The significant correlation between organic matter, soil health, and crop growth deserves attention in many ways, including how no-till practices and the growing of cover crops can work hand in hand to provide those benefits.
That was the message from Julie Hager of the Natural Resource Conservation Service office in Brown County as farmers, representatives of farm equipment dealers and companies, crop consultants, and other interested persons gathered for a workshop program at the Wiese Brothers farm.
In addition to presentations on tillage and cover crops, many of the 110 attendees had a chance to upgrade their awareness and knowledge on crop planter maintenance and operating features on a late winter day when temperatures were well above those on at least some days when farmers will be planting in the coming weeks.
Marrying no-till and cover crops
Hager acknowledged that some farmers have had mixed results when trying no-tilling or growing cover crops. When done properly, and with the exercise of patience in continual years of no-till, there should be multiple benefits, she promised.
Seed placement both in a no-till setting and with the planting of cover crops is an important factor in determining the degree of success, Hager pointed out. While she described the soil health and conservation considerations, later presentations at the event focused on choosing the appropriate planting equipment and having it in proper working order.
Downsides of tillage
Hager suggested that the goals which many farmers hope to achieve by disking or deep ripping of soil can be obtained with the help of cover crops and with less of a downside, particularly the loss of soil and nutrients by erosion. One of the major downsides of tillage is how the available organic matter is exposed to oxygen, thereby leading to processes that cause it to dissipate, she said.
Tillage also disturbs the structural makeup of the traits of good soil, increasing the potential for erosion and compaction along with affecting earthworm populations, Hager continued. She pointed out that healthy soil will crumble, maintain itself in aggregates, and have a physical appearance resembling cottage cheese.
'Avoid the tillage trap' which reduces soil stability and makes it vulnerable to the vagaries of weather, Hager warned. She noted that the soil's aggregates and pores also increase its weight carrying capacity, thereby reducing the chances for compaction.
Mycorrhizae and other fungi that would otherwise nourish plant roots are also destroyed by tillage, Hager stated. 'Soil fuzz is plant root food.'
Organic matter benefits
Count on organic matter, obtained mainly from cover crop roots and biomass, to control swings in soil pH, improve water infiltration, reduce ponding and soil crusting, and to provide plant nutrients that would otherwise be supplied by synthetic fertilizers, Hager indicated. She said that manure alone does not provide the same benefits that a buildup of organic matter creates.
One very good sign of soil health is having it be dark, Hager noted. Even red clay soils can be darkened with a sufficient amount of organic matter, she stated.
Because of how important it is for the soil microbes and microorganisms that support plant growth, a carbon to nitrogen ratio of between 20 and 10 to 1 is another sign of good soil health, Hager observed. 'Microorganisms are the pinnacle of the system.'
Organic matter feeds the living elements in the soil, in large part by having plants convert sunlight into the sugars that are transferred to the soil, providing a boost to biological activity in the soil, Hager explained. That's why it's crucial to have plants growing in the soil for as much time as the weather allows, she said.
Hager showed a global video of the concentrations of carbon dioxide in the atmosphere — a color based depiction which shows how the levels fall dramatically during the growing season in specific regions and even shows spikes where there are widespread fires on the Earth's surface.
Capabilities of good soil
In an ideal situation, 60 percent of the soil pores will be filled with water, Hager stated. The proportion of those pores in the soil mass is greatly affected by the percentage of organic matter.
Every 1 percent increase in soil organic matter will boost that water storage capacity by up to 20,000 gallons per acre, providing a better reserve for plant growth, Hager observed. That 1 percent will also accommodate 1,000 more pounds of nitrogen per acre — 30 pounds of which would be available to plants, she added. 'Take advantage of that opportunity.'
Cover crop traits
Hager believes that many farmers are not aware that the roots of many cover crops go deeper than disk rippers typically do and would provide multiple benefits for soil structure and health along with generating crop nutrients.
'So what's the value of plowing?' Hager asked. She also pointed out that plant roots exude a carbonic acid that addresses soil compaction.
Cover crops represent another rotation, which is a practice that typically results in higher yields for the following crop. The best choice for a cover crop rotation is to have multiple species in the stand, she advised.
When establishing a cover crop, plant it as soon as possible after the removal of the previous crop, Hager stressed. If that happens to be winter wheat or some other early harvested crop, include as many species as possible in order to produce the maximum amount of biomass and root growth that the remainder of the growing season will allow.
Hager suggested at least three species and up to as many as nine. Within that group, include at least a few species that will survive the winter and begin growing in March or April of the following year before being terminated or harvested.
As an example, Hager recounted a visit to a 1,000-cow Pennsylvania dairy farm that grows triticale as a winter cover crop, chops it as a high quality forage in the spring, no-tills corn into the stubble and then applies 9,000 gallons of liquid manure per acre (the equivalent of a quarter inch or rain). She warned that an application of as much as 14,000 gallons would be detrimental to the very beneficial soil microbes.