Cultivating Questions Concerning the Bioextensive Market Garden
by Anne and Eric Nordell
One reason we continue Cultivating Questions is that SFJ readers – both horse farmers and tractor farmers – keep telling us that they’re trying out the alternative tillage methods described in this column. In response to this practical interest, we will also focus on adapting traditional tillage tools to new purposes. Of course, we can’t help throwing in a few notes about cover crops and crop rotation since these “tools” are really the key to making these alternative tillage techniques work on our farm.
In the last column, we looked at how the high-and-dry cover cropped ridges made it possible to begin planting on schedule despite the wet conditions we faced in April 2001. In this issue, we will try to describe how mulch tilling our flat fields saved the day when the weather turned dry in May.
A spring drought in the Northeast is kind of unusual, but by mid-May last year we heard from growers who were already pumping water on their fields to get their crops germinated. At this point, our cover cropped ridges had dried out too much for no-till planting without irrigation. So we decided to take a step down in elevation, and began tilling our flat fields.
These flat fields for EARLY planted crops, identified as #8 and #12 in the Crop Map in the last issue, were protected with a moisture conserving cover crop of winterkilled oats and Canadian field peas. One of the advantages of using these winterkilled cover crops is they do not suck precious moisture out of the soil in the spring like a live cover crop of rye. To the contrary, the dead residues blanketing the ground seem to conserve the whole winter store of moisture.
We try to prolong the moisture conserving effect of the winterkilled cover crops as long as possible by working the residues shallowly into the soil. Surface tillage with a disc or field cultivator keeps the “trash” in the top 2-3” of the soil where it will help wick rainfall into the earth, and trap moisture at the surface when it rises from the subsoil during dry weather. In some areas, this conservation practice is called “mulch tillage” because the mulch of crop residues on the surface helps to slow down erosion. In general, we have found that what is good for conserving the soil is also good for preserving moisture.
Mulch tilling the winterkilled cover crops has reliably held plenty of moisture for planting EARLY cash crops, like lettuce, spinach, onions and peas, over the years. If anything, this tillage-cover crop combination sometimes preserves moisture too well, delaying fieldwork and planting. One reason we adapted ridge-tillage to vegetable production is so we would have a high-and-dry alternative in wet conditions. By including both flat fields and ridged fields in our cropping plan, we thought we had our bases covered for both weather extremes.
However, the rapid change from wet to dry in 2001 proved to be more of a challenge than we had faced in the past. The dry weather that arrived the end of April, and finally made it possible to mulch till the winterkilled cover crops in our flat fields, persisted until the beginning of June. We simply did not receive enough rain during that time period to settle and moisten the shallowly tilled soil. Yes, there was plenty of moisture preserved beneath the two inch layer of dry soil and cover crop residues for transplanting lettuce and onion starts, but not nearly enough moisture at the surface for direct seeding fine seeded crops, like spinach and carrots.
We were really scratching our heads about how to keep up with successive plantings of these direct seeded crops when two clues to a solution arrived in the mail from the SFJ office. First, Lynn Miller’s excellent book on Horsedrawn Tillage Tools contained a whole chapter on lister planting and cultivation. It explained how this traditional dryland farming technique relies on planting the crop in the bottom of a furrow a few inches below ground level. The idea, as we understand it, is that more moisture is likely to be found at this depth than on the surface in arid areas. Also, future cultivations will fill in the planting furrow, burying weeds in the row and mulching the plants deeply with soil to hold in more moisture.
Unfortunately, the ingenious tools for lister planting and cultivation catalogued in Lynn’s book are not available here in the Northeast. And trying to build something similar from scratch seemed way beyond our ability. Fortunately, the Spring 2001 SFJ arrived in our mailbox shortly thereafter, and on page 90 a reprint of a 1918 ad for a unique corn planter attachment caught our eye. Guaranteed to improve germination even in rough, dry conditions, The Vivion Hoe and Gauge Attachment, pushes dry, coarse soil to the sides, clearing a fine, moist seedbed right in front of the planting shoe. This clever attachment reminded us, in principle, of the ridge-till sweep we use for knocking off the top of the cover cropped ridges.
Sure enough, the ridge-till sweep did a wonderful job of pushing the top inch or two of dry soil and trash to the sides of the planting beds, exposing a narrow strip of clean, moist soil for lister planting the fine seeded vegetables. By simply using our existing equipment for a totally new purpose, we were able to continue our successive plantings of spinach and carrots on schedule throughout the dry month of May.
Another critical piece in putting together the lister planting puzzle was figuring out how to cultivate a vegetable crop planted below ground level. We found a solution when attending a workshop on field crop cultivation put on that April by Klaas and Mary-Howell Martens, the 1300 acre organic grain growers we have featured in previous columns on nutrient management. The object of their cultivation system is to throw as much soil on the row as possible to bury weeds growing in the rows of their fast growing crops. To do this effectively, they removed all the rolling shields from their belly-mounted six-row International cultivators.
The castoff rolling shields looked like just the ticket for cultivating vegetables in high residue conditions, and the Martens were kind enough to give us a set to try out on our one-row horse-drawn cultivator. As shown in the photo essay in the last issue, the rolling shields seemed made-to-order for ridge-till cultivation with the horses. They also turned out to be the perfect solution for cultivating lister planted carrots and spinach by preventing the soil and cover crop residues (piled up on either side of the below ground planting zone) from burying these low growing vegetables. In retrospect, we ended up relying on the technology from two very different eras of agriculture to adapt lister planting to horse powered market gardening on the spur-of-the- moment.
We include a couple of snapshots of lister planting and cultivating in the following photo essay on mulch tilled vegetables just to show the importance of being able to adapt to the extremes in the weather. Looking back, it is clear that a diversity of tillage options played a major role in making 2001 our most productive year ever. Between the beginning of April and the middle of May, we went from no-tilling the tops of the eight inch high ridges to lister planting two inches below ground to adapt to the rapidly changing moisture levels in the soil.
The photo story also highlights some of the inter-seeding options we used in the EARLY crops last year. Again, our intention is not to advocate the oddball living mulches we use with this single row inter-seeding system, but just to show how it is possible to utilize the between-row areas to improve insect habitat, reduce erosion, conserve moisture, fix some nitrogen, and grow a good bit of extra organic matter. If nothing else, experimenting with these alternative practices continues to keep farming exciting as we begin our twentieth season of bio-extensive market gardening.
Alternative Tillage & Inter-Seeding Techniques For Dry Land Market Gardening
Mulch Tilling For Moisture
1a. An overview of the bio-extensive market garden in April showing the alternating fields of cash crops and fallow lands. In the foreground is a field of mulch-tilled oats and Canadian field peas ready for EARLY planted cash crops. In the second field grows a cover crop of winter hardy rye, building soil structure and reducing weed pressure for the EARLY market garden crops to be planted in this field the next year. Generally we turn under the rye in late June and replant the fallow field to oats and peas early in August following a bare fallow period midsummer.
One of the advantages of using a cover crop which dies back over winter is this winterkilled cover will not suck the moisture out of the soil prior to planting the EARLY cash crops. To the contrary, the mulch of dead oat and peas residues on the surface helps to hold in a whole winter’s store of moisture. By contrast, the over- wintering cover crop of two-foot tall rye in the fallow field has already used up a good portion of the accumulated winter precipitation. Planting an un-irrigated cash crop right after incorporating the rye would be a real mistake if the weather turned hot and dry like it did in May 2001.