The Water-Soil Nexus: Groundwater and Sustainable Agriculture

By jsalvino on FlickrBy: Alexis Van Gelder

It’s not a stretch to say that agriculture is incredibly dependent on water.  After all, in countries across the world, agriculture uses between 70% and 80% of the total water supply.  What may not be so obvious, however, is that water is also heavily reliant on agriculture.  In other words, the way farmers and ranchers treat their land can have a profound effect on water supplies, and specifically on groundwater resources.

How Water Comes from Dirt…

Over 40% of the water used in agriculture is withdrawn from the ground.  If this water is not replaced each year, the water table drops, and over time groundwater resources are depleted.  As a result, there isn’t enough water for crops to be planted and the land becomes unproductive.  Clearly, minimizing groundwater usage by employing efficient irrigation techniques is a good first step to avoiding this problem.  But the bigger question is, how do we replenish groundwater resources annually and ensure the water table doesn’t drop?  It seems that this would be the only feasible way for farmers to have a reliable and stable supply of groundwater to irrigate their crops.

The first thing to realize is that a region’s level of groundwater relies primarily on two factors: the amount of rainfall it gets and the quality of the land.  Obviously in places without much rainfall, groundwater levels remain low.  But in many regions of the world, there is plenty of rainfall, yet the water table still doesn’t get replenished and the land is as unproductive as a desert.  This transition from productive land to unproductive land is called desertification, which now spans almost one quarter of the Earth’s land surface.  As a result, one third of the world’s productive soil has disappeared, and if this trend continues, the soil in certain regions, especially where bedrock is only a foot or so below the land surface, will turn to dust and blow away.  So the question is, why is this happening?

The answer is poor land management, which ranges from improper resting of land and over-grazing of herds to the over-reliance on fertilizers, pesticides and herbicides and mono cropping.  Whether we’re talking about land used by large agribusinesses in the developed world or small farmers in the third world, rainwater does not absorb into the soil easily when land is not managed properly.  When the land doesn’t have enough vegetation or groundcover to protect it, the land becomes dense and impenetrable from the impact of rainwater droplets.  Instead of absorbing into the ground, the rainwater runs off the land and increases the effects of floods downstream.  Both floods and unproductive land are huge risks to a community’s regional food production capabilities.

Water-Friendly Agriculture

Luckily, there is a solution called sustainable land management (SLM), which is broadly defined as “a set of land-use practices that preserve the health of land, water, and vegetation.”  SLM techniques have proven to reverse the effects of desertification and increasing the productivity of millions of acres of land.  There are numerous techniques within SLM.  It isn’t a one-size-fits-all formula.  Each region has a unique natural habitat, soil composition and climate, all of which affect how SLM practices are implemented.  However, if SLM is applied properly, rainwater begins to absorb back into the soil and crops soon become more productive, increasing the land’s value and profits to farmers.  This in turn can create jobs and alleviate poverty in many regions.  Furthermore, because of a more reliable supply of food and water, regions using SLM practices are more stable, resistant to economic volatility and resilient during droughts, floods and other climate related crises.  The lesson: if we take care of our land, we can go a long way to creating a safe supply of groundwater and solving numerous other problems.

Alexis is a MBA candidate at the Presidio Graduate School.

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