Soil Foodweb Inc.
Dr. Elaine Ingham

              Introduction To Gardening With Nature

Many people are demanding organic, based on political, nutritional, and environmental reasons. Implicit in the reason to return to natural production methods is the fact that beneficial organisms are killed by the use of toxic chemicals. This sets up toxic chemical users to need more and more and more toxic chemicals to maintain the system to the point that an addiction to those toxic chemicals is formed. 

How do you “Just Say No” to that addiction?  Switching from using synthetic chemical fertilizers and toxic pesticides to using organic products does not fix the problem caused by toxic chemicals.  If we only use natural products that kill pests, weeds or diseases, the problem has not been solved, and the “organic grower” will not be successful.  “The switch” must involve a wholly new approach, which requires working with nature, instead of combatting and fighting nature. 

Gardening with nature is preventative. We deal with the cause of diseases, pests, or poor fertility.  The toxic chemical approach tries to suppress symptoms of the problem, instead of fixing the problem.  By merely trying to suppress the symptoms, the problem typically gets worse and worse, which leads to more and more chemical use. This results in a loss of nutrients, as well as the toxic chemicals leaching from the soil and polluting our water systems.  All this occurs because the beneficial soil life, which is normally present in healthy soil, is lost.

Chemical companies love people who mindlessly follow their instruction, never asking why growing food gets more and more expensive and involves ever greater amounts of ever more toxic chemicals.  Since toxic chemicals do not deal with the problem, but rather with symptoms, we get drawn into a chemical downward spiral.   If we try to stop toxic chemical use, our plants do not do well.  Failure is often the case if we try to get off the downward spiral by simply shifting to using organic products. 

To win our freedom from toxic chemicals, we must start gardening with nature. The key to gardening with nature—to true organic gardening—is to recognize the power of beneficial microorganisms, elements little known or understood by the general public.

Organic growing is different from using chemicals for several important reasons.  First, we need to have most of the nutrients present in the soil in non-leachable forms most of the time.  We need to have the mechanisms in that soil to convert those not-available-to-plant nutrients into plant-available nutrients IN THE ROOT ZONE, for the most part, not away from the roots. The mechanisms to do this conversion process are beneficial microbes -- bacteria, fungi, protozoa, nematodes, and microarthropods.  The beneficial species of these organisms are naturally found in healthy growing systems, not the disease species. 

Simply putting down the highest quality, most expensive organic nutrients in your garden is not likely to result in great plant growth, unless the correct microbes are present.  Beneficial bacteria and fungi are needed first to degrade any residual toxic chemicals in your growing environment.  Then bacteria and fungi are needed to tie-up nutrients so those nutrients are not leachable, and thus are not lost when water moves through the soil.  Finally, bacteria and fungi need to be eaten by protozoa and nematodes to release tied-up nutrients in a plant available form.  If any of the species that do this processing in your soil are missing, then we need to get them back.  If life is missing in your soil, we need to give Mother Nature a jump-start to help her reestablish the normal set of organisms, and thus, reestablish normal nutrient cycling. 

Clearly this process involves more than simply laying down a set of mineral nutrients. We need to educate people to understand that plants can, indeed, take care of themselves without people getting in the way.  No need to have complex feeding schedules and mind-boggling mathematical calculations on rates of adding nutrients or adjusting pH. In the gardening with nature approach, we provide nutrients and a diversity of microbes to transform those nutrients, and the plants do the rest. Microbes, then, hold on to nutrients and they no longer leach from the soil, so you can use far fewer nutrients. Microbes also restructure the soil by creating air passageways and cavities that enable water and air to be retained within the soil, so you use considerably less water. You save money, time, and energy, and the health of your plants improve. Plants contain more nutrients and have built up their immune systems to become resistant to problem pests and diseases, leading to higher yields and plants that grow bigger and faster.

There are some complications that can arise when gardening with nature. Most significantly, complications arise because our gardens are not isolated. Though we have added microbes and organic nutrients, we still may have problems from environmental disturbances beyond our control—pesticide drift from a neighboring yard, acid rain, freezing weather, scorching heat, chlorine and chloramine in our watering systems, or too many salts. We must continue to tend our gardens and be watchful. We must continue to add microbes and nutrients. However, less maintenance will be required each year, as our soils increase in organic matter and microbe populations. Maintaining a healthy population of 70 percent of beneficial microbes in soils and on plant surfaces will nurture a protective type of environment that will thwart any disease-causing organisms that may come along, simply by outcompeting them for food and space.

Excerpts from Preface to 10 Steps To Gardening With Nature: Using Sustainable Methods To Replicate Mother Nature written by Carole Ann Rollins, Ph.D. and Elaine Ingham, Ph.D.

             The Soil Will Save Us: A Manifesto For
         Restoring Our Relationship With The Land

What if we could reduce greenhouse gas emissions and grow enough food to feed our ballooning population using resources we already have? Kristin Ohlson, author of The Soil Will Save Us, thinks we can do just that. And like a growing number of scientists, farmers, and good food advocates, she believes that in order to fix the problems in the sky, we need to put our eyes and ears to the ground.

