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Crop rotations for vegetables and cover crops 2014, Pam Dawling


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Ideas to help you design a sequence of vegetable crops which maximizes the chance to grow good cover crops as well as reduce pest and disease likelihood. Discusses formal rotations as well as ad hoc systems for shoehorning minor crops into available spaces. The workshop discusses cover crops suitable at various times of year, particularly winter cover crops between vegetable crops in successive years. Includes examples of undersowing of cover crops in vegetable crops and of no-till options.
• Rotation planning for permanent raised beds
• 7 step rotation planning for row crops, steps 1-4
• A useful format for rotation plans
• A walk around our crop rotation
• Steps 5-7 of rotation planning
• Pros and cons of tight rotation planning
• Resources and contact info

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Crop rotations for vegetables and cover crops 2014, Pam Dawling

  1. 1. Crop Rotations for Vegetables and Cover Crops ©Pam Dawling 2014 Twin Oaks Community, Central Virginia Author of Sustainable Market Farming Published by New Society Publishers
  2. 2. What’s in This Presentation • Twin Oaks Gardens and crop rotations • Rotation planning for our permanent raised beds • 7 step rotation planning for our row crops, steps 1-4 • A useful format for rotation plans • A walk around our crop rotation • Steps 5-7 of rotation planning • Pros and cons of tight rotation planning • Resources and contact info
  3. 3. Twin Oaks Gardens We garden 3.5 acres of land, producing vegetables and berries for 100 people all year at Twin Oaks Community. We have a mixed garden system: • 60 permanent raised beds, each 4' × 90' (1.2 × 27.4 m), • 10 plots of 9,000–10,600 ft2 (836–985 m2), in three areas of row gardens.
  4. 4. Crop Rotations Bring Many Benefits Maximize productivity, Optimize the health and fertility of the land, Reduce pests and diseases, Increase opportunities to plant cover crops, Meet Organic Certification requirements, Make the planning work easier on the brain.
  5. 5. Before Planning a Rotation Decide how your farming will support you Decide what you want to grow Figure out how much of what you need Have an idea of when to plant each crop. Planning is definitely circular, but you need to start somewhere!
  6. 6. Permanent raised beds Photo Kathryn Simmons • We cultivate the 60 beds manually and with a walk-behind tiller. • We don’t use a permanent rotation plan - we like the extra flexibility of our ad hoc method. • We use the space very intensively and get high yields. • We plant a new crop as soon as we clear an old one. • Some beds will get two or three crops in one season. • If we have a 4-week gap in the summer, we grow buckwheat; if 6 weeks, we add soy to the buckwheat.
  7. 7. Photo Kathryn Simmons We use the beds for: • Crops we grow in small quantities (celery, okra), • Very short-term crops (like lettuce), • Things we need to cosset (eggplant, because of the flea beetles, or early muskmelons), • Experimental crops we want to keep a close eye on • Things that wouldn’t fit anywhere else. • Over-wintering crops we keep long after the rest of the gardens are in winter cover crops (kale, collards and leeks) - the raised beds are more accessible for winter harvesting. • Very early crops such as peas - the beds can be cultivated earlier than the flat gardens.
  8. 8. Raised Bed Planning • Twice a year: – in the winter for the crops planted before the end of July – in mid-June for the crops for the second half of the year. • This two-part planning allows us the flexibility to respond to unexpected situations: – crop failures, – sudden needs for more of something sooner than we’d planned, – something taking longer than expected to reach maturity. • A vital tool for this is our Colored Spots Plan, an outline map of the raised beds that shows the history of the crops planted in each one.
  9. 9. The Colored Spots Plan helps us see at a glance which crops have been planted where in recent years
  10. 10. Vegetable Sudoku We make a chart of how many beds of which crops we want, divided by family, along with the planting date and final harvest date. The amounts we hope to plant come from the previous planning stages. We try to have two or three years’ gap before the same crop family returns to a bed. We shoehorn in more crops during the season than we otherwise could. Sometimes this process leads to the sad realization that everything we want isn’t possible
  11. 11. Photo Kathryn Simmons  Sometimes it leads to a more creative solution - five rows of carrots in a bed rather than four; planting lettuce as we remove spinach, working along the bed.  We always have to do some backtracking and fudging of the rotation to a less-than-perfect match, but we do end up with a plan that uses the beds fully.  It might be a more efficient use of time to use a fixed rotation, but this flexible approach is a more efficient use of land.
