DOI: 10.5061/dryad.dt4jq
title: Data from: The Automated Root Exudate System (ARES): a method to apply solutes at regular intervals to soils in the field

description: 1) Root exudation is a key component of nutrient and carbon dynamics in
 terrestrial ecosystems. Exudation rates vary widely by plant species and
 environmental conditions but our understanding of how root exudates affect
 soil functioning is incomplete, in part because there are few viable
 methods to manipulate root exudates in situ. To address this, we devised
 the Automated Root Exudate System (ARES), which simulates increased root
 exudation by applying small amounts of labile solutes at regular intervals
 in the field. 2) The ARES is a gravity-fed drip irrigation system
 comprising a reservoir bottle connected via a timer to a micro-hose
 irrigation grid covering c. 1 m2; 24 drip-tips are inserted into the soil
 to 4-cm depth to apply solutions into the rooting zone. We installed two
 ARES subplots within existing litter removal and control plots in a
 temperate deciduous woodland. We applied either an artificial root exudate
 solution (RE) or a procedural control solution (CP) to each subplot for 1
 min d-1 during two growing seasons. To investigate the influence of root
 exudation on soil carbon dynamics, we measured soil respiration monthly
 and soil microbial biomass at the end of each growing season. 3) The ARES
 applied the solutions at a rate of c. 2 L m-2 wk-1 without significantly
 increasing soil water content. The application of RE solution had a clear
 effect on soil carbon dynamics but the response varied by litter
 treatment. Across two growing seasons, soil respiration was 25% higher in
 RE compared to CP subplots in the litter removal treatment, but not in the
 control plots. By contrast, we observed a significant increase in
 microbial biomass carbon (33%) and nitrogen (26%) in RE subplots in the
 control litter treatment. 4) The ARES is an effective, low-cost method to
 apply experimental solutions directly into the rooting zone in the field.
 The installation of the systems entails minimal disturbance to the soil
 and little maintenance is required. Although we used ARES to apply root
 exudate solution, the method can be used to apply many other treatments
 involving solute inputs at regular intervals in a wide range of
 ecosystems.
description: ARES soil
 variablesThis dataset describes
 soil variables (0-10-cm depth) measured in subplots with daily
 applications of root exudate solution (RE) or a procedural control
 solution (CP), applied using the Automated Root Exudate System (ARES)
 within experimental litter removal (0L) and control plots (1L) in an
 old-growth deciduous woodland in Wytham, Oxfordshire, UK. Full
 descriptions of the study site and experimental design are given in the
 paper and appendices. Data included in this file are: soil water content,
 soil pH and microbial biomass carbon and nitrogen measured in the subplots
 at the end of the growing season in the first and second year of
 treatments (September 2015 and 2016) as well as fine root biomass in the
 second year of the study (July 2016). Column headings and abbreviations
 are as follows: block = replicate block A-E; Plot = unique experimental
 plot identifier P1-P15; treatm = litter manipulation treatment, where 0L
 is litter removal and 1L is control; ARES = subplot treatment, where RE is
 root exudate solution and CP is procedural control; year = year of study;
 swc = gravimetric soil water content in %; pH = soil pH; MBC and MBN =
 microbial biomass carbon and nitrogen, respectively, in ug g-1; fine.roots
 = fine root biomass in g m-2.ARESsoilvar.csvARES soil respiration dataThis dataset describes monthly measurements of soil CO2 efflux, soil water content, and soil temperature in subplots with daily applications of root exudate solution (RE) or a procedural control solution (CP), applied using the Automated Root Exudate System (ARES) within experimental litter removal (0L) and control plots (1L) in an old-growth deciduous woodland in Wytham, Oxfordshire UK. Full descriptions of the study site and experimental design are given in the paper and appendices. Column headings and abbreviations are as follows: block = replicate block A-E; Plot = unique experimental plot identifier P1-P15; treatm = litter manipulation treatment, where 0L is litter removal and CT is control; ARES = subplot treatment, where RE is root exudate solution, CP is procedural control and 'plot' is the main litter manipulation plot; year = year of study; month = month of measurement; nom.date = nominal date of measurement (set at 1st of the month); time = consecutive time point during the study; swc = soil water content at 0-6 cm depth in %; temp10 = soil temperature at 0-10 cm depth; Rsoil = soil CO2 efflux in mg C m2-1 h-1; Flux = soil CO2 efflux in umol m-2 s-1; Comments = reasons for outliers and missing values; ObsDateTime = actual date and time of each measurement.ARESrespiration.csv