Cultivating Questions

Concerning the Bioextensive Market Garden

by Anne & Eric Nordell
photo by John Nordell
illustration by Ed Ochsner

The following letters from Hank Nadu and Rob and Winny Sachno raise farsighted concerns about the nutrient sustainability of our farm system. We don’t have the scientific training or years of experience to do justice to this important issue so we hope you don’t mind if we refer to some of our favorite farm books for added perspective. The authors of these books have certainly challenged our thinking about sustainability of both conventional and organic agriculture.

Hi Anne & Eric,
Just a quick note to say how much we enjoy your articles. We’re also looking forward to seeing your video (if we can use someone’s TV and VCR for 52 minutes). We’re also “off the grid”. It’ll be like a night out at the movies for us…
I am always finding (at garage sales and book shops…) early 1900’s books on farming and crops and even on systems of farming (as you use). The problem came, as I read recently, when at the turn of the century fertilizers and pesticides became a $500 million business. This was in 1910. The reason we enjoy your articles so much is that they are written in the same mindset of a self-sustainable system a lot of these old books were. Why go out and buy, when you’ve probably got all the answers right there on the farm?
A couple of questions if you get the time to answer them. What do you think the fertilizer content numbers would be on horse manure? The closest I was ever able to figure out from “book knowledge” would in my opinion have been like 8-1-1. Would you think this would or could be right? We are homesteading here (again) in the Adirondacks (western part). There has never been any farming here, so the land and soil has never been turned. Since we use horses for power, I was just curious as to what we’re lacking from just manure (horse and green) for fertilizer. We do use lots of lime.
Question #2: Do you use any kind of supplemental fertilizer on your farm? I mean like bags of Agway stuff?
From your writings you seem to love farming as much as we do (as you wrote, for now anyway). It’s a labor of love. I look forward to getting up every morning and saying goof morning to our team. As we’ve read in SFJ you can’t become friends with a tractor!
Thanks for your time & stay happy,
Rob & Winny Sachno
Cranberry Lake, NY

Dear Nordells:
Perhaps you could help me with a question that has concerned me for several years now. Although we garden to feed ourselves with chemical-free and nutritious foods, we hesitate to turn it into a livelihood because of concern for the fertility of our soil. Selling our produce seems but a systematic exportation of the soil’s fertility. Is it possible to even maintain fertility while selling what the soil produces?
Reading your excellent articles in the Small Farmer’s Journal it is obvious you have put much study and thought into cover crops, compost, etc. Are these along enough? I am wondering if we should put these into practice some of F.H. King’s findings in his Farmer’s of Forty Centuries!
I am most interested in hearing your thoughts on this subject.
Sincerely,
Hank Nadu
Gordonville, PA

“To build and maintain a sustainable agricultural system, people who garden should either integrate themselves somehow with a farm, or they should adopt some of the practices used on a farm to supply the fertility poured down their garden sink.” – Robert Parnes, Fertile Soil

One of our goals when we first started farming here was to develop the farm as a self-contained nutrient system. We have not let the fact that we have fallen short of that goal prevent us from forging ahead with our small business, doing the best we can given our personal limitations and other goals for the farm.

For better or worse we rely completely on cover crops and compost to maintain good growing conditions in the market garden. However, we continue to import the horse feed, bedding and rock minerals which are the basis for the compost. We do this primarily because of time constraints. But even if we had time to juggle both field crops and market gardening, we doubt we could have realized our goal in entirety because, as we look at it now, vegetable production is probably the least sustainable form of farming.

Unlike the almost complete recycling of nutrients which can take place on a livestock operation, we are always amazed – even a little disturbed – to see how many tons of fertility and organic matter leave the market garden each year with so little returned to the good earth. Between public perceptions, problems with contamination, and lack of infrastructure, it is not practical to recycle waste products from our customers the way livestock manures can be used to enrich the land. Along the same lines, when we finish cutting a planting of lettuce, or digging a crop of carrots, only a few wilted leaves are left behind in the field and the remaining root system is pretty pathetic compared to the sod left after a crop of hay made for animals right on the farm. Even the rampant vine growth produced by tomatoes and squash melt down to about nothing after frost compared to the blanket of coarse stalks following corn harvest.