  12. 12. The Row Gardens The main part of our garden is in three patches, with rows 180, 200, or 265 feet (55, 61, or 81 meters) long. • Initial cultivation is with a tractor and disks. – We also have a manure spreader for compost a seed drill for cover crops & a potato digger. • For some crops we create temporary raised beds, • Other crops are grown in rows “on the flat.” • Here we use our ten-year rotation, growing – major crops – most of our succession crops of beans, squash and cucumbers. • It’s a ten-year plan that rotates crops - it isn’t ten years between corn plantings or potato plantings.
  13. 13. Steps to Creating a Permanent Rotation 1. Figure out how much area is needed for each major crop (the ones needing the largest amount of space). 2. Measure and map the land available 3. Divide into equal plots 4. Group compatible crops together to fill each plot 5. Determine a good sequence 6. Include cover crops 7. Try it for one year, then make improvements
  14. 14. Step 1. Space Needed for Major Crops • Sweet corn: 6 or 7 plantings of about 3,500 ft2 (322 m2) each • Spring planted potatoes: about 7,000–9,000 ft2 (644–828 m2) • Summer planted potatoes: about 7,000–9,000 ft2 (644–828 m2) • Spring broccoli & cabbage: 4,000 ft2 (368 m2) • Fall broccoli & cabbage: 7,000 ft2 (644 m2) • Winter squash: about 8,200 ft2 (736 m2) • Watermelon: about 9,000 ft2 (828 m2) • Sweet potatoes: about 4,300 ft2 (396 m2) • Tomatoes: 4,000 ft2 (368 m2) • Peppers: 2,200 ft2 (202 m2) • Garlic: about 3,600–4,000 ft2 (332–368 m2) • Fall carrots: about 3,600–4,000 ft2 (332–368 m2)
  15. 15. Step 2. Measure and Map:  East Garden 227’ x 265’ (Includes asparagus in half of one plot) Map shows plots of 9,275- 10,600 ft2
  16. 16. Twin Oaks Community Gardens
  17. 17. Step 3. Divide the Land into Equal Plots In our gardens, the 7,000–9,000 ft2 (644–828 m2) crops (spring planted potatoes, summer planted potatoes, fall broccoli & cabbage, winter squash, watermelon) will naturally each fill one plot in our rotation, so that was a good size to aim for in setting plot size. This size produced 10 plots, suggesting a ten part rotation
  18. 18. Step 4. Group Other Crops Together to Use About the Same Area:  Two or three corn plantings together in one plot  (3,500 ft2 (322 m2) each)  Spring broccoli together with overwintered garlic  (4,000 ft2 (368 m2) +  3,600–4,000 ft2 (332–368 m2 ))  Tomatoes together with peppers  4,000 ft2 (368 m2) + 2,200 ft2 (202 m2) Left to right: Broccoli under rowcover, garlic, strawberries. Photo Kathryn Simmons Before step 5, we’ll look at charting rotations and take a walk down our garden paths
  19. 19. How to chart your rotation plan In 1996, inspired by Eliot Coleman’s New Organic Grower, we used cards to represent each major crop. We modified Eliot’s method, and put the cards in a circle, like a clock face with “hours,” and set about imagining a good sequence. Crop rotations are a cycle, and a circular design makes more intuitive sense to us, than a linear format. Squash Corn Potatoes Corn Broccoli Cabbage Tomatoes Water melon Corn Potatoes
  20. 20. Having the rotation in a useful format We drew up our ten year rotation on a piece of card with a small central disk attached by a brass paperclip so it can rotate each year to show which crops will be planted in which plots. We call this our Rotation Pinwheel We are still using the same piece of card we made in 1996, even though we started our second ten year sequence in 2006. It has seen quite a bit of White-Out! For my book, the publishers’ re-drew it tidily.
