Soil compaction of agricultural production in a global Life Cycle Impact Assessment method
Under the pressure of increasing productivity, many soils are being more and more intensively used, which can result in decreasing soil quality, also called soil degradation. That means adverse changes in soil properties leading to reduced capacity to function (1). It is seen worldwide as a problem, because it is often a long-term impact and is sometimes irreversible. One of the main threats to soil is soil compaction (2). On a worldwide level, agricultural mismanagement, deforestation, and overexploitation of vegetation for domestic and industrial use are severe causes of soil degradation (1, 3). In LCA there are only some indicators that address soil quality or soil degradation and in each case solely to the midpoint category (4).
In this abstract we present the first part of a new method to assess yield losses in agricultural production caused by soil compaction. We use data from the harmonized world soil database (5) for soil properties, crop procedure data from the tables of production cost calculations (6), specification leaflets of different agricultural machine producers in an empirical model (7). With two levels of soil moisture we can model the difference of the compaction impact on the crop growing during appropriate or wet conditions. The yield loss is modeled on different levels of soil depth. This is of particular relevance since the compaction in topsoil is classified as reversible in the medium term, which is not the case for the subsoil layers. The results of the model for e.g. wheat production at the Swiss Plateau deliver 6.3, 5.7 and 2.6 % yield loss in topsoil, soil between 25-40 cm depth and in subsoil during wet conditions. For appropriate soil conditions, on the other hand, the model delivers 3.7 % yield loss in the topsoil with no losses in subsoil layers. These modeling results indicate the necessity for a new LCIA method, which includes additional characterization factors to mitigate the amount of irreversible compaction in subsoil layers.
Our new LCIA method allows regionalized modeling of yield losses due to compaction impacts over the entire growing cycles for different crops and their production systems. Additionally our method relates soil moisture levels to the production steps showing more precisely the impacts of soil compaction.
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