Cultivating Questions: Alternative Tillage & Inter-Seeding Techniques
from issue: 26-3
Cultivating Questions Concerning the Bioextensive Market Garden
Alternative Tillage & Inter-Seeding Techniques
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.
2a. Tilling the soil shallowly before planting the EARLY cash crops helps to preserve precious moisture by keeping the coarse winterkilled cover crop residues near the surface where they serve as mulch. Here, Becky and Buster are laying out the planting beds with wide sweeps mounted on the old riding cultivator. Usually, we work the dead oats and field peas into the top two to three inches using a disc, “ridger” and modified spring tooth harrow before forming the planting beds with the cultivator and sweeps. For more details on the cultural and mechanical aspects of these surface tillage techniques, we refer you to previous installments of this column.
Lister Planted Vegetables
3b. In May of 2001, we faced an unusual situation. After mulch tilling the winterkilled cover crops as shallowly as possible we did not receive enough rain to resettle and moisten the inch or two of tilled-dry soil on the surface for the rest of the month. There was plenty of moisture preserved below the mulch tilled layer for transplanting vegetable crops without irrigation, but hardly enough moisture at the soil surface for germinating direct seeded crops. In order to keep our successive plantings of spinach and carrots on schedule, we adapted lister planting to vegetable production. By mounting the ridge-till sweep (featured in the Spring 2002 column) on the front of the cultivator, we were able to move the loose, dry soil and cover crop trash to the sides of the planting bed. The narrow tooth attached to the bracket at the back of the cultivator marked a planting furrow in the exposed strip of moist, crumbly soil, perfect for direct seeding the spinach and carrots with the walk-behind Planet Jr. seeder.
4b and 5b. The next challenge was to figure out how to cultivate a lister planted vegetable crop that was seeded below ground level. We decided to be proactive, and cultivated the lister planted spinach before it emerged in order to reshape and level the bed and make future cultivations easier. Lister cultivating the spinach like this simply would not have been possible without using the rolling shields shown here. They prevented the emerging spinach from being buried by the soil and clumps of cover crop residues mounded up on each side of the row. At the same time, the fingers around the perimeter of the rolling shields allowed a light mulch of fine soil to flow over the planting zone to help hold in moisture and speed germination.
6b. Thanks to mulch tilling and lister planting, the spinach, carrots, and other crops grown in our EARLY fields established themselves quickly so they could take advantage of the rains which returned in June. This photo of field 12 (see the Cropping Plan chart in the last issue) was taken right after a brutal hailstorm toward the end of the month. Although the storm shredded some of the crops, there was little evidence of washing in this mulch tilled side-hill field. Minimizing runoff with conservation tillage practices not only reduces soil loss, but improves rainfall infiltration so that soil moisture is distributed evenly over a rolling field like this. On our soils, working the coarse cover crop residues into the soil surface results in much more uniform crop growth.
To take over the job of erosion and moisture control once the mulch tilled oats and peas have completely decomposed, we inter-seeded the EARLY cash crops in field 12 with two very different types of living mulch. For short-term cash crops, like the lettuce, spinach and peas in the middle of the field, we planted a single row of fast growing sorghum-sudangrass in the middle of the pathways. Between the rows of slow growing aliums, like the leeks on the next page, or the sweet onions along the upper side of the field, we planted hairy vetch.
A Living Mulch Of Vetch In The Aliums
7c. The single row of vetch in the middle of the pathways created a beautiful, moisture conserving mat blanketing the soil between the leeks. In fact, by the middle of August, some of the vines had begun to climb up the leeks, interfering with harvest and threatening to overwhelm the crop. To remedy the situation we used dischillers on the cultivator to trim back the vetch vines on either side of the row.
8c. Up close, you can see how the dischillers serve as coulters in this case, slicing through the vetch vines next to the leeks. Trimming back this living mulch with cultivator gave us a whole new perspective on cultivation: instead of using this tool to control weeds and aerate the soil, we were now relying on the old cultivator to manage biomass.