Robert Parnes probably says it best in his thought-provoking guide to fertilizers called Fertile Soil which is offered through the “SFJ book service” as well as the publisher, AgAccess.

“A farm is a source of nutrients and a garden is a sink for nutrients. A farm produces hay and straw for mulch, and it produces animal manure, both of which contribute to the fertility of a garden. The garden takes all that fertility for producing a high intensity of valuable crops. Moreover, the tillage required to maintain a garden tends to destroy fertility, whereas tillage on a farm under ideal conditions, builds fertility.”

Parnes seems to suggest that one way to maintain fertility and soil structure in a market garden is to subsidize it with the surplus organic matter and nutrients generated by livestock based farm operation. When we started farming here in the early 80’s the livestock economy had hit bottom and many dairy farmers were bailing out, a trend which continues to this day at an alarming rate. In addition, the capital, labor and mechanization such a venture seemed of using the simplest of horsedrawn technology, keeping this a two-person operation, and remaining debt-free. In our minds, it seemed that if gardens were sinks for nutrients, than farms were potential sinkholes for money.

(We have since learned of pastured-based livestock systems which are affordable to the entry-level farmer and promise to be as profitable as market gardening if the same degree of attention is paid to management, value-added processing and direct marketing. For two good examples in The Small Farmer’s Journal, see Karl North’s “The Small Scale Integrated Farmstead” in the Fall 1991 issue and Joel Salatin’s book listed in the Book Service. We also know of many horse farmers who have successfully started more traditional livestock operations from scratch through careful and conservative banking, cutting costs, family and community support, and a keen interest in and understanding of the livestock market- and interest and understanding which neither of us posses.)

At the time, we didn’t see how we could afford to subsidize a livestock operation financially in order to subsidize a market garden with fertility. Instead, we tried the unusual approach of designing the market garden to look and function like a traditional farm operation. As we described in the winter issue, the cover crops in the fallow lands kind of substitute for the field and forage crops in old time crop rotations to rebuild soil structure after cultivated row crops. To make up for fertility exported from the market garden we purchase “surplus” nutrients from established farms in the area in the form of corn, oats and hay to feed our work animals, who through their manure, end up feeding the soil. The fact of the matter is the market garden is now profitable enough that we can begin to subsidize the improvement of the rest of the farm so that someday we might be able to generate those “surplus” nutrients on our own land.

As for present, we are in the midst of a long-term soil quality trial supported by The Pennsylvania Association for Sustainable Agriculture. One of the objects of this trial, which was begun in 1993, was to measure the nutrient sustainability of our system. For those interested in such things, we have included the first four-year report at the end of this column.

Please keep in mind that soil tests, at best, give just a snapshot of the nutrient status of a particular field and cannot begin to show the dynamic complexity of nutrient exchanges and transformations taking place in a biologically active soil. Likewise, the methods and numbers used for soil analysis will vary from lab to lab as will their recommendations. As one extension agent pointed out to us, soil testing is an inexact long-term trends in soil management.

Our curiosity for what this sort of testing might tell us came only after ten years of getting to know our soil through observation, intuition and working it with the horses. Looking at the wild roller-coaster ride of the organic matter graph in Table 4, we really don’t have a clue as to what is taking place in the soil. For that matter, all our hard work and planning is no match for the fundamental rhythms of Nature. Still, we like to think the market garden would not be the same without our influence. Just like our workhorses at play in my brother’s beautiful photo, they occupy a very small part of The Big Picture. At the same time, the scene would feel altogether different without their presence.

