Knowing Your Roots

Blog 32

The Central Sands is one of the nation’s premier potato and vegetable production areas, ranking 3rd in potatoes, 1st in snap beans and 3rd in sweet corn.  Agriculture in the Central Sands is vital to Wisconsin’s economy, generating over $6.4 billion in revenue and providing 35,000 jobs.  This agricultural bounty is possible because of the area’s broad expanse of fertile soils (developed as a result of retreating glaciers over 10,000 years ago), by our mild temperate climate, from the hard work and dedication of the farmers who settled, manage and continue to operate on the landscape and ultimately, the groundwater.  

A deep groundwater aquifer underlies the Central Sands.  This precious resource provides the ability to irrigate vegetable crops—irrigation allows for consistently high levels of productivity that provide a healthy, safe and abundant food supply.  This even occurs in the face of annually fluctuating climatic conditions; nature replenishes the aquifer every year with a generous 30 plus inches of rainfall.  For this we are fortunate. So when conditions are dry, the crops need more irrigation. When wet periods occur (for instance this spring) not only do the crops need less irrigation, but the aquifer recharges and the system rebalances.

Every farmer is acutely aware of the need to balance the water we take with what is returned. Farmers in the Central Sands are doing everything they can to keep the delicate balance between the water they use and what nature returns by being more efficient in how they irrigate. Every drop of irrigation applied is based on sophisticated scheduling programs that take into account exactly how much water each crop needs at each stage of its growth, how much water the soil can hold and how the weather will impact supply.  Water is then only applied to match the precise crop demand; the center pivot irrigation systems that deliver the water are also using cutting-edge technologies to increase precision. Farmers are now looking into the future and new ideas for investigating site-specific delivery, drip irrigation systems and even deficit irrigation—withholding water at less critical times to induce plant roots to delve deeper in search of soil reservoirs.  To be sure that the system stays in balance and that their innovations are having an impact, farmers have initiated an ambitious and extensive network to track groundwater fluctuations in irrigation wells across the Central Sands.  Almost 500 water-depth readings have been taken since 2012 and are backed by 20 continuous-monitoring wells installed by University of Wisconsin researchers in nested transects across the most sensitive sites.  Initial results are encouraging and show that the groundwater aquifer responded to the rains in 2013 with modest increases in depth that are helping to redress the water lost in the drought of 2011-12.

The investments made by farmers are being helped along by a gradual evolution of the crop landscape in the Central Sands. This process, which is influenced by changing economic times as well as the need to conserve water, has seen crop landscapes move slowly from high water use systems based largely on potatoes to a mixture of potatoes and processed vegetables (such as sweet corn and snap beans), which require significantly less water. It is happening slowly; in the decade between 1996 and 2006, potato acreage in the Central Sands decreased by 28% (59,500 to 42,800 acres), while sweet corn increased 36% (30,300 to 47,300 acres) and snap beans increased 26% (31,600 to 42,700 acres). But what does this mean in terms of water? Potatoes grow for 100-110 days, sweet corn grows for 84 days and snap beans grow for only 56 days. This means that potatoes use 22 inches of water, sweet corn uses 10 inches and snap beans uses only 7 inches. To put this in perspective, sweet corn uses 54% less water than potatoes and snap beans use 68% less!  Since acreage of sweet corn increased by 36% and snap beans increased 26% and potatoes decreased by 29%, the modern landscape is using significantly less water now than it was a decade ago, simply by these changes to the cropping systems!

This raises the intriguing possibility of designing crop landscapes in the future that can be equally profitable and yet require significantly less water.  How long can it be before we must examine the whole landscape and begin to question the impact of the non- cropland components, such as pine and deciduous forests, that each require almost the same water as potatoes?   Water conservation is in everyone’s best interest, and the farmers of the Central Sands have proven that better water management is both possible and profitable.

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