Soil quality decreases due to soil erosion, salinization, depletion and desertification. This is an increasing problem in agricultural areas, particularly in Africa, parts of South America and South-East Asia. The damage to the environment caused by soil degradation is not incorporated in the current life cycle assessment methodologies (LCA). Environmental life cycle assessment (LCA) is a method for determining the influence of products and human activities on the environment.
One of the causes of soil degradation is that modern agricultural techniques remove an increasing amount of nutrients from the soil. RIVM developed a first concept of an indicator with which the depletion (nutrient loss) from the soil can be identified. This indicator may serve as one of the building bricks for an integrated soil quality indicator for LCA in future.
In this study, the emphasis is on the loss of phosphorus with the harvesting of eight crops (cassava, rice, banana, maize, soy, sugar cane, wheat and oil crops). Phosphorus is, next to nitrogen and potassium, an important nutrient for agricultural crops. We chose phosphorus, since its behavior is soils is easier to understand than that of nitrogen and more data are available than for potassium.
A method was developed describing the loss of phosphorus from soil by harvesting crops. This indicates whether phosphorus depletion might be an environmental problem at a specific location. Per crop and per country, a yes/no signature is provided, indicating a potential disturbance of the phosphorus balance in the soil. This indicator is a first measure of the severity of soil depletion on a specific location or country.