The Delta soybean scene

BY LARRY G. HEATHERLY AND ALAN BLAINE

The August 1 Ag Report published by the Mississippi Agriculture Statistics Service projected average soybean yield at 27 bu/acre for Mississippi. This is higher then the average of the 1970's and 1980's, but 4 bu/acre lower than 1997 production in the state. Harvest of early planted, early-maturing soybean varieties started in mid-August in the Delta, and should be complete by now. Producer reports of dryland yields form the early harvests have ranged from the mid-teens (no significant rain since early June) to the low forties (rain in July). Yields form early soybean production system research at Stoneville ranged form the mid-20's (non irrigated, non-subsoiled) to the mid-30's (non irrigated, subsoiled) to the mid-60's (irrigated). Weather in 1998 was extremely variable, and we experienced August-type weather form late May on. This took its toll on the early planting, but probably will have a much greater effect on later-planted, later-maturing varieties that are just now beginning to be harvested.
Fields of dryland soybean with green plants having green pods, along with mature plants that had pods that were shattering, were prevalent in August and early September. Green plants with green leaves and immature green beans were those that had more available moisture within their individual microclimate. They out-competed neighboring plants for the limited soil water that was still available. Shattering pods on mature plants resulted form extremely high temperatures that dried pods prematurely to an extremely low moisture content. It was obvious that the green plants with "butterbeans" had a much higher yield potential then did the plants that dried prematurely and had under-developed seed. This variable maturity within a field resulted in harvest having to be done under less than ideal conditions, resulting in grain being contaminated with "Butterbeans", green stem pieces, and unshelled green pods with beans inside.
Although 1998 will be remembered for some time, there were a few production inputs that stood out dramatically. 1) Improved varieties have allowed for higher yields in high-stress years such as 1998. To verify this, just compare the projected 1998 average of 27 bu/acre to the 16 bu/acre Mississippi average yield of 1980. 2) Earlier planting has changed the way we think about soybean production. Even though the state average yield for 1998 may be lower than that of 1997, the yield is still higher than the low 20's average of the 70's and 80's. 3) Deep[ tillage resulted in some impressive yield responses in 1998. This is not a practice that can be performed every year on every acre, but it is one that will provide results as close as possible to irrigation without irrigating. 4) Seed treatments ensured excellent stands in 1998 early-season plantings. This input has drastically reduced the need to replant in these plantings, and this is a must if the system is to be used consistently.
Now is the time to start selecting soybean varieties for next year's planting. producers should have a good handle on how 1998's plantings did, and should use this as a guide for selecting varieties for 1999. Also, visits to variety trials and field days throughout the Delta should have left an impression on how available varieties stacked up against each other. For early bookings, this is all here is to go on since most 1998 variety trial information will not be available until November/December. In order to ensure that preferred varieties are obtained, it may be best to use 1997 variety trial information to select varieties for 1999 plantings instead of waiting for all available information form 1998 trials to make selections, and then having to book seed in early 1999 when supplies may be booked to depletion. Rest assured that there is nothing wrong with sticking with a variety that has continually performed well. Very few new varieties hit the market in any one year, and even if they do, yield information will be extremely limited. Under no circumstances should a sizable acreage be planted to a new variety based on only one year's data.
Early bookings of 1999 planting seed are a must to ensure actually getting the needed quantity of chosen varieties. Some companies are guaranteeing delivery of certain varieties that are booked early. Also, some companies promising penalty payments if orders are not delivered as promised. Producers should check with their seed supplier to determine which companies have these programs in place, but they should not let such offers unduly influence variety selections. To ensure that your seed needs are met, work closely with your dealer, book early, and let them know your needs. The over-bookings last year probably will result in a new way of doing business form now on, so the need for mutual trust and cooperation will be greater than ever.
Wheat planting on doublecropped acreage will begin during the next 2 to 3 weeks. Less than 150,000 wheat acres were harvested in Mississippi in 1998. Average yearly wheat yields in Mississippi have been erratic (18 to 49 bu/acre) over the last 10 years, and this, coupled with projected low prices, may result in even less acreage being planted in 1998. The low-lying, poorly drained clay soils of the Delta where wheat is likely to be planted following soybeans are subject to prolonged saturation during the fall and winter growing seasons, and this can be detrimental for wheat. The low yield potential of late-planted soybean following wheat compared to the higher yield potential of early-planted, monocropped soybean, plus the need to irrigated doublecropped soybean in order to achieve acceptable yields, are all factors to consider when deciding whether to double crop wheat and soybean.

Larry g. Heatherly is a USDA research agronomist at Stoneville, MS. Alan Blaine is an Extension Agronomist at Mississippi State University.

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Site last updated January 10, 1999.