The Soil Will Save Us is part soil science primer, part history lesson on environmental degradation and the efforts to fight it, and part manifesto on restoring our relationship with the land. The reader follows Ohlson as she travels the globe—from her childhood home near Cleveland, Ohio to Perth, Australia—to learn about how people can revive soils damaged by decades of drought, erosion, and poor land management.

Ohlson explains that plants naturally capture carbon from the air, in the form of carbon dioxide, and turn it into food for everyone from soil bacteria to human beings—or what ecologist Christine Jones dubs “the very first carbon-trading scheme.” This symbiotic process relies on the intricate relationships between light and dark, water and air, and the wide array of organisms that live in the soil. Ohlson likens the bustling world of soil microorganisms to Whoville, Dr. Seuss’ imagined city floating in a speck of dust, writing: “The Whoville in that teaspoon of soil is more like Mexico City. Imagine how many microorganisms are in a cup of healthy soil. More than all the humans who have ever lived.”

Ohlson argues that the rise of agriculture has actually diminished our understanding of the rich and delicate ecosystem just below the ground. She indicts industrial agriculture in particular, as harsh practices like tilling our farmlands and saturating the ground with synthetic fertilizers have led to a swift and steady decline in soil health. The effects on our climate have been staggering. “The world’s soils have lost up to 80 billions tons of carbon…[and] land misuse accounts for 30 percent of the carbon emissions entering the atmosphere,” Olson writes.

That’s right—that “unstoppable loss” of the Antarctic shelf and the ensuing 15 feet in sea level rise we heard a lot about last month? How we farm is a big part of the problem.

On the bright side, Rattan Lal, director of the Carbon Management and Sequestration Center (C-MASC) at Ohio State University, argues that we can capture some, if not most, of that carbon back by letting plants do what they do best: photosynthesis. “The carbon in the soil is like a cup of water,” Lal posits in the book. “We have drunk more than half of it, but we can put more water back in the cup. With good soil practices, we can reverse global warming.” Lal believes we can restore three billion tons of atmospheric carbon to the soil each year and he works with scientists on test plots around the world to develop practices to promote carbon sequestration.

It’s not just scientists who are repairing soils, however. On the other side of the globe, Olsen spent time with Allan Savory, who walks barefoot through the grasslands near Victoria Falls, Zimbabwe. “People with shoes aren’t aware of how damned hot the soil gets,” Savory said as he explained how the soil’s heat is a symptom of rampant desertification. A former botanist and zoologist, Savory founded the Africa Centre for Holistic Management because, like Lal, he believes we can bring our soils back to life. To do so, he enlists the help of those he once thought were responsible for the degradation he sees today: cattle.

Savory believed for years that range herds made the grasslands dry and brittle, until he visited a South African farmer who had managed to rebuild his soils by mimicking ancient grazing patterns among his cattle. As Ohlson writes, “humans unintentionally changed the way the herds impacted the grasslands when they domesticated them.” Allowing herds to graze in tight groups for short periods of time, like they do in the face of predators, could actually reverse desertification. The animals trample green plant material into the soil and create hoof prints that act as shallow pools for rainwater to collect. As the ground soaks up water, more and more plants and microorganisms once again find a suitable place to live.

In North Dakota, farmer Gabe Brown accidentally adopted practices similar to Savory’s. For four years, Brown lost most of his crops to extreme weather; in response, he planted cover crops and allowed his cattle to graze through the wreckage. “That was a tough time, but it was the best thing that could have happened, because I never would be where I am today without those four years. We were forced to change,” Brown told Ohlson.

Making the switch to more holistic forms of land management has helped save Brown money he would have otherwise spent on expensive synthetic fertilizers and has improved his soil health dramatically. This, in turn, has led to a healthy combination of plants, microorganisms, fungi, and insects that all work together to keep pests and disease at bay. His fields have never been more productive.

Ohlson weaves these stories together among many others and in so doing evokes the interconnectedness of the world underground. While much of The Soil Will Save Us celebrates the farmers and scientists who are leading the charge toward a better ecosystem, Ohlson reminds us that we all have a part to play. As eaters, we can support food grown in harmony with the soil, but that’s not all.

“What we do with our urban green matters, whether it’s in our yards or our parks or even our highway median strips,” she writes. Indeed, the soil can only save us if we start building a world where healthy plants can take root, no matter where they are.

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February 16, 2015

Ancient Rocks Show Life Could Have Flourished on Earth 3.2 Billion Years Ago
by Hannah Hickey

A spark from a lightning bolt, interstellar dust, or a subsea volcano could have triggered the very first life on Earth. But what happened next? Life can exist without oxygen, but without plentiful nitrogen to build genes – essential to viruses, bacteria and all other organisms – life on the early Earth would have been scarce. The ability to use atmospheric nitrogen to support more widespread life was thought to have appeared roughly 2 billion years ago. Now research from the University of Washington looking at some of the planet’s oldest rocks finds evidence that 3.2 billion years ago, life was already pulling nitrogen out of the air and converting it into a form that could support larger communities.

