysis, tissue analysis, and visual assessment is suggested” when making fertilizer decisions because the point is to have sampling and analysis done consistently every year to be able to compare the results to previous fertilizations and outcomes. The post-harvest application timing (landing between harvest and leaf fall) is key to restoring nutrients for the next season because “30% of the Nitrogen the vine will use is taken up post-harvest“. The same goes for Potassium however, about a month after harvest, the amount of Potassium the vine uptakes will decrease rapidly. Sufficient moisture in the soil is necessary for allowing nutrients to move from the soil into the roots because “fertilizers applied without adequate soil moisture after the application will not be brought into the vine for storage and may leech away over the winter.” Hydrated leaves are able to transpire,” which is necessary to move nutrients from the root-zone into the woody tissue of the plant.” If no water or fertilizer is applied, the vine’s nutrient levels will be low by the end of the season and the woody tissue will be dried out. Eventually, “these deficiencies will lead to uneven bud break, poor and uneven shoot growth, poor set, and a higher incidence of winter injury.” In the end,”if the vines look good going into dormancy, they are going to look good coming out of dormancy.”