Monthly Archives: April 2014

Open Source Seed Initiative holds launch event

2014-04-17 11.25.05The Open Source Seed Initiative held a launch event today on the lawn of the Microbial Sciences Building on the UW campus in Madison WI. The Open Source Seed Initiative is an effort to keep new seeds free to grow, breed and share, with the goal of protecting the plants from patents and other restrictions.

The group distributed seed packs containing 22 varieties of Open Source seeds to about 100 people in attendance. UW-Madison horticulture professor and plant breeder Irwin Goldman, who helped write the Open Source Seed pledge, released two carrot varieties he developed-named Sovereign and Oranje at the event.

The Open Source Seed Initiative (OSSI) was established in 2011 by public plant breeders, farmers, non-governmental organization staff and sustainable food systems advocates to increase the availability of plant germplasm-seeds-for public plant breeders and farmer-breeders to work with.

For more, see Novel Open Source Seed Pledge aims to keep new vegetable and grain varieties free for all 

Also, Plant Breeders Release First ‘Open Source Seeds’



Radishes: A new cover crop option

Planting forage or oilseed radishes began to take root several years ago, and their use as cover crops is growing. Both are members of the mustard family (Brassicaceae), which has a long history of being used for cover crops and animal forages. Forage radish (Raphanus sativus L. var. niger J. Kern.), also known as the daikon radish or Japanese radish, has a very large taproot. Originally developed for oil production, oilseed radish (R. sativus L. var. oleiformis Pers.) is similar to the forage radish, but its taproot is stubbier and more branched, and it tends to be somewhat more winter hardy than the forage radish.

Forage and oilseed radishes can be helpful in no-till operations where their large roots can help retain soil moisture and reduce erosion. They are excellent at breaking up shallow layers of compacted soils, earning them the nickname “biodrills” or “tillage radishes.” Once planted in late summer, the radishes are not harvested but die in the winter, decay, and contribute a nitrogen store for spring planting.

Dying off in the winter, the radishes leave root channels so that soil dries and warms up faster in the spring. As part of a recent Illinois extension telnet series on utilizing cover crops in conventional cropping systems,

Joel Gruver, assistant professor of soil science and sustainable agriculture at Western Illinois University, spoke on the benefits and management of brassicas and legumes as cover crops.“Cover crops are multi-functional,” Gruver said. “It is important to remember that capturing multiple benefits takes more management. Cover crops are not idiot proof, but there are few profits in idiot-proof systems! ”If you want to reduce soil compaction, good cover crop choices are radish, canola, turnip (and hybrids), sugarbeet, sunflower, and sorghum-Sudangrass, according to Gruver.

For nitrogen fixation, legumes such as clovers, vetches, lentils, cowpeas, soy-bean, and field peas are best. For nutrient cycling, Gruver recommended sunflower, sugarbeets, brassicas, and small grains. Brassica cover crops have a number of beneficial attributes, including rapid fall growth, high biomass production, a well-developed taproot, excellent nutrient-scavenging ability, high responsiveness to nitrogen, competitiveness with other plants, and special pest resistance capabilities.

According to Gruver, the large taproot of radishes and other brassicas gives the crops an above-average ability to penetrate compacted layers; this promotes deeper rooting by subsequent crops and increases water infiltration. The residue from brassicas decomposes very quickly, and this means that they immobilize less nitrogen than cereal cover crops and often result in net nitrogen mineralization. They also tolerate cold temperatures very well. An additional special feature of most brassicas is that they produce compounds, called glucosinolates, which are toxic to soil-borne pests and pathogens.

Mustards usually have higher concentrations of these chemicals. More than 100 different glucosinolates are found in brassicas. Breakdown products from glucosinolates are volatile and similar to the active chemical in the fumigant Vapam. Glucosinolate concentrations differ according to plant part, age, health, and nutrition. Despite this complexity,

Gruver said there is evidence that brassica cover crops can be used to reduce pests, pathogens, and weeds if the right species/cultivar is planted and managed strategically.
Benefits of radishes Various research groups have been growing different types of radishes in different areas to determine their efficiency as a cover crop.

