Keeping Grass in the Sweet Spot By Tom Krawiec ATHABASCA, Alberta:
The sweet spot for grazing is just before a plant goes into reproduction. When grazing, it does not mean every plant is at this stage, here I am referring to the sward being in the sweet spot.
Since species grow at different rates, it is next to impossible to graze a paddock in such a way
so that all plants are grazed just before going into reproduction. There are some species that reach maturity faster than other species. In our area, Timothy and smooth brome are two species that mature very quickly. I have been unable to graze to keep those two from going to seed without hurting most other species. So now, I don’t worry about those two going to seed and focus on the other species.
The sweet spot is where 15-20% of forages, other than Timothy and smooth brome, are going to seed. To check the accuracy of my assessment I look at the manure of the animals I am grazing.
Dr Kris Nichols, a soil biologist from North Dakota, explains that for soil biology to be highly active, we need to feed the soil more than once a year. When we graze swards with long recovery periods, the exudates normally released to the soil by vegetative plants, instead go into the formation of seeds. When this happens, Dr Nichols posits that the biology in the soil goes into semi-dormancy. Therefore, as graziers, we must keep forage in a vegetative state to enhance life in the soil.
Grazing plants too late in the growth cycle is as bad as grazing too early. Maybe that statement is a bit brash, but my intent is to make the case that overly long rest periods do not enhance soil biology as many practitioners believe.
If you can accept that soil life is nourished by root exudates, then the case can be made that the more we feed the biology in the soil, the healthier they will become. They will be more active, more robust, be more resilient to pathogens, and reproduce more. All these attributes contribute to a healthy, thriving, and increasing population. Most of the support I have for the benefit of grazing in the sweet spot is based on my own observations, which are certainly open to criticism. I am not a scientist so my findings are not based on rigorous scrutiny. However, I do have production records that record how much forage was harvested from each paddock. I use stock days per acre to assess whether a grazing practice is working. One stock day per acre (SDA) is equivalent to 24lbs of dry matter
By using stock days per acre, I have discovered that when a sward is given an overly long recovery period, it grows back to 50% or less of what it would produce if grazed in the sweet spot. As a producer that is very important if you make your living off your grass. The sneaky thing about this scenario is that you don’t know that you missed out on a pile of forage because it is difficult to evaluate something that isn’t there.
The only reason I know this is because I have kept records on my grazing charts for 20+ years and have seen a pattern emerge in relation to recovery periods. In fact, when people lament about the lack of grazing they achieved in a season it is invariably traced back to letting forage get into the reproductive phase. They either started too late or their recovery period was too long.
If the goal for a grazier is to keep your sward vegetative, then you have to start grazing before all your paddocks are ready. Jim Gerrish explains this very well in his book Management-intensive Grazing. Suffice it to say that starting early is imperative to grazing in the sweet spot
I have been challenged numer- ous times that long recovery periods promote diversity in your pastures and I have to agree with that statement. However, grazing in the sweet spot also promotes diversity. Does one system promote more diversity than the other? I don’t know and neither do the people who make this claim. What I do know, though,
is that increased production is achieved when grazing in the sweet spot. The records I keep prove that. I have also record- ed the forage produced when I let forage get into reproductive phase and when I kept it in the sweet spot. Grazing in the sweet spot produces more forage and better gains year after year in wet and dry conditions.
I know I have poked several bears with this article. That was not my intent. My goal was to point out that we can do better as graziers and we should. We compete for land with a highly subsidized grain business and there is the belief that grazing can’t produce what a crop can produce. This belief is so widespread that it is taken as fact. I don’t buy it and I hope more people start feeling the same way. In my own journey as a grazier, the best production I have done is 525 SDA from one pad- dock in one year. That is the equivalent of 12,600 lbs dry matter (DM) per acre. One stock day per acre (SDA) is equivalent to 24lbs of dry matter.
On numerous occasions I have achieved 325 SDA (7,800lbs DM per acre). Converted to $/ac, based on custom grazing rates in our area, those paddocks produced $372.75/ac and $230.75/ ac respectively. It is much easier to compete for land when your land is producing those kinds of returns.
It is my contention and experience that the way to get that kind of production is by grazing in the sweet spot. There is no science to back up my claim other than my own records. As a producer, though, isn’t production from our pastures really what we are after?
Tom Krawiec can be reached at [email protected]
