Agriculture Reference
In-Depth Information
fected vines. If you grow more than one variety, sample each variety separately. Choose
petioles from mature leaves five to seven leaves from the tip of the shoot. Petiole analysis
is usually done for nitrogen, phosphorus, potassium, boron, calcium, copper, iron, magnesi-
um, manganese, and zinc.
Major nutrient fertilizers can be applied in several ways. You can sprinkle powders or
pellets directly on the ground under and around the plant; if you have a drip system, apply
them under each dripper. Other fertilizers are soluble, and are mixed with water and ap-
plied through the irrigation system: this normally requires you to have a tank and pump to
disperse the product into the system. If you apply foliar sprays with a backpack sprayer, be
sure to use dedicated spray equipment that has not been used for a pesticide or fungicide.
Fertilize once when plants are dormant, taking care not to apply the fertilizer too early,
because that will stimulate new shoot growth. Early winter is the best time: you want the
plants to be dormant, so that the fertilizer doesn't cause a flush of late growth that could
be subject to frosts, but the winter rains will wash the fertilizer down into the root zone in
preparation for spring growth.
If you have had a soil or leaf (petiole) sample that showed deficiencies, recommended
application rates will be included in the analysis. Otherwise, use a balanced fertilizer ac-
cording to the rates specified by the manufacturer or supplier. If your soil is very fertile, cut
the suggested amount in half or even to a quarter, likewise for clay soils, which retain nu-
trients. In sandy soils, double the amount of fertilizer, as nutrients will leach more quickly
out of the plants' root zones.
Fertilize the vineyard again in early spring, generally basing the vines' needs on the
amount of vigor they show. Apply after heavy winter rains, but early enough so that spring
rains can move nitrogen into the root zone (especially if you have an unirrigated vineyard).
Late spring and early summer applications at light rates are recommended for drip-irrigated
vineyards, again, only if the plants lack vigor.
Compost for the Vineyard
Composting is one way to minimize the amount of additional nutrients you need to sup-
ply to the vineyard. Creating your own compost pile or piles is almost essential for an or-
ganic farmer. Compost also helps to improve soil texture, by adding organic matter to the
soil and increasing soil microbial activity.
There will always be some material around to dispose of. Kitchen scraps, grass clip-
pings, cuttings from the vines, garden waste—anything that can be broken down can be
added to the compost. If you are making your own wine, grape pomace is a great addition
to the compost pile.
