Rains throughout June caused delays with Mississippi's soybean crop that ranged from planting to spraying. Although a large percentage of the crop is ahead of schedule, a portion did not grow off as most would have liked.
The earliest-planted beans look great. Plantings from early- to mid-April were much slower growing off. The lack of growth was due to many things, but the number one factor was below-average temperature.
The differences between flat plantings and bedded ground have stood out statewide. In some fields, rowed-up beans are twice as tall as flat-planting beans. I'm not saying that plant height is going to be a problem; I'm pointing out the effect of drainage and temperatures on growth.
No-till plantings also stand out. Over the last three years, I have observed many problems in no-till plantings. The problems have been due to soil grubs, snails, slugs, three-cornered alfalfa hoppers, compacted soils, cool soils, grasshoppers, and diseases.
Widespread slow emergence this year was due primarily to cool conditions. When a lot of vegetation was present or burndowns were delayed, we complicated the problem. We can eliminate these concerns, but we must start early.
New seed-applied insecticides on the horizon may offer some relief, but if you consistently have a problem, some form of tillage may be the best short-term option. Make a mental note of the areas and make plans to break the cycle.
Consider the facts. Most of the problems can be reduced with minimum tillage or early burndowns.
Most acreage is not consistently no-tilled, a lot is minimum tillage.Tillage once every three to five years to address a problem will not be a major issue. This could be no more then just rowing up one year out of four.
Many soils in Mississippi will respond to tillage. It may be nothing more than a shallow cultivation after a hard packing rain, but the crop can benefit nonetheless. In years past, many people believed certain weeds would cause problems, but the widespread use of transgenic crops has helped.
Everything we do has pros and cons. Nothing is perfect, but we have thrown the book at some problems, particularly slugs, and nothing has helped.
Growth problems also occurred on some of our better soils. Slow emergence followed by slow growth was evident (widespread) on many historically-cotton fields. These soils are lighter in texture and color and often are low in organic matter.
Beans are normally more vigorous than cotton, but some of the problems we have observed on young emerging beans explain why cotton has had problems in the past. Although crop rotation has increased and helped in Mississippi, there remains a big need for more rotation.
Nitrogen deficiencies observed on various crops this spring could be minimized by applying some preplant nitrogen — broadcast rather than knifed in. This is especially true when it is cool or wet or a combination of the two. Large amounts of crop stubble which tie up soil nitrogen can affect early growth.
Another problem has been the failure to inoculate soybeans with nitrogen-fixing bacteria. Even some growers who inoculated soybeans have had problems. Soybeans are a heavy user of nitrogen, requiring 4 to 5 pounds of actual nitrogen per bushel. Correct a deficit situation as soon as possible.
Peak demand for nitrogen begins at bloom. The hardest decision is how much to apply. If you follow the rule of thumb (4 to 5 pounds of actual nitrogen per bushel of grain), it might take 240 to 300 pounds of actual nitrogen to make a 60-bushel crop. Before deciding how much nitrogen to apply, determine the stage of the plant and the time that has elapsed since emergence.
Every year is different; treat every field individually.
Alan Blaine is the Mississippi Extension soybean specialist. e-mail: [email protected].