Mulching with mustard (Sinapis alba) as winter cover crop

This year I experimented to saw mustard (Sinapis alba) in one part of my garden as winter cover crop to protect the soil from erosion, enhance soil organic matter content and soil structure and to suppress weeds. This part of the garden was a very weedy grassland before I decided to cultivate it this year. The seedbed was prepared with a soil cultivator. Sheep manure was added to the soil after drilling, and it was mixed up evenly. Even though I managed to sow late (25.11.2020), the emergence was satisfactory. The seeds were sown in rows, 25cm distance between rows in one part and randomly at the other part. I saw no difference in the efficacy, so both ways are fine. I used mustard seeds from a grocery in the rows and certified seeds at the randomly sown pot and both emerged well. The area was well covered with mustard plants during whole winter season, and it suppressed the emerging weeds during winter. The soil remained soft and moist during the whole winter, so I was very happy with the results. I was expecting the frost in the winter to terminate the crop, but this year the plants were covered by 30-40cm of snow whenever the temperature was very low, so they continued growing. Finally the cover crop was mowed on the 10th of February at the height of 30 cm to terminate it. This is the maximum height that is recommended to mow, after that the plant residues become hard and more difficult to decompose. After mowing the plant residues were left at the field to cover the ground. These residues were not enough though to suppress the emerging weeds in the spring. I tried to prepare seedbeds without soil tillage and saw mangold between the residues of the cover crop (08.03.2021), but it did not emerge well due to the dense weed cover. I had to drill again in the spring to clean the soil from the weeds. Next year I hope that the frost will terminate the crop, so the coverage of the soil will be more even than it resulted through mowing, so the weed suppression will be sufficient in the spring. I might also need to saw between the residues earlier in order to have less weed competition.

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