3lb's Guano Guide - The Scoop on poopin Organics Sun Nov 24, 2013 7:45 pm
by ozzydiodude • The Weird One | 2.469 Posts | 11518 Points
"Birds love the oil rich seeds of this fruitful plant and in their ecstasies of eating have swallowed many seeds whole. Throughout the ages Cannabis has flown here and there in the bellies of birds and then found itself plopped down on the earth in a pile of poop, ready to go."
Marijuana - The Cultivator's Handbook - 1979
Some ancient Italian in a proverb-making mood observed, "Hemp will grow anywhere, but without manure, though it were planted in heaven itself, it will be of no use at all." How lucky it is for Hemp to find Heaven in a pile of birdshit. How fortunate for the birds to find themselves high. How fortunate for the first men and women to notice how the little singing creatures became euphoric after eating the seeds of the tall, strong smelling plant. The planet is tight."
Marijuana - The Cultivator's Handbook - 1979
Growing up on a small family farm, one of the three little bird’s childhood memories include complaining to her father about being surrounded by the terrible smell of wastes from the livestock they were raising.
"Sweetheart, that's not stink . . . That's the smell of money," was Dad's reply.
She certainly understood the value of the livestock her family was raising for profit, which was where Daddy's money came from. Early on, she also made the connection between the farm animals and the tasty meat on their own table.
She understood another ironic meaning for her Dad's statement when one of her first paying jobs came shoveling stock barns at a State Fair. And finally, one day as she appreciated the fine aroma of some beautiful blooming wildflowers growing in a recently grazed pasture, she also began to understand the role manure plays as a fertilizer in making our soils rich and productive. Her Father’s saying about manure smelling like money was a few simple words, but, as was often the case with his wisdom, it held many meanings.
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The use of manure in agriculture is an age-old and time-honored tradition. Manure has been used as a soil amendment and fertilizer since before mankind first began recording words and symbols in writing. Scientists as prominent as Carl Sagan have suggested that the very first cultivated agricultural crop was likely cannabis. It’s possible that the mingling of manure and marijuana goes all the way back to the very beginning of mankind's attempts to grow crops for a purpose, rather than surviving by simple hunting and gathering.
Under the influence of some fine herb, it becomes simple to imagine going back in time. Looking back, in the mind’s eye we can see a tribe of nomadic people looking similar to modern man, but leading a primitive hunter-gatherer existence. We can imagine the clan following available game while taking advantage of locally available fruits and nuts. These men (and women) were not necessarily bigger or stronger than the wild animals they competed against for survival, but they were smarter. And during those seasonal migrations, one of those very distant ancestors likely noticed that their favorite herb plants were thriving especially well in areas where their nomadic tribe disposed of wastes near their seasonal camps.
They may have realized that the very herds of animals their clan had been following helped to distribute and nourish the plants they favored. Perhaps, as Bill Drake suggests, it was a discovery from a pile of birdshit where it all began. Regardless of where it started, with a little more thought, our ancestors realized that crops could be fertilized, and even grown with a purpose. Some speculate that this is how agriculture was born; that it all began with a fortuitously placed pile of shit.
In the end folks can call it what they like. Whether it's a fancier name like castings or guano, or one of the more common names like crap, poop, manure, or dung. In the end it's all just shit! The three_little_birds want you to know, however, that it can be very good shit. We want you to know that manures are one of the keys to unlocking the awesome potential of organic gardening.
In the immeasurable time prior to the invention of agriculture, before man began to till the soil, dead and rotting vegetation naturally returned to the earth as rich and fertile humus. In traditional forms of farming, our ancestors learned to use the components of animal dung and bedding wastes in a sustainable fashion. Before the discovery of chemical fertilizers and pesticides, manure was used as a resource, not a waste product. Natural humus, built up during the ages before agriculture, was replaced by manure, rich in nitrogen and other elements that plants depend upon. Today, that is no longer true.
From an environmental perspective, manure is a resource that is being wasted at a terrible rate. In some agricultural areas where a large number of livestock are concentrated and raised, manure is not a resource, but rather, it has become an environmental hazard. Consider, for instance, that a single hog will produce 3000 pounds of manure in under a year. It’s easy to see then how the large concentration of wastes found in corporate factory farms can rival a good-sized city for the total volume of organic waste produced.
According to one estimate, the USA alone has something in the range of 175 million farms animals. That multitude of animals excretes over two billion tons of waste per year. Due to mismanagement, misuse, and ignorance, very few of the potential nutrients from these wastes are returned to the land, less than 20% according to some estimates. Instead, this incredible mass of manure threatens to pollute river, streams, lakes, and even the subterranean groundwater that supplies many folk with their drinking water.
Therefore, finding proper solutions for the treatment and disposal of all that manure, in an economically feasible fashion, is an absolute necessity of modern agriculture. In the end, good stewardship requires sustainable farming practices that concentrate on finding a balance on the farm. So, as long as humans raise and consume animal livestock, as long as we keep animals such as horses for purpose or pleasure, it is wise to properly use manure to build and sustain our soil.
As a side note, one advanced form of gardening, vegan organics, does offer hope for budding organic gardeners who will have nothing to do with the use of manures and guanos. We mention this since some folk might be dismissive of the very thought of handling animal dung, and some indoor gardeners might be repelled by the thought of bringing it into their homes or grow areas. Perhaps for some folk this will be enough reason to decide this particular form of organic gardening is not for them.
We hope not because working with manures in your garden does not have to include large messes or smells . . . it's just a question of knowing your shit!
For a simple definition, manure is the dung and urine of animals. It is made up of undigested and partially digested food particles, as well as a cocktail of digestive juices and bacteria. As much as 30% of the total mass of manure may be bacteria, so it should be no surprise that dung can serve as excellent inoculants for a compost pile. Mixing manure in your compost can provide all the necessary bacterial populations to quickly and efficiently break down all the other materials common to the heap.