Judging from the graphs in Tables 1 and 2, our part in the nutrient picture might be a little clearer. At least there seems to be some connection between applications of composted horse manure and phosphorus and potassium levels. Unfortunately, we have not yet tested the horse manure itself but somehow the Sachnos’ fertilizer analysis of 8-1-1 doesn’t sound quite right to us. In the chart reproduced from the Parnes’ Fertile Soil, the average nutrient content for a ton of horse manure is listed as 12lbs nitrogen, 4 lbs phosphorus an 10 lbs potassium, with a good bit of the nitrogen and potassium found in the urine. Written as a percentage, the NPK value might be something like .6%-.2%-.5%. The actual fertilizer analysis might be even lower as not all of the nutrients in manure are immediately available. Of course, the amount of nutrients which actually reach the field would depend entirely on what the horse is fed, the quality and quantity of bedding used, and how and when the manure is handled, stored and spread. (For a lighthearted account of how, we have tried to preserve the value of hot horse manure, see “Work Hogs and Horse Manure in the Spring 1991 SFJ and the shots of the “anal retentive horse stall” at the end of the video tape.)

If our horse manure, once composted, contains an average compost value of 1% nitrogen, and we apply 5 tons to the acre as usual, then our crops would be receiving roughly 100 lbs. of nitrogen per acre which is adequate for most vegetables. However, less than half of the nitrogen in compost is generally available the first year. We like to think the cumulative release of nitrogen from past incorporations or compost and leguminous cover crops, along with the nitrogen contributions from the soil humus itself, makes up the difference.

As far as maintaining long-term nutrient sustainability with horse manure alone we are more concerned about phosphorus than either nitrogen or potassium because this essential nutrient is more poorly represented than the others. In this respect, horse manure is not a “balanced” fertilizer. This might explain why our soil test reports have shown a slow but steady decline in phosphorus levels over the years. Based on the results of the soil quality trial to date, it looks like adding rock phosphate when applying compost to the fields is one way to reverse the trend.

Keep in mind that there are many conflicting ideas out there about the amounts of each nutrient- and in what ratios- it actually takes to grow a crop. Instead of getting too wrapped up in this debate, we tend to agree with Robert Parnes that energy may be the most important “nutrient” for organic farmers because energy is what drives the whole soil system. This is where we think the cover crops kick in because the convert sunlight into free energy right in the field stored in the form of carbon. When incorporated, the carbon in the cover crop residues slowly release the energy needed by the soil life to make a full spectrum of nutrients available.

With this sort of reasoning in mind, Parnes has developed an energy index to show the true value of fertility inputs. For example, chemical fertilizers come out about zero on the energy index because they contain hardly any organic matter or carbon. A ton of horse manure, on the other hand, is worth about 25 gallons of #2 fuel oil. It is nice to think our hayburners are producing “fuel” for the soil!

Those of you who have seen the video will have to be the judge as to whether a system driven by compost and cover crop energy provides adequate fertility. To be truthful, the yields or some of the heavier feeding crops, like potatoes and squash, probably run well below commercial averages. From our point of view, this is the quality, flavor and aroma of produce grown at the natural pace set by the soil’s energy that attracts direct market sales and leads to much higher than commercial returns per acre.

No doubt about it, we have a long way to go to match the energy and productivity of the Farmers of Forty Centuries. Their ability to sustain large populations on a limited land base, as described in detail by F.H. King in his extraordinary book, has been a real inspiration to us.

“Organic matter contains more energy than anything else of value to plants, and yet few people credit organic matter as the fuel for the soil furnace. In fact, this energy reduces the need for fertilizers by facilitating the storage of water, the fixation of nitrogen, the dissolution and accumulation of minerals, the effortless movement of roots through a superior soil structure, and the production of growth hormones and vitamins…”

“The energy in organic matter has a value, and the organic matter should be given for this value. Why? Because quantification helps to justify to cost of producing and recycling residues. Quantification also allows us to estimate the loss when organic matter is depleted and helps us determine if purchased organic fertilizers are worth the cost…”

“A simply way or quantifying the value of the energy in organic residues or fertilizers is to determine the amount of fuel oil that contains the same quantity of energy… For example, we find that a ton of fresh cow manure contained find that a ton of fresh cow manure contained 20% organic matter that has the same amount of energy as 20 gallons worth of fuel oil. If fuel oil costs 1$/gallon, a ton of this manure contains $20 worth of energy in addition to the value of its nutrients.” – Robert Parnes, Fertile Soil

In terms of understanding which agricultural practices might be applicable to us, we have found it helpful to study the conditions which King suggests contributed to the East Asian success. For one, he points out in the opening pages that a favorable climate played an essential role in the “permanent agricultural” he observed while traveling through China, Japan and Korea around 1910. A long, warm growing season couples with consistently high rainfall made it possible for the East Asian farmer to grow a series of densely planted crops in quick succession, in this way producing on one acre what might otherwise require ten. The cropping patterns Kind described remind us of the “bio-intensive” gardening techniques advocated by John Jeavons and others in the U.S.

