Cultivating Questions

Concerning the Bio-Extensive Market Garden

by Anne and Eric Nordell of Trout Run, PA

Farm Tour Queries

The questions and comments cultivated in this column were provided by a busload of Ecological Farmers of Ontario on their way to the Rodale Field Days, July 19, and participants at our annual farm tour, October 8. This collection of questions represents just a small fraction of the topics that came up at these informal get-togethers. We intend to continue the conversation in a future CQ.

How did you implement the bio-extensive system? Did you start out with alternating half-acre strips?

It took a few years before the basic layout came together. The first year we plowed up four acres of the old hayfields (corresponding to fields 1-8 on the map) and planted oats for the work horses. We also put out about a quarter-acre of medicinal herbs and vegetables to see what would grow well in our area. Digging quackgrass out of these trial crops on our hands and knees convinced us that we needed to use the summer fallow to deal with this perennial weed before committing to a larger acreage of produce.

To the best of our memory, we tilled and bare fallowed the oat ground after harvest, then planted this four-acre block to a cover crop of rye in late September. The next year, 1984, we summer fallowed the even-numbered fields (2,4,6,8 on the map) and planted a fall cover crop in preparation for vegetables in 1985. In the odd-numbered fields (1,3,5,7) we frost seeded the rye with clover in March of 1984, then plowed down the clover in the summer of 1985, fallowed the ground, and planted a fall cover crop in preparation for vegetables in 1986. In this way we established the alternating half-acre system with odd-numbered fields cover cropped/ fallowed in odd-numbered years and even-numbered fields cover cropped/ fallowed in even-numbered years.

Meanwhile, the original trial site (corresponding to fields 9 & 10) had expanded to two-thirds of an acre. The soil tilth here had really deteriorated after a couple of years of cultivation so we transitioned this area to bio-extensive management in 1985, the same year we brought fields 11 & 12 into production. (Due to the lay of the land, fields 9-12 are onethird acre in size.) We initiated the summer fallow in the Contour Strip (approximately two-thirds of an acre) in 1997 as detailed in the Weed the Soil video.

Instead of alternating strips, would it work to have two big fields that alternated between vegetables and cover crop/fallow?

We could see some real advantage to this two-field arrangement. For example, it could simplify management and make fieldwork more efficient. In addition, you would have fewer field edges to contend with. Also, if the two fields were separated by a large distance or natural barrier, such as a forest, this two-field system could prevent the migration of certain types of insects and diseases with the vegetables from year to year. On the other hand, the alternating strips of cover crops in our layout may provide more diversity while creating temporary natural barriers between successive plantings of vegetables. In our rolling land, the patchwork of cover crops and EARLY and LATE planted vegetables helps with soil conservation. The half-acre strips also define permanent management units for cover cropping, tillage and rotation planning.

I use a rotation of corn, wheat, oats, and hay. Cultivating keeps the quackgrass under control in the corn, but the quackgrass takes over again when growing the small grains.

We found the same thing happened when growing oats for the horses in the fallowlands. Unless we had already eradicated the quackgrass with the summer fallow, it survived and multiplied while the oats were growing. To make matters worse, many annual broadleaf weeds had the opportunity to produce viable seed before the oat crop was harvested, undermining our goal of weeding the soil. Consequently, we discontinued growing oats for the horses in the market garden.

Have you tried a summer fallow to clean up the quackgrass?

Yes, I plowed up the sod and worked it for about a month, then seeded buckwheat. By fall, the field was still infested with quackgrass.

Based on our experience here, it is necessary to use three months of tillage to completely get rid of the quackgrass rhizomes. It is also important to plow the sod as shallowly as possible to keep the roots near the surface where they can be dried out with a springtooth harrow. If plowed deeply, the rhizomes are protected from the harrow and can survive a long time underground.

We would not recommend an extended bare fallow period for steep, erosion-prone land. On the other hand, it takes only one full-summer fallow to deal with the quackgrass. That is, this practice should not have to be employed again unless quackgrass is brought into the field on equipment or allowed to creep in from the field edges.

Do you cultivate the borders of the market garden to prevent quackgrass and other weeds from encroaching into the fields?

