Below-Ground Plant Production in a Perennial Grass Ley (Festuca pratensis Huds.) Assessed with Different Methods

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Abstract
(1) Below-ground biomass in a second year meadow fescue by (Festuca pratensis Huds.) was estimated using two different field methods: soil coring and ingrowth mesh bags. Five different estimates of below-ground production was calculated. (2) Soil samples were collected and washed, and ash-corrected dry masses were determined twice monthly during the growing season. Samples were sorted into living roots and remaining organic material at four of the fourteen sampling occasions. Below-ground production, calculated as the difference between the annual maximum and a preceding spring minimum, varied between 0.19 and 0.27 kg ash-free dry mass m-2, depending on the fraction (living roots or unsorted soil organic material) used in the calculations. (3) The decomposition rate of soil litter (defined as the dead organic material found by washing soil samples collected in spring before start of growth) was estimated in a separate litter-bag experiment. The below-ground production was corrected using this decomposition rate, taking into account that measured increases were underestimates due to concomitant root death and decomposition of soil litter. The seasonal below-ground production was then calculated to range between 0.36 and 0.46 kg m-2. The higher estimate was achieved when the increases in living (0.19) and dead roots (0.27) were summed. (4) Mesh bags containing root-free soil were inserted into holes made in the soil in early spring and were removed when core samples were taken. The production, estimated as the maximum amount of roots found in the bags, was 0.29 kg m-2. (5) The lowest production (0.19 kg m-2) was considered to be an underestimate since root death and decomposition during the growing season were not considered. The highest estimate (0.46 kg m-2) was suggested to be the most accurate estimate of the below-ground production.