Aquaponics: soil-free farming at Nelson & Pade

previous arrow
next arrow

Rebecca Nelson always had a passion for raising fish; by the time she was 10, her family’s home was filled with aquariums.

Her partner, John Pade, grew up on a dairy farm, learning a lot about livestock and agriculture. The two combined their skills and interests in 1984 when they founded Nelson & Pade, Inc.

While the buzz word in agriculture these days is “healthy soil”, the Montello company is producing an abundance of food — both vegetables and fish — without any soil.

In their 14,000-square-foot commercial greenhouse, Nelson & Pade Inc. utilizes cutting-edge technologies to grow tilapia, lettuce, herbs, tomatoes, kohlrabi, radishes, and other vegetables. The fresh fish and vegetables are made available at local farmers’ markets and sold to restaurants, retail stores, and schools in Montello and throughout Central Wisconsin.


Known as aquaponics, the system combines aquaculture (fish farming) with hydroponics (soilless plant growing) through an integrated system.

Large tanks hold fish that are fed pellets or other protein-rich food. As their water is refreshed, the old water passes through a biological filter and on to trays of growing media (usually a fine gravel) for plants. In the trays, nitrifying bacteria convert the waste ammonia from the fish into the nitrates vital for plant growth. The growing plants remove more and more of the nutrients, filtering the water until it is clean enough to return to the fish tanks.

These recirculating farms can be small scale, to grow fresh food for a family, or larger, to feed a village or community or can be built as a commercial enterprise.

Nelson and Pade, Inc. offers aquaponic systems and growing supplies, training and workshops, consulting, information on aquaponics and tours of their aquaponics greenhouse in Montello.

Since the company started, Nelson and Pade have taught the system to thousands of people from many states and from 103 countries in the world.

The commercial greenhouse also houses the University of Wisconsin–Stevens Point Aquaponics Innovation Center (AIC) and classroom. Since December 2014, AIC has been working with Nelson & Pade Inc. to further aquaponics research and technological development in areas such as optimizing walleye growth, investigating effects of certain pharmaceuticals on aquaponics systems, and tracking aquaculture farming in Wisconsin.

In conjunction with AIC, Nelson & Pade Inc. offers a popular, three-day Aquaponics Master Class with hands-on sessions that focus not only on aquaponic methods, but also on economic and business considerations.

School visit

When students from the Waupun School District’s Charter School, School for Agricultural and Environmental Sciences (SAGES) visited the aquaponics facility last month they entered through a set of double doors. That, according to the tour hosts, is designed to keep insects out of the greenhouse. Throughout the facility insect screening is in place to prevent infestation by pests.

Matt O’Connell, an employee of the company for two years, described the system for monitoring insects. He says, “In the growing beds there are sticky traps to monitor pests that get in. When insects do get in, they are devoured by the beneficial insects that live here.”

In the classroom the SAGES students had already learned that humans and fish need oxygen and plants need carbon dioxide. They had learned scientific terms like good and bad bacteria, nitrites and nitrates. On the tour they saw firsthand what these mean to a healthy ecosystem and raising food.

O’Connell explained how this system uses bacteria to break down the waste into food for the plants.

He says, “The plants grow and then clean the water that returns to the fish tank.”

While the ammonia from the fish waste is actually toxic to the fish, the system is designed to convert nitrite to nitrate.

O’Connell also shared what he describes as an easy way to remember how the system works by converting nitrites to nitrates.

He said, “Nitrite is a fright. Nitrate is great.”

Students were most impressed when he held up the flat board of healthy green lettuce revealing the long roots that dangled below in the water.

He told them, “It takes just 40 days for a head of lettuce to grow and develop in this system and the only main input into the system is fish food.”

previous arrow
next arrow

Leave a comment

Your email address will not be published. Required fields are marked *

Una idea sobre “Aquaponics: soil-free farming at Nelson & Pade”