50 years box plot experiment in Grossbeeren (1972 - 2022) - Plots

The Box Plot Experiment in Grossbeeren was set up in 1972 to investigate the effect of different fertilization strategies within an irrigated vegetable crop rotation system for three different soils. Therefore, this vegetable long-term fertilization experiment can be used to investigate different plant-soil-systems under the same climatic conditions. The experimented was halted in 2022. The experimental site (52°21’01.30’’ E, 13°19’05.47’’ N, 50 m a.s.l.) is located in the transition zone between the more maritime-affected Northern German Plain and the continental climate of the European mainland. Weather data were collected in an agrometeorological station close to the experimental area. The long-term means (1991-2020) for air temperature and annual precipitation are 9.7 °C and 492 mm. The single plots are quadratic concrete boxes with walls of 10 cm thickness, a surface area of 4 m2 and a depth of 75 cm. The upper 50 cm are filled with the tested soils; the lower 25 cm comprises a coarse-sandy drainage layer. The three soil types are Arenic Luvisol (weak loamy sand), Gleyic Fluvisol (heavy sandy loam) and Luvic-Phaeozem (medium clayey silt) according to the World Reference Base – WRB (and the Bodenkundliche Kartieranleitung – KA4). Within 10 rotations, the vegetable species white cabbage (Brassica oleracea L. var. capitata f. alba), carrot (Daucus carota L.), cucumber (Cucumis sativus L.), leek (Allium porrum L.) and celery (Apium graveolens L. var. rapaceum Mill.) were cultivated. No celery was cultivated during the first rotation. The experiment consists of 12 fertilization treatments in different combinations of mineral N fertilization and organic amendments and as quadruplicate for each of the three soils. The experimental set-up scheme can be found in the supplementary material. Mineral N fertilizer was applied as calcium ammonium nitrate. Mineral P and K fertilization was uniform for all treatments. Total N and total C in soil, plant and organic amendments were determined using a CNS analyser VARIO El (Elemental Hanau) since 1995 and before by wet combustion with K2Cr2O7 und H2SO4. C and N in the soil samples and N in the plant samples were analysed annually. The C contents of the crop residues (leaf + stalk + root) of the five vegetable species were investigated irregularly. In autumn, the soil was annually dug up to 20 cm by using a spade. Weeds were removed by a combination of mechanical (cultivator, rake or hoe) and chemical measures. Insect pr