This year was officially declared the International Year of Soils by the United Nations.  As part of the year-long celebration of soil, the Soil Science Society of America has assigned a different theme to each month of the calendar. This month has been officially dubbed “Soils Clean and Capture Water” month.

So how exactly does soil clean and capture water?  This blog will explore these amazing capabilities within your soil.

Soil helps filtrate water as it seeps through the many layers of soil.  This process of water flowing through the soil layers acts as a physical filtration system. On a chemical level, soil particles carry a negative charge which attracts and captures positive ions typically found in water like calcium, magnesium and potassium.  This frees nutrient-rich ions from the water for absorption by plants in the soil.  The soil also transforms particles in the water biologically through covalent bonding.  In this process, soil serves as the largest bioreactor on the planet. Microbes within the soil interact with organic particles in the water and can decompose and transform chemicals like nitrogen into ammonium ions or even nitrogen gas.

The process of soils filtering out pollutants and other particulates depends heavily on the type of soil the water comes into contact with.  For example, rough, loose soil has large pores which do an inadequate job of filtering the fine particles present in the water whereas super-fine soil has pores so small that it doesn’t allow water to flow through it.  The ideal soil for filtration lies in somewhere in the middle of these two types where there are small pores to filter out particles, but also larger pores that allow water to flow through.

In many cases rain falls onto non-porous surfaces causing it to run over the surface and can often collect contaminants like fertilizers or animal waste as it flows into nearby bodies of water. Managing the landscape and soil is an essential way to minimize pollutants from contaminating larger bodies of water and increase the absorption of rain into the land and soil.

Soil helps capture water because it slows down its ability to flow (as compared to it landing on non-porous surfaces on which it flows freely over).  Not only does this allow the soil the time and means for filtering the water, it also takes longer for that water to flow into nearby streams or lakes and in turn, results in that water entering the system much cleaner that it would if it flowed over the land accumulating contaminants.

Check out NACD’s new Soil Health Section on our website for more great information about healthy soil.

You can find out more about this month’s theme by visiting the Soil Science Society of America’s International Year of Soils webpage.

Tags: Soil Health, International Year of Soils, Soil, water, Soils Clean and Capture Water, water filtration