Ray Weil, Charlie White, and Yvonne Lawley at the University of Maryland have studied the use of for-age radish. Although it is fairly new to the Mid-Atlantic region, the use of forage radish as a cover crop has some advantages over other cover crops in the region.

Mathieu Ngouajio and Dale Mutch at Michigan State University have experimented with the use of oilseed radish. Because of its quick establishment and rapid growth in cool weather, it has been used successfully in Michigan as a cover crop in diverse production systems.

According to the Michigan re-searchers, the classification of these and other types of radishes is not well defined because they can easily cross-pollinate, and therefore distinctions among subspecies are often blurred. Most of the traits and management recommendations described in this article apply to both forage and oilseed radishes.

One of the great features of forage radish cover crops is that they can be used as a biological tool to reduce the effects of soil compaction, hence the term “tillage radish.” The roots of all cover crops can penetrate compacted soils in fall to some extent because they are growing when soils are relatively wet and soft. But the Maryland researchers found that forage radish roots can penetrate plow pans or other layers of compacted soil better than most other cover crops. The thin lower part of the taproot can grow to a depth of 6 ft or more during the fall. The thick, fleshy upper part of the taproot grows 12 to 20 inches long and creates vertical holes and zones of weakness that tend to break up surface soil compaction and improve soil tilth.

After the cover crop dies in the winter and its roots decompose, the remaining root channels are used by the growing roots of following crops to penetrate compacted deep soil layers.In Maryland research, four times as many corn roots penetrated compact subsoil after a forage radish cover crop than after winter fallow, and twice as many as after a rye cover crop. Data suggests that biodrilling with cover crops like forage radish can substitute for expensive and energy-intensive deep ripping and other mechanical methods to reverse soil compaction.

Some farmers plant forage radish in 24- or 30-inch-wide rows to maximize its root-to-shoot ratio. They then plant the following summer crop in these same wide rows to alleviate restriction of root growth into the sub-soil.In a similar manner, oilseed radish produces large taproots. Upon decomposition, these roots leave large holes in the ground that improve water in-filtration and possibly soil microbial activity. Oilseed radish emerges shortly after planting and provides quick ground cover that smothers weeds. When planted in fall, it prevents weed germination and, consequently, seed production.

Early planted forage radish can also produce a dense canopy that all but eliminates weed emergence in the fall and winter. To obtain this near-complete weed suppression, forage radish should be planted by September 15 (in Maryland) with a stand of 5 to 8 plants/ft.

The near-complete weed suppression can be expected to last until early April but does not extend into the summer cropping season. Oilseed radish can scavenge nitrate from deeper soil layers after harvest of the cash crop.

Upon decomposition, the nitrogen uptake becomes available to the next cash crop. In the Michigan State tests, a cultivar called Renova, for example, was shown to recycle more than 140 lb of nitrogen/acre in a growing season. In muck soil, the common cultivar recycled more than 60 lb of nitrogen/acre in two months. The Maryland group found that, unlike rye and other cereal cover crops whose residues decompose slowly and immobilize nitrogen in the spring, for-age radish residue decomposes rapidly and releases its nitrogen early.

In fact, on sandy soils, it is important to plant as early as possible, following forage radish cover crops, to take advantage of this flush of nitrogen before it leach-es out of the rooting zone. Forage rad-ish recycles large amounts of N taken up from the soil profile in fall and can reduce the need for nitrogen fertilizer in spring.

Growing radishes as a cover crop

Oilseed radish cultivars used as cover crops include the common variety, Adagio, Arena, Colonel, Remonta, Revena, Rimbo, and Ultimo. According to the Michigan researchers, most of these cultivars are imported from Europe. The common cultivar is the most readily available in Michigan.
Oilseed radish seed is generally more expensive than seed of other cover crops commonly grown in Michigan. Whether planted in spring, late summer, or early fall, oilseed radish grows quickly and produces a large amount of biomass in a relatively short time. Four oilseed radish cultivars (Adagio, Arena, Rimbo, and common), seeded in August, were tested in Michigan over two years and produced similar amounts of dry biomass. Total biomass generally exceeds 4 tons/acre.

