Making strategic decisions about building soil fertility.

By Neal Kinsey, Kinsey Agricultural Services
What good is a soil test if it costs too much to follow the advice given? Many growers express concern about the expense involved in meeting fertilizer requirements, even when they recognize the importance of following recommended guidelines. Once it can be determined that the soil analysis accurately reflects the fertility of the area being evaluated, those results should then be used as a tool to help clarify what needs to be done based on the needs and goals for that specific vineyard. Without understanding what is desired or expected by the grower, the best economic approach may not align with the recommendations that are offered.
It is crucial to tailor the recommendations to the grower’s specific expectations and objectives. Too many soil samples are taken in a hurry, sent in a hurry and results are expected “in a hurry” as well. Consequently, valuable information that could be most helpful for recommending the best program to the grower may not have even been the most affordable proposal.
Most soil laboratories provide a worksheet to be filled out as completely as possible by those sending samples for analysis and recommendations. Use of that information helps to make the best recommendations and to minimize delays in getting the results back in the shortest possible time.
Worksheets sent along with samples for testing should include options for different recommendation programs: Excellent, Building, Maintenance, and Minimum. If no preference is given, the default is usually for the Excellent program. Many growers choose the Excellent program, sometimes by default, until they realize the associated costs— too much, even when such a program helps produce better quality or higher yields. Rebuilding soil fertility can be costly, especially where crops have been produced there repeatedly without adequately replacing essential nutrients that have been removed.
When growing grapes for years on the same land, without replacing what is taken out year by year, failure to replenish critical nutrients helps make restoring the lack of minerals for the highest levels of soil nutrition for grapes an expensive process. It is important to consider how long it has been since key nutrients, such as sulfur and micronutrients, have been adequately applied. Large numbers of vineyard soils sampled throughout the world still show to be sorely lacking in vital minerals. Even soils that have received manure or compost and “token amounts” of various trace elements in purchased fertilizers for years often still fit into this category.
Limited funds do not mean there are no viable approaches based on soil test needs? The question becomes which needs will deliver the greatest advantage for producing the best crop? While most growers aim for excellent soil conditions for growing their grapes, the costs of catching up after years of constant removal can be significant.
This financial challenge often leads those who make the final decisions to consider minimum programs for vineyard fertility. However, minimum programs should only be considered when there is absolutely no other choice, and even then, keeping in mind that such means should only be considered as a very temporary solution. Using this type of program risks depleting nutrients that are currently sufficient which can seriously impact the condition of future crops depending on whether soil levels at the time these measures are initially instituted are poor, or good, or merely adequate.
To be sure such measures are not a mistake, consider one other question. How qualified is the person who makes such a decision? Is it based on the ability to distinguish between which soils perform the best, those that perform well or the problem areas? And can that be determined just by observing the test results without knowing where they were taken? If not, then are they qualified as decision makers to decide what will and will not hurt each of those soils and the grapes to be grown there?
There are yet additional choices that can be made when it costs too much to achieve an excellent soil fertility level in the shortest period for the needs of each vineyard. For most vineyards, the fertilizer budget does not cover all that is needed to bring every one of the nutrients back in line at once. When such may be the case, prioritizing which nutrients will provide the most benefit based on overall needs helps maximize results for the money being spent. This enables the grower to go down the list and put the money where it will provide the most benefit.
When funds are limited to such an extent that a grower cannot afford to follow the complete program, then spend the available budget where it will make the most difference for the grapes being grown there. In other words, request excellent soil fertility recommendations in at least one area of your property so you can see the difference in production and quality. This will help create more profit by investing back into one of the most important resources you have: your soil.
The better vineyards will generally need far less in terms of nutrients to reach excellent condition while the poorer producing vineyards can be quite expensive to get to that higher level of performance. If vineyards are rated based on performance using a scale of 1-10 with 10 being the best, generally the return on investment will tend to be better on the “8” field than on the “3” field.
Once confidence in the program has been built and proven to be worthwhile on a smaller portion of land, there is another option that some grape growers choose regarding achieving optimum performance from each field. Instead of excellent, in the beginning check the box for the soil building program and ask that all nutrients be prioritized according to the fertility needs of the crop to be grown there. First spend the allocated fertilizer budget on priority #1, then go to #2 and so on until the budgeted amount for that field is used up. In this way, to the extent that “soil feeder” types of fertilizers can be applied to build fertility instead of fertilizers that are “plant feeders” used to supply the same nutrients year after year, the soil can be improved and the priorities adjusted as progress is made. This allows spending the budgeted amount for fertility every year but putting that money where it will make the most difference for fertility and consequently the production improvements in each field.
Growers often want to experiment with several types of soil building practices to determine which yields the best results for their operation. Some prefer using soil amendments as the preferred route, while others believe that cover crops or grazing livestock sufficiently improves soil fertility for vineyards.
Each operation is unique, so it may be most beneficial to consult knowledgeable consultants and educators, as well as observe what other producers are doing, to gain insight into what might work better for each operation.
Based on fifty years of working with soil fertility on vineyard soils, our experience has been that on average to poor soils it can require decades to build up soils growing cover crops or grazing livestock. Both are beneficial for specific purposes, but to restore needed fertility, use of mineral rich fertilizers and soil amendments take at most only a few years to accomplish the needed changes.
More on that subject next time.
To learn more about the types of soil recommendations that Kinsey Agricultural Services provides, contact Neal at neal@kinseyag.com.
















