Cultivating Questions: Ridge-Till Revisited
by Anne and Eric Nordell
Over the past six years of cultivating this column, we have tried to answer the questions addressed to us via rural delivery. For a change of pace, we decided to devote this space to a topic of interest at the small group tours held at our farm last year. Many of the participants seemed genuinely excited about trying the alternative tillage techniques we have adapted to market gardening. Of particular interest was our experimental practice of no-till planting vegetables on cover cropped ridges.
We will let the following photos tell the story of how this hybrid planting system evolved. The Ridge-till Revisited photo essay begins with a brief review of the principles and practice of horsedrawn ridge-tillage as described in the Winter 1998 column. It then looks at the advantages of reducing tillage even further in the case of no-tilling the ridges with alliums in 2001. The results of this new development were so encouraging that we think it might be the key to no-tilling produce in our cool climate. Our optimism is based on the fact that the soil in the cover cropped ridges stays much warmer than under the same amount of cover crop residues in a flat field.
Ridge-till Revisited also details recent mechanical and biological improvements which have made ridge-till planting and cultivation more efficient and effective using the team and the old riding cultivator. We realize that these tools and techniques may not be of practical interest to most growers. We document them here just to underscore the importance of building a measure of flexibility into a sustainable cropping system.
For instance, the raised ridges made it possible to begin planting on schedule during the wet month of April last year. In the next issue, we hope to show how we were able to keep up with our successive plantings of peas, lettuce and spinach during the drought conditions of May by forming low planting beds and adapting lister planting to vegetable production.
Just to show how easy it is to design this sort of flexibility into a well-defined rotation, we have included our 2001 crop plan in this column. The map indicates the essential elements of the bio-extensive cropping system – alternating the half-acre strips between cash crops and fallowlands, and rotating the cash crops between those planted EARLY and those planted LATE. The accompanying field notes detail the diverse mix of cover crops and tillage techniques which can be plugged into this simple, straightforward rotation. We think this “organized flexibility” helped to make last year our best season ever despite the wild swings in the weather.
2001 Field Notes
rye and italian ryegrass skimplowed mid-August and replanted to oats middle of September
rye and vetch skim-plowed late April and planted to squash peppers, dried flowers, summer lettuce, spinach and peas late May and June, and interseeded with sudex followed by a cover crop of rye seeded mid-October; beets and carrots planted early July and interseeded with rye
rye cover crop surface-tilled in July and planted to a mix of sudex, field peas and forage soybeans early August; mulched strawberries in middle of the field surface-tilled late July and planted to ridged rye the end of August
oats ridge-tilled in April and planted to spinach, peas and carrots interseeded with buckwheat followed by a rye cover crop in mid-September; no–till garlic on north edge double-cropped to late lettuce and spinach
rye and triticale on north half of field deep plowed late June and replanted to oats and buckwheat which was surface-tilled mid-August, then replanted to oats on ridges late August; rye on south side deep plowed early May and replanted to oats which was surfaced-tilled late July, then planted to oats and peas on ridges late August
rye and hairy vetch surface-tilled mid-May and planted to fall lettuce, spinach, carrots and cole crops mid-July through August, and interseeded with rye late August
rye, spelt and italian ryegrass deep plowed mid-July and reseeded to rye and hairy vetch mid-August
oats, peas and forage soybeans surface-tilled in April and planted to early potatoes, lettuces, zukes, peas, onions and strawberries; strawberries and onions on south side of field interseeded with hairy vetch late June; everything else interseeded with buckwheat followed by a rye cover crop mid-September
rye, spelt and triticale surface-tilled early July followed by oats and Canadian field peas planted mid-August
rye and vetch deep plowed early May and planted to storage potatoes, spinach and carrots late May, then interseeded with sudex and vetch followed by a rye cover crop seeded early October
rye deep plowed late May and replanted to buckwheat, italian rye grass and clover mix mid-June
surface tilled oats, peas and beans planted to sweet onions, zukes, lettuce, peas and spinach in May and interseeded with sudex and/or vetch followed by a rye cover crop early October
Building the Ridges
1A. We formed these ridges the end of last summer in field 5. The cover crop of oats and Canadian field peas just getting started on the ridges grew about 20” tall before dying back at the onset of winter. Note the large quantity of coarse organic matter worked into the hilled up soil. We have found that concentrating lots of fresh organic matter into the ridges noticeably improves soil quality and planting conditions in a ridge-till system on our silt-loam soils.
