Decades of farming can influence the levels of total dissolved solids (TDS) or salts contained in drinking water supplies. Our drinking water comes from rivers, streams, lakes and underground aquifers. When there is runoff from rain or over irrigation of crops fields TDS will eventually influence these water sources. So how does growing crops add TDS to these sources?
Besides water being the universal solvent and dissolving the minerals already contained naturally in the soil, there is the application of fertilizers. Fertilizers increase crop growth and help supplement soils deficient in these minerals (nutrients)
There are two different types of fertilizers, organic and inorganic fertilizers. Organic fertilizers come from composting, the decay of natural food scraps and natural wastes. These fertilizers may not contain a sufficient amount of nutrients required for healthy crop growth.
Inorganic fertilizers are made from chemical compounds, and the three main nutrients are phosphorous, potassium, and nitrogen. Plants love these nutrients the most. Secondary nutrients are sulfur, calcium, and magnesium. Micronutrients are boron, cobalt, copper, iron, manganese, molybdenum and zinc. These nutrients (minerals) make up TDS, which through the application of fertilizers and irrigation can make their way into drinking water sources and add to natural TDS levels.
- California EPA: Water Boards
- Central Arizona Salinity Study - Phase I: Salinity and Total Dissolved Solids (PDF)
- City of Boulder/United States Geological Survey (USGS) Water Quality Monitoring: General Information on Solids
- How Stuff Works: What is Fertilizer and Why Do Plants Need it?
- Wise Geek: What Is Inorganic Fertilizer?