CASE STUDY 2
Montana Highway 84
Public Road Right-of-Way
Reconstruction and widening of Montana Highway 84 resulted in disturbance of the adjacent roadcut. Insufficient topsoil was available on the project to cover the cut slopes, so slopes were seeded with a native grass mix. Cheatgrass invaded and became prevalent on this south-facing and harsh site.
Micronutrient fertilization was implemented in 9/22/16.
Demonstrate the efficacy of micronutrient fertilization in promoting the growth of perennial grasses.
Granular 350 pounds fertilizer/acre
Granular applications of 70 and 175 pounds fertilizer/acre were also implemented and were unsuccessful.
Granular fertilizer was applied using a hand broadcast spreader to the 0.1 acre plot 50x87 feet in dimensions.
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Overall: The treated plot was successful in increasing perennial grass cover from less than 10% cover to 28% cover in the fourth growing season and outcompeting cheatgrass on the same site which was 6% cover in the fourth growing season. The adjacent untreated control plots exhibited 41% vegetation cover of cheatgrass in the fourth growing season while perennial grass remained nearly constant during the period of monitoring at 12-14%. These plots were not seeded so any change in perennial grass cover resulted from natural colonization from existing plants and/or seed and propagules in the soil. This test plot was also important because it showed the ineffectiveness of fertilizer applied at rates of 70 and 175 pounds/acre while the 350 pound/acre treatment described in this narrative was successful. Another important observation is that while the adjacent landscape has dense stands of annual grasses they have not reinvaded the treated plots, rather the perennial grasses have become well established and are outcompeting the annual grasses.
Commentary: Since the literature is full of citations about the inadvisability of adding ‘fertilizer’ to perennial grass communities that are dominated by annual grasses, a nitrogen-only test plot was implemented at this site and showed rampant growth of the annual grasses which outcompeted the desirable perennial grass plants. The NutraFix fertilizer product described in this case history has low nitrogen levels and is comprised primarily of micronutrients allowing for the inverse result: perennial grasses outcompeting annual grasses.