Black plastic mulch is a commonly used tool in row-crop and hemp agriculture as it increases the growing degree days (GDD) for the crop being produced as well as suppresses weeds that would otherwise grow up in the row. So what’s a GDD? Good question. A GDD is a measurement of the amount of heat units gained in any given day of the growing season. So, for instance if the high of a day in July was 78 F and the low was 50 F the average would be 89 F. Using a baseline of 50 F a GDD would be summed by any degrees over 50 F so 89-50= 39 GDD for that day in July. Over a season these GDD accumulate and give us an Idea of when a crop should be ripe as well as if a crop should even be planted in that region. So, there are both weed suppression gains and also economic gains due to black plastic mulch in that you can grow a larger plant, faster in a cooler climate.
All this sounds great right? Not to us! plastic mulch is a one-time use item and when the season is over it gets ripped up and thrown away in the landfill. Over one acre there are about 7,000 ft of black plastic equaling hundreds of pounds of trash. Recycling you would hope to be a more utilized option but muddy plastic is not what large scale recycling operations receive. To think, in Oregon, where we can’t even get plastic grocery bags anymore, there must be another way right? So, we set out to learn what our options were and after some research into the subject of living mulch we decided this was a good choice for us to trial in the 2019 growing season.
So, what is living mulch? Living mulch is exactly what it sounds like, it’s a mulch cover that is made up of living plant matter that can have many benefits for both the crop, soil and the insect ecosystem in the area. We decided to use buckwheat as our mulch in the center 7 rows of our field as it can tolerate low water needs and has a large leaf area in place of the black plastic mulch (which we did still used on the rest of the field, remember this was a trial). We broadcast and raked our seed in late June and with the help of some early July rains, all the seed sprouted and gave us great weed suppression throughout the year.
The bees loved the buckwheat as well as many other beneficial insects like lady bugs, spiders and green lacewings. As expected though, due to a decrease in GDD in the buckwheat trial, we noticed a reduction in hemp plant size with-in the trial block. Also worth mentioning- we planted the buckwheat block last (June 25th) compared to the adjacent blocks June 10th and June 15. So some of the size comparisons could be attributed to that.
Alas, as harvest began to approach we leveled the buckwheat by driving over it will a four wheeler and dragging a 4×4 (one of many super expensive pieces of equipment we have)and opened up the plants to a bit more light exposure about two weeks before we picked. When we started preparing to harvest for flower we saw the immediate difference in flower quality that the buckwheat rows were able to produce and this is when I fell in love with this trial! The size of flower was about the same maybe a little smaller compared to the plastic mulch control, but the density was incredible with perfectly ripe dense golf balls on all the plants 10 days earlier than anywhere else. With this trial done we would like to continue experimenting with the use of buckwheat and different legumes like peas and vetch or clover for nitrogen fixing to lesson our environmental footprint and replenish the soil from which we reap the rewards while also allowing us to produce the highest quality smokeAble product for our customers. This to us, is what it means to be regenerative farmers.