Multi-purpose living mulch improves soil health and farmer’s bottom line
Who doesn’t like a two-for-one deal, or a double-double, win-win? A team of USDA scientists in the upper Midwest is working on a double-cropping system that is showing promise as a way to improve a farmer’s profit margin by growing cattle feed between rows of a cash crop, in this case corn or soybean.
In the off-season, the second crop acts as a living mulch that prevents soil erosion and improves soil health.
For good measure, the second crop—kura clover—improves the soil’s ability to absorb rainfall by as much as 10 times over conventionally planted fields. This is important because excess water is one of the primary causes of yield loss in the Corn Belt. And, being a perennial crop, kura clover saves farmers money because it doesn’t need to be reseeded every year, unlike annual cover crops.
“Living mulch is a companion crop system that provides the benefits of a mulch in annual row crop systems through the use of a low-growing perennial ground cover,” said John Baker, soil scientist and research leader at the Agricultural Research Service Soil and Water Management Research Unit in St. Paul, Minnesota. “We use kura clover, which lives for many years without requiring replanting, and we can plant corn and soybeans into it.”
According to Baker, cover crops protect against soil erosion and loss of nutrients, improve the infiltration of water, and help insulate surface soil temperatures. Below ground, cover crops improve soil structure, help assimilate excess nitrogen, and sometimes store carbon. Legume cover crops can also provide nitrogen for the subsequent crop, reducing fertilizer use. Kura clover provides all those benefits.
The kura/corn living mulch system offers flexibility to dairy farmers, Baker said, because in any given year it can be managed either for corn silage or for hay. Silage is green fodder that is compacted and stored in airtight conditions without first being dried, and later used as animal feed in the winter. If the corn is managed for grain rather than silage, yields are typically somewhat lower than conventionally managed fields, but the corn stover can be sustainably harvested and provide an additional income source for farmers. Stover is what’s left of the corn plant after the crop has been harvested—leaves, stalks, and cobs.
“This is an ideal system for silage production,” he said. “There are two major environmental drawbacks to typical silage or stover harvest systems: They leave the soil bare and unprotected after harvest, and they can lead to long-term decrease in soil organic matter because none of the aboveground portion of the corn plant is returned to the soil. The living mulch protects the soil surface and provides carbon to maintain organic matter.”
The primary challenge to using kura clover as a cover crop is that seeds are sometimes difficult to find, and farmers must exercise some patience as it grows.
“It’s a bit of a tortoise-and-hare story,” Baker said. “Kura clover puts much of its initial resources into roots and rhizomes (root systems that grow horizontal roots and shoots at various intervals), so initially it will look like the weeds have the upper hand. However, each time it’s mowed, the kura comes back stronger and, eventually, the grower is rewarded with a healthy, vigorous cover crop that can last for decades.”