Why Equine Adaptive Grazing?

Ever since I first read about using adaptive grazing for horses, I've been itching to give it a try with my own small herd. After my 3-day Soil Health Academy class in Iowa last month, I decided to brave our Texas heat and get after it. My goal is to have my herd eat 50% of the available forage, without going back to nibble the regrowth. Read on to see why that is so important:

Over grazing seriously impacts the health and yield of pasture plants. It also contributes to overgrowth of less-desirable species, which tend to colonize barer soil. Even one animal can overgraze a multi-acre pasture by selectively grazing and re-grazing the same favorite plant, as I learned first hand when I turned poor old Lakota into a pasture by himself when the rest of the herd ostracized him. Even though he had more forage than he could eat, by the end of the month, there were areas nipped to nearly bare ground, right next to grass 12-15 inches high. Have you ever been to a buffet and noticed people converging on the fresh, hot dishes as they get brought out, ignoring the other food? Our livestock prefer the fresh growth over the old, mature grass, so it gets overgrazed. The regrowth is sweeter than the old growth, so horses keep going back to the previously grazed area to get their sugar hit.

If I needed further proof, I took this video yesterday. I sat for 10 minutes with my 18 year old and my yearling, letting them graze. (The 18-year old is terrified of the bridge obstacle, on which I was sitting, so this is part of reconditioning his association with it). Note they are standing next to lush grass, about to be cut for hay. Both horses exclusively ate the really short, recently mowed grass, even though it is getting brown, aside from 1-2 bites of the longer grass.

Overgrazing plants is detrimental in so many ways! The below-ground mass of a plant is proportional to the above ground mass. Grazing up to 50% of the leaf, has little effect on the leaf, but taking more than 50% causes a rapidly increasing shrinkage of the plants roots. This is good to keep in mind when cutting hay, as well. Better for long-term productivity to set the cutter at 5-6 inches rather than cutting as low as you can.

Plant root mass mirrors above ground leaf area. Grazing or haying more than 50% damages roots. (figure credit: Soil Health Academy)

Grazing to the ground also seriously slows down regrowth, as illustrated below. This has compounding effects on soil health. These include exposed soil heating up and damaging the soil microbiome and further damaging roots. Less roots in the ground also mean the microbes aren't getting fed by the plants, either. Exposed soil is more susceptible to erosion and compaction. The bare ground also allows dormant weed seeds the chance to sprout. In the areas we overgrazed last fall, we first had an overgrowth of clover, in the spring, which inhibited the bermudagrass. Those same areas are now covered in nightshade, which sprouted because there was little or no bermudagrass.

Overgrazing significantly delays plant regrowth. Figure credit: Soil Health Academy

Dedicated practitioners of adaptive grazing say the productivity of their pastures increases by 2-3 fold in many cases. This is entirely believable, just on the basis of quicker regrowth. Add in the compounding effects on soil microbiology and more uniform utilization and it's an easy sale. I am expecting additional benefits including having my grass-sensitive horse need less days on dry lot and needing to feed less hay. I suspect there will additional, hard-to-quantify health benefits as the horses consume a more diverse diet and less over-stressed/over-sugared short grass.