  21. 21. Walk Around our Rotation Year 1. Winter Squash followed by Rye and Austrian Winter Peas • 8200 sq ft of winter squash will satisfy our needs. That fills one plot. • Winter squash are sown in late May, so there is time for a legume winter cover crop to reach flowering before we need to prep the soil for the squash. • We have one other main crop also in the cucurbit family: watermelon, so we plan to keep that distant time-wise in the rotation • Winter squash finishes on our farm on Halloween, early enough to include crimson clover or Austrian Winter Peas in the following cover crop mix
  22. 22. Year 2. Late Sweet Corn and Sweet Potatoes • Our late (6th) corn sowing and our sweet potatoes are both planted late in the season. Having them share a plot works in terms of allowing the preceding crimson clover or Austrian winter pea cover crop time to flower. • Late corn can be under-sown with oats and soy to provide a winter cover crop that is easily incorporated before the potato planting next March. • The sweet potatoes finish in October, too late to sow oats before next year’s spring potatoes. So we follow the sweet potatoes with wheat. Sweet potatoes and late corn. Photo Bridget Aleshire
  23. 23. Year 3. Spring Potatoes Followed by Fall Brassicas • Potatoes are said to do well after corn, so we put our spring potatoes after the previous year’s late corn, and our summer potatoes after the previous year’s middle corn planting. • We harvest the potatoes in early July, till in compost and immediately transplant our fall broccoli and cabbage. • We undersow the fall brassicas with a mix of clovers (white, red and crimson) about a month after transplanting. This becomes Year 4’s All Year Green Fallow. Potatoes emerging in spring. Photo Kathryn Simmons
  24. 24. Year 4. All Year Green Fallow  The clover sown under the fall brassicas grows all next year, if all goes well.  We have contingency plans:  In spring, once the warm weather has arrived, if the weeds are too bad, or the clover stand not thick enough, we turn the clover under and sow sorghum-sudangrass hybrid with soy. This gets mowed to a foot (30 cm) when the sorghum-sudan is four feet (1.2 m) tall, to encourage deeper rooting for better soil drainage, and can stay until killed by the frost.  If the plot is looking good, we let the clover grow all summer, mowing to prevent the clover seeding.  In August, we review again: if we still have the clover we may turn it under and sow oats. Or we may leave it over winter. Fall broccoli under-sown with clovers
  25. 25. Year 5. Early Sweet Corn, Half Followed by Garlic • We get two food crops in year 3 and none in year 4. The Green Fallow is ready for disking early in year 5 to plant our first sweet corn. • The early corn can be followed by fall garlic. Sweet corn under-sown with soybeans. Photo Kathryn Simmons
  26. 26. Year 5-6. Sweet Corn → Oats →Garlic →Buckwheat →Carrots A tight rotation:  After early corn in year 5, we sow oats and divide the plot.  We keep half for spring broccoli in year 6.  We mow the other half from time to time until late fall (year 5), then disk and plant garlic.  We harvest the garlic in June of year 6, sow buckwheat and soy,  Then sow fall carrots in late July or early August.  That half-plot grows 3 food crops in 2 years. Garlic harvest, Photo Rayne Squier
  27. 27. Year 6. Spring Brassicas in the Other Half. Spring broccoli and cabbage can be followed by rye, hairy vetch and Austrian winter peas sown in early September, in good time to grow a thick stand for no-till tomatoes in year 7. Photos Kathryn Simmons
  28. 28. Year 7. Paste Tomatoes and Peppers • We mow the cover crop close to the ground, let it wilt for a day, then transplant paste tomatoes and peppers into the dead mulch in early May. • The mulch does break down after about six weeks, so then we roll out bales of spoiled hay between the rows. • This crop doesn’t finish till the frost, and we have all the posts to remove before we can sow a cover crop, so it is usually rye with Austrian winter peas.
