Several questions are coming in about variety selection as we move later in the planting window. Last year, some of our best rice was planted the last few days of April and the first week of May, especially in North Arkansas and Missouri. However, based on long term data, we are getting in the window where there is greater probability for yield potential to be 85 to 90% of the optimum planting window (March 20 to April 20).
 
CL163 did show tremendous promise last year as it was more stable than other Clearfield® varieties when subjected to the extreme July heat during the late reproductive growth stage. In large scale trials and seed production fields, this variety routinely dried 165-plus bushels per acre when planted in the late April-May planting window. During its development, heat tolerance selection pressure was placed on CL163 during the extremely hot summers of 2010 and 2011. It stands to reason that CL163 has the genetic potential to provide stable yield performance during hot temperatures.
 
Based on the Horizon Ag regional crop reports below, a lot of the upper Mid-South rice is in the early seedling stage. If pH is high and soil test P is low, the odds are in your favor to obtain a modest yield increase from phosphorus (P) fertilization. Research has demonstrated that P fertilizer applied from just prior to planting until preflood results in the greatest yield response. For years, many growers have used ammonium sulfate (AMS) as an early season N application. Very little N is absorbed by the plant until the 4 to 5 leaf stage. At this point of growth, N uptake starts in an exponential fashion. Therefore, if rice is flooded at 4 to 5 leaf, seldom will growers realize a yield response to the early-season ammonium sulfate application. However, if conditions persist that make it impossible to fertilize and flood rice at 4 to 5 leaf, and rice is not flooded until after tillering starts, the early season N application becomes more beneficial.
 
Diammonium phosphate (DAP) has almost the same concentration of N as ammonium sulfate. Therefore on soils where P is greatly limiting yield potential, consider using DAP alone early in the season to provide P and early season N. If P is moderately limiting, consider blending ammonium sulfate and DAP equally with the total product rate equaling 100 pounds per acre. If sulfur (S) is limiting, ammonium sulfate can always be blended with preflood and/or midseason urea to supply the same amount of S as the typical application of ammonium sulfate would provide early in the season.

Positive Early Growth Habits

The Horizon Ag variety trials are emerged and growing fast. With a new slate of varieties coming along, I’ve spent a great deal of time evaluating their early-season growth habits. In our strip trials, CL163 has separated itself among the Clearfield varieties in terms of vigor. We’ve touted this variety as one that works extremely well on heavy clay soil, and its vigor is a contributing factor as aggressive germination, emergence and growth are real assets on the tougher soils.
 
Though CL151 has proven itself to perform very well through the years, it has average vigor and most often benefits from a gibberellic acid (GA3) seed treatment. CL172 behaves similar to CL151. We continue to believe this variety will perform very well, but it will also benefit from a GA3 seed treatment. One promising feature I observed with CL172 is as soon as the leaves were out of the ground it grew very aggressively and tended to outrun some of the other varieties. CL153 thus far has performed similarly to CL163 in that it germinated and emerged fairly quickly in comparison to the other varieties.