Most cultivars produce more shoot than root biomass, but the common cultivar produces more root biomass and tends to have a better balance of shoot-to-root biomass. Because oilseed radish establishes very fast, even under moderate drought situations, the plants provide good protection against wind and water erosion, which can be particularly helpful for muck or sandy soils. Oilseed radish seeding rates are typically 10 to 20 lb/acre. Studies conducted in Michigan showed that rates of 10, 15, and 20 lb/acre produced similar amounts of biomass. Low rates are generally recommended because of the high cost of seeds. In some situations, however, high rates may be more beneficial. These include cases where control of weeds, diseases, and nematodes is the primary focus. Oil-seed radish leaves low surface residue in the spring, so it is very appropriate for crops that require a well-prepared seedbed. To improve weed and pest management, planting oilseed radish on the same field more than two years in a row is not recommended.

The Maryland researchers recommend seeding at 8 to 10 lb/acre using either a conventional or no-till drill or by broadcasting at 12 to 14 lb/ acre to establish a good stand of for-age radish. When using a drill, seeds are best planted between 0.25 inches deep (when moisture conditions are good) and 1 inch deep (during dry conditions). When broadcasting, germination will be best if the seeder is followed by a corrugated roller or very light disking to encourage some seed–soil contact.

Aerial seeding has been successful using 14 to 16 lb/acre broadcast into standing corn or soybean canopies that have begun senescence (yellowing of lower leaves). Forage radish usu-ally emerges within just three days if the soil is warm and not too dry. Even unincorporated broadcast seed will achieve rapid germination if seeding is followed by a timely rain or irrigation. Forage radish has a very flexible and aggressive growth habit and will spread out in a rosette to fill the space it is given. Radish plants—especially their fleshy root—will become much larger when grown at lower plant densities. In the Mid-Atlantic, forage radish grows best when planted in late Au-gust or early September, but significant amounts of N can be captured by this cover crop when planted as late as October 1. Forage radish planted in late September may be less susceptible to frost and more likely to overwinter.

When planted in late March as a spring cover crop in Maryland tests, forage radish did not emerge quickly or grow as well as when planted in fall.Forage radish is tolerant of frost until temperatures dip below 25°F. It takes several nights of temperatures in the low 20’s to kill forage radish. If mild temperatures resume and the growing point is intact, green leaves may grow back. Under the freeze–thaw winter conditions of the Mid-Atlantic, forage radish tissues (shoots and roots) decompose rapidly once killed by frost and leave only a thin film of residue by March. Research indicates that forage radish winter cover crops can fit well into corn silage and vegetable crop rotations that have openings for cover crop planting by the end of August.

Forage radish has successfully been aerially seeded in early September into standing corn grain and soybeans on commercial farms. Because forage radish seeding rates are low, the seed may be mixed with other cover crop seed of similar size to bulk it up for more even aerial seeding. If planted in late September, growers may not achieve effective biodrilling and weed suppression, but significant amounts of nitro-gen can still be captured.

Avoiding problems
According to Gruver, the brassicas have some special management concerns. They are not well adapted to poorly drained soils. Forage radish does not tolerate very wet soils, so avoid planting it in low spots that collect standing water. Some brassicas have proved difficult to kill with glyphosate—requiring rates of at least 1 qt/acre and possibly multiple applications.

Gruver recommends adding 1 pt/acre 2,4-D if possible. Also, they are sensitive to a number of herbicide carryovers. Many of the Group 2 herbicides and the triazine herbicides can have soil residuals that may injure oilseed radish seedlings.In Maryland, researchers found that nitrogen deficiency will limit forage radish growth and may limit its ability to compete with weeds or grow through compacted soil.

Nitrogen deficiencies have been observed when planting after silage or grain corn on sandy soils or soils that do not have a history of manure application. Nitro-gen-deficient plants have also been observed to be less susceptible to frost and are more likely to overwinter. If they survive the winter, forage radishes may be attacked by harlequin bugs and flea beetles. Seed production by oilseed radish may lead to volunteer plants in succeeding crops. In Michigan, this is normally not a problem because oilseed radish planted in August or September will be killed by frost before setting seeds.

