Rice: Optimum Seeding Rates Best For Max Yield Potential
Reducing input costs is a priority in this tough farm economy. There is a fine line, however, between cutting costs and spending dollars where they have the greatest chance of return. For example, starting with a clean field and keeping it clean through flooding is money well spent.
However, continuing to try to salvage a field post-flood often costs more than the cost of applications will return. Another input producers may be tempted to eliminate this year is insecticide and fungicide seed treatment. It’s been proven time and time again that starting with a healthy plant increases your potential yield and can minimize other input costs between planting and flooding.
Seeding rate reduction is something that will most likely be considered by many. Even though the newer varieties are more vigorous and can better compensate spatially than the older varieties, there is still an optimum plant population at which if you are below, can cost more in yield reduction than you saved in seed cost.
So what is too much? A good rule of thumb is to target for a stand of about 15 to 20 plants per square foot. Typically, a drilled seeding rate of 25 to 30 seeds per square foot will result in a final plant population of 15 to 20 plants per square foot. Of course, numerous soil and environmental factors can impact final plant stand. In poorly prepared seed beds and fields with salt issues and/or pH issues, the seeding rate will need to be increased to compensate for plant loss due to poor seed to soil contact, or salt injury, or the lack of tillering often seen in higher pH soils.
Many times, instead of seed per square foot, people talk about pounds of seed per acre. This is fine, but it is important to remember that seed sizes vary between varieties. For example, CL151 has approximately 19,600 seeds per pound and CL111 has closer to 18,000 seeds per pound.
This means at a seeding rate of 65 pounds seed per acre, CL111 will have 27 seeds per square foot, whereas CL151 would have 29 seeds per square foot. The final plant population for both of these seeding rates should be optimal. However, when you try to cut the seeding rate to 50 pounds per acre, the difference in two seeds per square foot can mean the difference in an optimal stand versus a below optimal stand.
The graph below shows a Horizon Ag seeding rate study with CL111 and CL151. Yield can really be impacted below the 60 pound per acre seeding rate for CL111, whereas the CL151 yield loss is impacted below 55 pound per acre seeding rate Just remember, seeding below recommended seeding rates can reduce your overall yield potential before you even begin the season. Start with a clean seed bed and with the proper amount of seed to maximize your yield potential.
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