Long-Term Soil Ecosystem Studies

a) Soil description Albic Luvisol (FAO) Ap 0-30 cm: silty sand, single grain structure; Al 30-50 cm: silty sand, single grain structure; al/IIBt 50-60 cm: silty/loamy sand, single grain/subpolyhedric structure; IIbt 60-80 cm: loamy sand, single grain/subpolyhedric structure; IICv >80 cm: loamy sand, single grain/subpolyhedric structure. b) Soil properties * Depth of root limiting layer: No root limiting layer * Approximate water holding capacity: 21 mm per 100 mm * Approximate soil organic matter content: 1.2% * Approximate carbon content: .7% * Approximate carbon:nitrogen ratio: 10 * Approximate soil bulk density: 1.7 g/cm3 * Approximate minimum ground water level: 2000 cm * Percent clay (i.e. particles less than 2 um): 4% * Percent silt (i.e. particles between 2 um and 63 um): 23% * Percent sand (i.e. particles between 63 um and 2000 um): 73% * Approximate soil pH: 5.5 * Approximate minimum soil pH: 5.5 * Approximate maximum soil pH: 5.5 * Method of determining soil pH: CaCl2 archive - b) Soil sampling * Details of soil sampling method: 25 single samples are taken per plot using an auger, combined to give a mixed sample. The samples are generally taken from 3 replications (nos 4,5,6; ie 96 plots) at irregular intervals, depending on special research projects. Due to the large number of treatments (32) sampling is sometimes limited to selected treatments. * Soil is separated into layers * Details of measuring depths and soil layers: 0-16,16-30,30-50 cm. The frequency of sampling is generally the same for all layers. solid - Soil measurements made and frequency * Total carbon: Irregular - 1937,52,56,62,67,70,88,89,90. * Method of measuring total carbon: Different methods used during the course of the experiment. The latest sampling used gas chromatographic determination of CO2 and N2 after dry combustion of soil (with Nitrogen Analyser Carlo Erba 1500). * Total nitrogen: Irregular (1937,52,56,62,67,70,88,89,90). * Method of measuring total nitrogen: Methods have varied during the course of the experiment. * Total mineral nitrogen: 1989,1990 only * Method of measuring total mineral nitrogen: NO3 - Na-Salicylate method; NH4 - Nessler's Reagent * Soil bulk density or weight: Irregular (1961/2,67-70,88) * Other nutrients: pH (1923,26,29,31,32,34,39,46,47,52,56,62,67,70,75,85,88,89, 90). P (1924,32,38,49,52,56,62,67,70). K (1924,32,38,56,62,67,70). Ca (1956). Mg (1956). Cd,Pb,Cu,Zn (1988/89). * Atmospheric inputs: Measurements of nutrient inputs (several anions and cations) contained in rainfall are available (long term values from other experiments in the research station). * Other measurements: Soil: several microbiological parameters (1988-90). Plant: sociology of weeds (1988-90); investigaations into the yield structure of cereals (ears/sq m, 1000 grain weight, grains/ear, grains/sq m, nos of fertile and sterile spikelets, etc), since 1967. vegetative - Yield: Annual * Total above-ground dry matter: Annual * 1967-70: N,P,K. 1989/89: Cd,Pb,Cu,Zn (selected treatments).