-The development and survival or disappearance of civilizations has been based on the performance of soils to provide food, fibre, and further essential goods for humans. Amongst soil functions, the capacity to produce plant biomass (productivity function) remains essential. This function is closely associated with the main global issues of the 21st century like food security, demands of energy and water, carbon balance and climate change. A standardised methodology for assessing the productivity function of the global soil resource consistently over different spatial scales will be demanded by a growing international community of land users and stakeholders for achieving high soil productivity in the context of sustainable multifunctional use of soils. We analysed available methods for assessing the soil productivity function. The aim was to find potentials, deficiencies and gaps in knowledge of current approaches towards a global reference framework. Our main findings were (i) that the soil moisture and thermal regime, which are climate-influenced, are the main constraints to the soil productivity potential on a global scale, and (ii) that most taxonomic soil classification systems including the World Reference Basis for Soil Resources provide little information on soil functionality in particular the productivity function. We found (iii) a multitude of approaches developed at the national and local scale in the last century for assessing mainly specific aspects of potential soil and land productivity. Their soil data inputs differ, evaluation ratings are not transferable and thus not applicable in international and global studies. At an international level or global scale, methods like agro-ecological zoning or ecosystem and crop modelling provide assessments of land productivity but contain little soil information. Those methods are not intended for field scale application to detect main soil constraints and thereby to derive soil management and conservation recommendations in situ. We found also, that (iv)

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Aim of the study was the evaluation of the present state and further development of drought risk to agricultural sites in Northeast (NE) and Central Germany in consideration of climate changes. Based on the Medium Scale Agricultural Site Map, soil‐hydrological data were derived for heterogeneous soil areas. They refer to the landscapes in NE and Central Germany characterized by low precipitation, marked spatial soil heterogeneity, and a high share of hydromorphic soils. The soil data were linked with long‐term climate records of 368 stations for the period 1951–2000 as well as a climate scenario for the period 2001–2055. The plant water supply was calculated for three crop groups: cereals, root crops, and grass. The current and future development of drought risk of agricultural land of NE and Central Germany was evaluated. Starting in 1951, the water supply over the vegetation period has been decreasing with time for all crop groups up to now and may continue up to the year 2055 at most sites. However, there are also regions with increased plant water supply. The federal states of Brandenburg and Saxony‐Anhalt showed the strongest water deficit. Especially in these states, the plant water supply is strongly limited for cereals already today and probably may get worse for all crops in the future. On an average of the years, drought may limit plant growth in parts at >40% of agricultural land. In the federal states Mecklenburg‐Western Pomerania, Saxony, and Thuringia, the plant water supply mostly will stay in an approximately sufficient range due to higher precipitation and more favorable soil quality. The results are a background for the assessment of land‐use planning and evaluation of current and future soil‐ and site‐specific crop growing suitability on a medium scale.

In recent years, the addition of microorganisms such as Plant Growth-Promoting Bacteria (PGPB) and mycorrhiza are becoming more popular, both in research as well as in practical use. While inoculants are usually not necessary for plants cultivated outdoors on biologically active soil, they can be useful on sterile substrates, newly created artificial landscapes, and also in soils that have been managed using non-selective sterilization methods, such as fumigation. In a multi-year lysimeter experiment, we investigated the influence of a commercial mycorrhizal inoculum on water use efficiency and biomass production of maize (Zea mays), sunflower (Helianthus annuus), sweet clover (Melilotus officinalis), sweet sorghum (Sorghum bicolor), cup-plant (Silphium perfoliatum) and tall wheatgrass (Elymus elongatus subsp. ponticus cv. Szarvasi-1) when exposed to high or low groundwater levels. Results showed that all plants benefited from the mycorrhizal association. Mycorrhizal-inoculated plants were more successful in terms of dry matter production and water use than the non-mycorrhizal plants. The source of the mycorrhiza-autochthonous or introduced-made no significant difference. The results indicate that inoculation with mycorrhiza and promotion of the naturally abundant mycorrhiza in agricultural production systems can significantly contribute to a sustainable production of crops. Effects depended on plant species, cultivar, soil type, groundwater level and the mycotrophy of the individual crop species.

Besides nutrient composition, the hydraulic performance of horticultural substrates is a main issue for evaluating their quality for horticultural purposes. Their water and air capacity and their suitability for transporting water are important hydraulic quality indicators. Shrinkage and water repellency could have a negative impact on storing and transporting water and solutes. The commonly used methods and devices for quantifying the water retention properties of horticultural substrates (sand box, pressure plate extractor) are outdated. The measurements are time-consuming, the devices are expensive, and the results are affected by uncertainties. Here, the suitability of the extended evaporation method (EEM) and an associated HYPROP (HYdraulic PROPerty analyser, device was successfully tested for very loosely-bedded horticultural substrates. EEM and HYPROP enabled the simultaneous and effective measurement of the water retention curve and the unsaturated hydraulic functions. The measurement time of horticultural substrates ranges between 7 and 10 days. Furthermore, the shrinkage properties and the water rewetting time can be measured with the HYPROP system. Results using 18 horticultural substrates are presented. These results are discussed and compared with natural organic and mineral soils showing the specific hydraulic performance of substrates for horticultural applications.