Later in this book, King points out that the cultivation practices in areas which experience a harsher climate and less dependable rainfall are much more extensive by comparisons. For instance, he relates in great detail how the farmers in the unirrigated sections of the Province of Shantung, China, plant their crops in single row beds, or ridges, and pay constant attention to cultivating to preserve soil moisture by creating “earth mulches” after each precious rain. You can imagine these “bio-extensive” practices sounded familiar to us! In fact, it was King’s description of the Shantung technique of interplanting single rows of successive grain crops right into the pathways of the established crop which inspired us to try seeding single rows of hairy vetch between potatoes and strawberries as shown in the video.

King emphasizes throughout the book that population density was the most important factor shaping the agriculture of the Far East. Intense population pressure necessitated putting every square foot of arable land into production. At the same time, it provided the willing workforce required to maintain the soil in a high state of cultivation and fertility.

The closet equivalent that comes to mind here in the Northeast was the “hay” day of market gardening in New Jersey in the mid-1800’s as described in Ten Acres Enough, which Lynn recently brought back in print, and those great gardening classics by Peter Henderson. As we understand it, two opposites may have spurred the surge in small independent growers putting the land into highly intensive cultivation: the markets presented by the exploding population in nearby Philadelphia and New York resulting from the Industrial Revolution; and the large volumes of manure produced by the hundreds of horses employed in city transportation. Application rates of 50 to 100 tons to the acre of horse manure were not unusual at the time for intensively cropped market gardens. Much of the hay and oats which fed all those gardens. Much of the hay and oats which fed all those horses which produced all that fertilizer came from hill farms like ours, creating a significant nutrient drain across parts of Pennsylvania and New York. Of course, once the internal combustion engine replaced the draft horse, Jersey growers lost their source of fertility.

Now as we see it, the big difference between the New Jersey market gardeners and their East Asian counterparts was that the Farmers or Forty Centuries based their nutrient sustainability on the careful composting of renewable resources close to home. You might say their locally grown food system was sustained by a locally grown food system was sustained by a locally grown food system was sustained by a locally grown nutrient supply. Judging from King’s account, the farm families of the Far East devoted fully as much time to collecting materials to maintain fertility as they did tending their crops. These materials, gathered primarily by wheelbarrow and by hand, included green manures and animal manures gathered from wastelands, tons and tons of much soil dredged from nearby canals, ashed from fuel collected in the forested hills, and night soil deposited by travelers or “boated in” from the closest city.

By relying on fertility sources close to home, these industrious farmers were able to control and maintain these resources indefinitely, albeit, with a tremendous amount of labor. In a sense, they “farmed” the surrounding non-arable areas for nutrients in order to “garden” the cultivated land intensively, effectively closing the gap between what Parnes call “the source” and “the sink.”

We have also tried to close the gap between the source and the sink thinking this may be the next best thing to a completely self-contained farm system. However, here in the Northern Tier, where land seems plentiful and there are relatively few people, we are in just the opposite situation of the Farmers of Forty Centuries. Instead of taking time from picking, packing and marketing to glean organic matter from the surrounding countryside, we have found it more practical to set aside land to grow our own organic matter right where we need it in the form of cover crops. Likewise, the hay and oats, which energize the workhorses, compost and soil, we purchase from neighboring farmers whose families have kept the land productive for generations. On the other hand, trucking in a mined product, like rock phosphate, probably does not fit The Big Picture of a truly permanent agriculture. We’ll let you know in 4,000 years!

