Modelling of Substance Cycles in Soils: Early Detection, Prediction and Root Cause Analysis

Nutrients and pollutants accumulate over time in soils, and these processes are difficult to assess. Element balance modelling allows the early detection of undesirable developments in the soil and enables the formulation of predictions and scenarios. This modelling instrument serves in the development of preventive measures in soil protection.

The goal of modelling element balances is to analyse the causes of detected changes in the soil and to predict the outcome of adjusted measures for a sustainable soil use. Simple surface balances or more complex soil process models can be used to elucidate how agricultural management impacts the soil quality, soil function and soil risks in the long term. Complex soil process models allow analyses and predictions on regional and site-specific scales in order to examine changes in soil characteristics related to management, soil cultivation, site properties and soil properties.

Figure: With a substance balance, links between site properties and environmental conditions and between agricultural land use and substance cycles in the soil can be identified. (Source: Maharens, Federal Environmental Agency Dessau).

The modelling approach, depending on the study question, is specified in space and time: Thus, the analysis can target a management site, a farm or a rural region, and span a day, a month or a year – either retrospectively or prospectively. In the NABO analyses, element balances are calculated for nutrients (nitrogen, phosphorous. potassium,) and for inorganic (cadmium, copper, zinc, uranium) and organic pollutants (e.g. pesticides).




Long-term Nutrient and Pollutant Balances at NABO Sites

For nutrients (N, P, K), heavy metals (Cd, Cu, Zn, U) and selected plant protection products, simplified annual surface balances are generated. Here, management data have to be considered to ensure comparability of the balances with the measured changes in the soil. From the results, indicators and recommendations for a sustainable soil use can be derived.


Applications of Plant Protection Products (PPP) at NABO Sites

The long-term contamination of soil with residues of plant protection products (PPP) has so far rarely been examined. Therefore, the extent to which active ingredients of PPP contaminate the soil and their persistence are mostly unknown. The National Soil Monitoring Network NABO assesses the long-term PPP applications at the sampled sites. Thus, potential residues of selected active ingredients can be examined in the future.


Recording Management and Land Use Data for NABO Sites

Data of agricultural management are an important basis for the interpretation of changes in soil quality. For almost 50 agriculturally used NABO sites, management and land use data are collected annually.


The Dynamics of Substance Cycles in Soil - Modelling of Soil Processes

Long-lasting substance inputs do not necessarily lead to accumulation in the soil. Besides management, various soil processes and properties co-determine the substance cycles. For a better understanding, these relationships are examined with soil process models.

Agri-environmental Monitoring: Heavy Metal Balances as Indicators

The Federal Office for Agriculture FOAG conducts a monitoring based on agri-environmental indicators (AEI) to allow an assessment of the impact of agriculture on the environmental quality. The National Soil Monitoring Network NABO calculates the annual copper and zinc balances for the AEI farms and deduces indicators. These data are published in the Agricultural Report.


Isotope Method for Source Analysis of Metals in Soil

The NFP69 project MISOTRAG («Stabile Metal Isotopes as a New Tool to Improve Sustainability of Agricultural Production Systems») examines whether cadmium, copper and zinc accumulate in agricultural soils and what amounts can be taken up by plants.


Regional Soil Monitoring Tool for Sustainable Substance Cycles

The NFP68 project iMSoil («Regional Soil Monitoring Tool for Sustainable Element Cycles on Agricultural Soils) develops an instrument for soil protection. A regional soil monitoring tool should allow the early detection of increased inputs of pollutants, test the efficacy of suitable measures on endangered soils and help deduce suitable indicators.


Cadmium and Uranium Contents in Soils: Screening of Arable Soils in the Midlands

Do soils treated with mineral fertilisers contain elevated levels of pollutants? How large is the load of pollutants that enter the soil with the fertilisers? In fact, the application of mineral fertilisers in agricultural production systems can cause increased inputs of potentially toxic metals in the soil. A screening of arable soils was used to evaluate the risk of arsenic (As), lead (Pb), cadmium (Cd) and uranium (U) accumulation through the input of P mineral fertilisers.


Element Cycles in Agricultural Soils on the Swiss Central Plateau (Mittelland)

In the NFP68 project «National Land Management Model», a substance balancing model is being developed that explicitly calculates substance cycles for soils of the Swiss Central Plateau (Mittelland). This model is intended to estimate the impacts of regional management strategies and national regulatory instruments on the nutrient and pollutant cycles in arable and grassland soils. One of the model’s strength is the possibility to identify where land use and management change over the years. The model also allows estimating trends in the substance cycles.