1.3.3 The fertilization plan

What is basal fertilizer?

The purpose of basal fertilizer is to promote proper development of young vines and their roots. By adding a soil-enriching agent or a fertilizer, the goal is to enrich the soil in preparation for replanting. Oftentimes, fertilizer is added once liming has been completed to balance the pH of the soil, or indeed it is used to enrich poor soils with crucial organic matter. Fertilizer can also readjust biological activity or mineral levels in the soil (for example K/Mg ratio).

The plot’s soil analysis should govern decisions regarding basal fertilization. Then, the plan should be implemented like a classic fertilization operation. The main inputs are soil-enrichers, but fertilizer can also be used when necessary. Plant compost and manure are more common. Nutritional intake should be slightly higher for new plantings than established vines to ensure high-quality growth.

The soil's needs determines the choice of fertilizer

In general, the soil composition should be analyzed regularly (every 4 years or so) to monitor any changes, needs or deficiencies throughout the vine’s cultivation. Consequently, it is unnecessary to fertilize immediately after grubbing up. If this is not the case, or if the last analysis is more than 4 years old, a soil analysis after grubbing up shows the state of the plot and its possible needs before replanting.

Soil samples are taken from the top 30 cm. The chemical analysis will provide information on the CEC amount and its saturation percentage as well as the soil’s mineral content. Finally, the biological analysis shows organic matter levels as well as the biological activity of the soil, particularly when you calculate the C/N ratio.

Key criteria to take into consideration when planning future plantation objectives:

• pH of the soil’s water : below 6, a corrective liming is recommended, when it is between 6 and 7, a maintenance liming is an option, when it is higher than 7, no addition is generally required.

• The S/CEC ratio: when the ratio is over 100, it means that the CEC is saturated, and no addition is necessary. When this ratio is between 80 and 100, it is possible to add lime, but in general, simple monitoring is preferred. On the other hand, when the ratio is less than 80, maintenance liming may be necessary to saturate the CEC.

• The C/N ratio: when it is less than 12, no action is necessary, so no fertilizer is needed. When the ratio is between 12 and 15, a slight enrichment on one or two occations can suffice, when it is higher than 15, fertilizer intake should be spread over 4 years. The frame of reference varies depending on the type of soil. For example, it is normal to have a lower C/N when the soil is sandy whereas it will be higher in a clay-based soil.

• OM: when it is higher than 3%, it does not need to be added. When it is between 2 and 3%, a light addition of compost is possible. Finally, when it is less than 2%, a corrective supplement is recommended. The soil analysis will determine organic matter requirements, but it should be noted that OM levels are often higher in fallow ground than in established vineyards where a classic fertilization maintenance program is in place.