Short Corn, Big Potential for Dairy Farmers

Can corn planting strategies reduce our reliance on herbicides?  That's the idea behind research led by Plant Science PhD student Noelle Connors, whose work focuses on sustainable weed management in dairy cropping systems. Many Pennsylvania dairy farmers grow corn in a double-cropping system, planting corn silage followed by a winter small grain silage each year. Keeping weeds in check across those systems is primarily achieved with herbicides. Connors is exploring how a new type of corn, paired with smart planting practices, can shoulder more of that work and rely less on herbicides. 

The key is a new generation of short-stature corn hybrids. For years, researchers knew that planting corn densely in narrow rows could shade out weeds by blocking the light they need to grow. The problem was that standard corn hybrids planted at high populations can lodge - that is, tip over, which cuts into yield. Short-stature hybrids are bred specifically to resist lodging, which finally makes dense, narrow-row planting a practical option. Connors' experiment compared these new short-stature hybrids against standard ones, combined with cultural management practices like high plant populations and narrow row spacing (comparing 15-inch rows to the standard 30-inch). 

To test the system, her team transplanted three troublesome weed species, burcucumber, common cocklebur, and Palmer amaranth, into the plots at different times to mimic the various points at which weeds might escape control during a season. They then measured how the different practices affected weed biomass and seed production, along with corn silage yield and quality. They also tracked how much light passed through the corn canopy, as well as soil moisture and temperature, to understand how the treatments changed conditions on the ground. 

The results were promising: High-population planting tended to improve silage yield in both years of the study, with only minor quality differences between the hybrids. When it came to weeds, the timing of weed emergence had the biggest effect: delayed emergence substantially reduced weed biomass and seed production. Among the planting strategies, narrow rows combined with high populations were the most effective at suppressing weeds and limiting their seed production. "This practice has the potential to reduce weed biomass and seed production by up to 99% depending on species, emergence timing, and environmental conditions," Connors said.  

This work reflects the philosophy of regenerative agriculture. Rather than relying on chemicals, it uses crop competition to manage weeds, and it's carried out in a no-till, double-cropping system that keeps living cover on the soil throughout the year. It's also a coupled animal-plant system, since dairy manure serves as the primary source of nitrogen for the corn. Together, those pieces reduce the field's dependence on outside inputs while supporting soil health. 

By identifying the best ways to manage these new short-stature hybrids, Connors' research offers a potential path to strong yields and better weed control in one package. Since weeds are suppressed by the corn itself rather than by herbicides, farmers stand to cut both their input costs and the environmental risks that come with chemical weed control: a win for the farm and the land alike.