“People always had the idea that the really ancient biosphere was just tenuously clinging on to this inhospitable planet, and it wasn’t until the emergence of nitrogen fixation that suddenly the biosphere become large and robust and diverse,” said co-author Roger Buick, a UW professor of Earth and space sciences. “Our work shows that there was no nitrogen crisis on the early Earth, and therefore it could have supported a fairly large and diverse biosphere.”

The results were published Feb. 16 in Nature. The authors analyzed 52 samples ranging in age from 2.75 to 3.2 billion years old, collected in South Africa and northwestern Australia. These are some of the oldest and best-preserved rocks on the planet. The rocks were formed from sediment deposited on continental margins, so are free of chemical irregularities that would occur near a subsea volcano. They also formed before the atmosphere gained oxygen, roughly 2.3 to 2.4 billion years ago, and so preserve chemical clues that have disappeared in modern rocks.

Even the oldest samples, 3.2 billion years old – three-quarters of the way back to the birth of the planet – showed chemical evidence that life was pulling nitrogen out of the air. The ratio of heavier to lighter nitrogen atoms fits the pattern of nitrogen-fixing enzymes contained in single-celled organisms, and does not match any chemical reactions that occur in the absence of life. “Imagining that this really complicated process is so old, and has operated in the same way for 3.2 billion years, I think is fascinating,” said lead author Eva Stüeken, who did the work as part of her UW doctoral research. “It suggests that these really complicated enzymes apparently formed really early, so maybe it’s not so difficult for these enzymes to evolve.” Genetic analysis of nitrogen-fixing enzymes have placed their origin at between 1.5 and 2.2 billion years ago.

“This is hard evidence that pushes it back a further billion years,” Buick said. Fixing nitrogen means breaking a tenacious triple bond that holds nitrogen atoms in pairs in the atmosphere and joining a single nitrogen to a molecule that is easier for living things to use. The chemical signature of the rocks suggests that nitrogen was being broken by an enzyme based on molybdenum, the most common of the three types of nitrogen-fixing enzymes that exist now. Molybdenum is now abundant because oxygen reacts with rocks to wash it into the ocean, but its source on the ancient Earth – before the atmosphere contained oxygen to weather rocks – is more mysterious. 

The authors hypothesize that this may be further evidence that some early life may have existed in single-celled layers on land, exhaling small amounts of oxygen that reacted with the rock to release molybdenum to the water. “We’ll never find any direct evidence of land scum one cell thick, but this might be giving us indirect evidence that the land was inhabited,” Buick said. “Microbes could have crawled out of the ocean and lived in a slime layer on the rocks on land, even before 3.2 billion years ago.”

Future work will look at what else could have limited the growth of life on the early Earth. Stüeken has begun a UW postdoctoral position funded by NASA to look at trace metals such as zinc, copper and cobalt to see if one of them controlled the growth of ancient life.

Other co-authors are Bradley Guy at the University of Johannesburg in South Africa, who provided some samples from gold mines, and UW graduate student Matthew Koehler. The research was funded by NASA, the UW’s Virtual Planetary Laboratory, the Geological Society of America and the Agouron Institute. For more information, contact Buick at 206-543-1913 or


Healthy vineyards grow more than grapes  

Napa Valley Register, 2.17.14, by Howard Yune

CALISTOGA: What helps to absorb greenhouse gases, extend the life of farmland and keep soil moist in times of drought? At one of the Napa Valley’s most famed wineries, growers turn their eyes downward for their answer – toward the humble-looking, easy-to-miss plants between the rows of grapevines.

Most visitors at the Chateau Montelena grounds may first notice the columns of vines producing grapes for its famed vintages. On Sunday afternoon, however, a group of visitors turned their attention instead to the Blando Brome grasses, barley and other ground-cover plants filling the 8-foot-wide gaps between the rows.

Encompassing a program of cover crops and extensive composting, its supporters say, is the goal of allowing the soil and its inhabitants to fulfill their normal purposes.

“It’s all about balance; we want to maintain what we already have (in the soil),” said Dave Vella, Chateau Montelena’s vineyard manager. “We’re not going to ‘improve’ on anything. … You have to look at soil like a big checking account; you make a deposit and you get a return, but you can’t keep withdrawing from the soil.”

About a dozen species of soil-hugging vegetation serve as counterpoint and guardian to Chateau Montelena’s famed vines. By pulling carbon dioxide from the air, retaining water, harboring pest-hunting insects and strengthening the ground against erosion, the plants form what its creators – Vella and the agronomist Bob Shaffer – describe as a safeguard against the fields’ exhaustion, a step they urged other farmers to emulate to lessen the burden of fertilizer and pesticide costs.

On Sunday, Shaffer and Vella led about 20 visitors past vineyards serving as living test beds for different cover plants and farming techniques. Between certain vine rows were experimental plant choices such as strawberry clover or Cucamonga brome; other rows had been left unmowed for a season, to lessen soil compaction that would slow the absorption of water.

Such experimentation, according to Shaffer, will permit future growers greater economy in the use of fertilizer, by learning which minerals already are plentiful. The light-touch approach also is meant to preserve the earthworms, nematodes, bacteria and other organisms that break down plant matter into the organic material that gives crops – including grapes – their character and quality.

