By Gregg Brann and Pat Truman
The benefits of cover crops are well documented. Following this year’s drought, the advantages of establishing a cover crop on your pastures could pay off down the road.
Cover crops help improve soil quality, but require a plan for continuous soil cover, plant diversity and retention of plant material.
Plant cover crops when primary crops are not growing. As little as 90 days are needed to grow a cover crop. Aerial seeding can aid in quicker establishment of cover when primary crops are still in field. On pasture and hay land, maintain vegetative and residue cover on the soil year around. Plants growing and plant residue insures that fertility, available water holding capacity, crop production, weed control and animal health will be more consistent, even in times of drought. Flooding damage is also reduced since water infiltration is improved and less runoff occurs. Managing for better soil quality improves soil functions, the quantity and quality of water, plant and animal resources, while reducing energy demand, therefore the entire environment is improved.
Here are some points to consider:
Soil Quality, also referred to as soil health, is defined as how well soil does what we want it to do. Reducing or eliminating tillage has a major influence on soil health. Other management factors which improve soil health are: crop rotation, cover crops, residue management, quick canopy, balanced fertility, higher yields, and live roots throughout the year. A cooler moister soil has more biological activity throughout the year, residue and canopy are key in maintaining these conditions.
Benchmark conditions: Assess the current soil conditions: surface residue, green plant cover, root depth, plant vigor, low oxygen indicator plants, compaction, low fertility, soil erosion, moisture holding capacity, soil life (earthworms, macropores, rhizobia nodules on legumes, dung beetles in pasture, length of time it takes for manure to decompose).
Soil Structure and Rooting Depth: Assess compaction with a probe or even a wire stuck in the ground to feel resistance in the field, and then check in the fence row where no traffic has occurred. A penetrometer or compaction meter is the ideal tool to use. There will normally be some increase in penetration resistance between a surface layer and a subsurface or subsoil layer. Dig a hole generally to 6 or 8 inches deep and assess the soil structure and root form in the surface layer. Granular structure generally is ideal in the surface layer It is normal, even in healthy soils to have blocky structure in the subsurface and subsoil layers, however the structural units should ideally be well defined with roots moving around and through the blocky soil aggregates, and show evidence that humus or clay has been re-deposited on the surfaces of the blocky aggregates and in pores by moving water. Relatively young soils on flood plains may have not yet formed structure in the layers below the surface layer. Assess the soil structure: is it platy (compacted), blocky, or granular (generally preferred). Tap roots that are J shaped or fibrous roots that are weak or that stop at a certain depth are generally an indication of a root restricting layer that may be compacted or dense. Tap roots can improve issues with compaction in the subsoil, and fibrous roots help to improve aeration and lower bulk density.