Growing watermelons is nothing new for Steven Kirk.
Kirk has grown watermelons, in combination with cover crops, for several years – more so as a cultural practice than a research study. That all changed three years ago, when Deborah Finke, an associate professor in the Division of Plant Sciences, was able to secure a grant from Ceres Trust to study how cover crops can be integrated into an organic watermelon production system to reduce weed pressure, attract beneficial insects and build soil health.
Kirk, a research specialist in the Division of Plant Sciences, serves as the technician on the project, which takes place at the Bradford Research Center, in Columbia.
“Generally, when you plant your production crop, you come in after harvest and plant your cover crop,” Kirk said. “We’re looking at those systems, as well as researching what happens when you plant a living cover crop in combination with your production crop.”
The grant from Ceres Trust was part of its Organic Research Initiative, which began in 2009 with a focus on providing research results for organic farmers.
Kirk planted around an acre of watermelons as part of the project. The project is broken up into smaller plots to feature different cover crops and different planting intervals. Kirk is using three cover crops in the study – buckwheat, cowpea and yellow sweet clover. The cover crops were planted at four different intervals: one week before the planting of the watermelons, the same time as watermelons, one week after the planting of watermelons, and two weeks after the planting of watermelons.
“While the project has several foci, my primary objective is looking at the weed control and soil health in this cover crop and watermelon system,” Kirk said. “It’s an organic project, so we don’t have the same tools in our toolbox as conventional farmers. We’re really just planting everything and letting it go to see how well, and if, the cover crops suppress weeds.
“A farmer could get a lot more production off of this land, obviously. We try to mimic farming practices as closely as we can with our projects – we want our data to be transferable. Our goal is to help the local producers. We can afford to take the risk. If a projects flops, we can provide the results and help inform individuals on the pitfalls we encounter in order to help them to avoid the same problems in their fields. For a farmer, this is oftentimes their livelihood. They can’t afford to take the same big risks as researchers can.”
All of the plots are tilled just prior to each cover crop planting to get a jump start with weed suppression.
“We’ve tilled everything right before we plant,” Kirk said. “If it’s dry on Thursday we’ll till the land to plant on Friday.
“Although there has been a big push in recent years to reduce tillage, it is still one of the top weed control methods in organic production. We hope to find that using a living cover crop can reduce the amount of tillage while building healthy soils and reducing erosion.”
This is the final year of the project, so Kirk is still waiting to complete his data collection. He has noticed a few trends during the first two years of the study. So far, both buckwheat and cowpeas have done a nice job of suppressing weeds. The cover crops planted after the watermelons have also seen better success.
“The cover crops planted one week and two weeks after the watermelons are at a little bit of an advantage,” Kirk said. “We are able to till right up until we plant those cover crops. Since the watermelons have only been in the ground for a couple weeks, their vines haven’t spread. We can till right up until we plant the cover crops. We can get to those weeds before we even plant.”
The clover has been a little bit tougher to judge. The clover Kirk used during the first year of the project never took hold. Kirk switched to a different variety and saw better results last year. However, the clover has struggled again in 2018. Kirk is actually doing a separate clover study to nail down what varieties do well in central Missouri.
“The first variety was more suited to areas south of where we are,” Kirk said. “We switched to a different variety last year. You have to have rain when you need it for clover to succeed, and, in Missouri, that rain isn’t always guaranteed.”
The Missouri weather will definitely play a role in the study. Rainfall amounts were strong in 2017. This year hasn’t been as helpful in terms of rainfall, and Kirk has spent much more time watering the watermelons this year, while the cover crops have to rely only on the rain.
The watermelons were planted toward the end of May and the beginning of June during each year of the project. Harvest takes place during the first part of September. Watermelons don’t need a ton of water to be successful. Watermelons are a unique vegetable, as it vines out instead of staying in place.
“Watermelons do really well in Missouri, actually,” Kirk said. “You can overwater them, so you have to be aware of that.”