Fall Soil Sampling

Kory Zeigler

AGRONOMIST, MOUNT AYR

As harvest continues and crops are coming out of the field across our area, it is time to think about soil sampling. A soil sampling program should be a part of all farming operations and for all crops. Just putting on a standard rate of fertilizer does not guarantee that the crop will yield to your expectations.  Soil is very complex, and all parts must work together and be in balance to produce optimum yield levels.
              Higher fertilizer applications do not always equal higher yields. If something in the soil is out of balance you might not get proper nutrient availability from the fertilizer you applied. For example, pH is a very important part of the puzzle and needs to be checked by taking a soil sample. If the pH of your soil is too high or too low, your crops may not be able to take up the nutrients they need. Raising soil pH is typically done by applying lime; however, applications may need to be made every several years to keep it in the optimum range. Soil pH will naturally lower over time from commercial fertilizer application (especially nitrogen and sulfur fertilizers), rainfall, and even due to normal plant growth. In addition to looking at pH values, soil sampling can tell you if you need to adjust the amount of fertilizer you apply.
              Taking a few samples per field is better than nothing, but with conventional soil sampling, you really do not get to see or manage the variability in a field, and it is difficult to make an accurate recommendation from a few random samples. Statistically speaking, if you are flat rating your fertilizer, possibly as low as only 5-10% of the field may be getting the correct rate. Grid sampling is the best way to see how a field varies and helps us make smarter fertilizer recommendations. Grid sampling will have multiple sample points across the field and will often reveal spots that are very low in nutrients, spots that are very high in nutrients, and also variances in soil pH. From these grid sample results we can make variable rate recommendations for lime and fertilizer that help farmers allocate their fertilizer investment more wisely. Grid sampling does not always reduce the amount of fertilizer applied to the field, and in some cases, it may ask for higher fertilizer applications than normal. However, if we can take money that was being spent in one spot in the field that does not need it and relocate to a spot that needs more, we can better meet the needs of the crop. Regardless of what your fertilizer budget is, our recommendations can be tailored to meet your goals and help you achieve a better return than spreading a constant rate across the field. Once completed, grid sample results will generally be used for 4 years and then retesting can occur to validate our results/management.
              Grid sampling is a great starting point to improving yields and on-farm profitability. Few fields have the same nutrient levels across the field, and variable rate application allows growers to vary their fertilizer rates and input costs across different areas of the field, which can lead to higher yields and more profitability. At UFC we have several options for grid sizes to fit your budget, as well as variable rate crop nutrient recommendations made possible by precision farming software. If you would like more information on reading a soil test, grid sampling, variable rate nutrient application, or any other precision ag need, please contact your local UFC agronomist.