Optimizing returns on every dollar spent on fertilizer and crop nutrition holds the key to profitable crop production. Ask The Agronomist, brought to you by eKonomics, provides crucial nutrient management answers as you prepare for the 2021 growing season.
Q: What is the biggest fertility challenge cotton growers face when aiming for higher yields and quality?
Mike Howell: Nitrogen management is critical for optimum vegetative growth and boll set. Growers who follow proper soil pH, timely soil and tissue testing, and fertilize to meet the crop's timely needs can increase yields and cotton quality. And with good cotton prices in 2021, this isn't the year to be cutting costs.
Q: Given nitrogen's importance, how can growers maintain balanced growth to reduce deficiencies?
Howell: Since most cotton is grown in sandy soil conditions, managing nitrogen is critical and always a challenge due to the potential for leaching, runoff or volatilization. Make sure you're getting nitrogen out when it needs to be there, which is why split applications work best in most scenarios. Side-dressing two to three weeks after first square should deliver adequate nitrogen needed during the reproductive phase. If you're not able to split apply, make sure to protect nitrogen with a stabilizer coating or use our ESN product.
We've seen over the past few years that many growers are putting out too much nitrogen. When the nitrogen rate gets too high, the plants tend to become more vegetative rather than setting fruits. And it can also impact fiber quality.
Q: How necessary is in-season testing to determine nutrient deficiencies?
Howell: Along with soil testing at least every two years, scouting for signs of deficiency and tissue sampling prior to first bloom is essential. You'll understand what's in the plant and what nutrients may be missing at that time. Then you have a chance to correct deficiencies before cotton reaches the bloom period when nutrient demand is critical.
Q: What other nutrients and micronutrients are critical to optimizing cotton production?
Howell: Phosphorus is usually added in small amounts to maintain proper soil level. We see more issues with a lack of potassium in the plant, such as more disease symptoms. Newer high-yielding varieties that tend to set fruit much faster won't set as many bolls if potassium is deficient.
While needed in minute quantities, micronutrients are very important and should be applied according to the soil report. We're seeing more deficiencies across the Southeast in recent years as micronutrients are getting left out of the fertilizer blend. All micronutrients are essential, so it's important to understand their role in cotton and add them as appropriate based on your soil test.
Q: Why is liming soil so essential to cotton production?
Howell: Soil pH is highly critical for cotton production because your entire fertility program will not be successful if your pH is below 6.0 or above 6.5. Within that range is where nutrients will be most available to the plants. So, pH is probably the most important factor to look at on your soil test.
Q: What Nutrien fertility products are helping cotton production?
Howell: To protect nitrogen investment against loss, growers have success with ESN. It provides a more extensive application window to add convenience. Plus, you don't have to worry about rain to get nitrogen in the soil. It allows for spoon-feeding of nitrogen over several months so that the cotton plant can maintain a balance between vegetative and fruiting growth.
Some of our Rainbow products are also good for cotton. They have micronutrients in a homogeneous granule to ensure good distribution in the field. That helps guarantee that they are all available for every plant to consume.
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