by Steve Fransen
Forage Agronomist,
WSU Cooperative Extension
Let’s say you have a sick animal on your farm and the vet is called. The vet makes a diagnosis, prescribes the appropriate medication and even administers the first dose with detailed instructions for you to follow for a complete recovery. You are left to do the rest and bring the animal back to proper health.
Are you willing to do the same thing for your pastures?
The most common questions I’ve been asked over the years is “What should I plant in my pastures?” followed by “What should I spray to control the weeds in my pastures?” Many pasture owners can identify some of the important forage species in our region and certainly some of the most common weeds. Some folks take soil tests, are willing to apply lime and fertilizers (both organic and inorganic), some make hay when excess forage is available, and some even attend grazing conferences to learn more about what to and not to do!
The adapted perennial cool-season grasses (such as perennial ryegrass, Italian ryegrass, orchardgrass and tall fescue) in the PNW region advance through various stages of its growth cycle, just like livestock. It’s just that until recently we really didn’t recognize all the independent components of the cycle and put them into an understood order. This process continues to evolve as we learn more from research, so this article should be considered a progress report of PNW pasture ecology, management and utilization. As we gain new information about the cycle and its parts the story will change to reflect this new knowledge.
The forage/pasture cycle begins in the fall, generally in September. In some cases the cycle actually begins about mid-August and in most cases the first phase of the seasonal cycle- that is, new grass root and seed head tiller initiation, continues into October. This is where our story begins, in the beginning.
Many folks don’t want to buy hay in September so they “slick” the pasture down thinking this saves them time, other fall work and hay for later feeding. Unfortunately, this strategy initiates several negative scenarios you may not be aware of. By slicking off (which often means overgrazing the pastures into the dirt) that important residual grass stubble (that stubble which is about 3” above the soil surface) in September several events are set into motion. The stubble is an important source of carbohydrates for fall root regrowth, and to feed the newly developing seed head meristem tissues that will be next years’ seed heads. Consider that stubble is the primer starting fall grass regrowth. When you lose this priming action, you have lost more than the value of the hay might have saved. What you have lost is future forage yield potential! Thus, you can count on lower forage yields, with a slicked September pasture, next year because the initial regrowth phase was surely slowed if not eliminated. Unless you fence an area of your pasture off in the fall that is not slicked off, you’ll never even know how much forage you’re losing through slicking off next year.
Next, you permit weed seeds a place to land on bare soil thereby giving them the greatest opportunity to become established. The grasses going into September weakened because they have just survived the summer stress period of higher temperatures and normally prolonged drought. So slicking off the forage in September weakens the grass plants for the next major stress period- the wet winter stress. I hope you now look at these supposedly positive aspects of September grass slicking or overgrazing and rethink your strategy this fall.
Fall is an excellent time to take soil samples, have them analyzed and apply lime. September is the best time to apply phosphorus (P) to the grassland because P is needed to develop new roots. I’d avoid heavy applications of nitrogen (N) as this restricts the grass from going into dormancy in the late fall for winter survival. Reasonable applications of N and sulfur (S) along with P and potassium (K) will start the process of increasing grass strength and vigor. The problem is you’ll not see the results for more than 6 months so patience is important- this is an investment into your pastures’ future. The first medication to bringing your pastures back to health is avoid overgrazing or slicking off pasture in the fall, especially September. Then apply nutrients based on good soil test information!
The wet winter stress period has some similarities to the dry summer stress period. The grass roots are shedding, that is the roots change color from bright white to gray to brown to black as these plant tissues die. I like to think of this in terms of our dog when she sheds her winter coat in the spring- same thing just different time of year. The plant is using carbohydrates in the stubble and roots for survival, the soils are cold so most grasses are in a state of dormancy or sleeping. The nearly constant daily rain continues to strike the barren soil if the grasses had been and continue to be slicked off. Some of our soils will go into an anaerobic state- a state without oxygen when filled with water and certain gasses formed in the soil can impede plant survival.
Avoid turning livestock out to trample and tear up the pastures, this is where that important sacrifice area comes in. The sacrifice area is torn up instead of the productive pastures during the wet winter months. Punching the soil through hoof action during the winter greatly increases soil compaction, and when you want water to enter the soil later it simply cannot. The second dose of medicine for your pastures is to use the sacrifice area and not the pastures during the wet winter period to avoid soil compaction and other problems later.