“It used to be said that wine is made in the winery. Actually, wine is made in the vineyard,” said Shaffer, a soil culture specialist in Honaunau, Hawaii who advises grapegrowers and other farmers. “If you run down your supply of food, you will see it in your grapes. Quality goes down, the color goes down and the yield goes down.”

Earlier Sunday, Vella said his plant-based, less resource-intensive approach had its roots years before he joined Chateau Montelena in 1985. His misgivings about the soil’s future inspired him to begin a manure application program, and then to accept Shaffer’s guidance on soil management starting in the mid-1990s.

“I’d been coming here since 1976 and I’d notice that between the vine rows, the wild mustard and weeds you see there were starting to look anemic – there was very little growth there,” he recalled. “That said to me that we were seeing depletion after having this land farmed for years and years.”

Later in the tour, a dose of replenishment arrived at Chateau Montelena – on the back of a truck. Onto a gravel road rolled an aromatic, chocolate-brown load of compost, which the Recology recycling and waste collection firm had broken down in a Vacaville plant from food wastes generated by San Francisco’s homes and restaurants.

Vella quickly grabbed a fistful from the chest-high pile, taking a deep whiff of its scent – the signature of humus, the broken-down organic matter that accounts for about half the composition of fertile soil. Added to vine rows already anchored by cover grasses, the combination would hold more water close to the vines’ root zones, helping preserve them through summers marked by two seasons of drought in Napa County.

F  or its growing popularity, however, composting presents farmers a basic problem – a tight supply awaiting relief from more efficient diversion of food wastes.

“We have all of this food we put our best land and our best scientists to grow, and yet half of (food waste) goes to the landfill? That is an insult to our farmers!” exclaimed Shaffer.

If the supply of compost can be increased, such techniques promise a less costly and more tenable path for future farming, said Recology spokesman Paul Giusti. “If you work with Mother Nature rather than try to fool Mother Nature, it seems to work a whole lot better,” he said.

Photo caption:  Dave Vella, vineyard manager at the Chateau Montelena winery near Calistoga, samples a load of compost at winery vineyards Sunday during a tour and presentation on the importance of cover-crop planting and composting to reduce the use of pesticides and fertilizer.

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October 19th, 2015

Differences in milk characteristics between a cow herd transitioning to

Organic versus milk from a conventional dairy herd

By: MICHAEL H. TUNICK, 1 * MOUSHUMI PAUL, 1 ELAINE R. INGHAM, 2 HUBERT J. KARREMAN3 and D IANE L. VAN HEKKEN1 1 Dairy & Functional Foods Research Unit, Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 600 E. Mermaid Lane, Wyndmoor, PA 19038, USA, 2 Soil Foodweb, Inc., 1750 SW 3rd St., #C, Corvallis, OR 97333, USA, and 3 Rodale Institute, 611 Sigfriedale Road, Kutztown, PA 19530, USA

Characteristics of conventional milk and milk from a herd transitioning from nongrazing to organic were studied by comparing adjacent farms over a 12-month period. Levels of short- and mediumchain fatty acids partially responsible for aroma and flavour were initially lower in the milk from the transitioning herd, but not after the cows had settled into an organic diet. Once that point was reached, the amount of a-linolenic acid in the transitioning herd milk exceeded that of the conventional herd. This case study demonstrates that subtle differences occur in the milk as cows transition to organic. Keywords Milk, Organic, Grass-fed, Fatty acids.

The market for organic and grass-fed dairy products continues to grow as consumers are willing to pay premium prices for food that they consider to be more healthful, flavourful or environmentally
conscious than the majority of food purchases. Many Americans are willing to pay more for milk that does not contain antibiotics, pesticides, or hormones that are not naturally present (Bernard and Bernard 2009). The question is whether organic milk actually contains a higher level of beneficial compounds than conventional milk from cows with no access to pasture. Benbrook et al. (2013) examined organic and conventional milk from 14 commercial processors across the USA over an 18-month period, finding higher omega-3 fatty acid concentrations in the organic milk. This work did not deal with milk at the farm level, although it indicates that a transition to organic management could be beneficial to the consumers who purchase the resulting milk. Within the past 10 years, most of the research on the differences between milk from organic and conventional dairies has been conducted in Argentina (Schroeder et al. 2003, 2005), Italy (Bergamo et al. 2003; La Terra et al. 2010), United Kingdom (Ellis et al. 2007), Switzerland (Collomb et al. 2008) and Sweden (Fall and Emanuelson 2011). The only such studies comparing organic and conventional bovine milk in the USA published since 2003 were by Croissant et al. (2007) and Khanal et al. (2008). Croissant et al. investigated two herds 80 km apart, with each herd containing Holsteins and Jerseys. The geography and weather may have affected the characteristics of the milk in that study. Khanal et al. looked at only five cows for 45 days. Current regulations require a 12-month transitioning period for a conventional dairy to be certified as organic (US Department of Agriculture, 2015). Information on the changes that occur in the harvested milk during this period, especially the rate at which any changes may occur, is lacking. A more thorough comparison of organic and conventional milk, including sizable herds and excluding the variables of terrain and climate, is necessary to determine the differences, if any, between these two management systems. This study investigates the characteristics of the milk over a 12-month period from a farm with cows transitioning from nongrazing to organic pasture. 


