Adequate Vegetative Cover Vital for Efficient Moisture Utilization

– Victor Shelton, NRCS State Agronomist/Grazing Specialist

This paddock may look messy, but what looks like a weed is actually a fantastic, highly nutritious native legume, tick foil (Desmodium).

I certainly didn’t expect the blessed amount of rain that has fallen on most of Indiana in the last month. In some areas, the amount could be considered more of a curse than blessing, especially on cropland. It certainly has made making dry hay a challenge. I am still happy to have the moisture.

My pasture was getting fairly dry before the rains started; dry enough that growth was slowing down. I had already slowed down the speed of the livestock to allow a little extra rest and now I have picked up momentium again. I’m delighted to see good regrowth of forage in paddocks not far behind where livestock had just been.

With more vegetation now and new growth still coming, it is not hard to maintain excellent cover and let the livestock take the best and leave and/or trample the rest. Measured soil temperatures under these conditions have been very good, usually in the upper 70’s at two inches of depth. This amazes me, especially with some of the extremely hot weather we have had lately. This temperature is very important. At soil temperatures in the 70’s, 100% of moisture is usable for plant growth. Highly disturbed pastures or overgrazed thin pastures usually have higher soil temperatures. If those temperatures reach 95-100 degrees, only about 15% of the moisture is now able to be utilized for plant growth, the rest is lost through evaporation and transpiration. It is not difficult to maintain cover and optimize all the vegetative growth and production we can get; just don’t get behind the eight ball.

Just a side note, cooler soil temperatures are enjoyed by the grazing livestock too. Some people get pretty serious about having shade for animals during hot weather. Shade certainly has benefits, especially when temperatures and humidity are both over 85. But, a cool water source close at hand and cool soil that’s being maintained by good ground cover also plays a very important part. Animals in pastures with good forage, cool soils and cool water at hand tend to lay down in the field more and don’t seek shade as much, even when available. The ground can be very cooling. Grazing livestock like water that ranges from about 37 degrees to 65 degrees. Doesn’t that sound like temperatures two legged critters like too? Most spring, well, and even a lot of municipal water is around 50-54 degrees.

By maintaining ground cover and the vegetative solar panel, with adequate moisture, production should be very good with the only other two main contributing factors being fertility and management. If grazing livestock are managed where they are moved to fresh forage on a regular basis and not allowed to continuously graze or take multiple bites on the same plant before being moved forward, maintaining cover is not difficult at all. They don’t have to be moved everyday, but the more often they are given new fresh forage, the more content they will be and also the less likely they will overgraze individual plants.

I’m a huge fan of utilizing long, fairly narrow, linear fields for pasture and using temporary fence to allocate new forage to the livestock. Generally, especially when new growth is limited, I recommend to use a back fence to prevent livestock from going back and regrazing forages that need to be resting for later use. With adequate amounts of forage to work with, especially when new allocations are higher in quality than where the livestock have just eaten, stepped, or soiled, backgrazing is very limited as long as you keep them moving forward in a timely manner. If you don’t move them quick enough and they run out of fresh forage, they will go back and take a second or third bite and/or graze regrowth which will retard future growth and grazing. This kind of system is very feasible and workable on fields where water is not readily available across the field. As long as the walking distance isn’t too far, generally no more than 1,200 feet, AND they are not in the field more than seven to ten days, this progressive forward moving will prevent most problems. Longer grazing periods or walking distances will promote backgrazing, trailing and movement of nutrients from outer reaches being grazed closer to the water source.

If you have any warm season grasses and you haven’t already started grazing them, now is good time to start. Most people tend to wait too long. These warm season forages can include swichgrass, big bluestem and Indiangrass. Switchgrass comes on the earliest, almost too early here in the Midwest because it is ready to graze about the same time cool season forages are also at peak. It can be taken as hay and then grazed later in July or August. You don’t want switchgrass to mature because quality will drop quickly. The same thing is pretty much true for big bluestem and Indiangrass. The best grazing and quality will be in the vegetative stage. If you’ve not started grazing it yet and see the beginnings of any seed heads, it is time to start. Big bluestem and Indiangrass should be 24 to 30 inches tall prior to grazing and then grazed ideally no shorter than about 12-15 inches. At these stop grazing heights, they will rebound quickly and provide a lot more growth. If taken down short, they will take longer to grow back. They rarely should be taken down less than six inches. These warm season forages absolutely love this weather we have been having. When grazing these forages, all of the cool season forages get a break and continue to grow to provide future grazing. As I’ve said many times before, more grazing days means less inputs and less work; remember, the cows are supposed to be working for you, not you for them!

Lastly, I want to talk about clipping just a bit. Everyone thinks that clipping pastures is always needed. I hear all kinds of reasons and some are valid. Weed control is certainly a good reason. The threshold for weed control is usually when weeds are reaching 30% canopy. At 30% canopy, weeds are blocking enough sunlight to really start impacting production. A noxious weed threshold is a lot less. Removal of seedheads is the next reason I hear and generally with the fear of pinkeye. It does take three constituents for pinkeye; a host cow, which often is a silent carrier, an irritant which could be a seedhead or dust creating watery eyes, and flies to transport it from the carrier to non-resistant animals. Lastly, and probably the most common reason is aesthetics. I have to admit that a nicely mowed pasture does look good, but more often than not, we are not able to clip high enough to not remove forage that could have been grazed. If vegetation is very heavy, a lot of that clipped vegetation ends up laying on top blocking sunlight and retarding growth. In forage studies, when I weighted before and after grazing on both unclipped and clipped, cows removed more from the unclipped than clipped meaning we not only were spending money where perhaps not needed, but we may have lost some grazing days too. Some things still just make me stop and scratch my head.

Keep on grazing!