FairShare’s Small-Scale and Organic Produce Educator, Claire Strader, worked with three farmers in 2016-17 to test in situ mulch as a way that organic farmers may explore no-till planting techniques.
Why a no-till technique? One of the most common criticisms of organic agriculture is that it relies too heavily on tillage. Tillage is known to have a negative effect on soil structure and leads to loss of organic matter and beneficial soil organisms. While organic vegetable
farmers already grow cover crops, practice crop rotation, and incorporate other techniques to counteract the negative effects of tillage, the results of this trial provide additional ideas on how to include some no-till tomato practices.
The trial: The project explored the use of season-long managed fallow concluding with high-residue, winter-killed cover crops to create a weed free mulch that does not need exact timing or special equipment for termination. The primary cover crop was sorghum sundangrass, which is known for producing large amounts of biomass. Before tomato planting, however, it was clear that the sorghum sudangrass residue would not provide adequate weed control for the cropping year. The project then pivoted to look at three supplemental mulch materials used to exclude weeds in the no-till tomatoes: green or black plastic, black landscape fabric, and marsh hay.
The results: There was no yield difference in the no-till vs the control plots, however labor and material costs varied. The landscape fabric required more labor, due to the time spent creating and planting into the fabric holes. This time could be reduced by laying two lengths of fabric side by side with a slight overlap, leaving a bed-length seam down the middle. On the other hand, marsh hay required less labor but had a higher material cost. That additional cost may be offset by improved soil structure and increased soil organic matter in the long-term, but it was not possible to quantify those benefits during the term of this trial. Also, though overall yield was the same in the end, the harvest in marsh hay system was delayed. This method might be valuable in conjunction with one of the other systems as a way to extend the tomato harvest season.
Read the full report, including recommendations for farmers here: Sorghum Sudangrass Residue as No-Till Mulch and Mulch with No-Till Organic Tomatoes. This project was completed with funding from North Central SARE.