Purchase oilseed radish seed early because it may be difficult to locate. Also, growers are warned that during warm spells in winter, rotting forage radish residues may produce a rotten egg-like odor.

Portions of this article were adapted from the following sources: “Forage Radish: New Multi-Purpose Cover Crop for the Mid-Atlantic,” published by the University of Maryland Cooperative Extension.

“Oilseed Radish: A New Cover Crop for Michigan,” published by Michigan State University Extension.

Optimizing Chlorine-Based Sanitizer Performance

Chlorine has been used for sanitation purposes in food processing for several decades and is perhaps the most widely-used sanitizer in the food industry. Safety concerns about the production of chlorinated organic compounds have been raised in recent years, and using chlorine-based sanitizers effectively is an important good sanitation practice. This study examined how pH, dilution, and chloride concentration of chlorine-based sanitizers affect their solution stability and antimicrobial activity. The researchers found that, in working with chlorine-based sanitizers, both pH and Cl- concentrations are important properties. While pH directly affects the antimicrobial activity of free chlorine, Cl− affects the chlorine stability and indirectly affects the antimicrobial activity. They concluded that low pH chlorine-based sanitizers have stronger microbicidal properties than near-neutral pH chlorine-based sanitizers. But, low pH chlorine-based sanitizers are unstable and can lose a significant amount of chlorine during storage. Since chlorine-based sanitizers are sometimes prepared ahead of time and used as needed in food-processing environments, it is important to understand that the level of residual Cl− in these sanitizers could reduce its antimicrobial efficacy over time. One way to maximize the effectiveness of chlorine-based sanitizers is to ensure that the pH of the solution is low when no storage is involved. When long-term storage is needed, the pH of the solution should be maintained at near-neutral pH, but a higher amount of electrolyzed oxidizing water should be used due to lower microbicidal properties than the lower pH solutions. 

For more, see

The Effect of pH and Chloride Concentration on the Stability and Antimicrobial Activity of Chlorine-Based Sanitizers, by Brian W. Waters and Yen-Con Hung

Journal of Food Science
Volume 79, Issue 4, pages M622–M627, April 2014

Manipulating Gut Microbiota through Diet

An estimated 100 trillion microbes in the human gut co-evolve with us and have a significant influence on our health. A group from Tianjin Univ. reviewed research exploring the dynamic changes of gut microbiota associated with human genotypes, age, and diet in “Diet Effects in Gut Microbiome and Obesity.” The review provides a better understanding of how the interrelationship between diet, intestinal microbiome and body immune system could aid the development of therapeutic approaches for various diseases. Manipulating gut microbiota through diet (both long-term and short-term diet patterns), probiotics and/or prebiotics, and antibiotics has the potential to prevent various metabolic disorders including obesity. Diets and gut microbes interact in several ways including selective bacterial fermentation of nutrients, lower intestinal barrier function, over-expression of genes associated with disorders, and disruptions to both innate and adaptive immunity.

For more, see Diet Effects in Gut Microbiome and Obesity by Jia Chen, Xianzhi He andJinhai Huang,  Journal of Food Science, Volume 79, Issue 4, pages R442–R451, April 2014

Book Review: Eggs, A Global History, by Diane Toops


Eggs, A Global History, by Diane Toops. Published by Reaktion Books

Eggs, A Global History, by Diane Toops
160 pages, Hardback, 56 illustrations, 47 in color
Published March 24, 2014
Reaktion Books Ltd

In “Eggs,” Diane Toops offers a wonder-filled exploration of egg history and lore, cracking the egg’s significance in culinary history, diet, health, culture, and food processing. The book is one of the most recently published volumes in The Edible Series of food histories (Reaktion Books, $14.23 each). Each book of the series details the history and culture of one type of food or beverage. Currently numbering more than 40 volumes, the foods range from beer to nuts, vegetables, beverages, grains, and formative prepared foods such as bread, cheese, curry, hot dogs, pancakes, cocktails, pie and cake.

