Soil WHC from Seed to Yield – Part 1
At CropMetrics, we consistently inform growers how VRI can influence productivity by maximizing input efficiency. But many times, people only think of VRI as an irrigation or water input tool. However, water is the catalyst of every main crop input’s success throughout the entire season and ultimately drives yield more than any other single input or tool. Let’s take a look at an individual field example from seed (START) to yield (FINISH), and see how water influences the entire plant life cycle in Part 1 of this 3 Part Blog Series.
Part 1: Seeding (START)
Starting with the seed and planting, emergence is one of the most vital components of the crop growth cycle. It is well documented that even and consistent plant to plant emergence is the key to higher yields. Let’s take a look at how soil type, and more specifically the soil’s Water Holding Capacity (WHC) affects plant emergence and the beginning of our new crop season.
The image below is an EC map along with the SSURGO soil types zones overlaid (yellow lines). In the EC map, the darker blue colors represent heavier soil types, and the orange color represents lighter soil types. This is a great example of how inaccurate SSURGO soil type zones can be, and how much more variability there is in the field identified by the EC data layer. The EC layer correlates with WHC of the soil — blue colors indicate more WHC, and orange/yellow colors indicate less WHC. How valuable is EC data to begin with compared to simply relying on SSURGO data? Is our emergence and plant development affected by either data layer?
The next image below displays as-applied planting data (red shaded color) overlayed the EC map. However, the reason there is only partial as-applied data is because this isn’t ordinary planting data… this is REPLANT as-applied data. Pay close attention to how well the replanted areas align with the heavier EC soil types of the field. This happened naturally from the grower spot planting on the go as needed to fill in the gaps of poor emergence. This was not made by following any type of map.
The poor emerging areas of the field was a natural reaction to the WHC of the soil. Often in the early planting season growers have to battle the common spring rain events. When growers think they are challenged to “get in the field” due to wet conditions, the seeds in the ground are challenged even more, and the effects of these challenges result in less than ideal emergence. The variability in the soil WHC directly affects the level of this natural challenge, which is displayed in the image below.
If the seed cannot optimally grow when suffocated with excess moisture, then how is the plant responding the rest of the year? What if irrigation applications are applied at the same rate to each of the EC soil types above? How much can understanding the WHC variability of your fields pay to increase production levels?