Mineral nitrogen from KCl extractions of soil from the Jena Experiment (Main Experiment up to 15cm depth, year 2005)

As an estimate of plant-available N, this data set contains measurements of inorganic nitrogen (NO3-N and NH4-N, the sum of which is termed mineral N or Nmin) determined by extraction with 1 M KCl solution of soil samples from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Soil sampling and analysis: Five soil cores (diameter 0.01 m) were taken at a depth of 0 to 0.15 m of the mineral soil from each of the experimental plots in April and September 2005. Samples of the soil cores per plot were pooled during each sampling campaign. NO3-N and NH4-N concentrations were determined by extraction of soil samples with 1 M KCl solution and were measured in the soil extract with a Continuous Flow Analyzer (CFA, Skalar, Breda, Netherlands).本数据集作为植物可利用氮的估算依据，收录了某大型草地生物多样性实验（耶拿实验（Jena Experiment）；详见下文）主实验样地土壤样品的无机氮检测数据。其中无机氮指NO3-N与NH4-N，二者之和被称为矿质氮（Nmin），检测方法为采用1 M KCl溶液对土壤样品进行浸提。 该主实验共设置82块20×20米的草地样地，所用植物种质池涵盖隶属于4个功能群（禾草、豆科植物、高大草本与小型草本）的60个物种。2002年5月，研究人员从该种质池中选取不同数量的植物物种播种至各样地，以此构建植物物种丰富度（1、2、4、8、16及60种）与功能群丰富度（1、2、3、4个功能群）的梯度。所有样地通过每半年一次的除草与刈割进行维护。 土壤采样与分析：2005年4月与9月，研究人员从每个实验样地的矿质土壤0至0.15米深度处，采集5个直径0.01米的土芯。每次采样作业中，同一样地的所有土芯样品将被合并为复合样品。NO3-N与NH4-N浓度通过1 M KCl溶液浸提土壤样品后测得，并采用连续流动分析仪（Continuous Flow Analyzer, CFA，Skalar公司，荷兰布雷达）对土壤浸提液进行定量检测。