9c. A couple of weeks later the effect of pruning the vetch with dischillers became more apparent. The web of dead vines in the row helped to hold in moisture around the base of the leeks. At the same time, this technique maintained a green carpet of live vetch in the erosion prone pathways.
This photo was taken during the peak of the second dry spell we faced in the 2001 growing season. Not only did the vetch appear to keep the soil surface cool and moist, but at this point the leek roots were foraging into the middle of the pathways, apparently seeking the free nitrogen being fixed on the root nodules of the leguminous living mulch. Another advantage we noticed, on closer inspection, was the mat of vetch vines provided an excellent habitat for ground dwelling beneficial insects, such as spiders, ground beetles and earthworms.
10c. For all of the above reasons, we think the single row of hairy vetch makes a compatible living mulch for long term row crops like the aliums. By contrast, you can imagine what a disaster it would have been to inter-seed the leeks with a taller growing living mulch, like the sorghum sudangrass to the right. This seven-foot cover crop would have completely shaded out the leeks and robbed this full season cash crop of precious moisture.
Sudex In The Lettuce, Spinach And Peas
11D. We planted the sorghum sudangrass, aka sudex, between the rows of short term crops in field 12, like the lettuce, spinach and peas flanking the zucchini and cucumbers under the floating row cover. These short-term, cool season crops would be harvested well before the heat loving sudex would have the chance to interfere with the growth and the harvest of these cash crops.
12d. By the time the zucchini plants were completely beat, the single rows of sorghum/sudangrass in the pathways between the adjoining rows of already harvested lettuce, spinach and peas, had grown well over the horses’ head. To cut the tall woody stalks into more manageable pieces, we first mowed the sudex with the sicklebar in the transport position, cutting the canes two to three feet off the ground.
13d. Then we made a second pass with the sicklebar on the ground, cutting the rest of the sudex off at the base. We were impressed with the large pile of high lignin, carbon produced in the same growing season as the short-term crops of lettuce, peas and spinach. Another advantage to planting a single row of sudex in the middle of the pathways, where compaction is likely to be concentrated during planting and harvest, is this cover crop has the reputation of being able to break up compaction through its aggressive root system. Its fast growing root system also makes sorghum sudangrass a good candidate for drought hardy midsummer living mulch.
In addition, we noticed that sudex attracted a lot of aphids during its early spurt of growth. Fortunately, we do not usually have aphid problems with our market crops (the one exception being fall turnips) or we might have been alarmed by their concentration on the sudex. Instead, we looked at the aphids on the sudex as a benefit because they brought in a lot more ladybugs than we usually see in the market garden.
Mulch Tilling The Living Mulch
14e and 15e. Discing in the living mulches of hairy vetch and sorghum sudangrass at the end of the season with Becky and our new horse, Frank. Mulch tilling the living mulches helps to hold the soil – and the moisture – while the winter cover crop of rye gets established, just like mulch tilling the winterkilled cover crops before planting the EARLY cash crops. In this case, we broadcast the rye seed before the last discing of the vetch and the sudex, the easiest way we know of to plant a cover crop in this much coarse residue.
We built the heavy-duty wood platform and guard rail on the old disc to add some extra weight for better penetration. The platform also gives us the option to ride the disc, chariot-style, for working up dry, hard ground and tough cover crop residues during late summer or fall or to sit on the forecart when discing soft soil and residues, such as the winterkilled cover crops early in the growing season.
16e. The rye seeded in the EARLY fields at the end of the season protects the soil over winter and begins the next fallow year cycle of cover crops, this time, in preparation for the LATE cash crops slated for the field in two years time. Building soil structure and reducing weed pressure with the cover crops in the fallow year before production has been the key to making it possible to experiment with alternative tillage techniques and living mulches without the use of chemicals or specialized equipment. In the next issue, we hope to highlight some of the new tillage-cover crop combinations we used to conserve moisture and improve growing conditions for LATE crops planted during the hot, dry months of July and August in 2001.