Since 1985, the farmers of selected agriculturally used NABO sites have annually recorded the management and land use data. Thus, valuable data sequences are available for 28 arable farming sites, 11 grassland sites and 8 sites with specialty crops (fruit-growing and viticulture sites).
The management data provided by the farmers are verified, harmonised and compiled in a database. This data processing generates for each site a uniform, annually validated management list, which is complemented with a uniform code key for agrochemicals. Currently, sequences of roughly 30 years exist for about 50 NABO sites; they include detailed information on applications of fertilisers (mineral fertilisers and animal manure, intensity), applications of plant protection products and crop rotation. These management data are valuable for answering various questions regarding soil functions and soil risks and are the basis for many environmental issues and models.
NABO sites for which the management data have been recorded annually since the mid-1980s.
Nutrient and pollutant balances
Based on the information regarding fertilisation practices, application of pesticides and on crop rotation, we can generate long-term surface balances for nutrients and pollutants. These provide a good overview of which substance flows are relevant for the individual substances due to management and crop rotation.
Nitrogen balance at an arable farmland site (top), phosphorous balance at an extensively used grassland site (bottom).
Modelling of soil processes
In comparison to a substance-related surface balance, more complex model approaches take into account other relevant soil processes, such as bioturbulation (mixing of the soil by soil organisms), the water balance, relocation to deeper soil layers and surface runoff.
The soil process model EPIC is calibrated by means of management/cultivation data, with which we can produce predictions for the NABO plots. On the one hand, this includes statements on how the nutrient and pollutant contents in the soil will change with the same cultivation. On the other hand, they can provide information on those soil processes that play an important role in the dynamics of material cycles.
Example of a soil process balance for phosphorous: the relevant inputs and outputs (above); the estimated development of phosphorous contents in top soil (below) with the surface balance and the process model (EPIC)
Material cycles of agriculturally used soils in the Central Plateau
Well-balanced nutrient cycles are essential for the sustainable management of agriculturally used soils. In fact, in the mid 1990’s, ecological measures were implemented in Swiss agriculture. Regardless, national goals to reduce the nutrient surpluses in agriculture were only partially reached.
With a material cycle model for the Central Plateau we can make visible where and how land use and management change over the years and estimate trends for material flows in agriculture. We can detect land use changes with the help of remote sensing data and the Google engine platform. We can connect the nutrient cycles with selected soil functions, for example, to evaluate filter and regulatory functions of nutrients in the soil. The model identifies risk areas with high nutrient deficiencies or nutrient surpluses as well as soils in which the regulatory functions are strongly influenced or even overstressed.