  29. 29. Year 8. Watermelon • Watermelons are not planted till mid-May, so the Austrian winter peas have time to flower before we disk the cover crop under in preparation for planting. • We have finished with watermelon harvesting by late September, so we disk the plot and sow rye with crimson clover for the winter cover crop. Crimson Sweet watermelon and morning glory. Photo Kathryn Simmons
  30. 30. Year 9. Mid-season Sweet Corn Mid-season corn is finished in time to establish rye and crimson clover, which will do well and produce lots of nitrogen and biomass before we need to plant the June potatoes in year 10. Three varieties of sweet corn sown on the same day, to extend the harvest. Photo Kathryn Simmons
  31. 31. Year 10. Summer Potatoes • Our second round of potatoes are planted in mid-June, giving the crimson clover plenty of time to flower before we need to disk and plant. • To combat the heat of summer, we hill and mulch the potatoes immediately after planting. • They are ready to harvest in October, and we follow with rye and crimson clover or Austrian winter peas. June-planted potatoes. Photo Kathryn Simmons
  32. 32. Step 5. Determine a good sequence To decide which crop should follow which other crop, we looked at the families of our major space users.  We have 3 big plantings of nightshades (solanaceae): two of potatoes and one of tomatoes and peppers together.  2 (spring and fall) of brassicas,  6 or 7 sowings of corn clustered into three plots,  2 of cucurbits (winter squash and watermelons),  1 of alliums (garlic),  1 of umbelliferae (fall carrots)  1 of ipomoea (sweet potatoes).
  33. 33. Give the Family Members Space! • We spread the 3 corn plots 3 or 4 years apart, • and the 3 nightshade plantings likewise. • We kept the winter squash 3 years after the watermelon. Squash Corn Potatoes Corn Broccoli Cabbage Tomatoes Water melon Corn Potatoes
  34. 34. Deciding the sequence • Folklore says some crops do better following certain other crops, but has it been tested? • Potatoes are said to do well after corn, so we put our spring potatoes after the previous year’s late corn and our summer potatoes after the previous middle corn planting.
  35. 35. Late Corn undersown with oats March- planted Potatoes Early Corn followed by fall Garlic (1/2) and oats (1/2) Garlic followed by Carrots (1/2). Spring Broccoli & Cabbage, then rye & vetch (1/2) No-till paste Tomatoes Mid-season Corn, then rye & crimson clover June- planted Potatoes Still looking for homes: winter squash, watermelon, sweet potatoes, fall brassicas
  36. 36. Late Corn undersown with oats March-planted Potatoes, followed by fall-planted broccoli & cabbage, undersown with clovers All-year Green Fallow Early Corn followed by fall Garlic (1/2) and oats (1/2) Garlic followed by Carrots (1/2). Spring Broccoli & Cabbage, then rye & vetch (1/2) No-till paste Tomatoes Mid-season Corn, then rye & crimson clover June- planted Potatoes Still looking for homes: winter squash, watermelon, sweet potatoes
  37. 37. Winter Squash Late Corn undersown with oats (1/2). Sweet Potatoes (1/2) March-planted Potatoes, followed by fall-planted broccoli & cabbage, undersown with clovers All-year Green Fallow Early Corn followed by fall Garlic (1/2) and oats (1/2) Garlic followed by Carrots (1/2). Spring Broccoli & Cabbage, then rye & vetch (1/2) No-till paste Tomatoes Water- melon Mid-season Corn, then rye & crimson clover June- planted Potatoes Next, we’ll look at cover crops, for good matches
  38. 38. Step 6. Cover Crops - Oats  For early spring food crops, a preceding cover crop of oats (maybe with soybeans) is ideal, as it winter-kills and is easy to incorporate.  Oats need to be sown at our farm in August or early September (by 9/17), so they need to follow an early finishing crop, such as spring brassicas, spring potatoes or early corn. Photo Oklahoma Farm Report
  39. 39. No-till Cover Crops  We plant our tomatoes and peppers into a mowed cover crop of winter rye, hairy vetch and Austrian winter peas. Austrian winter peas are said to reduce the incidence of Septoria leaf spot in following tomato crops, so we now include them in our no-till planting.  This reduces inversions of the soil, and the vetch (if plentiful) can supply all the nitrogen the tomatoes need.  Rye and vetch is best sown here in early to mid-September, creating another restriction on which crops the tomatoes could follow. Winter rye and hairy vetch. Photo Kathryn Simmons
  40. 40. Leguminous Cover Crops To get best value from crimson clover, we need to wait until it flowers — mid-April at the very earliest — before turning it under. So after crimson clover it’s best if the next food crop goes in after the end of April, such as later corn plantings, winter squash, transplanted watermelon, tomatoes, sweet potatoes or June-planted potatoes. Another factor is that crimson clover is best sown here before October 14, so it has to follow a crop that is finished by then. Crimson clover flower, Photo Kathryn Simmons
  41. 41. Late Fall Cover Crops Austrian Winter Peas can be sown as late as 11/8 here, so we add them to our later rye and wheat cover crop sowings.  Photo Winter wheat is easier to incorporate into the soil in spring, but winter rye can be planted later than any other cover crop.
