The New Agriculture Network's on-line newsletter with seasonal advice for field crop and vegetable growers interested in organic agriculture.
Vol. 2, No. 10 - September 15, 2005
In this issue
Next issue posted September 15. Read previous issues through our calendar of issues.
Soil quality, soil testing and organic standardsMichelle Wander, Natural Resources and Environmental Sciences Department
University of Illinois
"There is not to be found in chemistry a more wonderful phenomenon, one that confounds all human wisdom, than is presented by the soil of a garden or field."
-Justus Von Liebig 1859. Letter II. Letters on Modern Agriculture.
I. Soil quality and the organic standards
II. Evolution of organic and 'modern' perspectives on soil fertility
III. Current approaches
IV. The Blue Moon Farm experience
I. Soil quality has long been thought to lie at the heart of agricultural sustainability. Growers achieve certified organic status from USDA or one of the international certifying agencies (IFAOM or JAS) only after complying with standards that seek to improve or maintain soil's inherent fertility. Organic standards advocate growers use practices that build or enrich organic matter by using appropriate crop rotations and amendments. While vague in nature, proscribed practices are intended to promote the efficient cycling of nutrients, water and energy, and to increase soil's ability to resist and recover from disturbance. Specific requirements present in the standards focus primarily on what not to do or apply rather than on how to manage. As yet, there are no requirements to demonstrate that one has improved their soil using soil tests or other more biologically focused measures.
II. In "The Living Soil" (1943) Lady Eve Balfour outlined the principles of organic fertility when she suggested that reliance on chemical fertilizers was undermining fundamental soil fertility and argued the merits of what was then called humus farming. She claimed "humus benefits the soil in three ways: mechanically, as a plant food, and by fundamentally modifying the soil bionomics. Of the three, this last, hitherto largely ignored, is probably the most important.” She wrote on to highlight the importance of fungi to many crops and asserted that where humus is built up, crops would not suffer from disease or parasites. At that time, Balfour, Howard and Albrect were all exchanging ideas and working to advance the notion of holistic soil management through soil building. Their efforts were paralleled by those of Goethe and Steiner and their observations have been repeatedly shared by others who have noted that good stewardship pays. The upsurge of interest of these individuals and of J. I. Rodale was in part a response to the rise of modern agriculture, which was launched in the 1850s with Liebig's articulation of the 'Law of the Minimum.’ After disproving the humus theory by demonstrating that plants obtained only their mineral nutrition and not key constituents (carbon, hydrogen and oxygen) of their organic mass from soils, Liebig demonstrated how the most limiting nutrient constrained plant growth. He explained this law by describing the various elements required for mineral nutrition as individual staves in a barrel, where the shortest stave (the limiting nutrient) determines the useful volume of the barrel (the capacity of the soil to produce). Since that time, conventional management strategies have not effectively considered something that Liebig appreciated well—which is that physical and biological fertility of soils are the foundation upon which the barrel rests. Fertility management strategies that treat soils as an inert vessel through which plants are fed are rather difficult to adapt to organic production systems where soils are seen as a living system requiring nurturing. This disconnect has practical, environmental and economic dimensions.
III. Current and potential organic producers need improved access to information and tools to better manage nutrients while they simultaneously control pests, conserve tilth and protect the environment. University-based information specifically targeting organic growers is increasingly becoming available. The IFAFS Organic Agricultural Consortium will soon release an Organic Production Manual prepared by North Carolina State researchers that will initially be available at:
http://www.cefs.ncsu.edu/.
Some of the more applied material is more relevant to growers in the southeast, however, the chapter on fertility management contains basic information that should be generally applicable. Similar overviews of fertility are provided in materials from the University of California -- Davis, http://anrcatalog.ucdavis.edu/pdf/7249.pdf, and West Virginia University http://www.wvu.edu/~agexten/farmman2/organic/soilfert.pdf.
