Developing Sustainable Roller Crimped Cover Cropping Systems for Corn and Soybean Production: Effects on Cover Crop Winter Hardiness, Biomass, N Mobilization, Weed Suppression and Yields

Problem

Many common annual and perennial weeds have developed a resistance to synthetic herbicides, particularly glyphosate, and the main ingredient in Roundup®. A common response to this dilemma among conventional and organic farmers is to increase tillage and/or apply different herbicides.

The problem with increased tillage is that it increases erosion, negatively affects soil structure, reduces water infiltration, increases compaction, reduces soil microbial diversity and is energy intensive. In addition, tillage stimulates weed seed germination and encourages the use of herbicides that could lead to herbicide resistant weeds. During the growing season farmers cultivate to eliminate weeds but in-row weeds remain that often compete aggressively with cash crop growth.

Cover crops, especially cereal rye, have been widely used and recommended for corn and soybean systems but there are concerns of N tie up and potential allelopathy to the cash crop. Cereal rye is often not ready to terminate mechanically within the optimum soybean planting window. Growing Degree Units (GDU's) are reduced when this occurs. As a result, weed pressure increases and soybean yields are often reduced.

We want to test a system that might overcome this obstacle. Leguminous cover crops, such as hairy vetch, have been recommended in corn systems to fix atmospheric N and thus reduce synthetic N inputs but its inconsistent winter hardiness is a challenge.

There is no one panacea or approach to manage weeds, add N, build soil, and/or improve crop productivity. However, there is need to develop innovative, practical, and environmentally friendly practices that can serve both conventional and organically managed production systems. Staying in line with sustainability, there is an urgent call for the development of weed control and nutrient cycling systems that are effective in reducing our carbon footprint, whether electing to farm organic no-till or conventionally.

Solution

Three main components to our proposed solution: (a) cover crops, (b) mechanical termination and (c) reduction of fertilizer needs.

We want to plant soybeans and corn into a standing or roller crimped stand of cereal rye or hairy vetch/ oats mix to determine if the cover crop(s), along with the use of an organic bio-soil enhancer, can (a) help outcompete weeds, (b) produce a healthier plant overall, (c) reduce N-input, (d) improve soil properties, and (e) increase crop yields. No other North Central SARE projects have explored this possibility.

Experiment 1: Cover crops, tillage, roller crimper and organic bio-soil enhancer

The entire field at George Naylor’s farm has already been seeded into cereal rye. This experiment will be a split plot randomized complete block design with tillage (conventional or no-till) as the whole plot factor and an organic bio-soil enhancer (Sumagrow®) application (presence or absence) as the split plot. The entire field will be roller crimped and one-half will be tilled prior to planting.

Experiment 2: Cover crops, no-till, roller crimper, and organic bio-soil enhancer

The entire field at Billy Sammons’s farm has already been seeded into cereal rye. This experiment will be a randomized complete block design and test the organic bio-soil enhancer, (Sumagrow®), in stimulating soil biology and releasing soil nutrients for crop growth. The entire field will be roller crimped either just before planting or within 7 days of planting. Hairy vetch/oats will be the cover crop in year two on each farm.

Evaluation

Physical and biochemical diagnostic quantifiers will assess soil health changes on each respective field. We will also keep records of rye N mobilization, weed and pest suppression, biomass, root nodules, plant height, tap root depth and cash crop yields to measure/compare the effects of tillage and bio-soil enhancer application.