There was considerable flooding along the Missouri River in summer 2011, leaving many fields scarred and bare, without a crop. Producers should make field repairs as needed and seed a cover crop to help protect the soil and start rebuilding soil life before the 2012 cropping season. Cover crops benefit flood-damage soils in several ways.
- The residue from the cover crop will protect the soil from raindrop impact, reducing soil erosion and crusting.
- The upright cover crop residue will keep the wind and sun off the soil surface, reducing wind erosion, sandblasting, and soil water evaporation.
- The growing roots of the cover crop will help feed the soil biological life, especially arbuscular mychorrhizae fungi.
Crop Selection and Seeding Rates
Cool-season cereal grains are fast growing in the spring, provide standing residue fairly quickly and are easy to kill before seeding the cash crop. Consider seeding oats, barley, triticale, cereal rye or wheat (listed in order of preference, depending on seed availability) at a rate of 1-2 bu./acre. Use the seeding date typical for seeding oats in your area, usually when the soil temperature is above 35° F and rising.
Cover crop cocktails, a mixture of several species and plant types, provide different rooting patterns and varying plant architecture to add diversity to the system. The diversity is valuable for restoring microbial and physical soil function. Mixtures also provide good soil cover across a variety of conditions since cover crop types respond differently to varying soil and weather conditions. Several cool-season legumes, brassicas or other broadleafs could be seeded with the cool season cereal to aid in soil life recovery. The seeding rate of the cereal grain should be reduced about 50% if another cover crop is seeded with it.
A legume like spring forage peas (30 lbs./acre) or common vetch (10 lbs./acre) could be seeded with the cereal grain to fix some nitrogen, improving the cover crop benefits. Producers should use twice the recommended amount of the proper innoculant for these legumes as the native rhizobia bacteria were probably reduced during flooding. Taller cool-season brassicas and broadleafs like rapeseed (3 lbs./acre), mustard (3 lbs./acre), flax (5 lbs./acre) or Ethiopian cabbage (2 lbs./acre) also could be added to the cereal grain and legume seed mix to further improve the soil system. These cover crops stand nicely to help reduce wind erosion and have a vigorous taproot to help penetrate the soil. If you’re adding several of these other cover crops to the mix, the seeding rates of each could be reduced some.