Sustainable farming is all the rage these days, or so it seems. Farmers’ markets, farm-to-table restaurants, CSAs, pastured meat. It’s everywhere! But what makes a farm truly sustainable? Merriam-Webster defines “sustainable” as something “of, relating to, or being a method of harvesting or using a resource so that the resource is not depleted or permanently damaged.”
Basically a sustainable system is one that doesn’t consume inputs faster than they can be regenerated. The beauty of pasture based farming is that your inputs are sunshine, water and grass, all of which are completely renewable resources!
However, not all pasture-based farms are truly sustainable. A “sustainable” farm can quickly become an ecological disaster if not managed properly. The key to sustainable pasture-based animal husbandry is to know how many animals the land can support. For the sake of simplicity, I’ll focus on cows, but the principles can be applied to any livestock animal, or even crops.
Cows eat grass. Take a seed, add soil, sun and water and you get grass. Not all grass is equal. The soil quality affects the quality of the grass. If I eat nothing but cookies and candy, I’m probably going to end up pretty sick. On the other hand if I eat a lot of fresh fruits and vegetables, I’ll be in much better shape. The same is true of plants. They “eat” the nutrients in the soil. Good soil=good grass. Good grass=healthy cows.
Nutrients don’t just come out of nowhere. They have to be put into the soil. The more plants you grow, the more depleted the soil becomes. Like vampires, the plants suck the lifeblood right out of the earth. For many farmers, the solution is artificial fertilizers. Another option is herbivores (i.e. cows). As cows graze the pastures, they leave behind their nutrient-dense manure. No chemical fertilizer can compete. Manure is the number one way to strengthen a bad pasture and to make a good pasture better.
But even the best pasture can only produce so much grass. The most nutrient-dense acre still has its limits. The numbers vary by region, grass type, and grazing method so it’s hard to say you need exactly x acres per cow. For now let’s say you need 2.5 acres per cow for the year. If you have 250 acres of pasture, you can support 100 cattle.
What if you decide to put 150 cattle on those 250 acres? After all, you can make more money if you raise 50 extra cows. Maybe there is even demand for those 50 extra cows. Economics is all about supply and demand. If the demand exists, it may seem like it is your responsibility as a farmer to come up with the supply. But farming isn’t about economics. It’s so much more complex.
Here are the problems. First, those cows will produce more manure than the land can absorb and use. This excess becomes run-off and ends up in nearby streams and creeks. While it may be all-natural, antibiotic- and hormone-free manure, it’s still manure and not something we want in our water. What was once nutritious fertilizer becomes toxic pollutants.
Next you run out of grass. If you are smart, you start feeding hay before the cows graze the pastures down to far. But hay costs money. Whatever profit you gained by raising those 50 extra cows is being eaten away with each bale you buy.
To save on hay costs you leave the cows out on pasture a little longer. You make one or two more passes through the pastures. Now you have an overgrazing problem on your hands. When cows regraze pastures too quickly, the grass doesn’t have a chance to regrow properly. Most grasses should be at least 6-inches tall before they are grazed. If grass is grazed before properly maturing, the roots don’t have a chance to establish themselves and the whole plant can die. Dead grass doesn’t regrow and you end up with barren pastures.
I’m sure this goes without saying, but barren pastures can’t support any cows.
The same idea applies to pigs, chickens, sheep, llamas, whatever. Farming has natural limits and embracing those limits is at the heart of true sustainability.