During the first years on the farm we maintained a strip of cultivated soil the width of our springtooth harrow around the fields. However, due to the slope of some of our field ends, these headlands were very prone to erosion. Now we select a few fields each year for the cultivated-headland treatment, leaving the adjacent field ends uncultivated or mulched with straw to prevent washing. This strategy did not prove adequate this summer when we received an inch of rain in under ten minutes, ripping a foot-deep gully through the mulch and quackgrass roots at the east end of fields 5 & 6. To prevent this from happening again, we dug diversion ditches to move the excess water out of the market garden.

The potato vines are still green here, not died back like the other field.

In the other field, Field 5, we employed our usual method for delaying leafhopper damage by planting the potatoes early (4/18) and protecting the crop with floating row cover. Leafhoppers blew into our area much earlier than usual and attacked the potatoes as soon as we removed the row cover (5/31) to hill the rows, causing the vines to dieback prematurely. Field-run yield was modest, but adequate for our markets: approximately 10 tons/acre for the Dark Red Norlands; 8 tons for the Carolas and 5 ½ tons for the Superiors. Tubers were small to medium in size. Without the row cover and early planting, we imagine the crop would have been a complete failure.

The two rows of potatoes in the Experimental Patch which are still alive were planted the same day as field 5. The only difference is we mulched the potatoes with straw and sprayed them once with Entrust instead of using the row cover. We mulched the aisles of these widely spaced rows immediately after planting to preserve as much soil moisture as possible and then added mulch right next to the row as soon as the plants emerged to prevent the tubers from greening. An unexpected benefit from this experiment in improving moisture retention was significantly lower leafhopper pressure. The vines stayed green almost three weeks longer than in field 5, resulting in higher yields – 10 tons/acre for the Carolas; 8 tons for the Superiors – and lots of large tubers.

These cover crop peas look really nice. What is the variety?

This is the 4010 strain of forage peas. It is the most vigorous variety of field pea we have tried, germinating and growing well in less than ideal conditions. And in good pea weather the vines have stretched out over seven feet long!

How do you incorporate the pea vines?

We chop the vines at mid-bloom with the residue cutter shown in the Weed the Soil video and the Peak Water CQ (Summer 2008 SFJ). We let the vines dry down for a couple of weeks before applying compost and incorporating the peas with the undercutter featured in last issue’s column on Cultivator Setups. We typically level the undercut field with the spingtooth harrow and roller or rotary hoe, then seed oats on ridges in preparation for EARLY planted vegetables the next year.

How long does it take you to seed the ridges?

It took a whole morning to plant the ridges in field 8, maybe 3 ½ to 4 hours altogether. Our horse-and-hand method of seeding the ridges requires quite a few steps:

1. Broadcasting the oat seed with a hand-cranked seeder.
2. Incorporating the seed and building the ridges with two pairs of dischillers on the cultivator, one ridge at a time.
3. Seeding a single row of oats in the middle of the valleys with a walk-behind seeder to prevent erosion and increase biomass in the pathways. (Most of the broadcast oat seed gets concentrated in the ridges by the action of the dischillers.)
4. Rolling the ridges with the cultipacker to improve seed-to-soil contact and to flatten the ridgetops to facilitate planting the vegetables the next spring with minimum tillage.

Field 8 took a little longer to seed than usual due to a lot of short rows and taking the time to set up a forage radish comparison on the south side of this irregularly shaped half-acre field. We were concerned that if we broadcast the small radish seed before building the ridges that it would be buried too deeply in the soil for good germination. So we seeded twin rows of the “tillage radish” on top of the ridges with the walk-behind seeder after rolling the ridgetops with the cultipacker.

We conducted a similar comparison on the ridge slated for EARLY planted vegetables in Field 7. We thought soil tilth and moisture was superior in the ridges with winterkilled oats, but the spinach yielded better on the radish ridges. We will write up a full report for the CQ when we have the second year results of this experiment.

How much compost do you apply?

Our typical application rate before a cash crop is 8 cubic yards per acre (See “A Fertility History” in the Weed the Soil booklet for details on how the compost rate has changed over the years.)

