Fall is the time to begin planning for spring prescribed fire, regardless of what type of fuels you plan to burn. There are generally three primary components to a successful burn including: 1) the burn unit preparation process 2) the burn planning process, and 3) implementation of the burn. In this article we’ll cover the first step, which is preparing the unit.
In reality, unit preparation is integral to the planning process, as the burn will be much improved if the planner has a true ‘feel’ for the burn unit, including its boundaries, topography, fuel load, and potential hazards. This knowledge is best gained by visiting and even preparing the unit ahead of time. However, if there is uncertainty about the best layout for a burn unit, one should seek outside advice from a trusted resource before investing heavily into unit preparation or disking. Once the unit is prepared, a very accurate unit map can be produced, which is a very important part of any prescribed fire plan.
In South Dakota, it is generally recommended that you have at least one full season of rest prior to burning (especially in grazed pastures). Rest allows for the best possible establishment of a fuel bed that will allow for a complete and functional burn. We lose about ½ of the biomass left in a grassland over the winter due to breakage and wind erosion, so it is critical to enter the winter months with a full ungrazed/unhayed fuel load. Generally speaking, more fuel is better as it allows you to extend the window of opportunity to conduct the fire later into the spring, as the dry fuel load from the previous year will provide adequate fuel even as the grassland greens through late May. Without adequate fuel, the time spent preparing and planning for a fire can be wasted and disappointment with the fire effects is likely.
Firebreak preparation is essential to successful fire management. There are essential two main categories of firebreaks: hard and soft.
A hard firebreak is essentially one that simply will not burn and that will not allow fire to cross under normal circumstances. Examples of hard firebreaks are gravel roads, wide streams and rivers, tilled areas with mineral soil, etc. The CRP program does allow a producer to till the edges of a potential burn unit as long as there is a conservation plan and a restoration plan in place for the tilled boundary. Tilling the edges of native pastures or other native grasslands is never recommended, as it destroys the native sod base, opening up the land for infestation of weeds and likely reducing long-term productivity. Where land is covered by an easement or other similar conservation program contract, tilling may violate contract conditions.
Tilling traditional and no-till field edges: When burning in the vicinity of established crop fields, it is advisable to work with neighbors to ensure field edges are adequately disked or otherwise worked to the point that fire cannot spread across the previous year’s residue. This is advisable even on the edges of no-till fields, as this small investment will ensure that the fire does not escape the unit boundaries and consume the very valuable residue remaining across the entire field.
A soft firebreak will generally suppress the spread of fire due to a reduction in fuel load. Examples of soft firebreaks can be mowed lines, grazed areas, narrow watercourses, pasture roads, two-track roads, or any fuel change decreases the rate of spread of fire, thus giving the manager an opportunity to suppress the fire if necessary. When installing soft breaks by mowing, there are a few critical steps to consider:
- Timing: Mow when the grass is drying down in the fall. September through December create good opportunities, especially after the first hard freeze.
- Ground Conditions: Be careful. Wetter areas can often be mowed after frost or when the ground is firming up. Consider how wet the area will be in the spring. A soft firebreak in the spring can create many hazards with vehicles getting stuck, so plan firebreak locations appropriate to anticipated spring conditions.
- Topography: When possible, keep your firebreaks low on the landscape. Avoid ridges and hilltops in favor of flat or gentle slopes on the bottom of hills or near natural drainages when possible. However, if you have established trails and roads on hilltops and ridges, they can be utilized as well. If the low ground or drainages has significantly heavier fuel loads that make installation of firebreaks difficult, placement on ridges and hills may be a better option. One must always consider the predominant wind direction that he/she intends to use for the burn when making firebreak placement decisions.
- Tie firebreaks into standing water, roadways, or tilled fields if available, leaving no standing fuel between your firebreak and the water. Cattails and other vegetation can be easily smashed down with ATVs, UTVs, or light tractors. Additional vegetation can be mowed after freeze up if wet ground is an issue.
- Avoid wet areas and give wide birth to areas with heavy fuels such as brush piles, cattails sloughs, or heavy grass loads. Try to keep your firebreak in light fuels.
- Removal of mowed litter: It is very important to remove as much litter and duff from firebreak lines. Side delivery mowers, even finishing the line with a lawn mower, is a great option. Raking and baling are also options. Never leave raked and windrowed litter on the firebreak because it will create a hazard during the fire event. If the litter isn’t baled, simply rake it out 30 or 40 yards into the standing grass of the fire unit. Many times when you rake cut litter into standing grass, the windrow will eventually fall apart and spread out.
Spring 2017 Fire Courses
SDSU Extension, NRCS, Pheasants Forever, and other partners will once again be hosting a free 1-day introductory fire courses in various locations during spring 2017. Take advantage of this opportunity to become more familiar with burn planning, tools, techniques, and rules. Visit the South Dakota NRCS range and pasture page to view instructional materials related to prescribed burning.
Source: Pete Bauman, South Dakota State University