In general, such publications note the value of soil or plant tissue tests, but may not provide information that would allow an organic grower to easily adapt recommendations developed for conventional, simple rotations for use in their more diverse cropping systems. Crops grown in effectively managed organic systems, by this I mean systems that have built organic matter, can achieve crop yields that are equal to or greater than conventional counter parts at lower soil test levels. Such guides do not usually provide information that is detailed enough to help growers determine how to substitute locally available organic fertilizers for conventional inputs. For this growers must rely on vendors or consultants and/or conduct their own on-farm research to calibrate conventional tests. Unfortunately, the need to repeat field studies over time in order to account for weather affects or other factors that might influence outcomes in a given year, but not in the next, poses a large challenge to growers who are already coping with more demanding management systems. The need for growers to change varieties in response to price, markets or supply can make repetition of on-farm experiments over several years impractical. Some of these challenges, and of course the philosophy that underlies organic management, call for a different, more ecologically based approach to fertility management. Practical examples of this tact are more available in Europe (http://www.soilassociation.org/web/sa/saweb.nsf/0/5184f
d5c24b945ed80256dc00051d0c0?OpenDocument), where there has been a greater investment in the development of organic agriculture. Some of the exciting work ongoing at U.S. institutions, which unfortunately is not yet available for use, is focused on the development of nutrient budgets or accounting strategies.
IV. In the meantime, I'd suggest growers consider using a combination of testing and budgeting. It is a good idea to take soil tests at a consistent point in your rotation. Ideally this time point and your initial sample will serve as a valuable reference. Keep in mind that soil nutrient and organic matter stocks naturally fluctuate within a rotation so you might try to sample at the point where stocks are at their highest (ideally before your more nutrient-demanding crops are grown) or at their lowest point (possibly after crops are seeded and soils are prepared for cover or hay seeding). Soil samples need to be taken from a consistent soil depth and that depth and timing of sampling should be logically related to your tillage practices. Deeper tillage can lower the average concentration of nutrients and organic matter surface soils and look like declining fertility so you might consider using a deep sampling regime (1 foot instead of 6 inches) to reduce this problem. You may want to use time sampling and testing so that you have your results in hand before you need to apply fertilizers. Of course, if you are using a budgeting approach, you will already have a good idea about what you might need to apply. More likely, your test results will reveal the presence of stocks that you might not have assumed where there. Over-application of manures and composts is a concern for many organic growers, particularly those engaged in intensive vegetable production or with livestock operations.
At Blue Moon Farm we have been farming organic vegetables for nine years on some beautiful soils (Flanagan, Catlin, Drummer). We do have baseline samples from all areas of the farm and have now settled on annual soil testing of our actively cropped land. Beds are cropped for three years and then seeded to perennial legume/grass cover and left for three years. This is a more frequent testing regime than we need to have to follow trends. Samples are collected from the top 6-8 inches, which is similar to our primary tillage depth, from blocks that include adjacent beds that are managed similarly. Greenhouses are tested too. Over time we have been able to see organic matter levels remain constant and most nutrient stocks, particularly P, increase. Most test values are reported as high or very high. Abrupt and lasting increases were associated with single additions of compost amendments made at low rates (approximately 5 tons/acre). This surplus of P has really made us focus on growing our N. By tracking trends in test values we can also tell that our calcium to magnesium ratios are declining and that conductivity levels in our greenhouses are increasing. These test-based indications point to nutrient excesses, not deficiencies, but of course we don't have a test for N. In addition to tracking trends with soil tests, we have estimated the amount of nutrients that our typical crop rotation removes. We don't try to feed individual crops, which vary tremendously in their nutrient needs. For example, carrot and potato can remove 200 lbs of K per acre in a year while broccoli harvest only removes 45 lbs per acre. Mind you these crops take up more than this into their biomass. Using our 'averaging' method we estimate that during the three years of active cropping that takes place before we reseed our perennial cover to rebuild soil organic matter, crops remove 300, 40, 450 lbs of N, P and K per acre, respectively. If we only had this information and did not have soil tests that show K levels as high to very high, we'd worry about K levels since most organic amendments including composts and alfalfa meal have too much P and not enough K in proportion to the N they contain. Based on the admittedly back-of-the-envelope averaging/replacement approach, we can conclude that we should be careful about use of composts and apply them on a P basis. In theory we should attempt to use fertilizers that have high N/P and K/P ratios. If we felt we were not able to supply enough N through annual or perennial legume crops we could look to soy meal, which is affordable and has a high N/P ratio. If or when we start to worry about K, we could look to alfalfa pellets or hay which have high K/P ratios, but are not cheap.
