The author is a senior agricultural consultant at the Noble Research Institute, Ardmore, Okla.
In the fall, many southern growers implement a cover crop plan – perhaps by sowing small grains, winter peas, vetch, or clovers in their seasonal dormant perennial grass pastures. hot. These wheat pastures this winter can plan for a subsequent summer cover crop of sorghum, cowpea, Sunni hemp, sunflower, or other warm-season plants after harvest or grazing.
At the Noble Research Institute, we see cover crops as a versatile tool to consider as we strive to improve this land’s overall ecosystem, which is more than just soil. It is a living system of communities that work together through four interconnected and natural ecosystem processes. These are the energy cycle, the water cycle, the nutrient cycle and community dynamics. Let’s look at how cover crops can benefit each of the four.
Capturing the sun’s energy
The energy cycle is the process by which plants use energy from the sun to turn carbon dioxide into food for themselves and into soil microbes, which in turn become fodder for grazing animals and ultimately protein. for humans.
Cover crops give us the ability to capture additional solar energy for much of the year. We can also improve solar energy capture by having different leaf shapes, leaf types and architectures: long leaves, short leaves, tall plants, and short plants. Various types of plants develop a denser canopy to collect solar energy for the plant, the soil microbial community, and our grazing animals.
Improved soil properties
Water circulates in the soil ecosystem through evaporation, precipitation, infiltration and transpiration. Just as cover crops add a variety of aerial architecture options, they also provide different beneficial architectures underground, such as deeper, potentially anti-compaction roots that help open up the soil.
And because they attract soil life like earthworms, bacteria, and fungi, the roots of cover crops help form good soil aggregates, which are tufts of individual soil particles stuck together that create spaces. porous to allow water to seep through the soil and seep.
Cover crops also contribute to the water cycle by reducing the impact of raindrops. Rather than having bare soil exposed to the potential for water and wind erosion as well as excessive evaporation, it is protected either by the growing cover crop or by residue from a previous cover crop. More water soaks into the soil and less runoff or evaporates, making the land more resistant to future drought.
In Oklahoma, where wheat is a common forage for winter pastures, using a summer cover crop to protect what might normally be bare soil is a good insulation strategy. Rather than letting the sun “cook” the field water, plant a cover crop, let it grow large enough to cover the soil, then finish the cover crop and use its residue to protect the soil. Dead plants do not use water, the soil surface is covered, and water is not lost through evaporation.
Keep the nutrient cycle
The nutrient cycle is basically the transfer of nutrients between living organisms and non-living materials, with bacteria, fungi and other microscopic life in the soil playing an important role in recycling nutrients from the air. and water so that they are accessible to forage crops and animals that eat. them.
Again, the diversity of roots and root architectures that come from a mixed cover crop can extract nutrients from different layers of soil that our main forage crop does not normally reach. Plus, all plants take in energy, use photosynthesis to create sugar, and then release sugar from their roots. This sugar leak attracts microbes from the soil – bacteria, fungi, protozoa, and actinomycetes – and feeds them. In turn, microbes provide plants with nitrogen, phosphorus, potassium and all secondary nutrients.
Cover crops are a way to feed these soil microbes and benefit the nutrient cycle. Another way to help the cycle is to graze cover crops and recycle nutrients in the soil as manure.
Diversity drives the community
Community dynamics are the changes in the structure and composition of the ecosystem community over time, including changes in microbiology, plant and animal life. A great diversity of plants and functional groups will improve community dynamics. Adding cover crops to monoculture pastures improves plant diversity and ultimately community dynamics. A simplified way of thinking of this is like a city (community) that only has accountants versus one that has accountants, bakers, carpenters, doctors, electricians, firefighters, graphic designers, etc.
Another example of using cover crops with forage production is to combine them with corn grown for silage. Harvesting silage can leave the soil bare with no protective residue. Two effective ways to protect the soil and improve this system are either to include a cover crop with the corn so that the ground cover already develops when the silage is removed, or to plant a cover crop immediately after cut the silage.
A long-term investment
While there are costs associated with using cover crops, primarily for seeds and planting, it is worth considering growing cover crops as a long-term investment in the health of your land and of your soil. Even in the short term, it is possible to offset the costs of inputs like herbicides and insecticides when cover crops deter weeds by covering the soil and controlling pests by providing habitat for beneficial insects. Cover crops can also provide nitrogen and other major and minor nutrients that do not need to be purchased.
A better performing energy cycle, water cycle, nutrient cycle, and better community dynamics all add up to improved long-term production, leading to better profits: However, cover crops are not. not a quick fix. They are just one tool among many – like controlled burns, grazing, and adequate plant recovery time – to use in forage and pasture management for optimum production and soil health.
This article appeared in the January 2022 issue of Hay and fodder producer on pages 28 and 29.
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