2A. The trick is to shallowly incorporate a cover crop before building the ridges the last week of August. In this case, we surface-tilled a spring planted cover crop of oats along with a light application of compost and lime. We also worked the oat and peas seed into the surface of the soil at this time so that…
3A. …when we formed the ridges with the disc-hillers on the cultivator, the organic matter and seed was concentrated in the hilled up soil. We like to think of these ridges as long, low composting windrows where conditions are close to ideal for good decomposition.
4A. In fact, when we tried out the Solivita soil quality test kit from Woods End Lab, these ridged fields tested the highest in biological activity. The test results did not come as a complete surprise considering that the cover cropped ridges contained all the requirements for a high rate of biological activity as measured by the respiration rate of the soil. For one, the raised ridges are extremely well aerated. At this point they were also filled with a live and actively respiring root system. Most importantly, there was plenty of fresh organic matter in the hilled up soil to feed a growing population of earthworms and beneficial bacteria and fungi.
No-Tilling the Ridges with Garlic
5B. An added advantage of the cover cropped ridges is the soil remains much softer and looser than under the same cover crop planted on flat ground. For this reason, we decided to try using the old riding cultivator for no-tilling garlic on the ridges rather than the much heavier subsoiler pictured in the Summer 2001 photo essay on Horsedrawn No-Till Garlic. To be sure, the lightweight cultivator would not be practical for penetrating firm soil on flat ground, but it did a wonderful job of opening up a furrow on top of the cover cropped ridges for handplanting the garlic cloves.
6B. When we asked some of the participants at our small group tour last fall how they liked no-till planting garlic on the cover cropped ridges, they said it was actually easier and faster than their clean-tilled systems, and they commented on how nice and crumbly the soil was in the no-till planting furrow. This hands-on measure of soil quality particularly impressed us since we had received 3/4” of rain the night before and the soil in our flat fields that afternoon was way too wet for tilling or planting.
7B. This photo shows the 2001 garlic crop coming up on the ridges in Field 4 a full two weeks earlier than the mulched garlic planted on flat ground next door. To conserve moisture, we mulched the pathways with clean wheat straw, intentionally leaving the ridgetops exposed so that the soil would remain warm around the young plants. As a result, the garlic on the no-till ridges stayed two leaves ahead of the mulched crop all season long, maturing a week earlier and allowing us to spread out the harvest.
No-Till Onions on the Cover Cropped Ridges
8C. The whole month of April in 2001 was too moist to even consider tilling our flat fields. To plant the onions on schedule, we decided to try no-tilling this allium on the ridges as well. As you can see by the way the cultivator wheel was sinking into the pathway, the soil was still plenty wet the third week of April. The ridgetops, however, were perfect for no-tilling.
9C. A small coulter mounted at the front of the cultivator slices through the winterkilled cover crop on the top of the ridge. Behind the coulter we used the narrowest tooth we could find to open up a slit in the soil just big enough for handplanting the sets without disturbing the integrity of the ridge or the residues. This is the same setup we used for no-till planting the garlic into the live cover crop of oats and peas on the ridges in the fall.
10C. Just like the garlic, we mulched the valleys with straw and left the ridgetops exposed. We thought this was an ideal combination as it kept the onions growing where the soil was warm and well-aerated, but allowed the roots to search the large reserve of moisture in the cool, wet soil under the mulch in the pathways when the weather turned hot and dry. Whether or not this was the reason, the notill crop on the ridges outyielded our cultivated onions.
We felt there were drawbacks to this system as well. For example, mulching the pathways required more time and expense than cultivating the crop. There were also a few more weeds in the no-till onions. However, our biggest concern with the no-till ridge system was the way the soil baked hard and dry on the ridgetops. In fact, when we…
11C. …dug into the ridges with a fork, the soil broke into these large clods – quite a contrast to the loose, crumbly conditions we expect to find in the rows of our cultivated onions.
Initially, we thought the clods were an indication of poor soil quality. On closer examination, we noticed that they were full of worm holes. In fact, the ridges were riddled with worm holes right up to the hard surface. Apparently, the earthworms were attracted to the organic matter concentrated in the ridges as well as the cover crop residues decaying on the surface. Despite the outward appearances of the no-till ridges, we had to admit that the earthworms had done a superior job of aggregating and aerating the untilled soil. We plan to try no-tilling other crops on the cover cropped ridges this year – such as lettuce, strawberries, early potatoes and sweet onions – to see if this hybrid planting system is a dependable way to enhance soil quality while providing these crops with the right combination of soil temperature and moisture.
