Be Ready for the Spring Pasture Flush!
Crop and Soil Environmental News, February 1999
Paul R. Peterson
Extension Specialist, Forages
As burned up as pastures were last summer and fall, it is difficult to imagine that some day soon we will be faced with an overabundance of lush spring pasture. How we manage this period of high pasture productivity is critical. In a period of abundant growth, it might seem that we can get by with less management attention. However, our spring grazing management affects not only the degree to which we effectively utilize that growth, but also pasture performance for the remainder of the season.
Spring is when pasture growth in uncontrolled grazing situations gets most out of control. With cool-season pastures, the supply of available pasture forage reaches its peak during the spring. Too often, rather than make management efforts to utilize this abundance of spring forage, we are content to spend excess time and money in early summer brush-hogging the overmature forage that was wasted in the spring.
Typically, cool-season grass-based pasture systems are stocked conservatively, at a rate that the producer feels his farm can support during the summer months when cool-season species are lower in productivity. As a result, most pasture systems are understocked during spring. The resulting abundance of available forage allows grazing animals to fully express their selectivity. While rotational stocking gives us the higher stock densities that enable us to better control and utilize rapid spring growth, we can still end up wasting a lot of forage if we don't have a plan for managing it.
Several things should be kept in mind when animals are first "turned out" in the spring:
The amount of pasture forage actually consumed over a growing season with continuous stocking is only about 35% of what is produced. In contrast, pasture that is rotationally stocked with 1-3 day rotation intervals typically has over 70% of the growth consumed. This difference is due largely to more effective use and management of the spring flush with rotational stocking.
The additional problem that occurs if spring growth is not well managed is that too much selective grazing can occur, resulting in an excessive patchwork of over- and under-grazed areas. Diverse pastures are never (nor should they be) grazed to a uniform height. Attempts to achieve completely uniform utilization result in overgrazing of the most desirable pasture species. Overgrazed areas are often repeatedly overgrazed with each grazing cycle and thus have chronically reduced productivity during the remainder of the grazing season. In contrast, the undergrazed areas continue to be avoided by grazing animals, unless close mowing is performed to encourage new vegetative growth in those areas. With ineffective spring management, this pattern of under/over-grazing is maximized.
Another common mistake is to apply nitrogen to pastures in the spring. Since spring is the period when we often have more growth than we can effectively utilize, applying N not only exacerbates the problem, but it also discourages the ability of higher quality, N-fixing legumes to persist and contribute to the pasture canopy. In spring, nitrogen should be applied only in grass paddocks where hay cutting is anticipated. For pasture, save your nitrogen fertilizer for stockpiling.
It is difficult to avoid making a pass with the brush-hog over some paddocks at least one time during the year. However, we need to be careful not to brush-hog just for aesthetic reasons. While not as expensive as some other equipment operations, brush-hogging still does take time, fuel, and wear-and-tear on equipment. Paddocks that may appear from the road to have too many overmature plants remaining after a grazing period, may really be pretty well utilized when viewed on a walk through the paddock.
Don't be in a hurry to brush-hog after the first grazing cycle. This is often a wasted trip. Generally, if brush-hogging is necessary, it is better to wait until after the 2nd or 3rd grazing cycle when the grasses propensity to produce seedheads is over.
It is also generally not a good idea to force animals to "clean-up" overmature forage, regardless of what type of animal or stage of production, because they will generally selectively overgraze other areas before they will touch the stems and seedheads of overmature plants. It is better to try to stay ahead of maturation as much as possible and cut hay or brush-hog to take care of what gets away.