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Dry Matter Losses and Mineral Leaching in Bluestem Standing Crop and Litter

Koelling, Melvin R., Kucera, C. L.
Ecology 1965 v.46 no.4 pp. 529-532
Andropogon gerardii, biomass production, carbon nitrogen ratio, flowers, grasses, leaching, leaves, magnesium, mineral content, nitrogen, nitrogen content, phosphorus, potassium, silica, vegetation
Changes in mineral composition were observed for current growth and standing crop of prairie bluestem, Andropogon spp. Simulated litter samples of big bluestem, A. Gerardi, separated into foliage and flower stalk fractions were also analyzed over a 2—year period. Considerable leaching or transfer of various constituents, especially nitrogen, phosphorus, magnesium, and potassium, occurs in the standing crop prior to deposition in the litter. Potassium showed a 96% turnover in the vegetation before the end of the first year. Silica showed a distinct rising trend with age of the standing crop. This trend continued through the litter phase and accounted for a major portion of the total mineral oxide. Dry—matter losses in the litter samples were about 50% more rapid for foliage than for flower stalks. This difference in decay rates is attributed to less water—soluble product in the latter. Total ash after 2 years of decomposition in the litter samples was approximately twice the initial level for both foliage and flower stalks. Whereas percentage of nitrogen showed a decreasing trend during the first year in the standing vegetation, nitrogen levels increased on a percentage dry weight basis during the litter phase. Increasing nitrogen in the litter, compared to relatively more rapid dry—matter losses, suggested a narrowing of the C/N ratio as decomposition progressed. Higher nitrogen concentrations in the foliage collected from control plots than from burned plots are attributed to slower growth and less biomass production, compared to greater grass productivity on fire plots.