How are your cow pies doing?
Posted on: Oct 14, 2013
"Why?" you ask. Because they are a greater indicator of pasture performance!
The faster those cow pies are breaking down, the faster the cycling of nutrients in the system. When microorganisms of decay (soil bugs) break down old manure and old plant material, they are essentially adding fertilizer to the soil. If manure is breaking down too slowly, then the cycling of essential nutrients needed for plant growth is delayed, and overall plant productivity may suffer. This has implications for stocking rate and ranch revenue.
Here's what you need to look for: First, recognize the difference between biological decay and weathering. Decay is the result of bugs and soil microbes eating and disturbing cow pies and old plant material often from the bottom up. Weathering (often called oxidizing) is caused by sun and wind that physically deteriorates cow pies and old plant material, from the top down. Cow pies that are weathering tend to have a gray appearance, as if they have been sitting in the pasture for a while, which they have been. Cow pies that are decaying from the bottom up are often hard to spot, because they have been consumed by insects.
Consider the photo below, taken on a Montana ranch.
The cow pie on the left was over two years old, while the one on the right was deposited in the last growing season (yellow notebook and pen included for scale). Neither was breaking down biologically when this photo was taken, and the gray color of the cow pie on the left shows much weathering by sun and wind. This pasture, located in a subirrigated bottom, is only grazed in the summer growing season, so the presence of these cow pies suggests that mineral cycle was quite slow here. Nutrients were not cycling through the system as rapidly as they could. Further, plant productivity was 50% of the site's potential, so stocking rates were reduced, and the ranch's potential revenue was also reduced.
The above photo was taken in 2010, and the ranch at that point undertook a major shift in its grazing strategy. Multiple pastures were constructed using temporary electric fencing, and grazing durations were shortened in this area to between 10 and 14 days per pasture. Recovery times between grazing events now reach 90 days, where before recovering grasses may not have received growth opportunity at all.
The photo below shows the same area in September 2013.
Note that not a single cow pie is visible in this photo (they would be hard to see anyway since the grass is so tall). By changing the grazing program, cow pies have nearly disappeared, where they were once prominent. This is an indicator of the mineral cycle and suggests how well the pasture is performing. Plant productivity increased here substantially since 2010, and the ranch enjoys a 25% increase in stocking rate. It increased its revenue stream while maintaining the same cost structure, and cow pies were some of the initial indicators of the need for change.