The influence of inorganic nitrogen (N) inputs on decomposition is poorly understood. Some prior studies suggest that N may reduce the decomposition of substrates with high concentrations of lignin via inhibitory effects on the activity of lignin-degrading enzymes, although such inhibition has not always been demonstrated. The original purpose of E145 was to study the effects of nitrogen (N) addition on decomposition of seven plant substrates ranging in initial lignin concentrations (from 7.4 - 25.6%) over five years in eight different grassland and forest sites in central Minnesota. In 2020, four fungal substrates ranging in melanin concentration (a recalcitrant molecule in fungal cell walls similar to lignin) were added to four of the forested sites, with harvests to assess mass loss and remaining necromass chemistry occurring at subsequential intervals over a five-year period.
from: Hobbie, S. E. (2005) Contrasting effects of substrate and fertilizer nitrogen on the early stages of litter decomposition. Ecosystems, 8(6), 644-656. doi:10.1007/s10021-003-0110-7
Plots are 2.5 x 2.5m, located in each of 8 sites defined by dominant plant cover. Sites and plots were established in 1999. Within each site, each of twelve 2.5 m x 2.5 m plots received either a control treatment (water only) or a fertilization treatment consisting of 10g N/m2/yr of aqueous NH4NO3 (n = 6) in three applications per year starting in 1999.
Half (six) of the plots in each site are fertilized 3 times/ yr (May, July, October) with aqueous NH4NO3 to receive an annual total of 100 kg N/ha y
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