The currently available soil physical data are partly based on outdated soil schematisations (PAWN) and associated standard characteristics (Staring series). Also site-speific data is available (Priapus). However, the total number of (reliable) soil physical properties for a Soil Science Information System (BIS) is not sufficient to modify soil schematisations or to carry out studies nationwide (eg STONE) of regional (detail).
Soil physical information (water retention, conductivity) of good quality plays an important role in research on leaching of nutrients to groundwater and open surface water and ecohydrologial research. Currently, the Priapus and BIS-Nederland databases contain only for a few locations in the Netherlands acceptable soil physical data. In this project we propose to extend the databases with new data. In a predecessor of this project an inventory was made where the current information is located in the Netherlands and where additional information is needed. This will form the basis for the sampling and following characterization for the coming years.
The addition of a large number of new soil physics properties in Priapus and BIS-Nederland gives rise to the prossibility of making new standard schemes for nation wide calculations.
In 2011 an analysis is performed of existing soil physics data and the data that is needed to be able to generate a satisfying database of soil physics data. With use of this analysis a set of criteria is determined with which later aggregation of data can take place (Knotters et al., 2011; Alterra-rapport 2245). These criteria are: top and bottom soil layers, different deposit classes, texture, median sand fraction, clay fraction and fraction of the organic matter. Not all combinations (2364) can be measured. Therefore Knotters et al. (2011; Alterra-rapport 2245) proposed the Latin Hypercube-snap check as a means to add as much information to the database as possible with use of a limited amount of data. With this method at least all classes will be present with at least 2 different samples per class. The classes that are not yet present in the database will be sampled first. The amount of samples to be taken with this method is 50 at the least. All samples will be taken in duplo. With the duplos taken into acount this amount will therefore be 100. The soil physics determinations comprises texture, organic matter content, waterretention curve, (saturated and unsaturated) hydraulic conductivity curve, the dry bulk density and the composition of a profile description.
In 2012, by making use of the Dutch Soil Map 1:50 000, the field spots are selected to determine where and at which depth the soil samples have to be taken. Starting point is that the most prominent gaps in the existing soil database must be filled first. The loam and clay loam soils will be measured in 2012. The remaining gaps are filled in 2013 and 2014. Indicatively in 2012, 2013 and 2014 the amount of samples taken will be 25, 42 and 33 respectively. The project will be finished with a final report in 2014.