Alternative cover crops for fall and winter niches
Sieglinde Snapp,
Michigan State University, Horticulture
A living cover is the best protection available against erosion and nutrient loss. Farmers are aware of this, and often sow a cold-tolerant cereal such as wheat or rye to provide winter cover. Alternative cover crops are being experimented with as biological soil renewers, to promote an aggregated soil with reduced compaction and greater yield potential. Chief among these novel species are brassicas – e.g., oriental mustard variety ‘Pacific Gold’ - and legumes such as hairy vetch and sweetclover. The interest in brassicas is high due to the potential for bio-fumigation properties associated with the glucosinolates in the plant tissue (these are the compounds responsible for the ‘hot’ taste of mustard).
Introduction to promising brassicas and legumes
Mustards (Cruciferae or Brassica spp.) are broadleaf, cool-season spring annuals with a large, deep taproot. They can also be grown as fall annuals, but only if they are planted in the short window of late summer to early fall. If they are planted in early summer they will become reproductive too fast (flower early) and not produce much vegetative growth. If they are planted too late, e.g., after mid September, then they will have insufficient time to establish in most years and die early before producing much biomass, depending on when a hard frost occurs. The good news is that mustards emerge rapidly, in 5 to 10 days after planting, and will germinate in soil temperatures as low as 40 °F. In 4-5 weeks plants will completely cover the ground. Flower buds appear from 3- 5 weeks after emergence and yellow flowers are visible 1 week later. As soon as yellow flowers are observed a management plan to control growth and incorporate residues should be implemented. This is to prevent early maturation of some seeds and nip the potential for future weed issues in the bud. Indeterminant seed production and rapid maturation are common traits associated with this family, which have been aptly nick named "fast plants."
Management of mustard cover crops requires attention to soil preparation and planting, due to the very tiny seed size of this family. Mustard should be planted into firm seedbeds free of weeds and residues. This plant prefers neutral pH, but can be planted in slightly acid or slightly basic soils ranging from 5.5 to 8.3. The seed rate varies depending on farmer objectives, as a high seeding rate of 12 to 16 lb/acre is required if a pure stand is being grown to incorporate green tissue in a biosuppression system. Alternatively, an 8 to 12 lbs/acre is a widely used recommendation for use of mustard in mixtures with a cereal or as a sole cropped cover crop where the intention is to leave the mustard as a winter cover and compaction-breaking intervention.
In general, mustard will establish well if broadcast to ½ inch and harrowed or irrigated into sandy soil. At time of planting the soil temperature has to be at least 40 to 45°F in the soil surface. Recent research findings indicate that maintaining moisture is important as well as adequate soil temperature, particularly in a dry fall. Not all farmers have access to irrigation, and other options are being tested at KBS-MSU and East Lansing MSU sites, including sowing of seed in combination with a manure treatment. This has been shown to consistently enhance biomass produced by over 25%, compared to biomass from cover crops sown in the absence of manure amendments.
Hairy vetch is the most cold tolerant annual legume that is grown widely as a cover crop. The good news is that it can be planted as late as mid October and survive across much of lower Michigan and states south of Michigan. However, in general no significant growth will occur until Spring, unless it is planted earlier (by mid September). Hairy vetch produces more biomass than almost any other legume grown as a winter annual, and it is widely adapted to different soil types and climates. This makes it important for organic growers to consider as a nitrogen source, providing soil cover and nutrient-enriched residues over the winter when few annual legumes grow. However, it has a vigorous climbing growth habit which makes it very difficult to manage if winter wheat or other winter cereals are grown as crops. Hairy vetch is not recommended for use in fields where winter cereal production is planned or currently grown. Red clover is generally a much better-suited winter legume for integrating into a winter cereal production system.
