[Follow-up to Growing cover crops as if they are cash crops] Now that we’ve tilled in that buckwheat and planted radishes, turnips, bok choi, arugula, and other mustard greens there, we can give you an update on the experience. The buckwheat worked well–we mowed it at the right time, just as it was flowering but before it set seed, and I used the discs on the same day, which helped break up the roots and cover up the mowed buckwheat to speed decomposition. Our discs are a little wimpy (but we got them for free–thanks Janet and Rob!) so I was worried they wouldn’t tear up the roots, but the soil looked fluffy and loose and the buckwheat was totally dead when I was finished. Then we waited a week and I disked again, and then a week later I rototilled for a nice flat seed bed, as we were direct seeding, not transplanting. There were some buckwheat stems still visible in the soil, but they didn’t slow down the precision seeder. The seeding was quick and easy.
That’s the good news. The medium news is that the sorghum-sudan grass is a little out of control. Seeding it in a mix with buckwheat worked well; we mowed the patch when the buckwheat started to flower and the sudan grass was still little. Well, at least we mowed where we could. The patch neighbours a melon planting whose vines had spilled over into the cover cropped area, so there was nothing we could do without damaging our melons. (Note to selves: plant sprawly viney things next to things that don’t need to be mowed!) So now we have tall woody grass that is trying to flower, which is bad–we don’t need another weed in the fields–so this week Heather went through and cut off the flower heads by hand. We will still have to deal with all of the slow-to-break-down plant material come fall, but luckily we tried sorghum-sudan grass in a non-crucial area of our fields, so (hopefully) it won’t slow us down too much next year. (Thanks to Michael and Arden of Great Day Gardens for the sudan grass seed–we promise we will try it again!)
And then there is the bad news: the area that didn’t get a cover crop at all, and, predictably, grew up in weeds. Just as predictably, that field looked really trashy even after I chisel plowed (that’s a deep plow that breaks up roots and compaction without turning over the soil) and disced twice. The weeds had grown tall and deep-rooted, and then they flowered, so their carbon-to-nitrogen ratio changed to favor more carbon, which doesn’t break down quickly. So we’ll most likely be kicking ourselves when we transplant kohlrabi into that bed in a couple weeks because we’ll have to move aside plant residues to get to actual soil.
So while we feel like we did a better job this year than last, this mixed bag of experiences serves to motivate us to continue to try to improve our crop succession planning for next year. We clearly still have a lot to learn.