This year we will be participating in another strawberry experiment with my friend Joji Muramoto who is a researcher at The Center for Agroecology and Sustainable Food Systems. I enjoy working with Joji because not only are his experiments well designed and thorough, but he seeks to answer questions that are of great interest to growers. In the past we’ve helped him with his fertility trials–comparing rates and timing of compost and fertilizer application in organic strawberries.
The experiment this year will focus on mustard seed meal on a small portion of our strawberry field. Mustard, along with other members of the brassica family including broccoli, have long been known to contain compounds known as glucosinolates. When the residue of a broccoli crop or a mustard cover crop is incorporated into the soil, these compounds have been proven to reduce the amount of soil borne diseases. (We’ve experimented with different cover crops in the past and typically plant Sudan Grass before strawberries.) Since they can also reduce the number of viable weed seeds in the soil, these crops are sometimes referred to as “biofumigants”.
As it turns out, if the right varieties are used, the meal that is left after mustard seeds are pressed for oil can also contain high levels of glucosinolates. Mustard seed meal also contains around 6% nitrogen and can be used as a fertilizer. Recently a farmer owned company called Farm Fuel Inc. started up here locally which makes biodeisel from mustard seed oil and sells the meal as a soil amendment.
Because rents are so high around here, large scale strawberry growers (even organic ones) are very reluctant to tie up land in cover crops in the middle of summer. And since mustard seed meal can be made into pellets that can be applied less than a month before planting, it is much more likely to be adopted. The fact that it serves as a fertilizer will only make it more attractive.
This year’s experiment is designed to find out the optimal application rates for mustard meal. It will have three different application rates in twelve different combinations–with or without compost and with or without supplemental fertilization–in four replications for a total of 48 plots. This week we will spread the meal on top of the beds and then make a pass with the tractor rototiller to shallowly incorporate it. Then we lay down our drip tape, cover the beds with plastic mulch, and pre-irrigate to activate the glucosinolates. We then wait three weeks before planting the berry plants. Over the season next year, we will compare the yields of marketable fruit between the plots, and Joji will monitor weed biomass, plant size, fertility, and the presence of fungal diseases.
Cooperating in these studies helps to forge a good relationship with researchers and insures that we are kept in the information loop. And at a time when the only alternatives conventional growers are proposing to the ozone depleting fumigant methyl bromide are even more toxic (methyl iodide), it feels good to be playing a small part in finding a real alternative.
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