Specialty crops, such as fruits and vegetables, require special considerations in terms of soil management and fertility. As the growing season winds down and more crops are harvested, you may feel as though you have nothing left to do except wait to start it all over again in the spring. Soil that is continuously cropped with fruit and vegetable crops can become depleted of key nutrients rather quickly and, now is the best time to work on addressing issues that you may have with your soil. Additionally, addressing issues with your soil may even resolve other issues such as disease and weed pressure.
An important aspect of determining whether you have areas that need addressed or even how to address them is to take soil samples. Soil sampling is the most direct way to understand what is going on in your soil. Most soil test will give you the results for the macro nutrients phosphorus and potash, which are used in the highest amounts by the plants. They will also usually include the secondary nutrients calcium and magnesium, that are used to a lesser degree. Soil test results may also show you your soil pH, organic matter percentage and the cation exchange capacity. All of these factors are important in making a decision on your soil fertility and soil management strategies.
Before diving into any of the topics surrounding soil management and soil fertility after a growing season, it is first important to understand the basics of nutrient uptake by the plant. The roots are the main pathway in which nutrients are transported into the plant. In order for this to occur, the nutrients must be in a form in which they are mobile. The nutrients are mobile in the soil when they are broken down or dissolved into the soil solution, at which point, the roots are able to take them in and move them throughout the plant.
The process of a nutrient breaking down or being dissolved in the soil solution takes time. That is one of the major reasons to address soil fertility concerns in the fall. Being able to apply certain nutrients, such as potassium, in the fall and allowing them all winter to break down and become available to the plant is optimal. Certain nutrients like nitrogen, you can apply right before planting, as nitrogen is available to the plant for uptake rather quickly after application. Regardless of whether you are addressing soil fertility issues in the fall or the spring, it is important that you do so with careful consideration for nutrient loss. Nitrogen is a very mobile nutrient and can be lost through several pathways fairly easily. It is also of your best interest to make soil amendments based on a recent soil test report. How else would you know what to apply or how much? Knowing what your soils already have and how to make them better will not only prevent over application that could lead to nutrient runoff, it will also save you money. Over buying and over applying nutrients is doing nothing but pouring money down the drain.
Another important factor of your soil management decisions should be based on your soil pH. Each crop type will have a more specific optimal pH, however, in general a pH between 6.0 and 7.0 is recommended for most crops. Being able to maintain an appropriate pH level will also help to influence plant growth due to optimal nutrient uptake. At a pH of approximately 6.2-7.3, nutrient availability is at its highest. With a pH any lower or higher than this range, nutrient availability sharply declines. So even if you were applying the correct amount of nutrients or over applying because the plants weren’t responding to the fertilization, having a pH outside of the optimal range is likely preventing the nutrients from becoming available for plant uptake.
Soil fertility is one of the biggest factors that influence crop yield. Foliar feeding has its place with specialty crops; however, it should not be relied on to address issues with crops that are due to poor soil nutrient management. Excessive foliar feeding, especially with nutrients that are not mobile in the plant, is costing you money that you are not getting a return on. If you are having issues year after year that you are associating with soil fertility issues, address the issues in the soil. Remember that the roots are specifically there to take up water and nutrients. Not only will improved soil fertility help with crop yields, it will also improve overall plant health. A healthy plant is a strong plant, and a strong plant stands up better to disease and insect pressure.
Take the time this fall to take soil samples. Work with your local co-op or soil lab and address the nutrient concerns in your soil. Your soil is worth your time and investment. You should put in the effort to take care of the soil and consider even improving it and leaving it in a better condition for future generations. I heard it said once that despite all of our accomplishments, we owe our existence to a six-inch layer of topsoil and the fact that it rains. Take care of your soil and it will take care of you.