Last Fall, we started an experiment in coyote brush control by mowing several pastures that had a high concentration of brush where grasses were being outcompeted. Coyote brush encroachment gobbling up good pasture is an issue for ranchers on California coastal rangeland where TomKat Ranch is located. We are careful to consider when and where to remove the brush as it is vitally important to acknowledge the ecosystem services provided given that they are tremendous habitat for coastal rangeland birds and other animals. Providing a balanced habitat positively contributes to regenerative ranching promoting biological diversity in the pasture. Just as we want a diverse group of grasses, a diverse group of trees and shrubs can contribute to the diversity in soil microbes possibly raising our levels of carbon sequestration. Finding the right mix is the goal and through monitoring with Point Blue Conservation Science and other collaborators, we hope to find that recipe soon for our region.
There are only a few options when considering coyote brush control. Historically, the indigenous peoples here on the south coast of San Mateo County used fire as a source of control for their farming practices. Prescriptive burns are something that would be interesting to try someday, but it is extremely important that it is done very carefully and truly requires community support. Herbicides are another way to control, but are not a consideration for TomKat Ranch due to possible negative effects to the microbial populations in the soil around the targeted plants. Mechanical removal is an effective method to remove the brush by simply using equipment that pulls the brush out of the ground–roots and all. This might be a more permanent way to control, but does have a down side in that the soil is highly disturbed and if a large rain event happens, there could be negative erosion consequences. It really doesn’t take too long to go from a small rill to a large gulley as we’ve learned here at the ranch. Lastly, mowing was the option we chose for a quick way to remove the brush and give the grasses a chance to get a headstart when the rains arrived. While this is an effective way to remove the top canopy of brush, the roots are still left intact able to resprout relatively quickly. How quick, is what we aimed to find out and to see if maybe the grasses could still get a leg up on the brush.
It’s been about 4 months since we mowed and the grasses are indeed growing, but not as fast as the coyote brush it seems. It’s hard to say because some of the grasses look like they are struggling to “take off”. Whereas, the coyote brush is more able to handle the intense canopy removal without skipping a beat as the root systems are already established and ready to power stem and leaf growth. The good news is that even when this is happening, we are gaining carbon benefits from the photosynthesis that is occurring from the new growth. Now if we could just convince the cows to eat it!
The coyote brush does have a high brix and nutrient content so it’s not out of the question that it could be good forage…for somebody. Perhaps, adding goats and/or sheep to this method of control would be a good way to add nutrients to the soil and control the coyote brush through browsing. Goats can peel bark and that can kill the brush back. All of this said, if you’ve ever tried herding goats, this sounds much simpler than the actual reality they present you.
It will be interesting to try mowing in a more productive pasture where grasses are a little more established and the land has a better historical use than this location where it was conventionally farmed with fertilizer inputs and tilled. This area may need a jumpstart like the pasture adjacent to it where we are experimenting with a compost application trial. Similarly farmed, it will lend some experiential evidence as to whether we should apply compost here and try another mowing or try something else. One of the drawbacks to mowing is that heavy equipment must be used creating stripes of compaction. You can still see where the tire tracks are after 4 months which included some very heavy rains. It would be interesting to take some bulk density measurements to determine what the impact is of driving heavy machinery across a pasture. Calculating the surface area of the stripes might be fairly informative as to whether or not this would be a good practice to continue just from that perspective. This would similarly inform us more about our compost spreading applications as they also require heavy machinery. What are the compaction costs to these methods?
Judging by the photos taken in November and the photos taken in March, you can see the coyote brush has broken bud and raring to go. It appears at this rate, the effectiveness of the mowing is fleeting as the brush will probably be the same size it was in probably another year as when we mowed it. The amount of fuel it required to mow, may never be recovered through regenerative ranching practices if this treatment is required every two years. Perhaps, the goats and sheep will be the extra tool in the tool box to supplement the effects of mowing to reduce the brush in strategic areas. Or, maybe plucking them from the ground with some mitigation to the disturbed soil like spreading hay to prevent the bare ground exposure would be a more effective plan.