  42. 42. Popping in Summer Cover Crops  If we have a four week gap between crops in warm weather, we sow buckwheat.  If we have 6 weeks, we sow soy with buckwheat.  Japanese Millet  Sorghum-sudangrass Shown here after mowing. Photo Kathryn Simmons
  43. 43. Cover Crop Opportunities  In spring, summer or fall, between one vegetable crop and a later one  In fall, after vegetable crops, for winter  Undersowing at last cultivation (oats and soybeans in corn shown here.)  Frost-seeding of small seeds such as clover: broadcast in the early morning, when ground is frozen. As it thaws, the water draws the seeds down into the soil. Works well for clovers.  Late winter or early spring, if the area will not be planted with vegetable crop until late spring. We use oats.  To replace a crop failure. Photo Kathryn Simmons
  44. 44. Fitting the Cover Crop With the Goal  Smothering weeds: sorghum-sudan, cereal rye, buckwheat, brassicas (we don’t do brassica cover crops – rotation, bugs).  Fixing nitrogen: clovers, vetches, Austrian winter peas, cowpeas, soybeans, lentils, sunn-hemp.  Scavenging leftover nutrients : small grains, brassicas, annual ryegrass (we don’t use annual ryegrass either – danger of it becoming a weed)  Improving soil drainage: sorghum-sudangrass, sunflower, daikon, sweetclover, alfalfa, brassicas, sugar-beet or forage- beet (never tried that.)  Grazing: brassicas, clovers, small grains, annual ryegrass.  Bio-fumigation: brassicas, sorghum-sudan, sunn-hemp, sesame.  Killing nematodes: Pacific Gold mustard, white lupins, Iron and Clay cowpeas, OP French marigolds, sesame.
  45. 45. Incorporating Cover Crops into the Soil • If possible, grow to early bloom for max biomass, and with legumes, max nitrogen • Incorporate before plants set seed • Mow with a rotary mower (eg bush hog) which chops the plants into small pieces. (Sickle-bar mowers and scythes leave long strawy plants) • Till shallowly, put cover crop where soil life is most active, not deeper. • If direct-sowing the next crop, incorporate cover crop 3-4 weeks before sowing date, especially winter rye. A cover crop of rye, hairy vetch and crimson clover. Photo Kathryn Simmons
  46. 46. Step 2 revisited. Put the Crops on the Map On a blank map of the plots we write in which major crops will go in which patch, using the Rotation Pinwheel. We block in the area needed for each major crop and calculate the remaining space in each plot. Our ten plots are not exactly the same size and our main crops don’t all need equal space either, so some plots will have spaces of various shapes and sizes and others no gaps at all.
  47. 47. Tractor Work and the Map: West Garden and Central Garden West Garden 180’-65’ x 243’ Central Garden 200’ x 50’, plus 25’ x 60’ “dogleg” Maps show plots of 9,000-10,000 ft2
  48. 48. Planning the tractor work In the margins of our maps, we write when that patch will need disking or other tractor work. Usually we have five spring diskings: 1. As soon as possible in February, for the spring broccoli, cabbage and potatoes; 2. In mid-March, for the 2 early corn sowings; 3. In mid-April, for watermelon, peppers, winter squash and sweet potatoes; 4. In mid-May, for summer potatoes and middle three corn sowings; 5. In mid-June, for the late corn. Spring broccoli transplant, Photo Kathryn Simmons
  49. 49. Fitting in succession crops Next we look for any extra space in the plots, to fit in the minor crops: succession plantings of beans, summer squash and zucchini, cucumbers, edamame, cantaloupes and anything we didn’t manage to find room for in the permanent raised beds. Green beans, Photo Kathryn Simmons
  50. 50. Succession Crops Planning Chart • We list the spare spaces in the plots (in order of availability) • and the crops we hope to plant (in date order). • At the beginning and end of the season, and in mid- season when space in the main plots is tight, we also look for spaces in our raised beds. • Then we pencil in arrows, fitting the succession crops into the spaces available.