In a concise volume, Toops covers the many varieties of eggs, chicken, goose, duck, fish, ostrich or even alligator, that have been eaten throughout history. Because of their worldwide ubiquity and historical importance, the chicken egg is the main focus of the book. Topps describes history, cuisine, health aspects, cultural importance, and commercial processing of the egg.

With unhurried, clear and straight-forward writing, Toops covers a lot of egg lore and egg usage. Some of my favorite takeaways from the book:

  • Ancient Egyptians ate all birds eggs, considering them wholesome, when boiled, fried, poached or used to bind ingredients in sauces.
  • The Egyptians devised a method to incubate eggs in dung heaps to increase supplies for their workers.
  • The Chinese domesticated and organized ducks in yards some 4,000 years ago, and were building egg incubators by 246 BC.
  • An Andalusian cookbook, written in the thirteenth century, records the first recipe for a food fried in egg batter, first use of tempura.
  • China is the world’s largest egg producer and more than 65% of global egg production takes place in Asia.
  • During recent years there has been significant growth in the use of egg products. These are eggs which have been taken out of their shell and include liquid and frozen yolk, albumen, egg blends, and ready-made omelettes.
  • Eggs should be at room temperature if they are to combined with a fat and a sugar. Cold eggs may harden the fat in a recipe, causing the batter to curdle and affecting the texture of the finished dish.
  • White eggs are most in demand among American buyers, but they have the same nutritional value as brown eggs.
  • The color of the eggshell is directly influenced by the breed of the hen. As a general rule, breeds with white feathers lay white eggs and those with red feathers lay brown eggs.
  • Before refrigeration, to keep eggs fresher longer, farmers sealed the pores of the shell to prevent loss of moisture. The most efficient coating being mineral oil, still used today.
  • Many cultures consider the egg a symbol of rebirth and celebrate spring with festivals, in which eggs play a prominent role.
  • Egg rolling on the lawn of the White House is an American tradition started by First Lady Dolley Madison.

The many images provided in “Eggs” are a special bonus given the importance of eggs as symbols in art. The provocative, Concert in the Egg is granted a two-page spread. The painting is considered a copy of a lost work by Hieronymus Bosch. The images highlight the many ways eggs are consumed from Chinese Tea Eggs, and the Tex-Mex breakfast dish, migas, to balut, the national street food of the Philippines. The balut is fertilized duck egg and depending on the age of the embryo can include a beak, bones and feathers. For an adventure in balut consumption, see: We Ate Balut — The Absolute Strangest Food You Can Find In New York City

The book has an extensive collection of recipes in an appendix from the earliest recorded Roman egg dishes up to current recipes. For example, Libum was a sacrificial cake sometimes offered to household spirits during Rome’s early history. For a version of the Libum recipe see this Nova site on Ancient Roman Recipes. Some of the other recipes include definitive egg and egg-based dishes such as custard, souffle, deviled eggs, hoppelpoppel, and mayonnaise.

“Eggs” is one of best in the wonderful Edible Series of food histories. It captures all the lore and history of the other volumes but also gives an excellent synopsis of the important industrial processing side of the egg.

Toops even tackles the age-old, which came first question and concludes, to quote, “We will probably never know for certain which came first, but an egg is an egg is an egg, and that is enough for us to know.”

Bravo Diane!

A personal note: I would be remiss if I didn’t mention that Diane Toops was a treasured colleague of mine when I wrote for food industry publications in Chicago. Often thrown together for press conferences, field assignments, and trade shows, I found Diane to be a wondrous spirit. Always bringing an informed curiosity to every situation and the people around her, Diane could be trusted to find the positive always. Kitty Kevin, a close friend of Diane, has written, “A Legacy of Listening: A final scoop on our late Diane Toops.”


