Comparison of ceramic suction cups and KC1 extraction for the determination of nitrate in soil

Abstract

Comparisons of nitrate concentrations in soil core extracts and ceramic suction cup isolates were made on a coarse sand and a sandy loam to evaluate the methods for estimating nitrate concentrations percolating through the root zone. On the coarse sand the comparisons were made at 80 cm on three dates during the winter of 1988/89. For each date, 103 soil samples and 101 or 102 suction cup isolates were taken. On the sandy loam the comparisons were made at 25 and 80 cm on two dates in March 1990. For each date and depth, 57 soil samples and 55-57 suction cup isolates were taken. On the coarse sand the mean nitrate concentrations were the same for the two methods. On the sandy loam the results obtained using the two methods differed significantly in only one of the four comparisons. However, the results indicated that the suction cup isolates differed slightly from the volume-averaged concentrations obtained from the soil samples. The type of frequency distribution, normal or lognormal, seemed to be influenced both by the mean nitrate concentration and by the soil structure, and thus by the pattern of percolation. The size of sample required to estimate the mean nitrate concentration with a probability of 95% and a precision of 10% varied from 7 to 106.

The Role of Plant Diversity and Composition for Nitrate Leaching in Grasslands

“…Although measurements of soil inorganic nitrogen concentration (extraction with salt solutions) were done in other manipulative biodiversity experiments (Naeem et al 1995, Tilman et al 1996, 1997a, Hooper and Vitousek 1997, Kenkel et al 2000, Niklaus et al 2001, methodological caveats restrict the possibilities to interpret those results in terms of leaching losses. This is mainly due to the high variability of soil nitrate both in space and time (Webster et al 1993, Djurhuus andJacobsen 1995), and a lack of water percolation at the time of soil sampling, which may lead to subsequent plant uptake or microbial immobilization of nitrate (Hooper and Vitousek 1998). Lastly, and most importantly, soil extractions alone are inappropriate to determine leaching losses because of the need to have an independent estimate of drainage, which is necessary to calculate nitrate load (Armstrong and Burt 1993).…”

Variation in Soil Nitrate Concentrations in Two N-Saturated Norway Spruce Forests (Picea abies (L.) Karst.) in Southern Bavaria

“…This includes a methodical study with KCl extractions by Djurhuus and Jacobsen (1995). Gensior (2003) found a good match between nitrate concentrations in seepage water and soil solution at the Bavarian Level II sites.…”

Nitrate leaching as affected by long‐term N fertilization on a coarse sand

“…This can be ascribed to the low field capacity, which means that nitrate is leached quickly through the soil profile and thus changes in the plough layer are quickly reflected at the 80 cm depth during periods of percolation. At the time of soil sampling in late autumn, the main part of nitrate was leached from the soil profile as the highest concentrations and leaching (Table 2) concentrations in the Jyndevad soil (Djurhuus & Jacobsen, 1995), the results point out the difficulties in using soil samples exclusively to predict and evaluate leaching.…”

“…Soil water was extracted from two ceramic cups per plot, installed at a depth of 0.8 m as described by Djurhuus & Jacobsen (1995). There were eight samplers per treatment.…”