DOI: 10.20387/bonares-aj26-ny65
title: INPLAMINT.Soil_microbial_stoichiometry_Chronosequence_Inden_2019

description: This dataset includes data on soil stoichiometry (total organic carbon and total nitrogen), soil microbial stoichiometry (microbial biomass carbon, and -nitrogen), and microbial basal respiration along a 55 year space-for-time chronosequence of reclaimed agricultural land after brown coal mining. Samples were taken in May 2019 from the restored land adjacent to the open-cast brown coal mine Inden, NRW Germany (6◦15’0’E to 6◦21’0’E and 50◦50’5’N to 50◦53’0’N). 
Thirteen reclaimed sites of ages 1, 2, 4, 6, 7, 13, 18, 24, 29, 40, 44, 48 and 55 years after reclamation were sampled. At each site, soil was sampled from the reclaimed arable field and from the grass margins directly adjacent. Exceptions are for the two youngest sites aged one-two years restored in 2017 and 2018, where no grass margins were present. The 2018 site further differed from other sites in that there were 2 arable land use types; bare soil with no vegetation (2018_F) and land cultivated with Triticale sp instead of Alfalfa (2018_G); and lastly, a site of unlevelled freshly deposited mounds of soil approximately 1m high (2018_FD). 
The soils from the grass margins were formed from the same loess material as the reclaimed arable fields of the same age, but differed in that they had continuous vegetation cover and were not ploughed. Per field, five technical replicates, each consisting of five pooled soil cores (6 cm Ø, with a depth of 10 cm), were collected. At the adjacent grass strips three technical replicates consisting each of two soil cores were sampled. All samples were sieved (2mm), roots and stones removed and stored at 4°C prior to analysis.
The mining company RWE was responsible for the restoration of the land after mining and managed the sites for 7 years before returning the land to the previous owners. The reclamation process is highly standardized. New agricultural top soils are formed of a 2m layer of homogenized loess substrate (containing 1% former topsoil), which are continuously restored at the backside of the mine once excavation is finished.
In the first three years after reclamation, fields are cultivated with alfalfa (Medicago sativa) in the absence of fertiliser and biocides. Four to seven years after reclamation, fields typically undergo a wheat and barley crop rotation and are fertilised with N:P:K (1:0.4:0.6) of 437 kg ha−1 annum−1.
After 7 years of recultivation by RWE, soils were returned to the original land owners and were managed with a sugar beet-winter wheat crop rotation. Farmers resumed conventional agricultural management as per the German Federal Soil Protection Act. Farmers used official agricultural services like the chamber of agriculture to comply with the German fertilization regulation and good professional practice of plant protection. 
Chloroform fumigation extraction method CFE) was used to determine microbial biomass carbon and nitrogen. In the particularly nutrient poor soils, it was not possible to differentiate the nutrients stemming from the microbial biomass from the background nutrient levels. This is the reason for missing values in the nutrient poor soils. 


Research domain: Soil Sciences

Research question: With this dataset we investigated the build up of carbon and nitrogen in soil and in microbial biomass with increasing soil age after restoration.