Natives & Cover crops

Nurse crops, cover crops or temporary cover, regardless of how you refer to them the idea is the same – use an annual species to help prepare, protect and improve the soil conditions of your site during the process of establishment of the permanent cover. Permanent cover for our world usually refers to the use of native plant species to provide a long-term sustainable solution to ground cover needs. 

Cover crops have been used in agriculture and gardening from the very beginning of time it seems. In general, cover crops are reemerging more and more in the regenerative agriculture and soil health movements. Not only do they aid in soil health, but they can also be a big addition for the grazing industry. providing meaningful high nutrient forage for most all grazing livestock. In addition, it is very common in the construction industry and site development process to have a cover crop specified to aid in temporary stability of the site during the establishment period for permanent cover. More often than not, a single species of cover crop is specified as a companion crop during the seeding of turf on construction sites or right of way projects.

Looking for a solution to improving soil quality and improving the results of single cover crop usage, the Missouri Native Stewardship Services team has researched the use of cover crops in all industries. Regenerative agriculture and soil health movements have examined and applied the wisdom of cover crops uniformly in their processes. What has been most interesting, not a single cover crop species but a polymerous mix of three to twelve species of cover crops – all planted at the same time –has become the norm in this corner of the green industry. Depending upon length of cover required, types of improvements to the soil which may be needed and the potential use as a forage – the polymerous mix is specified. The results have far greater benefits than perhaps initially intended. Cover crops improve the soil health, sequester carbon in the soil, improve soil permeability, increase pollinator services, shade the soil from solar heat,  and armor the soil against erosion. 

All in all, diverse cover crop mixes are amazing actually

Choosing the species of cover crops being specified, the project can improve in very targeted ways. For example, cover crops create their maximum benefit in many cases at the time they are flowering- typically 75-90 days after planting. These benefits include fixing nitrogen in the soil, scavenging phosphorus, fixing carbon in the soil and improving permeability. Often the job sites we work on are greatly disturbed in the grading process. As a result, the topsoil is redistributed or absent from the final seed bed soil profile. Utilizing experience guided with results from a soil test, often the final graded soils need assistance to foster successful seed germination, growth and sustainability.

Industry wide practices include the addition of topsoil, compost or biochar’s to improve poor soil health. All are reasonable avenues and amendments to be considered. However, in some cases due to financial restraints or the sheer size of the site – soil amendments are difficult to include or incorporate. It is for all these reasons that Missouri Native Stewardship Services considers the use of a polymerous cover crop mix. An example of an application for a polymerous cover crop mix would include a solar site or construction site requiring establishment at a less-than-ideal time of year for native perennials to be seeded. Since most native species require a winter or cold stratification

process, the classic seeding time for these species would be between December and February. Most industry contractors would recognize this time of the year as “mud season” or the worst time of the year to meaningful grade to prepare a seed bed. Often the site owner or contractor owners a window of April – October for seeding of native perennials. Thus, the difficulty of providing consistent results and meeting contract expectations. Over the last five seasons trails of combined cover crop mixes and native perennial seedings have been carried out on new solar sites, bmp construction sites and native seeding

projects. The results are very promising with observed success favoring late season (August- October) establishment periods

Designing a polymerous cover crop mix incorporates the needs of the site with the abilities or natural results created using these annual species. Most every seed house or Co-op across the country stock classic cover crops species ideal for their region. Often, they are available as single species- depending upon the outlet, some will custom blend to meet your needs.

Nitrogen Fixing: Most legume species fix 100# or more nitrogen per acre during their period of growth. Legumes are both cool season and warm season oriented. Thus, by combining both, a broader opportunity for improvement can be created. Conversely the mix could be loaded with one or the other tailoring the mix for a specific season of use.

Cool Season Legumes: Winter Austrian Peas, Balansa Clover & Berseem Clover

Warm Season Legumes: Soybeans, Cow Peas, Sun Hemp, Red Clover

Phosphorus Gathering: Many of the annual grass species used as cover crops are proficient at gathering phosphorus from the soil and leaving it in usable form for the next planting. In addition, other species are noted for their ability to scavenge and leave behind

phosphorus.

Annual Grasses: Winter Wheat, Annual Rye, Jerry Oats, Pearl Top Millett, & Barley

Other Crops: Buckwheat

Tilling Species: Cover crop species can be selected uniquely for their rooting ability. This includes both depth and relative size of the root mass developed in a short period of time. -Many of the above species will root 30-36” deep into the soil within their growth cycles. The creation of large macropores within the soil profile are key to converting dirt to meaningful and productive soil. For example, daikon radish varieties can create 2’ diameter

holes 20” in depth or more in a single growing season.

Tilling Species: Peredovic Sunflower, Turnips & Diakon Radish

We have settled on several variations of cover crops depending upon the time of year we apply them the nature of the site. Our standard mix though includes nine species blended together 1000# or 2000# at a time. This mix includes Berseem Clover, Winter Peas, Perdovic Sunflower, Brown Topped Millett, Barley, Turnips, Buckwheat, Balansa Clover, & Jerry Oats. Combined together as a mix we apply 50# per acre- which equates to 883,000 seeds per acre or more. We have found that not all species germinate at once, so the dormant seed germinates later when the weather is more favorable for that specific species. As a result, the cover crop mix provides season long control in armoring the soil from wind and water erosion. Termination most often occurs during a winter freeze but can also be accomplished with a low mowing of herbicide application. The season’s long growth typically lasts till the germination of the desired permanent native perennial cover the next spring. Native seed can also be direct no-till drilled through the cover after a winter frost or freeze. Eight of the nine species in this seed mix have the ability to penetrate 30-36” in depth during a 90 day growth period. Only Buckwheat has a shallower rooting habit of 20” in depth.