  51. 51. Step 7. Look to Improve Probably the biggest snag for us in using this rotation is:  it doesn’t take into account that parts of the gardens with poor drainage are less suitable for some crops. One year tomatoes were going in one of our potentially wetter areas. El Nino - wet spring! So the previous fall, before sowing our cover crop, we made raised beds. We mowed the no-till cover crop, crossed our fingers and planted. As it happened, no wet spring!  For us, making temporary beds or planting on ridges in the wetter areas is easier than changing the crop rotation.
  52. 52. Why we like planned crop rotations This tight crop planning might sound mind-boggling, but for us it’s very worthwhile.  The division of the gardens into 10 plots gives us mental and psychological advantages - we don’t have to think about the whole of the area all of the time.  In spring we “open up the rooms” one or two at a time to plant. By the beginning of July everywhere is in use.  In August we start to put the plots “to bed” with their winter cover crops.  Annual expansion and contraction of the space needing our attention helps us to stay sane and focused and keep perspective.  This system helps us get high productivity from our land, while taking good care of it.
  53. 53. Perhaps you have lots of land? • At Twin Oaks the land available for vegetables is finite. • Years ago, researching plant spacing for watermelons, (trying to plant closely while keeping the melon size and yield up) I spoke with a farmer in the Midwest. • He said if farmers there wanted more watermelons, they would plow up more land, not try to plant them closer. • On the East Coast, land for farming is less available and more expensive. • If you have lots of land, you might prefer bio-extensive planting Crimson Sweet watermelon, Photo Kathryn Simmons
  54. 54. Resources - General  ATTRA  SARE -A searchable database of research findings  SARE Crop Rotations on Organic Farms, A Planning Manual, Charles Mohler and Sue Ellen Johnson, editors.  The organic agriculture community with eXtension. Publications, webinars, videos, trainings and support. An expanding, accessible source of reliable information.  Growing Small Farms: click Farmer Resources. Debbie Roos keeps this site up to the minute.  Jean-Paul Courtens , Roxbury Farm Under the Information for Farmers tab you’ll find great stuff.
  55. 55. Resources - slideshows  Mark Cain Planning for Your CSA: (search for Crop Planning)  Planning the Planting of Cover Crops and Cash Crops, Daniel Parson SSAWG 2012  Cover Crop Innovation by Joel B Gruver  Cover crops for vegetable cropping systems, Joel Gruver,  Tom Peterson Farm Planning for a Full Market Season Appalachian Farmers Market Association and Appalachian Sustainable Development season.pdf  Many of my presentations are available at Search for Pam Dawling.  Crop Rotations  Cold-hardy Winter Vegetables  Fall Vegetable Production  Feed the Soil  Intensive Vegetable Production on a Small Scale  Succession Planting for Continuous Vegetable Harvests  Sustainable Farming Practices  Crop Planning for Sustainable Vegetable Production
  56. 56. Resources - books  The Complete Know and Grow Vegetables, J K A Bleasdale, P J Salter et al.  Knott’s Handbook for Vegetable Growers, Maynard and Hochmuth  The New Seed Starter’s Handbook, Nancy Bubel, Rodale Books  The Organic Farmer’s Business Handbook, Richard Wiswall, Chelsea Green  Sustainable Vegetable Production from Start-up to Market, Vern Grubinger,  The New Organic Grower, Eliot Coleman, Chelsea Green  Extending the Season: Six Strategies for Improving Cash Flow Year-Round on the Market Farm a free e-book for online subscribers to Growing for Market magazine  Sharing the Harvest, Elizabeth Henderson and Robyn Van En  Organic Farmer’s Business Handbook, Richard Wiswall  Gardening When it Counts, Steve Solomon  Grow a Sustainable Diet: Planning and Growing to Feed Ourselves and the Earth, Cindy Conner, New Society Publishers. DVD/CD set Develop a Sustainable Vegetable Garden Plan  Crop Planning for Organic Vegetable Growers, Daniel Brisebois and Frédéric Thériault (Canadian Organic Growers
  57. 57. Crop Rotations for Vegetables and Cover Crops ©Pam Dawling 2014 Twin Oaks Community, Central Virginia Author of Sustainable Market Farming Published by New Society Publishers