Hairy vetch has an undesirable trait called hard seed, from 3 to 15% of the seed depending on the seed batch and variety of hairy vetch. My laboratory is collaborating with Dr. Sarrantonio at University of Maine to select for vetch species and varieties with greater cold tolerance and reduced percentage of hard seed. Hard seed causes problems as is facilitates the long-term survival of hairy vetch seed in the soil seed bank (up to 20 years survival), and thus enhances the potential of hairy vetch to become an undesirable plant in the future, e.g., a weed. Winter survival of hairy vetch varies with the variety. Unfortunately currently it is difficult to buy a specific variety of hairy vetch. Research indicates that ‘common’ hairy vetch, that is, a locally-grown hairy vetch from your nearest forage seed or mill is likely to be the most adapted to your area. We are investigating vetch genotypes from Siberia and other areas where we expect greater cold tolerance may be present, but at the moment it appears that ‘common’ hairy vetch can generally outperform named varieties of hairy vetch such as AU Early Cover.
We plan to also work with Dr. Walter Goldstein of Michael Fields Agricultural Institute to screen yellow sweetclover varieties for improved performance. At one time sweetclover legumes were one of the most important biannual legume species grown for soil improvement, and this is a species that should be looked at again for the potential benefits from nitrogen fixing properties and deep rooted, winter survival. Growers - if you have experience with hairy vetch, red clover or sweetclover and their use as green manures and cover crops we would appreciate hearing from you! Please feel free to contact me, Sieg Snapp, at snapp@msu.edu or 517-282-5644.
Technologies to promote fall establishment and winter survival
In addition to using locally adapted materials, another way to improve winter survival and performance of alternative cover crops is to plant following the best practices. Pre-germination of seed requires that farmers spend time soaking the seed, but it usually markedly improves plant stand and establishment. Soaking hairy vetch for approximately 12 to 24 hours before planting to pre-germinate is particularly effective in a dry fall such as we are experiencing this year. Applying irrigation or a dilute manure slurry after broadcasting or drilling (shallow) seed will also markedly improve cover crop establishment in most cases.
It is not always feasible to pre-germinate or irrigate recently planted cover crops, so we are experimenting to develop a simple ‘priming’ technique to prepare cover crop seed. This involves a short soak of seed in water (about 2 to 6 hours), followed by either immediate planting or drying the seed for use at a future planting date. ‘Primed’ seed hydrates the seed and activates enzymes in the seed, which can increase the vigor of the young seedling. It is a technology used in production of some crops, such as most commercial seed for carrots and sugar beets, which are commonly primed. Primed seed that has been dried can be kept for several months before it is planted; this is unlike pre-germinated seed which must be planted immediately. The difference between the two technologies is that priming requires a short soaking period followed by drying the seed (which allows flexibility regarding the planting time), whereas pre-germination of seed usually involves a longer soak treatment and requires immediate planting of the seed. These are some of the technologies which can be considered as tools for enhancing cover crop establishment in the harsh environment of the fall seed bed, where cool temperatures and a rough seed bed after harvest often provide a less then ideal condition for germination and growth.
To sum up, fall planted mustard will need about 45 days from planting to incorporation. Mustards are rapid growing species and can become a weed in a subsequent crop, so it is very important to not let this cover crop produce seed (Snapp, S.S.and D.R. Mutch. 2003 Cover crop choices for Michigan vegetables. Michigan State University Extension Bulletin. E2896, see http://web4.msue.msu.edu/veginfo). Hairy vetch is a winter annual and often produces very little biomass in the fall, but early spring growth can be substantial. Incorporate shoots from alternative cover crops into the top 6 inches of the soil via flail chopping, immediately followed by disking. This will optimize soil and plant tissue contact, one of the keys to promoting healthy soil and over the long run, healthy crops.