“…The foreigner accuses the Chinaman of being always long on time, never in a fret, never in a hurry. This is quite true and made possible for the reason that they are a people who definitely set their faces toward the future and lead time by the forelock. They have long realized that much time is required to transform organic matter into forms available for plant food and although they are the heaviest users in the world, the largest portion of this organic matter is predigested with soil or subsoil before it is applied to their fields, and at an enormous cost of time and labor, but it practically lengthens their growing season and enables them to adopt a system of multiple cropping which would not be otherwise possible. By planting in hills and rows with intertillage it is very common to see three crops growing upon the same field at one time, but in different stages of maturity, one nearly ready to harvest, one just coming up, and the other at the stage when it is drawing most heavily on the soil. By such practice, with heavy fertilization, and by supplemental irrigation when needful, the soil is made to do full duty throughout the growing season.” – F. H. King, Farmers of Forty Centuries

Resources:
Henderson, Peter, Gardening for Profit: A guide to the Successful Cultivation of the Market and Family Garden, Orange Judd & Co., New York, NY, 1867; Jeavons, John, Ecology Action, 5798 Ridgewood Rd., Willits, CA 95490-9730, (707) 459-0150, How to Grow More Vegetables, Ten Speed Press, 1991; King, F.H., Farmers of Forty Centuries, Rodale Press, Emmaus, PA 1911; Parnes, Robert, Fertile Soil: A Grower’s Guide to Organic and Inorganic Fertilizers, AgAccess, P.O. Box 2008, Davis, CA 95617, (916) 756-7177, 1990; Roe, Richard, Ten Acres Enough: The Small Farm Dream is Possible (by Lynn and Ralph Miller), SFJ, PO Box 1627, Sisters Oregon 97759 (541) 549-2064 1982 (original 1864).

“’The number of men employed throughout the year on a market garden of ten acres, within three miles of market, planted in close crop, averages seven; this number is varied in proportion, somewhat, according to the quantity of glass in use. I have generally employed more than that, fully a man to an acre, but that was in consequence of having in use more than the ordinary proportion of sashes. This may seem to many an unnecessary force for such a small area; but all our experience proves, that any attempt to work with less, will be unprofitable. What with the large quantity of manure indispensable, 75 tons per acre; the close planting of the crops, so that every foot will tell; the immense handling preparatory for market, to be done on a double crop each season, one marketed mid-summer, another in fall and winter, a large and continued amount of labor is required… Every operation in cultivating the ground is done by horse labor, whenever practicable to do so; but it must be remembered that the crops of a garden are very different from those of a farm; the land is in most cases (particularly for the first crops) planted so close, that nothing will do to work with but the hoe.” – Peter Henderson, Gardening for Profit

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Long-Term Soil Quality Trial 1993-1996
PASA On-Farm Demonstration Report
Anne & Eric Nordell

Demonstration Statement
At the start of this soil quality trial in 1993 we had ten years of experience growing organic vegetables and herbs on six acres of Leck Kill channery silt loam in northern Lycoming County, PA. We were interested to see if twice yearly soil testing would improve our understanding of our production system which relies on light applications of compost and a full year of overcropping to build the soil and bring weeds under control before each cash crop.

Specifically, we wondered if soil testing could help us to:

1. Identify the strengths and weaknesses of our crop rotation as it passes over four contiguous fields (#3-6) in the 12 field market garden;
2. Determine how frequently we should apply compost to maintain desirable nutrient levels and if adding rockphosphate to the compost applications at a rate of 500 lbs./acre would halt the slow but steady decline in phosphorus levels;
3. See if a full fallow year of clover would create better growing conditions for LATE planted cash crops than our normal cover crop/bare fallow/cover crop fallow sequence; and
4. Understand why previous soil tests showed such dramatic fluctuations in organic matter levels- 2.7% in 1986, 4.0% in 1989, 3.1% in 1992.

Procedure
For consistency’s sake, we relied on Brookside Lab in New Knoxville, Ohio, to analyze soil samples as we had done in the past. Brookside’s regional crop consultant, Dean Madigan of Towanda, PA, pulled 15 or more core samples from each of the four ½-acre fields in May and October of the past four years. We found it helpful to graph the results in order to identify trends and to compare soil test results with specific soil management practices.

