Larry Heatherly at the USDA Agricultural Research Service in Stoneville, Miss., is tweaking the early soybean production system research he has been doing for years. While he is still interested in getting soybean plants up and growing before the hot summer sun begins baking the Delta landscape, he's now taking his drought-avoidance system one step further by testing a new “ultra-early” soybean production system.
In this his first year of his ultra-early study, Heatherly planted maturity Group 0 (MG0) soybean varieties alongside his maturity Group 4 plots, using March 23 and April 20 as planting dates. “Ultra-early planting of ultra-early soybean varieties may offer additional opportunity to shorten the growing season and avoid drought,” he says.
According to Heatherly, his early soybean-production system involves planting early-maturing varieties in late March and early April, avoiding much of the drought stress that normally occurs during critical developmental stages. By planting the shorter-maturity soybean varieties earlier, the varieties should reach bloom to pod-fill when soil moisture is relatively more plentiful and showers are common, permitting good yields without irrigation.
The March-planted Group 0 soybeans in his 2001 field plots reached bloom in late April and began pod set May 21, while his April-planted varieties reached bloom in mid-May and began pod set June 6. In comparison, the Group 4 varieties, planted on the same dates, reached bloom more than one week later and began pod set a full three to four weeks after the Group 0 soybean varieties reached the same developmental milestone.
Both the Group 4 and the Group 0 varieties were planted on 20-inch rows using a seeding rate of 45 to 50 pounds of treated seed per acre. The Group 0 varieties took between 91 and 98 days to reach maturity and were harvested beginning June 29. Yields for the ultra-early varieties ranged from 28 bushels per acre dryland to 56 bushels per acre on irrigated ground.
Heatherly reports excellent seed quality with the Group 0 soybeans he tested and says the lack of canopy associated with these ultra-early soybeans doesn't appear to result in a weed infestation problem due to the very short season and early harvest.
“The Group 0 soybeans are definitely too short season, but what we need to do is gravitate up from there. We need a 110- to 120-day maturity soybean that's somewhere between a Group 0 and a Group 4,” Heatherly says. “We're still focusing on drought avoidance. We're going to do that by continuing to plant early and by planting earlier-maturing varieties.”
“If you take all costs into account at today's soybean prices, or at the $5.35 per bushel loan rate, it will take 37 non-irrigated bushels and 51 irrigated bushels to break even,” he says. “That seems hopeless, but our production costs using the ultra-early-planted Group 0 system were the lowest I've seen in all of the years I've been in the research business. Costs were well below $100 per acre from planting to harvest.
Heatherly adds, “In an ultra-early production system planting ultra-early soybeans, a 28-bushel yield coupled with the lower cost per acre is probably close to break even. This lets us know that we can produce a respectable dryland yield with very short-season varieties.”