BonaRes SIGNAL, Site: Mariensee and Reiffenhausen, soil characteristics

This data was collected in grassland agroforestry (=alley cropping of willow strips and grassland strips) at Reiffenhausen/Germany ((Salix schwerinii x S. viminalis) x S. viminalis and grass-clover mixture) and Mariensee/Germany (S. schwerinii x S. viminalis and grassland mixture consisting of Lolium perenne, Festuca pratensis, Phleum pratense, Poa pratensis) during 2016. Data was taken at 3 replicates (Mariensee)/ 4 replicates (Reiffenhausen) each in the tree strip component (=Tree) of agroforestry, the grassland component of agroforestry at different distances from the tree strip (1m, 4m, 7m) and at the conventional grassland (=Conv) adjacent to grassland agroforestry. The soil samples were dried at 40 °C for five days and passed through a 2-mm sieve. Soil organic C and total N were determined using a CN analyzer (Elementar Vario El; Elementar Analysis Systems GmbH, Hanau, Germany); for soil samples with pH ≥ 6.0 pre-treatment for the removal of carbonates was performed (Harris et al. 2001). Soil pH was determined with a soil:water ratio of 1:4. The effective cation exchange capacity (ECEC) was determined as the sum of the cations determined by percolation of the soil with unbuffered 1 mol L-1 NH4Cl followed by analysis of the exchangeable cations (Ca, Mg, K, Na, Al, Fe, and Mn) in the percolate using an inductively coupled plasma-atomic spectrometer (ICP-AES; iCAP 6300 Duo VIEW ICP Spectrometer, Thermo Fischer Scientific GmbH, Dreieich, Germany). Soil base saturation was calculated as the percentage of exchangeable bases of the ECEC. Soil texture was determined for the top 0.3-m depth using the pipette method with pre-treatments for removing organic matter, iron oxide and carbonate for soils with pH ≥ 6 (Kroetsch and Wang 2008). Soil bulk density was determined using the soil core method (Blake and Hartge 1986) for the top 0.05-cm depth at all sampling locations. We used the measured soil bulk density to convert nutrient element concentration from soil mass basis to nutrient stocks on an area basis.