When we bring summer squash and zucchini to the farmer’s markets in early June customers always ask us if the squash and zucchini are actually from our farm. Which of course they are. We work hard to have fruiting crops early in the season. We learned from past CSA member surveys that a month of greens is just too much for most people. In order to add variety to the shares we had to create the right growing environment for those heat loving crops like cucumbers, zucchini, peppers, and tomatoes.
These summer crops don’t like cold soil, their roots need warmth to grow and take up nutrients. Other crops like peas, radishes, and arugula like cool weather. For that reason you only see peas in the spring and arugula and radishes in the spring and fall. It is much more difficult to create cool growing conditions in the heat of July than warm growing conditions in the months of May and June.
We call the summer fruiting crops our “plasticulture” crops. (Which is now a misnomer as we no longer use plastic but we use the name anyway.) Tomatoes, cucumbers, peppers, etc want to grow in warm soil. If we waited for the soil to warm up enough for these plants you wouldn’t get tomatoes in your share until late August. In order to get zucchini in June and peppers in mid-July we need to ramp up the soil warming process. We do this with a layer of black biodegradable “plastic-like” product made of non-GMO corn starch called Biotello. We have a tool pulled by a tractor that lays down the sheet of Biotello and buries the edges with soil so it doesn’t blow away. The tool also lays a thin plastic tube for watering the crops under the Biotello.
(Disclaimer in the U.S. Biotello is not one of the products listed as a certified organic material. Biotello is a certified organic material in Canada and Europe. Here in the U.S. certified organic farmers are still required to use petroleum based real plastic mulch. This product has to be picked up and thrown away. Biotello breaks down in the soil.)
The black surface of the Biotello holds onto the heat from the sun and therefore the soil underneath is warmer than bare soil. We plant the crops into the Biotello and then cover the beds with wire hoops and a white fabric cover. This creates a little mini greenhouse out in the field. The fabric lets in light and water but keeps out the cold and any harmful insects. Once the plants begin to flower we remove the row cover for pollination. By this time the plants are also so tall they are pushing the row cover off anyway. Then we cultivate the soil in between the rows followed by a thick layer of straw mulch.
This straw mulch serves a number of purposes. One, it helps control weeds in between the rows. Two, it covers the soil preventing any erosion during hard rains. The straw also keeps the vegetables clean. No soil can splash up on the tomatoes or cucumbers so we don’t need to wash these vegetables.
Using Biotello also makes irrigation much more efficient. We put the water right at the roots, under the plants, and a layer of Biotello. There is little or no evaporation during irrigation. Plants like tomatoes are also very sensitive to diseases that develop on wet leaves. Watering the tomatoes under the ground keeps the leaves dry. We can also add nutrients to the irrigation water that help prevent disease and improve the health of the plants.
Six to seven acres of this system is a lot of work. But, considering the amount of vegetables that we harvest from these crops it all weighs out in the end. We pick veggies from this field from the first week of the CSA deliveries to the first frost which is almost five months of harvesting. This system has other benefits, too. We use less water to irrigate during hot & dry periods. We are able to recycle nutrients from our fallow fields through the use of the straw mulch that we make from these fields. Most importantly, the soil is covered for most of the season.
This kind of farming creates the conditions for improved soil health. Constant tillage to keep the weeds under control causes organic matter to burn up and breaks the soil’s natural structure. With the thick layer of straw and the Biotello the soil doesn’t need to be disturbed to keep the weeds under control. At the end of the season we work under all of the straw and seed a cover crop adding a tremendous amount of organic matter to the soil. We see this field as a way to maintain or improve our soil health while providing all of you with an abundance of tomatoes, peppers, eggplant, cukes, onions, summer squash, and zucchini. It is a win-win for everyone.