When do you apply the compost?

We apply compost for EARLY planted vegetables during the preceding fallow year, either before planting the oats on ridges, like in fields 2 & 8, or on top of the winterkilled cover crop in the fall, such as the sudex in field 12. For LATE planted vegetables, we apply compost to the overwintering cover crops either late in the fall or early in the spring. Our original reason for applying the compost well ahead of the vegetables was to enhance the growth and/or decomposition of the cover crops. Now this schedule is necessary to meet the National Organic Program requirements for applying raw manure since our hog-composted horse manure does not qualify as “compost.”

For the quick succession of vegetables in the portable hoophouses, we apply compost right before planting. In this case we use compost finished in a homebuilt tumbler to meet the NOP guidelines for in-vessel composting.

How much of the market garden do you cover each year?

Half of the market garden routinely gets an application of compost each year in preparation for the vegetables. We also apply compost to the squash strips in the fallow fields where we grow-our-own mulch as described in the Summer 2008 and Spring 2010 SFJ. And, in recent years, we have run out of space and ended up using a quarter-acre of the fallowlands for the last plantings of fall greens (south half of field 10 and north edge of field 8 in 2012). If we have extra compost, we use it before heavy feeding cover crops in the fallow fields, such as the sudex in fields 4 & 8. Including the compost used in the portahoopies, we cover almost three-quarters of the market garden most years with the compost generated by four work horses.

Do you use any other kind of fertilizer?

We use rock minerals to balance the nutrient content of the horse manure and the soil. For example, we amend the horse manure with colloidal clay rock phosphate during the collection phase of the hogs composting process. This form of soft rock phosphate helps to tie down the nitrogen in the manure and compensate for its low level of phosphorus. Our typical compost application rate of 8 yards/acre usually includes 150-250 lbs of colloidal phosphate.

At times, we have layered small quantities of rock minerals – such as high-calcium lime, dolomitic lime, gypsum, Azomite and calcium borate – with the compost when loading the manure spreader to address the marginally low levels of calcium, magnesium, sulfur and trace minerals in the soil indicated by lab analysis. More recently, we have switched to a calcified seaweed material called Physiostart which contains all of these nutrients in a convenient, pelletized form. This Extra-Fert Product from Timac is available at our local Agway feed store and is approved for organic production by our certifying agency.

The accompanying chart shows the amount of nutrients (in pounds per acre) applied to the fields with our typical application rate of compost (amended with soft rock and calcium borate) and Physiostart. The compost analysis was performed by Penn State; the nutrients in the calcified seaweed determined by the fertilizer label. The chart also includes the soil analysis, reported in pounds per acre, from a sample taken from field 11 in late November of 2010 after the harvest of fall broccoli, lettuce and carrots. In preparation for these LATE planted vegetables, we applied compost and Physiostart at our normal rate the third week of March to an overwintering cover crop of clover which we turned under the last week of May.

We split the soil sample from field 11 and sent half to Logan Labs and half to Penn State. We have relied on the fertility management guidelines provided by Logan Labs for the last seven years. Previous to that, we used Brookside Labs beginning in 1985. Both labs determine the ideal level of nutrients (shown in the parentheses) using the Albrecht Theory of cation balancing. Fertilizer recommendation from Penn State (also noted in parentheses) is based on sufficiency trials for growing a crop of broccoli.

Not surprisingly, the soil test results for field 11 are more closely aligned with Logan Labs’ ideal levels than Penn State’s recommendations. Both labs, to differing degrees, indicate that the bio-extensive method, relying on modest quantities of compost and rock minerals to grow lots of cover crops, may not maintain optimum levels of available phosphorus while oversupplying potassium. Keep in mind that earlier testing with Brookside Labs showed we had built up a very high level of reserve phosphorus in the soil. (Logan Labs and Penn State do not perform this test.) The crops in field 11 did not show any signs of phosphorus deficiency. To the contrary, production was excellent and customers raved about the flavor of the fall vegetables.

What is the organic matter level of your soil?

