Many of us pay hardly any attention to the ground and simply stride across it unseeing. Yet the soil we tread is what gives us life: as arable land it feeds us, in general it stores water and nutrients, and because it absorbs carbon, it has an impact on the amount of CO2 in the air and in turn on global warming. But our soil is ailing, says Sonia Meller, soil scientist at ETH Zurich: “Intensive agricultural use has worn out the soil in many areas.” That’s why she and agricultural scientist Hélène Iven have developed Digit Soil, the first sensor to measure soil quality on site – quickly and cheaply.
Unhealthy soil
The need for improved and more systematic soil monitoring is painfully urgent. According to the Food and Agriculture Organization of the United Nations (FAO), a quarter of all agricultural land was already highly degraded as of 2011. This means that the soil contains hardly any organic matter, which is where life-giving transformation processes take place. As insects and microorganisms decompose this dead plant and animal matter, using enzymes to break it down into its chemical components, they produce raw materials and nutrients for new plant growth. With advancing degradation, however, soil loses this ecological function and becomes barren. It can no longer offer a habitat for microorganisms, nor can it store water or nutrients. At this point, even fertiliser is no help – the nutrients would simply wash away in the next downpour.