Milk Two farms located <1 km apart in Berks County, Pennsylvania, designated CONV (conventional) and TTO (transitioning to organic), supplied the milk for the study. The CONV farm had 64–74 cows, with a Holstein-to-Jersey ratio of 9:1 and a rolling herd average ranging from 9580 to 9933 kg milk over the course of the study. Cows received total mixed rations consisting of high-moisture maize silage, alfalfa haylage, ryelage (all produced on-farm) and a supplement of soya beans, wet brewer’s grain and minerals (Table 1). Cows did not have access to pasture. The TTO farm had 51–63 cows with a ratio of Holsteins to Jerseys and Jersey crosses of 3:1. The rolling herd average began at 10 230 kg milk and decreased during the transition phase to 8164 kg milk at month 7 and 6767 kg milk at month 12. Cows received dairy mineral supplements and averaged 53% of their dietary energy from fresh pasture during the grazing season, which ran from mid-April to mid-October. The pastures were well-established fields certified as organic and consisting of alfalfa, orchard grass, perennial rye, red clover, timothy and white clover. Weeds were also present and consumed by the cows, including dandelion, lamb’s-quarters, narrow leaf plantain and smooth pigweed. Somatic cell counts in the milk for both herds were <500 000 throughout the study. Fresh raw milk (1.2 L) was obtained from the farms’ bulk tanks in the morning after 5 min agitation, poured into 3.7- L resealable plastic storage bags (Ziploc, S.C. Johnson & Son, Racine, WI, USA) and immediately frozen. Milk was collected weekly over the course of 50 weeks from 6 May 2011 through 12 April 2012. No samples were collected at week 30, 34 and 35 (Thanksgiving, Christmas and New Year holidays). Milk was transported to the US Department of Agriculture laboratories, placed in a secondary vacuum bag (in case the original bag opened or ruptured), thawed, redistributed in smaller aliquots and refrozen for individual assays. Portions of the thawed milk were centrifuged to obtain lipid fractions for fatty acid assays.

Table 1:
Feed used in this study Conventional Organica Composition of ingredient Concentration in feed (g/100 g) Composition of ingredient Concentration in feed (g/100 g) Haylage 31.2–43 g/100 g dry matter, 3.3–7 g/100 g protein, 1 g/100 g fat 5.9–9.7 38 g/100 g dry matter, 7.4 g/100 g protein, 1.7 g/100 g fat, 3.8 g/100 g ash 37.5 Maize silage 34–38 g/100 g dry matter, 2.3–2.9 g/100 g protein, 1–1.3 g/100 g fat 21.1–31.4 35 g/100 g dry matter, 3.3 g/100 g protein, 1.5 g/100 g fat, 1.1 g/100 g ash 35.3 Ryelage and hay Ryelage: 31 g/100 g dry matter, 4 g/100 g protein, 1 g/100 g fat 19.2–29.7 Hay 8.9 Maize High moisture: 70 g/100 g dry matter, 6 g/100 g protein, 2.7 g/100 g fat 8.7–9.0 Dry and ground 7.7 Grain Wet brewer’s 23.6–24.4 Spelt 2.8 Soya beans Roasted and ground 3.1–3.7 Roasted whole 5.0 Mineral supplement Custom mixb 6.5 Custom mixc 0.44 Other ingredients CaCO3 0–0.21 Kelp meal 0.07 a Comprised 47% of diet. Remaining 53% was pasture; dried pasture samples contained 90.3–91.5 g/100 g dry matter, 14.2–17.3 g/100 g crude protein, 2.3–2.9 g/100 g crude fat and 8.1–9.6 g/100 g ash. Total diet averaged 50.1 g/100 g dry matter, 7.4 g/100 g crude protein, 2.5 g/100 g crude fat and 3.1 g/100 g ash. b Consisted of ML 100512 (Cargill Animal Nutrition, Minneapolis, MN): 31.4 g/100 g crude protein, 5.23 g/100 g crude fat, 4.5 g/100 g Ca, 0.4 g/100 g P, 2.7 g/100 g salt, 1 g/100 g Na, 2 g/100 g Se, trace amounts of MgO, Cu, Mn, Co, Zn, I, and vitamins A, D and E. c Consisted of 0.28 g/100 g salt, 0.07 g/100 g MgSO4, and 0.07 g/100 g RC Gold (yeast, lactic acid bacteria, and vitamins A, D and E; Fertrell, Bainbridge, PA)


Compositional data (solids, total fat, total protein and lactose) were obtained in accordance with AOAC Method 972.16 (AOAC International 2012) by MilkoScan Minor (FOSS, Eden Prairie, MN, USA). Ash was determined by AOAC Method 945.46 (AOAC International 2012) and dissolved in nitric acid (2 g/100 mL) to determine the mineral contents (Ca, Cu, Fe, K, Mg, Mn, Na and Zn) using an ICP-OES spectrometer (iCAP 6300 Duo, ThermoFischer Scientific, Madison, WI, USA). The pH was determined by PHM82 pH meter (Radiometer, Copenhagen, Denmark).