Hope for Chronic Garlic Eaters

No one likes to have allyl methyl disulfide, diallyl disulfide, allyl mercaptan, and allyl methyl disulfide on their breath. But, despite these odorous garlic breath volatiles, most of us can’t resist adding a little, and sometimes a lot, of garlic to spice up a dish. Well, there may be some relief for garlic lovers and those who have to talk to them. Ryan Munch and Sheryl Barringer from The Ohio State Univ. examined the ability of a variety of foods and beverages to reduce garlic breath in “Deodorization of Garlic Breath Volatiles by Food and Food Components.” (Journal of Food Science) Garlic breath volatiles were significantly reduced by parsley, spinach, mint, raw and microwaved apple, soft drink, green tea, and lemon juice when compared to a water control. Chlorophyllin and whey protein treatments did not significantly reduce the volatiles.

The authors believe that enzymatic deodorization may have occurred in parsley, spinach, mint, and raw apple treatments, while the deodorization effects of microwaved apple, lemon juice, and green tea were likely due to polyphenolic deodorization. The lack of enzymatic activity in the microwaved apple may explain why it was less effective than raw apple in breath deodorization. This suggests that enzymatic deodorization is more effective than polyphenolic deodorization.

Acidic pH may have been involved in the deodorization of lemon juice and soft drink breath experiments, but, according to the authors, its mechanism for breath deodorization is unclear and needs further examination. The authors believe that future work using sensory evaluation is needed to determine which of the treatments have the most noticeable effect on breath odor.

They conclude that with consumption of full-flavor garlic, it is not yet possible to completely avoid bad breath. So eat that heaping plate of hearty garlic-flavored spaghetti sauce with raw apple slices, spinach salad, and green tea, but it may be best to avoid others until you
can use some mouthwash.

Cover Crops on the Edge


The traditional use of cover crops provides a range of benefits, mainly soil fertility improvements, soil erosion management, and weed and insect pressure reduction. Benefits of the practice vary by location and season, but at least two or three usually occur with any cover crop. As an additional measure, combining cover cropping with conservation tillage can also lead to reduced energy use.Beyond their on-farm use, research conducted over many years indicates that clever cover crop choices have both local and larger-scale ecological benefits.

According to a report by the USDA Economic Research Service titled “Environmental Effects of Agricultural Land-Use Change” (, the large-scale production of just a few crops has contributed to the degradation of water quality with sediment,nutrients, and pesticides; hydrologic modifications contributing to flooding and groundwater depletion; disruption of terrestrial and aquatic wildlife habitats; emission of greenhouse gases; and degradation of air quality with odors, pesticides, and particulates.

Ultimately, farmers tend to make strictly economic-based production choices, according to the report. Producers tend to keep highly productive land in crop cultivation regardless of changing economic conditions. But an increase in commodity prices or production input costs encourages farmers to expand production to less productive land or to shift less productive croplands to other uses. Agricultural and conservation policies also affect land use. 

Cover crops can provide many different benefits in modern crop-ping systems, according to Dr. Eileen Kladivko, professor of agronomy at Purdue University. However, they require a higher level of management and some experimentation to achieve maximum benefit.

“There are several good reasons to re-evaluate cover crops right now for use in modern cropping systems,”said Kladivko. “These include higher fertilizer prices, higher energy costs, water quality concerns, soil tilth and compaction issues, and concerns about replacing organic matter with increased residue removal practices.

Cover crops are most commonly found in areas with longer growing seasons,” Kladivko noted, “such as the southeastern U.S. or areas with soils that are steeply sloping, low in organic matter, or sandy and blowing; they are also commonly found on vegetable and melon farms (for sand blasting control), organic farms, mixed farms that use cover crops for grazing, and farms around the Chesapeake Bay that participate in a cost-share program for nutrient management to reduce losses to the bay.

“Traditionally there has been a low level of use of cover crops in the Mid-west as compared to a region such as the Southeast,” Kladivko said. “However, recently there has been an in-creased interest in the use of cover crops in the Midwest, especially the eastern part of the Corn Belt region,to prevent nutrient input loss and improve water quality.” 

A good fit for using cover crops in the Midwest would be after corn silage and after winter wheat, Kladivko said, “These situations have enough time for seeding and growth and provide significant benefits for soil structure,weed control, and nitrogen production if legumes are used. If corn stoveris removed for biomass, cover crops should also be grown to protect soil productivity.”