Ridge-Till Peas and Spinach
13D. Thanks to the high and dry ridges, we were also able to begin our successive plantings of peas and spinach on schedule despite the wet weather last April. To plant these crops without an expensive no-till seeder, we simply knock the top off the ridges with the cultivator. In the process, the winterkilled cover crop residues are moved into the pathways, exposing a narrow strip of clean soil for direct seeding with our existing equipment.
14D. For knocking the top off the cover cropped ridges, we put this extra large sweep right behind the coulter. The East End Welding Shop custom fabricated this ridgetill sweep for us, working off the photos of Ken and Martha Laing’s ridge-till planter in the Winter 1998 Small Farmer’s Journal. We provided the 16” sweep from Central Tractor and the shop welded the high sides on the wings. The new ridge-till sweep does a much more dependable job of clearing the residues off the ridge and making a level seedbed than the salvaged rototiller middlebuster portrayed in the 1998 photo essay on “ridge-till vegetables.”
15D. Up close, you can see how the coulter slices through cover crop residues on top of the ridge just ahead of the sweep which moves the soil and trash into the pathways. Note how crumbly and mellow the undistributed strip of clean soil looks right behind the ridge-till sweep. In this minimal-till system, we are relying entirely on the root system of the winterkilled cover crop, and the high rate of biological activity in the ridge, to make good conditions for direct seeding rather than depending on a lot of soil manipulation to prepare the seedbed. (If necessary, we sometimes lightly till the ridge-till seedbed before planting a fine seeded crop like carrots.)
16D. One of the advantages of the ridge-tillage system over a strictly no-till approach, is that cultivation can be used to control weeds and preserve moisture. However, we have learned that some kind of crop protection is necessary for ridge-till cultivation when the plants are small. For instance, we put these rolling shields on the cultivator last year for the first cultivation of the ridge-till peas to protect the crop from the lumps of soil worked up in the untilled pathways.
17D. The rolling shields also prevented the clumps of cover crop residues in the pathways from burying the emerging crop of ridge-tilled spinach. Originally, we used dischillers on either side of the row to protect the plants during ridge-till cultivation. Now we use these rolling shields for ridge-till cultivation because they do a much better job of loosening and leveling the soil next to the row and without all the constant adjustment involved with using the disc hillers for this purpose.
We would also suggest the following tips for the first time ridgetiller: Delay ridge building until early fall so that the cover crop on the ridge does not grow more than 12” tall before winter. The residues from a short cover crop will be much less challenging to cultivate than a tall stand of oats, especially if tangly field peas are mixed in. Waiting for the winterkilled cover crop residues to breakdown as long as possible before ridge-tilling in the spring will also make cultivation much easier until you gain familiarity with the system. We also suggest using no more than two sweeps or shovels on each cultivator gang to prevent plugging up with trash. It helps to think of the first time through the ridge-till crops with the cultivator as “primary tillage” rather than fine cultivation.
18D and 19D. These photos were taken a couple of weeks later right after the second ridge-till cultivation. It always seems like a miracle how quickly the soil mellows out and the cover crop residues break down in this minimum-till system. Now that the crops are well established, we seed a living mulch in the middle of the pathway to help protect the soil and add a little more diversity to the crop mix. We like to use the walkbehind seeder for this job because it is so fast, easy and dependable. Here, we are using the seeder to plant a single row of oats and buckwheat between the rows of ridge-tilled peas and spinach.
20D. The beauty of seeding just a single row in the pathway is we know the oats and buckwheat will not compete with the cash crops for moisture or nutrients or interfere with the harvest. As you can see, the single row of oats and buckwheat also prevented the soil from washing during the brutal hailstorm in June that dropped an inch of rain in under ten minutes. Despite the storm damage, we gleaned 50% of the peas and harvested three more pickings of spinach before it went to seed.
21D. By the time the spinach had shot up a tall seed stalk the oats and buckwheat had also produced a good bit of biomass. What we like about this single row interseeding system is it makes it possible to grow a cash crop and a cover crop at the same time all before the end of July. This interseeding mix provides some insectiary benefits along with the extra organic matter and soil protection since the blossoming buckwheat attracts many beneficial insects and pollinators to the market garden.
22D. Checking the soil in the rows of the ridge-tilled spinach at this time, we found the earth looking very loose and crumbly. What a contrast to the large clods filled with worm holes in the ridges of no-till onions! The difference between the soil conditions found in these two minimum-till systems is especially striking given the fact that both the ridge-till spinach and the no-till onions were planted in the same field on the same soil type at the same time of year. At this point, we do not know which image of tilth suggests the best long-term development of the earth, but we do know that experimenting with these alternative tillage techniques has taught us to rethink how we “see” soil quality.