Fatty acid profiles: 
The fat in each sample was obtained by centrifugation of the milk at 50009 g for 30 min at 10 °C. The fatty acids were converted to methyl esters using a procedure based on Christie (2003). Each lipid sample, weighing 100–125 mg, was dissolved in 2.5 mL hexane (Fisher Scientific, Fair Lawn, NJ, USA) prior to the addition of 100 lL sodium methoxide (25 g/100 g methanol); Sigma-Aldrich, St. Louis, MO, USA). After 5 min of shaking by inversion, 5 lL glacial acetic acid (J.T. Baker, Phillipsburg, NJ, USA) was added to lower the pH, and 1.0 g anhydrous CaCl2 (Mallinckrodt Specialty Chemicals, Paris, KY, USA) was added to capture any water. After an hour, the liquid was centrifuged at 700 g for 2–3 min. The supernate was pipetted into a 2-mL vial with a screw cap containing a Teflon-faced silicone septum (Supelco, Bellefonte, PA, USA), the hexane was evaporated under nitrogen, and 1.0 mL ethyl acetate (Burdick & Jackson, Muskegon, MI, USA) was added. An autosampler injected 1.0 lL into a HP 6980 gas chromatograph equipped with flame ionisation detection (HewlettPackard, Santa Clara, CA, USA) and an SP-2380 fused silica capillary column (60 m 9 0.25 mm; Supelco). The resulting chromatographic peaks were integrated with the instrument’s software to produce percentages of fatty acids in the fat. Multiplication by the concentration of fat in the milk yielded concentrations of fatty acids in the entire sample. The chromatographic reference standards were C4:0- C24:0 methyl esters and conjugated methyl linoleate (GLC448 and UC-59M, respectively; Nu-Chek-Prep, Elysian, MN, USA). Samples were analysed in duplicate and averaged over each month.

Protein profiles:

Water-soluble milk protein extracts were obtained using a protocol based on a procedure by Quiros et al. (2007). A 30-mL milk sample was centrifuged at 20 0009 g for 30 min at 4 °C, and the resulting supernate was subsequently filtered through Whatman no. 1 filter paper (GE Healthcare, Piscataway, NJ, USA) and lyophilised. Protein mixtures were dissolved in water containing 0.1 g/100 g TCA (Acros Organic, Fair Lawn, NJ, USA) to generate 10 mg/mL solutions. Injections of 100 lL were analysed by an Agilent 1200 series reverse-phase HPLC (Agilent Technologies, Santa Clara, CA, USA) using a Vydac C18 column (5 lm, 4.6 mm i.d. 9250 mm; Grace, Deerfield, IL, USA) and monitoring absorbance at 215 and 280 nm. The stationary phase was 0.1 g/100 g TCA in water. The liquid phase was 0.1 g/100 g TFA in acetonitrile, shifting from 0 to 20 g/100 g over 30 min, followed by 20 to 35 g/100 g over 5 min and finally 35 to 80 g/100 g over 45 min.

Volatile compounds:
Milk volatiles were extracted using a SPME static headspace method. Samples for the SPME study were held at 80 °C until analysis. To avoid contamination by volatiles in the laboratory, samples were defrosted overnight at 24 °C in a dedicated refrigerator. For each run, 4 g NaCl (SigmaAldrich) was added to 10 mL milk to produce a saturated NaCl solution to enhance volatile collection. An internal standard of 0.10 mg/L 2-methyl-3-heptanone (SigmaAldrich) was added for quantitation purposes. Amber glass vials (20 mL) with polytetrafluoroethylene/silicone septum caps (Supelco) were used to minimise light exposure. Samples were vortexed for 10 s and then placed onto a CombiPAL autosampler (CTC Analytics, Swingen, Switzerland). Volatiles were adsorbed using a 2-cm, 50/30-lm-film-thick DVB/CAR/PDMS Stableflex SPME fibre (Supelco), while the sample was exposed to continuous agitation at 500 rpm for 5 min at 60 °C. Analytes were desorbed using a splitless injector at 250 °C for 5 min. An Agilent model 7890A gas chromatograph (Agilent) coupled with an Agilent model 5975C mass spectrometer was used to analyse the sample headspace components. The GC oven temperature was held at 33 °C for 4 min, then increased by 15 °C/min to 250 °C and held for 2 min. Separation was accomplished with a 0.6 mL/min flow of helium through a 30-m, 0.25-mm i.d., 0.25-lm-film-thick DB-5 column (Restek Corp., Bellefonte, PA, USA). Volatile compounds were identified by the NIST internal library in the ChemStation software (NIST/EPA/NIH Mass Spectra Library, version 2.0 days, December 2005) and by comparison with runs of known standards (Sigma-Aldrich) using the identical methodology. Relative abundance was calculated using the integrated ChemStation software by comparing peak areas with that of the internal standard. Samples were analysed in duplicate and averaged over each month.

Colour was measured using a HunterLab Color Quest XE spectrophotometer (Hunter Associates laboratory, Reston, VA, USA) fitted with a reflectance port of 2.54 cm in diameter according to the HunterLab Application for measuring translucent liquids. Frozen milk was thawed, warmed to 25 °C for 15 min and gently mixed. Approximately 100 mL of milk was poured into a 50-mm glass cell, placed at the port, covered for the measurement and then discarded. Three measurements of the CIE L*, a*, b*, WI and YI values were taken from each sample and averaged.

