Soil Erosion from Agricultural Land Use Change
Humans have the power to influence the functioning of the Earth’s Critical Zone through the activities, that affects major elements of normal soil functioning. In this blog post, we focus on land use change because of agricultural activities. In the last ~50 years, there is rapid increase in agriculture to feed the exploding population size. However, we did not consider what our impacts might be.
Agricultural soil erosion is triggered by vegetation and soil disturbance in upland areas. In the case of agricultural soil erosion, at least 80% of the eroded sediment is re-deposited within a short distance (<5km) of the source, in colluvial or alluvial sediment stores.
There are several impacts of the impact of this erosion. Firstly, there will be huge losses of N for the crops. Since soil organic matter usually contains 5-10% of N, erosion affects the N cycle. These N are redistributed, either to return back to the atmosphere after being displaced from soil, or enter the groundwater as a form of contamination. In places like the sub-Saharan Africa, where the input of nutrients is scarce, the loss of N is a huge threat to their crop growth. Additionally, the erosion also results in redistribution of P. These P is lost to groundwater in large amounts. Also, erosion can lead to a large release of Si into aquatic environments. This is a combined effect of the increased dissolving of Si from soil, as well as increased soil drainage.
Such loss of N, P and Si could severely hamper the healthy growth of crops. On the environmental pollution front, the excess nutrients entering groundwater and potentially becoming a drinking water source is known as contamination. As for N & P in particular, their increased presence in aquatic ecosystems would lead to accelerated primary production of algae. As for Si, their increased concentration in aquatic ecosystems could lead to bioaccumulation and biomagnification in organisms when they enter the food chain. Notably, since Si is also a heavy metal, their accumulation can become toxic and cause chronic respiratory effects.
That’s all for today! We will be back with another post soon 😄
References:
Govers, G., Van Oost, K. and Wang, Z., 2014. Scratching the Critical Zone: The Global Footprint of Agricultural Soil Erosion. Procedia Earth and Planetary Science, 10, pp.313-318.