Spring 2008

Spring is a great time to appreciate the diversity of agriculture in the Southeast region. Vegetable and citrus harvests are in full swing in Florida, potato planting is underway in North Carolina, and land is ready to plant 2 million acres of rice in AR, LA, MS, and MO. Over 5 million acres of winter wheat has been, or is being topdressed with N fertilizer, with sugarcane not far behind. Corn acreage is not expected to fall much from the approximately 10 million acres planted last year. However, cotton acreage may be lower than we’ve seen in the southeast since 1983. Strong wheat and soybean futures are pushing many growers out of cotton for another year. The greatest declines are expected in MS (31%), AR (30%), and TN (29). In the eastern part of the region, NC and SC are expected to reduce their cotton planting by 22 and 20%, respectively.

Many growers are still looking at nutrient inputs as a way to save money in 2008. Dr. Larry Oldham, Nutrient Management Specialist at Mississippi State, is responding by saying : I’m hearing people say they cannot afford fertilizer this year. The question is…can you afford not to fertilize?” His data show that while it is possible that the percentage yield decrease due to not applying soil test-recommended P and K may be minimal (8%), if fertilizer is not used when soil tests are in the low range yields can be as much as 25% lower. “At a 50 bushel per acre potential soybean yield, taking 12.5 bushels out of the picture, at $12 per bushel for soybeans, the cost of not applying is $150. Management needs to assess whether this is acceptable given their production system and variables in addition to fertilizer costs: soil-specific yield potential, irrigation, pest management, weather, variety yield potential, etc. Soils testing in the very low range require even more detailed decision processes.” Jason Kelley, Extension Wheat Agronomist in AR, echoes these sentiments saying, “I believe cutting back on fertilizer would be the wrong thing to do. With grain prices at these levels, it does not take much of a yield response to get your fertilizer money back”.

Even considering the economics, it is critical that growers continue to think about maximizing nutrient use efficiency to maintain profitability and minimize nutrient losses. Applying nutrients at the correct rates at the right time of the growing season are sure ways to improve efficiency.

Despite the declining acreage, grower interest in K fertility of cotton is very high heading into the 2008 growing season. This interest was evident at the recent Beltwide Cotton Conference, when a special session on K fertility was standing-room-only. The increased concern is likely because growers are reporting K deficiency showing up in fields where it had never been a problem before. For more information on K fertility in cotton, see article Number 5 in the Spring 2008 series of Plant Nutrition TODAY. A more detailed look at K nutrition, including the complexity of the K cycle, K in soil, uptake mechanisms, K role in plants, and plant response to K fertilizer is available in the slide set "Advanced Topics in K Nutrition".