Corn Production in a Living Mulch to Conserve Soil and Reduce Fertilizer Inputs in the Northern Corn Belt

View the project final report

Commodities

• Agronomic: corn, hay

Practices

• Animal Production: feed/forage
• Crop Production: cover crops, double cropping, intercropping, multiple cropping, no-till
• Education and Training: demonstration, farmer to farmer, workshop
• Production Systems: general crop production

A system for producing corn in a living mulch of kura clover has been developed and tested in Wisconsin. We determined that grain or silage yields were not increased by addition of N fertilizer to corn growing in kura clover living mulch that had been suppressed by herbicides. Zone tillage was an effective substitute for herbicidal killing of kura clover in the corn row, but mechanical suppression (mowing) of kura clover in the inter-row area resulted in yield loss compared to inter-row clover suppression with herbicides. Corn grown in a zone tilled kura clover field, with inter-row clover suppressed by glyphosate, and no N fertilizer, produced similar grain and silage yields as conventional corn production.

Introduction:

Alfalfa-corn rotations occupy approximately 6 million acres of Wisconsin cropland (Wisconsin Dep. of Agriculture, Trade, and Consumer Protection, 1997). This rotation evolved as a means to meet feed requirements of livestock, as a cheap way to meet N requirements for corn production, and as a means to conserve soil on hilly landscapes. Conservation tillage systems (i.e., where residue provides at least 30% ground cover) in these rotations lower the risk for soil erosion, particularly during crop establishment (Wollenhaupt et al., 1995); yet, as recently as 1995, only 14.5% of Wisconsin’s 4 million acres of forages were established using such systems (Conservation Technology Information Center, 1995). Tillage incorporates beneficial crop residue and exposes soil aggregates to direct impact from rainfall. Crop residue and living plants reduce soil erosion in the rotation by intercepting rainfall and limiting sediment detachment, surface sealing, and sediment transport in runoff (Gallagher et al., 1996; Wollenhaupt et al., 1995; Zemenchik et al., 1996). Zemenchik et al. (1997) illustrated that once alfalfa is established, the risk for soil erosion is much less than at any other time during the rotation. Extending the soil-conserving characteristics of established perennial forages throughout a crop rotation with corn would greatly improve soil conservation.

Living mulches are plants intercropped with a cash crop that can decrease erosion (Wall et al., 1991), suppress weeds (Enache and Ilnicki, 1990), reduce insect pests (Litsinger and Moody, 1976), and in the case of legumes, supply N (Scott et al., 1987). Corn yields in such systems can by equal to or greater than those in conventional corn production systems in regions where seasonal precipitation in typically high and uniformly distributed, such as in the north central USA (Zemenchik et al. 2000; Affeldt et al. 2004).

Kura clover is a long-lived, perennial, rhizomatous legume (Bryant, 1974) that tolerates frequent defoliation in monoculture (Peterson et al., 1994) or in binary mixture with grass (Kim, 1996) and is suitable for hay or pasture production in the north central region of the USA (Sheaffer et al., 1992). Kura clover is adapted to long, cold winters (Sheaffer and Marten, 1991) and has persisted for greater that 20 years.

Characteristics of kura clover made it an outstanding candidate for evaluation as a living mulch for corn production. Based on earlier research in our laboratory, we concluded that corn can be produced in this type of system if kura clover is adequately suppressed with herbicides, but yields were not consistent (Zemenchik et al. 2000). While kura clover recoveres from suppression, cool temperatures after sowing can delay corn development, resulting in reduced corn stands and yield. That research demonstrated that for the kura clover living mulch to be consistently useful for corn production, there needs to be a combination of killing or severely disrupting kura clover in the corn row, suppression of kura in the inter-row area, and ability to control both recovering kura and germinating annual weeds 30 to 40 days after sowing.

Our current research incorporates a band kill plus broadcast suppression of kura clover and has employed herbicide resistant corn technology to provide flexibility in control of both kura clover and annual or perennial weeds after corn emergence. Affeldt et al. (2004) reported that broadcast suppression of kura clover with a low rate of Round-up, band killing an 8-inch strip over the corn row just after planting, and use of either Round-up Ready or Liberty Link corn hybrids with partner herbicides applied 30 days after sowing provided consistent results over four environments. Recovery of kura clover after 1999 corn production at Arlington, measured in spring 2000, was about 80% of control plots in mid-May and 100% of control plots in mid-June.

The kura clover living mulch system for corn production is ready to be tested at the on-farm level. Quantification of N credits will give farmers information necessary for making a decision about the utility of learning how to grow corn in a living mulch and changing their production practices. Although the kura clover living mulch system utilizes minimal and relatively environmentally safe herbicides, we think it necessary to explore options to substitute some or all herbicide with mechanical suppression of kura. Furthermore, zone-tillage has been shown to provide earlier soil warming and improved yield compared to strict no-till corn production (Cox et al., 1990). Our project aimed to address these issues.

1. To determine if mechanical suppression can replace herbicide suppression of kura clover in the corn row and inter-row area.

   To determine the N fertilizer replacement value of kura clover living mulch.

   To determine and overcome limitations to farm-scale use of the kura clover living mulch system.