That is a difficult question for us to answer because we have seen such large fluctuations in soil test numbers over the years. Check out the charts summarizing the organic matter results from a long-term soil quality trial sponsored by the Pennsylvania Association for Sustainable Agriculture (PASA). Fall and spring soil testing by Brookside Labs showed remarkable changes in OM for fields 3-6 in the market garden. Split samples sent to Woods End Lab during the last four years of the trial recorded even greater variations which did not necessarily follow the same path as the Brookside graph. A follow-up split-sample soil testing experiment in the year 2000 documented huge swings in OM taking place in one growing season.

When we asked soil scientists about the perplexing results, we received four very different answers:

“Soil organic matter should not change by more than one tenth of a percentage point from year to year. Anything greater indicates sampling or laboratory error.”

“Large fluctuations in organic matter are just what you should see in a biologically active system as the soil transforms raw organic matter into humus.”

“It is necessary to have the same lab technician do the soil organic matter test every time in order to get consistent results.”

“Your farm is an anomaly!” We certainly hope the last comment is the correct explanation. Otherwise, we cannot recommend organic matter testing as a useful tool for evaluating soil management.

2012 Crops and Cover Crops

Field 1 3/21 shallow plow crimson clover; 5/12 salad mix, spinach, lettuce, glads, beans, peppers, zukes; (north side) 9/17 rye @ 140 lbs/A; (middle) 6/26 interseed vetch @ 15 lbs/A; (south side) 6/11 mulch with rye from Field 2

Field 2 5/21 mow rye for mulch in field 1 & 3; 7/14 undercut stubble; 8/8 Esker oats @ 4 bu/A (too thick); 10/15-10/25 no-till garlic into ridges in middle of field

Field 3 3/14 skim plow rye; 5/6-6/18 lettuce, spinach, peas, strawberries, beets, beans, leeks, carrots; (north side) 6/17 mulch leeks with rye from field 2; (middle) 6/14 i.s.vetch @ 15 lbs/A; (south) 8/14 i.s. vetch @ 18 lbs/A

Field 4 4/6 shallow plow crop residue & mulch; 5/2 4010 forage peas @ 140 lbs/A; 6/22 undercut peas; 7/9 Hawk 12 sudex @ 60 lbs and crimson clover (old seed) @ 30 lbs/A; 8/22 mow sudex and use south half for mulch in field 5

Field 5 (north half ) 3/22 undercut vetch; 4/13-4/19 beets, spinach, potatoes; 9/17 rye @ 140 lbs/A; (south half ) 3/13 Esker oats @ 3 bu/A; 6/11 undercut oats; 7/24-8/7 brassicas, lettuce, spinach; 8/1-9/1 mulch with rye from onions in 11 and zukes in field 6 and with sudex from field 4

Field 6 (north 2/3 of field) 3/14 skim plow strip in middle of rye for 5/7 zukes & cukes; 5/21 mow rye for mulching zukes; 6/27 undercut stubble; 7/14 med. red clover @ 20 lbs/A; 9/17 rye & vetch in zuke strip; (south 1/3) shallow plow mulched strawberries on 8/16; 9/25 rye @ 140 lbs/A

Field 7 4/14 mulch no-till garlic with wheat straw; 3/16 rotary hoe oats on ridges; 3/19-4/13 strip-till spinach, peas, beets, salad mix; 9/25 rye @ 140 lbs/A

Field 8 (north side) 3/22 overseed i.s. vetch with oats; 6/11 undercut oats & vetch; 7/24-8/7 spinach, salad mix, beets, beans; 8/4-8/7 i.s. vetch @ 18 lbs/A; (rest of field) 4/3 undercut mulch & crop residue; 5/24 4010 forage peas @ 140 lbs/A; 8/9 undercut peas; 8/30 Kame oats on ridges @ 3 bu/A (also experimental twin rows of forage radish)

Field 9 4/30 shallow plow rye; 6/25-7/5 carrots, brassicas, lettuce, spinach, salad mix, beans; 8/4-8/14 i.s. vetch @ 18 lbs/A

Field 10 5/21 mow rye for mulch in field 11; (north half ) 9/6 rye @ 100 lbs/A and vetch @ 30 lbs/A (3 weeks late); (south half ) 8/13-8/22 lettuce, spinach, salad mix; 8/13 i.s. vetch @ 18 lbs/A

