Boosting Yields
Effective Use of Soil Tests and Herbicides
As for applying phosphorus and potassium, Casteel relies on soil tests to understand the fertility level. Wasting soil amendments where they’ re not needed results in a loss of time and money and also contributes to compaction with having to do another pass over the field.
Farmers should be cautious to avoid unnecessary applications of herbicides.
“ The real key to look at is what herbicide and which weeds are we going after,” Johnson said.
“ Look at the weed emergence sequence. [ For instance ] lambsquarters, foxtail and giant ragweed emerge early, like [ in ] April. I’ ve seen giant ragweed as early as spring break when we’ ve had a mild winter. Morning glory, crab grass and those types don’ t come up until early to mid-June and are a big head [ while ] palmer amaranth and waterhemp come up in between.”
By carefully scouting and observing what weeds are problematic, farmers can time herbicide spraying right after the weed has germinated, which is generally when the plant is most vulnerable.
“ I like to put it in within a week of planting time,” Johnson said, but added that farmers should review the label for the right application time.
Tillage can be used for weed control, but Johnson cautioned farmers to consider if the“ gains in efficiency warrant the results. Think about that trade-off,” he said.
Cover Crops and Pest Control
Cover crops can also help reduce weeds and the competition they bring to the crop. Johnson believes that 2,500 pounds of biomass per acre is the minimum threshold for weed suppression. That’ s about 8,000 pounds maximum at planting.
“ Once you’ re at 8,000 pounds, you start having issues with how well you can place seed and the planting equipment,” he said.“ For most of us in the Eastern Corn Belt, covers play
very well with residual herbicides. If we can get the residual herbicide applied to the cover crop biomass, we’ ll eventually get that washed down into the soil.”
Casteel said that insecticide seed treatments haven’ t been proven to affect his harvest much.
“ If yours are the first beans up, there will be a little feeding but nothing having to warrant an insurance seed treatment,” he said.
As for rodent control, working with an entomologist can help farmers know what kinds of pest pressures they can anticipate for the season. Johnson encourages farmers working with herbicides to pay attention to mixing directions for the highest efficacy.
“ Some herbicides work better with oil; some with non-ionic surfactant,” he said.
Products with certification by the Council of Producers & Distributors of Agrotechnology means that the product has been certified to contain the ingredients on the label and that their performance is useful. With products that are not certified,“ you may not get the right bang for your buck,” Johnson said.
He also looks at calculating the amount of spray necessary based upon the hardness of the water.
“ Ammonium sulfate ties up the hard water cations,” Johnson explained.“ It keeps them from sticking to the herbicide in the tank. The ammonium binds to the herbicide molecule and makes it more oil soluble so that it will more easily diffuse into the plant cuticle.”
He calls corn the“ diva crop” as it can be fussy about temperature and other field conditions. Excess moisture and the resulting fungus often require farmers to look at fungicides. But Johnson warned that as with herbicides, it pays to know the properties of the water the farmer adds to the tank.
“ Scour the labels of fungicides to see if there are warnings about pH,” he said.“ If there was, I’ d get swimming pool test kits and do a jar test at the right ratios. If it’ s in a danger range, there are pH buffers you can buy to keep it in the right range.”
February 2025 | www. FarmersHotLine. com | 17