Spring comes in slowly as winter rains begin to retard. Grass roots start growth first, and are then followed by top growth. As temperatures increase, so does the growth of our perennial cool-season grasses. Let’s use 42 degrees Fahrenheit as our average baseline temperature for grass growth while legume baseline temperature is closer to 50 degrees Fahrenheit. Grass root growth continues through the spring period but slows down just after peak forage yield. Spring is an excellent time to apply nitrogen and other important plant nutrients (see OSU publication FG-63 revised). Avoid the temptations of turning livestock in too early as hoof action will still compact the soils; destroy plant crowns, etc. More importantly, grasses are trying to recover from the winter and build strength to support the largest amount of forage to be produced during the entire growing season. Spring overgrazing can establish areas of different palatability within the pasture. Here selective grazing will be more magnified in the summer, and summer regrowth likely will be less and plants will be under greater stress because higher temperature and drought. As we change in latitude from south to north in the PNW region, spring occurs faster in the south and can be delayed three weeks or more in the north. Selection of the proper maturity group within the grass variety by latitude and soil conditions will enhance spring and total forage production. Grass roots expand and remain white during the spring growth and this root system is establishing the plants and ability to survive the upcoming summer stress period.
Summer stress is a time of slow summer growth; grass roots are shedding and are turning colors from white to gray, to brown and black again. For the west side, summer starts in mid to late June, July and August, until the root regeneration cycle starts again. The remaining grass stubble in the summer is the main pool of available sugars that jump starts the September root regrowth process so the more the stubble is damaged in the summer, the longer it takes for root regrowth the establish in the fall. I also think there is less total fall root regeneration from damaged summer plants. Just about anything that damages the stand or plants in the summer will directly effect the initial forage cycle in the fall.
Summer is the finish line in the forage calendar. Your pasture will make it to the finish line, but the question is what shape will they be in when they arrive? The stronger and fit an athlete at the end of a race the faster they recover. The same is true with our perennial pastures.
The final medicine I have to offer is: do not overgraze pastures in the summer nor damage plants since fall regrowth will be delayed and forage yield will be reduced compared to a well managed pasture. Many folks have heard about stockpiling forage for animal use in the fall and winter. I’d suggest we think about preserving grazeable forage as a source of sugars, N and S that stimulates above ground fall growth. This is also a source of P that stimulates below ground root growth when the forage cycle begins. Summer is setting up the fall recovery cycle that establishes the rest of the pasture calendar and the following year’s production.
A TV commercial about 15 years ago had the punch line “pay me now or pay me later”. A few years ago a national trend started to move from being a livestock producer to a grass farmer. Are you willing to do what is necessary for the grass to become a successful, profitable and environmentally sound grass and forage producer? To do so means to not overgraze at any time of the season. Weeds in a pasture are an indication that something has gone wrong in the pasture.
To achieve desired pasture response, means strong, vigorous roots and maintaining proper stubble heights. The forage calendar should become part of your full forage management design and plan in the future. Don’t be afraid to adjust, adapt and improve this tool as you learn more about your individual pastures and your own management style. We can’t control the environment to any degree but we can certainly learn to work within the environment we live in. We have opportunities to make the situation either better or worse. Seldom do things in nature stay the same. The more carefully you look, the more changes you’ll see. Even when you think nothing is changing, the small changes are constant. Also what you do within one part of the cycle has ripple effects throughout the rest of the cycle.
By starting on the right foot in September, the cycle is primed. You have established the top potential yield next year at this time! By reducing winter stresses, the cycle is jumpstarted for spring. In the spring as most people think, we have our best growth and highest yields. But are these yields the best yields that you can produce? Only monitoring an area where you’ve practiced what we are recommending will show you on your own farm. But it will show up for you. Summer is the final phase of the cycle and like all races, it isn’t over until you cross the finish line. Summer is the finish line and only the strong survive! Those who make it over the finish line are weakened by the experience but are also ready to recover and start over again. This is where we end this concept- with September and the fall period where the forage calendar and the forage cycle starts once again. This is the core of the medication you’ll need to establish and maintain productive pastures. Just like the vet, we have a solution to the problem, now we must apply the treatments and follow through until we have reached the goal of healthy and productive pastures. It is very possible and I’ve seen it done by others and have done it myself.