Editor’s note: This announcement was excerpted from a release for Michigan farmers written by Susan Smalley, Extension specialist with MSU’s C.S. Mott Group for Sustainable Food Systems.
The North Central Region Sustainable Agriculture Research and Education program (NCR-SARE) has posted its 2005 call for Farmer Rancher Grant Proposals at www.sare.org/ncrsare/cfp.htm. Don't let the length of the call scare you -- the proposals are short and not difficult to develop.
Who can submit a proposal? Farmers and ranchers the twelve North Central Region states.
What can the money go for? Projects that:
1) test, evaluate, and adapt sustainable agriculture practices for farming operations;
2) learning circles, educational events, field days or demos to
get sustainable ag information to farmers;
3) develop new technologies for sustainable agriculture; or
4) create or modify equipment for sustainable agriculture. The project may focus on adults, youth or both.
How much money is there? Overall, about $400,000 has been allocated. An individual farmer may receive a grant of up to $6,000 and a group of three or more unrelated farmers may receive up to $18,000.
When: Monday, Sept. 26, 2005, 4:30 to 7:00 p.m. local time. Sandwiches and beverages provided.
Indiana
Southeast Indiana - Gary Reding
We’ve had quite a summer this year with our organic crops. First a wet spring then a dry July only to be followed by a sudden rain, this was followed by more rain with wind. It has been an interesting one to watch and manage around. We received 2.6 inches of rain on Aug. 5-6. It came at the last moment possible to save our popcorn and soybean crops, plus refresh our pastures. The hot July encouraged the popcorn to grow profusely to heights I have never seen in this variety before. The rain came at pollination and just as the crop was starting to fire at the bottom. I thought we were saved. It stayed cloudy and cool and all the rain soaked into the spring moldboard plowed ground and the crop woke back up. Then a few days later we got another rain while the ground was still saturated, but this one came with some 40 mph wind. The wind blew about 20 percent of the popcorn over at the ground. Just as it was starting to gooseneck back up we got another 2 inches of rain with the tail winds of Katrina over night. Upon waking the morning of Aug. 5, I looked out the window and saw most of the popcorn lodged. You can see from one end of the field to the other on quarter-mile long rows. The stand was thick enough that it did not go flat to the ground everywhere. My only hope now is to have a dry spell from now to harvest to keep from getting mold and disease in the kernels. If that happens, the popcorn value dissipates. We have very little insect problems and the plants are still attached to very nice root systems.
The soybeans were helped by the rains and not affected by the winds. They look very good now and have a promising yield potential. We have walked one field by hand twice and it is very clean of all weeds. The only insects we’ve seen while walking were the lady bugs and just a few grasshoppers and Japanese beetles. No defoliation to speak of.
Our pastures and hay fields have held up well to the summer for the most part. The second cutting was lower yielding than most times and the third was not possible. I have decided to graze the re-growth to avoid cutting it too short in the late of summer. The cattle withstood the heat of July well and have now started their growth spurt from fall grass.
We hope to be harvesting the soybeans and popcorn in the next two to three weeks.
I would like to plant spelt and triticale on the crop ground for cover and leave the best fields to be harvested for grain next summer. We will rotate some beans to popcorn and some popcorn to beans. The remaining will be in spelt and triticale.
I will need some more acres for organic popcorn production next year. If anyone is interested, please call 812-663-9546.
South Central Indiana - Dale Rhoads
At the end of the last reporting period three weeks ago we had experienced another set of torrential rains along with high temperatures. Since the rains, temperatures have been a little cooler. These heavy rains affected our salad greens crop and fall planting.
The rains beat down the tender leaves of salad greens and caused perfect conditions of heat and humidity to cause excessive disease problems. Essentially this shut down or greatly reduced our salad greens operations for three weeks until later crops in our succession planting came to maturity. We are now back into full production with salad greens.
