Warm v. Cool Season Grasses

As promised, here's some follow up from last week's post about the field day. Let's take a closer look at grass management! 

Native Prairies had cool season (C3) and warm season (C4) grasses. Having both in your pasture mix helps ensure soil health by keeping a consistent cover on the ground, maintaining soil temperature and moisture levels. Living soil contains protozoa, nematodes, and a few other organisms that swim, they require moisture. If it's dry, they go dormant, and if soil dries to quickly (which happens if you hay at high noon) they die and lose you lose soil health/soil organic matter. By seeding and managing for a diverse mix of grasses, you are ensuring soil health and the long term health of your pasture and its ability to grow grasses.

Moisture can evaporate from four feet deep, unless we have ground cover
— Doug Peterson, NRCS

SidebarWhat's all this about C's? Check it out, it has to do with how a plant captures carbon during photosynthesis, and their environmental requirements for growth. 

Cool season grasses have two growing seasons - Spring and Fall. But warm seasons put on more tonnage in their one season than cool season grasses do in their two seasons. To help your pasture recover and produce more tonnage, rest the grass during the growing period.

To manage warm season, you have a set of cows that have lower nutritional requirements and graze them through a paddock after the yearlings go through. Warm season gets grazed down to a different length depending on how long the rest period is ie. hammer down grasses in May and rest June/July. Warm season grasses grow when cool seasons don't. So, the rest period for your pasture, if managing for warm season, might be in June/July to allow it to put tonnage on, but some years you might want to graze it because those are the months when it is highest quality and your animals need the nutrition.

According to soil health specialist, Doug Peterson, the trick with managing grasses, or rather the habit to avoid is to NOT grazing the same way year after year.