Analysis of variance was performed using the GLM and mixed models in the Statistical Analysis System (SAS Institute Inc 2011) with farm and month as the dependent variables. Differences between means determined using the Bonferroni test are described as significant when P < 0.05.

 Composition Table 2 shows the compositional data for the milk over the 12 months of the study. No significant differences between the CONV and TTO milks were observed in any month. None of the eight minerals commonly found in milk that were measured in this study were significantly different between farms or over time. Values were similar to reported values (US Department of Agriculture 2013).

Table 2:
Overall composition of milk from conventional and transitioning-to-organic milking herds Conventional Transitioning RMSEa Proximate composition (g/100 g) Fat 3.63 3.63 0.270 Protein 3.29 3.26 0.118 Lactose 4.78 4.80 0.098 Total solids 12.5 12.4 0.348 Mineral composition (lg/g) Ca 1400 1400 125 K 1400 1400 254 Na 680 640 33 Mg 150 150 12 Zn 4.5 3.8 0.83 Cu 0.63 0.61 0.32 Fe 0.54 0.55 0.25 Mn 0.18 0.29 0.01

Table 3:
Monthly averages of fatty acids in the fat portion of raw milk from conventional (CONV) and transitioning-to-organic (TTO) milking herds, in months where differences are significant (P < 0.02) Month Farm 6:0a 8:0 10:0 12:0 14:0 14:1 15:0 16:0 16:1 17:0 18:0 18:1 t-18:1 18:2 18:3 CLA (mg/g fat) May CONV 17.2 11.7 26.9 30.7 111.9 11.7 11.6 14.4 204.8 TTO 8.4 6.7 13.8 16.8 77.4 6.1 8.1 26.5 307.2 June CONV 10.7 24.0 27.5 104.8 17.1 144.7 239.1 TTO 8.0 17.0 19.8 83.4 26.8 121.4 293.6 July CONV 18.1 142.1 5.6 TTO 22.5 120.1 8.2 August CONV 24.9 28.8 103.9 29.3 5.4 8.3 TTO 19.4 22.6 90.5 47.1 7.6 12.4 September CONV 6.8 33.3 TTO 13.7 25.1 October CONV 306.2 142.4 4.8 TTO 349.9 115.7 8.3 November CONV TTO December CONV 4.8 TTO 6.8 January CONV 298.4 33.7 33.9 5.0 TTO 346.1 21.6 25.5 7.0 February CONV 30.5 5.0 TTO 21.2 6.6 March CONV 13.2 33.0 4.5 TTO 11.3 22.4 6.9 April CONV 4.1 TTO 6.9 a Abbreviations for fatty acids: 6:0, caproic (hexanoic) acid; 8:0, caprylic (octanoic) acid; 10:0, capric (decanoic) acid; 12:0, lauric (dodecanoic) acid; 14:0, myristic (tetradecanoic) acid; 15:0, pentadecanoic acid; 16:0, palmitic (hexadecanoic) acid; 16:1 palmitoleic (hexadec-9-enoic) acid; 17:0, margaric (heptadecanoic) acid; 18:0, stearic (octadecanoic) acid; 18:1, oleic ([9Z]-octadec-9-enoic) acid; t-18:1, vaccenic ([E]-11-octadecenoic) acid; 18:2, linoleic ([9Z,12Z]-9,12-octadecadienoic) acid; 18:3, a-linolenic ([9Z,12Z,15Z]-9,12,15-octadecatrienoic) acid; CLA, conjugated linoleic acid.

Fatty acids:
Months in which the fatty acid profiles were significantly (P < 0.02) different between farms are shown in Table 3. The levels of caproic acid (hexanoic acid, abbreviated 6:0), caprylic acid (octanoic acid, 8:0), capric acid (decanoic acid, 10:0), lauric acid (dodecanoic acid, 12:0) and myristic acid (tetradecanoic acid, 14:0) were significantly lower in the TTO milk in month 1, 2 and 4 (May, June and August) of the study. A significant shift in fatty acids occurred in the rumens of the TTO farm cows as they transitioned to a grass diet. At the end of the summer, when the transitioning cows switched to stored grasses, differences began to centre on longer-chain fatty acids (16 carbon atoms and higher). Longer-chain fatty acids have high perception thresholds (elevated concentrations are required for humans to be able to detect their aroma or flavour) and play a small role in flavour, but smaller fatty acids have low thresholds and provide characteristic flavours to dairy products. All of the milk samples contained polyunsaturated fatty acids (PUFA) tied to positive health effects: rumenic acid (cis-9 trans-11 18:2), vaccenic acid (trans-11 18:1) and alinolenic acid (18:3). Rumenic acid is the predominant isomer of conjugated linoleic acid (CLA), which appears to act against atherosclerosis, cancer, diabetes and deposits of adipose tissue (Belury 2002). Vaccenic acid is the only known dietary precursor of CLA, and research suggests that its consumption may impart health benefits beyond those associated with CLA (Field et al. 2009). a-Linolenic acid appears to decrease the risk of cardiovascular disease (Hu et al. 1999; Burdge and Calder 2006). After a 2-month lag at the start of the transition, the TTO milk fat contained significantly more linolenic acid than the CONV milk fat in nearly every month. The rumenic and vaccenic acid contents of the CONV and TTO milks were similar, although the rumenic acid content in the TTO milk was significantly higher than that of the CONV milk in August. This disparity was evidently due to the dietary differences between the herds. At month 12, when the transitioning cows had settled into an organic diet, only the a-linolenic acid content was different between the two herds. Benbrook et al. (2013) also found higher levels of a-linolenic acid in organic milk. The TTO milk contained higher amounts of PUFA than the CONV milk. The recommended dietary requirement for PUFA is 6–11% of total energy (WHO 2008), so milk should be considered as adding to the total PUFA in the diet while not providing all the PUFA recommended.