Field 11 3/19 chop and rotary hoe oats on ridges; 4/5-5/18 scallions, peas, onions, beets, spinach, salad mix; 6/23-7/2 mulch onions with rye from field 10; 9/25 rye @ 140 lbs/A

Field 12 3/27 undercut i.s. vetch; 6/9 Hawk 12 sudex @ 55 lbs/A; 7/26 & 10/13 mow sudex

[1] View from the east end of Field 5, June 19, 2012. We planted clumps of buckwheat in the EARLY planted potatoes on the north side of this half-acre strip to draw predators and pollinators into the market garden. Starting buckwheat under the row cover with the potatoes noticeably increased beneficial insect activity during the cold, wet start of the 2011 growing season but did not seem to make any difference in 2012 when the native plants surrounding the market garden bloomed way ahead of schedule.

To the left of the potatoes, a cover crop of spring oats has been undercut in preparation for planting fall lettuce, spinach and brassicas on the south half of Field 5. Yes, the whole field had been slated for LATE planted vegetables. However, we needed to use the north half of Field 5 for fall greens during the preceding fallow year. It made better rotational sense to follow this LATE planting of lettuce, salad mix and spinach with EARLY potatoes in 2012 rather than another planting of LATE greens.

[2] Up close of Carola potatoes and buckwheat starting to flower in Field 5. Although the potato leafhoppers were already flitting around the foliage, the crop put on such vigorous growth that the vines shaded out the living mulch of hairy vetch getting established in the pathways. We seeded the single row of vetch on June 8 right after the second hilling of the potatoes.

[3] Hopperburn was very evident in the potato patch by the fourth week of June. On July 14, when this photo was taken, there was not much left of either the vetch or the potatoes.

[4] Two rows of potatoes in the Experimental Patch on June 19 – Carolas on the left and Superior on the right. The widely spaced rows were mulched with rye from Fields 6 & 10 to hold in as much moisture as possible. We sprayed these unprotected potatoes with Entrust on May 23 for flea beetles. The mulched potato plants were noticeably smaller than the row covered crop in Field 5 when we took this photo. On the other hand, we had a hard time finding leafhoppers.

[5] On July 14 the mulched vines were starting to show advanced stages of hopperburn, but were still green and alive. The extra 2-3 weeks of photosynthesis along with plenty of soil moisture resulted in a significantly higher yield with much larger tubers than under our usual management in Field 5.

To the left of the mulched potatoes you can see the cover crop of peas planted in Field 8 on May 24. Despite hot, dry conditions in June, the 4010 forage peas produced a respectable amount of high-nitrogen biomass.

[6] Delayed by some much needed rain, we were not able to chop the vines with the residue cutter until July 26. We allowed the tangly residue to dry down for a couple of weeks before…

[7] …applying compost with Physiostart layered in the manure spreader. In preparation for the tillage radish comparison, we marked out a section along the south side of Field 8 that would not receive compost. We wanted to see if the radishes would retrieve enough nitrogen from the subsoil to make additions of compost unnecessary.

[8] Right after spreading the compost on August 9, we made the first pass over the crispy-dry pea vines with the undercutter setup on the riding cultivator. Mounting the long shank at the back of the gangs provides plenty of clearance for cover crop trash. The sweep-and-potato-shovel combo attached to the bottom of the shank shallowly undercuts a 12” wide strip of ground and throws enough soil on the brittle pea vines to initiate decomposition. With one wheel of the cultivator in the furrow made by the previous round, we work our way across the field forming ridges roughly 18” apart.

[9] Five days later we made the second pass with the undercutter. This time we moved the shank from the center of the heavy-duty cross-bracket to the right nine inches. We also shifted the right wheel axle out about the same amount. In this offset position, the undercutter splits the ridges formed during the first pass in half while allowing the wheels to track in the new and old furrows.

On 8/25 we leveled the undercut field with the springtooth harrow and rotary hoe before seeding oats and radishes on ridges the last day of August. This was a week later than intended for this experiment due to receiving 11 ½” of rain over July and August.