DOI: 10.71615/bexis.32254
title: Rhizosphere soil nutrients and microbial biomass from 12 common grassland species (Hainich 2023)

description: The project PEGasuS targets at disentangling the mechanisms of grassland plant-soil interaction along the gradient of land-use intensity (LUI). Based on ecological theories, a coupling between plant, microbial and soil stoichiometries, as well as ecoenzymes is hypothesized. A hotspot of these couplings is the rhizosphere.&lt;br&gt;This dataset contains rhizosphere nutrient analyses for soil nutrients and microbial biomass, as well as pH and soil water content. We sampled 15 EPs (experimental plots) in the Hainich (Germany), 10 EPs with corresponding reduced land use plots (RPs) from the REX I experiment and 5 EPs with a historic low LUI. The soil samples were collected in May 2023. We gathered data on carbon, nitrogen, phosphorus, potassium, sulfur, silca and magnesium.&lt;br&gt;The data collection/analysis was part of the project PEGasuS within the framework of the DFG-funded joint project Biodiversity Exploratories (https://www.biodiversity-exploratories.de).
description: Study design: We sampled the rhizosphere soil of 12 common grassland plant species (4 forbs, 4 grasses, 4 legumes). For the project we sampled 10 plots of the REX I (31457) experiment (EPs and RPs) and 5 additional low-LUI EPs (average LUI &lt; 1.1) in the Hainich region. REX I was implemented to test the effects of extensification. To implement, RPs are only mown once per year. | Sampling design: In May 2023, sampling was performed along the plot borders of the EPs to minimize effects of other experiments performed on the plots. For each target species present on a plot, three individuals were randomly selected to sample rhizosphere soil. Per plant infividual 8 - 10 rhizosphere soil samples were taken in a depth up to 10 cm using a soil corer with 0.8 cm diameter. The accumulated soil from all three indivuals per species was mixed together. After sampling the soil was kept in coolers and later stored in freezers at -20 °C. | Sample preparation: Prior to analyses, rhizosphere soil samples were sieved (5 mm) and remaining roots were removed with tweezers. | Sample analysis: The pH level (measured in H2O at a soil : deionized water ratio of 1 : 2.5) and the soil water content (difference of fresh weight and weight after drying at 105 °C) were determined. One aliquot was used to quantify C, N, P, K, sulfur (S), silica (Si), and Mg in a 0.01 M calcium chloride (CaCl₂) solution for simultaneous determination of macro and micro elements in soil microbial biomass. In brief, four grams of dry-weight equivalent soil sample were shaken for one hour in 80 ml 0.01 M CaCl2. &lt;br&gt;Another aliquot was subjected to the chloroform fumigation extraction method to estimate element contents in microbial biomass. Nutrient contents in fumigated extracts were determined using the same CaCl₂ extraction protocol, with microbial nutrient pools calculated as the difference between the two. A TOC-analyzer was used to measure organic C and total N in extracts (Shimadzu). All other elements were quantified by ICP-OES (Spectro ARCOS). | Equipment: Soil corer&lt;br&gt;TOC-analyzer (Shimadzu)&lt;br&gt;ICP-OES (Spectro ARCOS)