With the fall herbs, brassicas and cole crop plantings we had several crops planted one to two weeks and in various stages of germination and seedling emergence. These heavy rains caused a crust to build on the soil adversely affecting seedling percentages. We ran a roller-type device over affected areas and did some watering. For the most part germination was successful, but several crops did not germinate well and it was too late to replant.
Cooler conditions and shorter days have brought tomato production in the greenhouse to an end. We have been pulling the plants and letting large green fruits ripen in the greenhouse.
With shorter days and the entire fall succession planting germinated, we have taken our shade cloths off the salad greens areas. In the last two to three weeks we’ve planted all of the rest of the salad greens beds for the fall, beds that normally would be planted in weekly successions; we do this because of the slow growth. Typically in the fall we might be cutting and letting regrow up to eight 3 x 100 foot salad greens beds as compared to in the spring and summer when we actively cut off two to three beds at most. These planted beds include one that we’ll put under a heavy row cover once regular frosts start slowing down and/or affecting the quality of the uncovered beds.
Currently I am finishing up with the farm maintenance projects I have been doing this summer. We are pulling the last of the tomatoes out of the greenhouse, doing lots of weeding of salad greens and fall crops plantings and harvesting Asian pears. (A note on Asian pears: this was a very light year for stink bug pressure on Asian pears. Pears got tiny hair line cracks from frost, but grew out of them in funny citrus like/segmented shapes. Our local crow flock ate significant quantities of several varieties. I have surprised and shocked the crows several times and now they are staying out of the remaining varieties so far. If they return we are going to try putting out a plastic owl.
In the next two weeks we’ll be prepping greenhouse for early winter salad greens crops, tilling and germinating weeds for creation of stale seed bed. We continue to harvest Asian pear varieties as they ripen. We plan to install drain tiles in a field that has drainage problems. We are starting to wrap-up areas as they finish production and will plant them to winter rye. A few areas that have been neglected this summer will be mowed.
Central Indiana – George Mears
After an extremely dry spring in May and June, rains in July saved the crop. The pasture is as bad now as it has ever looked—grass is dead, but tap-rooted weeds are doing well. The undersown cover mix in wheat wasn¹t a good stand. It has been disked down and then seeded with buckwheat. The ground was very dry at seeding. Disked and used packer wheel after spreading the buckwheat and a little lime. Now it has rained and maybe the buckwheat will come up. Group 2 soybeans are being harvested in the area. The beans are small; what would normally be 75-bushel beans are yielding 60 bushel because it has been dry.
Some in the area are talking about 200 bu/acre corn, on soils with heavier clay.
Michigan
Southeast Michigan - John Simmons
Hot and dry! Small grain harvest is complete with average yields and quality. Red clover seed harvest is underway with early fields yielding more than average. Later fields look closer to average. Moldboard plowing of oat/clover fields for fall spelt planting is on hold because of dry fields and poor plow penetration. Plowing will not continue until one-quarter inch or more of rain is received. Third cut alfalfa harvest is underway—early fields provided a modest yield of very high quality hay. No rain—nice and green. Soy aphid counts have declined as predator numbers have increased. Soy fields are yellowing leaves and beans and dropping leaves; harvest is likely three weeks away on beans. Corn is fully dented, some has matured or at least "ear-dropped" from lack of moisture. Sunflowers are mature and drying down; harvest is likely three weeks away. Buckwheat is completing flowering stage. Lower seeds on plants are mature and dry. Harvest will be based on seed drop, likely two weeks, give or take. Clover interseeds in buckwheat fields look good. Clover covers in small grain fields are finding water and continuing growth. Seed set on small grain clover looks good. Pasture is adequate in rotational pasture fields, both clovers and grasses are recovering well. Milling/cleaning of fall seeded grains continues. Farm sales of seed are slow, as many growers wait until fields are prepped to acquire seed. An apparent early/timely soy harvest should make winter grain planting easier than in the past couple of years.