Results
Nutrient Levels – Our primary interest in testing nutrient levels was to see if our low input approach to vegetable production was maintaining major nutrients at adequate levels. The fields used in this trial showed phosphorus (P) and potassium (K) levels as low as 70 lbs./acre when first tested in 1985. At that time these fields had received 4 tons/acre of lime but no manure or other inputs. To jumpstart the system we applied 20 tons/acre of trucked in sheep manure and 500 lbs./acre of soft rock phosphate that fall. The following years we have relied on cover crops and light application of compost made from the manure of our four workhorses, two pigs, and three dozen chickens. (We added soft rock phosphate [total P 18%] during the composting process at a rate of approximately 40 lbs./ton.)

Soil tests for these fields taken over the years leading up to this trial indicated moderate to high levels of K (4-6% base saturation percentage) and moderate but declining levels of P. Calcium levels climbed into the 2,500 – 3,000 lbs. Range (65%-70% b.s.p.) while magnesium dropped to 3-400 lbs. (12-16% b.s.p.). pH declined from 7.0 to 6.7 over the same eight years and now averages about 6.4.

(Note: An identical soil sample from field 4 came back from the Penn State Lab with very different results in the fall of 1993. For example, the Penn State report showed 3,700 lbs. of calcium (76% b.s.p.) and a pH or 7.1 alone with a recommendation to apply 240 lbs./acre of actual P to grow a crop of onions.)

The soil test reports from the four year soil quality trial suggest to us that applying light coats of compost three years out of four might maintain P and K levels better than our normal rate of two out of four years represented by fields 4 and 5 in Tables 1 and 2. Annual applications, on the other hand, may result in unnecessarily high levels of P and K where nutrient levels are adequate to begin with- field 3 had received five applications of compost during the four years preceding this trial. Considering that field 6 had not received any compost in the four years up to this trial, annual applications of compost may be a good strategy for improving under-fertilized land.

The four years of soil testing also indicated to us that spreading 500 lbs./acre of black rock phosphate (total P 30%) with compost applications could reverse declining P levels. In the field, crops responded with a deeper green color and higher yields for peas and beans. Based on the results from field 3, continued applications of black rock are not necessary where P levels are already adequate. The soil test results also suggest that K contributions from light adequate. The soil test results also suggest that K contributions from light applications of compost are relatively short-lived, again indicating that more frequent applications (three out of four years) might be desirable.

Organic Matter
The graph in Table 4 seems to highlight a pronounced seasonal effect on organic matter levels. However, we could not see any connection between organic matter levels and observable changes in soil structure or cropping practices (such as compost applications, row crop cultivation, cover crop sequences, bare fallow periods, or a full year of clover sod.)

We asked a number of soil scientists and other researchers to look at these soil test reports and we received seemingly contradictory advice: Yes, seasonal fluctuations up to a full percentage point are normal for healthy soils and reflect the natural buildup of organic matter over the cold winter months and the breakdown of organic matter during the warmer summer months when the soil is more biologically active. No, organic matter (OM) readings should not change by more than a tenth of a percent. Larger fluctuations in OM indicate sampling or laboratory error.

As a check on laboratory error, we sent two identical soil samples from field 4 in the fall of 1993 to Brookside Lab which uses the Loss-On-Ignition test for organic matter. OM readings from the identical samples came back 2.2% and 2.7%, just within the lab’s acceptable margin-of-error. We also sent identical samples from all four fields in 1995 and 1996 to Woods End Lab in Mt. Vernon, ME, which uses the Walkley-Black Oxidation Test for organic matter. These reports showed almost as dramatic fluctuations in OM but the changes did not appear to correlate with either seasonal or cropping influences.

Our conclusion is that OM testing may no be helpful as a soil quality tool except possibly for tracking very long-term trends. As an alternative, we asked Woods End to test the soil samples for water stable aggregates and soil respiration rate. We will give a full report on these tests once we have four years worth of data.