Protein profiles:

The elution pattern of protein generally showed very little in terms of hydrophilic peptides, meaning that slight or no degradation of the proteins occurred. This result was expected as the samples were raw milk and therefore did not undergo any processing that might alter the structure or chemical integrity of the proteins. Also as expected, the major proteins were large intact hydrophobic proteins, consisting of the caseins and whey proteins. These proteins were particularly monitored in each sample to determine whether any changes were detected from sample to sample. Representative chromatographs from different months throughout the study show the overall distribution of proteins (Figure 1). The large peaks were composed of a number of different proteins (as1-, as2-, b- and j-caseins, and whey proteins) that coelute. While the relative heights of the peaks may have changed, showing that the overall concentrations of these proteins may be different with respect to each other, the composition of the proteins remained the same throughout the time period studied. The farming system employed in this study did not affect the overall protein composition of the milk obtained.

Volatile compounds:
A total of 11 volatile compounds were identified in the raw whole milk. Acetone, 2-butanone, hexanal and octanoic acid (Figure 2) were the predominant volatile compounds in the milk, and other aldehydes, fatty acids and ketones were also present (Figures 3–4). All of these volatiles have been previously found in milk (Marsili 1999). The levels of some of the volatiles varied greatly throughout the year (Figures 2– 4) and were probably due to the composition of the feed or the pasture plants. The levels of most of the compounds in the TTO milks were in fairly small ranges throughout the year. In the CONV milk samples, hexanal, octanoic acid (Figure 2), pentanol (Figure 3), 3-methylbutanal and heptanone (Figure 4) reached their highest levels in the colder months. The TTO milk usually contained less hexanal, pentanol, butanoic acid and heptanone than the CONV milk, whereas nonanal was the only volatile in the TTO milk that was usually at a higher level than the CONV milk. The milks would therefore be expected to have a different aromas and flavours.

Milk colour was fairly stable between farms and over time with only a few differences noted. The whiteness values reported as L, which ranged from 64.3 to 72.1, were not significantly different, while the WI values ranged between 9.46 and 33.7 with only three means different from each other (means for TTO in March and April, were greater than TTO in May). No differences were noted for the a* values, which ranged from –1.90 to –2.29; negative a* values indicate the degree of greenness. Overall, the milk from TTO had significantly higher yellowness values than CONV milk, with the milk from TTO in July–November > CONV in March–April. The b* values ranged from 3.36 to 4.54 for TTO and 1.6 to 3.51 for CONV. The YI values ranged from 6.18 to 9.02 for TTO and 1.98 to 6.90 for CONV. Other studies have reported that organic milk is typically more yellow than milk from conventional herds, which could be attributed to the level of pasture in the diet, the breed of cows and the fat content of the milk (Hulshof et al. 2006; Croissant et al. 2007). b-Carotene imparts a yellow colour to milk fat (Panfili et al. 1994), is usually elevated in cattle on fresh forage and in cattle breeds such as Jerseys and is presumed to be the reason the TTO milk was yellower. Although both farms in this study had Jersey cows in the milking herd, TTO had one-fourth Jerseys in the herd compared to only one-tenth at CONV.


The fatty acid profiles of the CONV and TTO milk differed at the start of the transition period because of changes in the rumens of the transitioning animals. The profiles were similar after 6 months, except the TTO milk usually contained significantly more a-linolenic acid. The TTO milk was yellower than the CONV milk through most of the study. The levels of volatile compounds were variable throughout the 12 months period, but the composition and protein profiles were not different. A transition to organic pasture management appears to result in changes in fatty acid composition and volatile compounds in milk. A better understanding of factors affecting differences in milk from organic and conventional farms, including soil type, pasture quality and weather, is needed. The impact of seasonality on TTO and CONV milk also needs to be investigated.

The authors thank the following Agricultural Research Service employees for their contributions: Kerby Jones for his assistance in the fatty acid procedures, Susan Iandola for performing the GC-MS analyses, James Shieh for performing the compositional analyses and John Phillips for the statistical analyses. The authors also thank Rita Seidel of Rodale Institute for her assistance in obtaining the milk samples. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture. USDA is an equal opportunity provider and employer.

URL Accessed 12/4/2014.

Modifying soil to enhance biological control of below ground dwelling insects in citrus groves under organic agriculture in Florida. 

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