Why do my yields vary across the field? The yield across a field will vary due to numerous factors – some cannot be controlled, others can be managed.

A key factor in field variability is water holding capacity. This is the soil’s ability to hold water. The more water it can hold, the more resilient the crop will be during dry conditions. Some soils will hold high amounts of water for long periods of time, causing crop stress from too much water. This will usually be in different areas within the field. Identifying these areas in your field is your first step to managing your field for greater productivity.

Does soil type cause this variability? The characteristics of the soil, such as soil depth to underlying rocks or shale, or the depth to clay soil, are the cause for yield variability. The soil type itself has only a small impact on the production differences within the field. This is revealed very well by yield data since the yield differences rarely show up on soil type changes. But yield differences standout when there is a change in the deeper soil profile. Therefore, soil type itself does not make up the variability.

Can I ever get my field to produce evenly? The answer is “Likely not”. When production is higher, more nutrients are used by the crop. If you do not replace those nutrients, crops will have fewer resources to produce more yield. Also, if crop production was below average, less nutrients were removed and therefore do not need to be replaced but can be used somewhere else where return is greater, making you more profitable. This is the reason Ag Essentials recommends grid soil sampling. Your crop yield average will go up when the deficient field areas are found and corrected.

Another advancement in managing field variability is developing zones across your farm. This will allow you greater ability to adjust inputs so that you can achieve the greatest economic advantage. For this method to be successful, it requires greater knowledge and documentation of the variability of your farm.

Your ability to manage your field and farm’s crop production variability will be the key to your success, now and in the years to come!

Lynford Kurtz    August 2015