According to Kladivko, cover crops are important in nutrient cycling.They trap nutrients that would other-wise “leak out” during fallow periods through leaching, erosion, or runoff and can release those nutrients later—ideally at the time needed by the next crop. Cover crops can translocate nutrients from deeper in the subsoil to near the surface and increase soil biological activity in topsoil, potentially releasing nutrients from soil minerals.

Most cover crops do not “create”nutrients in soil; instead they recycle and release. However, leguminous cover crops do add nitrogen to the soil through atmospheric fixation. A large body of research indicates that losses of nitrate and phosphorus from corn and soybean fields in the Upper Mississippi River Basin contribute to contamination of the Mississippi River and the Gulf of Mexico.For example, the northern portion of the Gulf of Mexico ecosystem, which contains almost half of the nation’s coastal wetlands and supports commercial and recreational fisheries, has undergone profound changes due to nutrient enrichment of Mississippi River water from land-based sources. Nutrient over-enrichment can lead to excessive production of algae. When this organic material sinks and be-comes decomposed, dissolved oxygen in bottom waters is reduced. Research indicates that this has resulted in seasonal hypoxia (very-low-oxygen water)over the Louisiana continental shelf. Hypoxic waters can cause habitat and marine life loss, affecting commercial harvests and impacting the ecosystem. 

Even when farmers carefully man-age fertilizers and put on only what is needed by the crop, substantial nutrient losses occur during the fall, winter,and spring when corn and soybean are not growing and the fields are bare.Nutrient loss happens, in part, because there are extended periods during each year when living plants are not removing nutrients from the soil and the nutrients are susceptible to losses.

Summer annual grain crops, like corn and soybean, accumulate water and nutrients only for about four months of the year. The remaining months of the year have been called the “brown gap” because there are no “green”plants that serve to protect the soil and recycle nutrients. One way to prevent these losses is to grow plants to take up nutrients and protect the soil surface when the main crops are not present. Cover crops, living mulches, and perennial crops can bridge the gap between harvest and planting of corn and soybean. 

Cover crops only grow during the period between harvest and planting of the main crops. Living mulches grow year round between the rows of the main crop but are suppressed with mowing or herbicides during the summer. Perennial crops (e.g., alfalfa) replace the corn and soybean crops altogether. All three of these approaches have advantages, disadvantages, and potential applications. 

Advocates of cover crops mention the concept of agricultural multifunctionality, which is defined as the joint production of agricultural commodities and “ecological services.” The term, “eco-agriculture” has also been used to describe how land can be managed to sustain a range of eco-system services, including food and fiber production. Examples of eco-system services include increased recreational opportunities in agricultural landscapes and protection of biodiversity and water quality.

“Giving up production on just 5% of a producer’s most marginal land can pay dividends in terms of overall environmental friendliness,” says Dr.Paul Porter, a professor in the Agronomy and Plant Genetics Department at the University of Minnesota.Overall, these ecosystem services can be highly valuable. For example,the USDA-NRCS Conservation Re-serve Program has been estimated to produce $500 million per year in benefits from reduced erosion and $737 million per year in wild-life viewing and hunting benefits at a cost of approximately $1.8 billion.Continuous living cover crop systems are one component of the agricultural multifunctionality effort.

Continuous living cover systems are agricultural cropping and livestock production systems that maintain continuous living cover throughout the year. This includes those based on perennial plants such as trees,shrubs, grasses, and legumes, as well as annual plants grown in combination, such as the use of cover crops as row crops. 

“All farming decisions are based on economics, but for some farmers,it may make sense to convert some of their least productive acres into wetlands and open that to hunters or conservation,” Porter says. Individual growers will consider a variety of factors in determining whether a cover crop might be right for their particular situation such as: soil erosion and conservation, soil fertility, pest management, growing season, biomass production to increase organic matter, and the producer’s resource-suitable acreage, irrigation capability, available labor,equipment, costs, capital, and personal goals and interests.