Knowing Your Roots

Blog 17When it is warm and dry, you have probably noticed that plants require a lot of water to stay healthy, but did you know that only 10% of the water a plant receives actually remains inside of it to support life processes? Plants lose the other 90% of their required water (liquid) as water vapor (gas) to the atmosphere through a process known as evapotranspiration (ET), which is a combination of water the plants emit from pores in their leaves (transpiration) and water that evaporates from soil and plant surfaces.  ET uses a tremendous amount of solar energy, and this energy use coupled to the plant water use is referred to as the water-energy cycle of a landscape. When humans alter the composition of plants across a landscape (i.e. urbanization, agriculture), they also alter the water-energy cycle. 

At the University of Wisconsin, Professor Chris Kucharik’s Agroecology Research Group studies the effects of agriculture and urbanization on the water-energy cycle. Mallika Nocco, a doctoral candidate, focuses her research on how irrigated agriculture in the Wisconsin Central Sands alters the water-energy cycle.  Ms. Nocco studies irrigated agricultural land use at both the regional and local scale by conducting field experiments, running computational models, and consulting with local growers and stakeholders. She works with Isherwood Farms (a 1,500 acre, 7th generation family farm nestled close to the Buena Vista Marsh in Portage County) to better understand the relationship between irrigated agriculture and the water-energy cycle. One of her primary research goals is to develop realistic water budgets for common cropping systems in the Wisconsin Central Sands. This involves understanding the ET and groundwater recharge (water returned to the aquifer from irrigated cropping systems).  Since ET cannot be easily measured directly, data have to be collected to help infer ET levels, and data measured include plant growth, leaf gas exchange, soil moisture and drainage below the root zone. By collecting these data on a working farm, Mallika is able to develop and ground-truth regional predictions of ET associated with key agricultural crops, which are important estimates as growers try to match irrigation with crop need.

Furthermore, Mallika is developing and validating regional predictions of ET and groundwater recharge using a numerical agroecosystem model called Agro-IBIS that simulates the movement of water, energy and nutrients in both agricultural and natural landscapes. Agro-IBIS uses meteorological data, soil/plant properties, and agricultural practices to “grow” virtual crops or native vegetation over a specific landscape. She plans to use Agro-IBIS simulations over the entire Wisconsin Central Sands region to better understand how ET and groundwater recharge from different irrigated cropping systems and natural landscapes change in space and time with the hope that these water budgets will inform stakeholders in their water management strategies. This research will play a critical role as growers in the Central Sands strive to use ET to balance crop need, irrigation, and aquifer recharge to conserve the water resources of Central Wisconsin for future generations.

For more information, contact Mallika Nocco at nocco@wisc.edu.

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