Manures can contain the full range of major, minor, and micronutrients that our plants need for strong health and vigor. Most manure will contain these nutrients in forms that are readily available to plants. The organic components of manure will continue to break down slowly over time, providing food for plants in the longer term as well. When composted with even longer-lived rock fertilizers such as Rock Phosphate or Greensand, manures can be used for true long-term soil building.
In addition to providing excellent service to gardeners as a potential fertilizer and soil builder, guanos and manures can also both be effectively applied as teas. Manure and guano teas act as fertilizers, providing available nutrients in forms easily assimilated by plants. They also serve as very effective inoculants of many beneficial bacteria
The nutrient value of manures can vary significantly from species to species, due to different digestive systems and feeding patterns. Even within a species, the fertilizer content of dung will vary depending on factors such as diet, the animal’s general health, as well as their age. Young animals devote much of their energy to growth, so their manure will be poorer in nutrients than that of mature animals. A lot full of baby pigs on starter feed will deposit wastes with a different nutrient value than the wastes produced by a lot full of swine ready to go to market.
An animal’s diet certainly plays a factor as well. The Rodale Book on Composting (an excellent resource) uses the example of an animal fed only straw and hay. The waste from that animal will be significantly different in nutrient content when compared to a sibling fed a diet including more nutritious feed such as wheat bran, cottonseed meal, or gluten meal.
The purpose an animal is used and bred for can even cause the nutrient value of a manure to vary. Dairy cows serve here as an excellent example. Milk production is somewhat taxing, even to a dairy cow. In addition to large amounts of calcium, milk also contains high levels of nitrogen, phosphorus and potassium, the three primary plant nutrients. Since so many nutrients are being used to produce milk, less actual plant fertilizer will be available in those animal wastes for soil building.
Another factor that will change the fertilizer value of manure is relative age and the way it has been handled. Manures left exposed to the elements will quickly lose their nutrient value. Rain can quickly leach soluble nutrients from manure. A thin pile of crap can lose as much as one half of its fertilizer value in under a week. To fully capture the nutrient potential of manure, it’s necessary to compost the shit quickly while it’s still fresh.
With the exception of guanos (which are mined fossilized waste deposits) and castings (which are mild and well digested), it is generally advisable to compost wastes and manures before direct use in your garden. When added directly to soil, fresh manures can act in a similar fashion to chemical fertilizers. The Nitrogen in fresh manures (ammonia and highly soluble nitrates) can burn delicate plant root systems and even interfere with seed germination.
Another good reason to compost manures before use is the fact that some animal manure can be full of weed seeds. Proper high temperature composting techniques can kill those unwanted guests as well as many potential soil pathogens. Used alone, animal manures may not be completely balanced fertilizers. However, once the manures have been properly amended and composted, any imbalances can be easily corrected and the manure itself can be broken down and digested into nutrients that are both balanced and available for our favorite plants and herbs.
Proper composting will actually increase nutrient value in manure. Some types of bacteria in a compost pile will “fix” nitrogen. This preserves this essential nutrient by preventing escape as gaseous ammonia. If the conscientious composter prevents leaching, all of the original phosphorus and potassium can be preserved. As an added benefit, the composting process will increase the solubility of these nutrients.
We want to continue our discourse with a simple listing of manures that can be used to good effect by budding gardeners. But, we would be remiss if we did not begin by first discussing the few manures we believe are NOT suitable for use in gardening.
Human wastes, as well as the wastes of domestic cats and dogs, are considered totally unsuitable for use as fertilizer. DO NOT GARDEN WITH THESE WASTES! With these sources, too large a potential exists for the spread of deadly parasites and disease. Just say no to any suggestion for the use of those few manure sources.
That said, there are a great variety of guanos, manures, and castings that are safe and available for use by the enterprising horticulturalist. The list includes but is not limited to:
• The Manures
1. Chicken Manure
2. Poultry Manures (including Duck, Pigeon & Turkey Manure)
3. Cattle Manure
4. Goat Manure
5. Horse Manure
6. Pig Manure
7. Rabbit Manure
8. Sheep Manure
• The Guanos
1. Bat Guano - (including Mexican, Jamaican, & Indonesian bat guanos)
2. Seabird Guano - (including Peruvian seabird guano)
• Miscellaneous Wastes / Manures
1. Earthworm Castings
2. Cricket Castings
3. Aquarium & Aquatic Turtle Wastewater
5. Green Manures
Now it's time to describe the various manures and their unique attributes.
Bird Manures - are treated separately from animal manures since fowls don't excrete urine separately like mammals do. Because of this, bird manures tend to be "hotter". Overall they are much richer in many nutrients than animal manures, especially nitrogen. Because of their higher nutrient content, some growers prefer birdshit to the other animal manures.
Chicken Manure (1.1-1.4-0.6) - is the most common bird shit available for farmers. It's high in nitrogen and can easily burn plants unless composted first.
Feathers (often included with chicken manure) tend to further increase available nitrogen - an added bonus. A small amount of dried chicken manure can be used as a top-dressing or mixed in small concentrations directly into soil. Chicken manures are probably best used after complete composting. Chicken droppings are often composted with other manures as well as green matter, leaves, straw, shredded corncobs, or other convenient source of organic carbons. Chicken manure is also a common ingredient in some mushroom compost recipes. One potential concern for the budding organic farmer, is the large amount of antibiotics fed to domestic fowl in large production facilities. It is also suggested that some caution should be used when handling chicken droppings, whether fresh or dried. Dried chicken shit is very fine and is a lung irritant. Caution is also counseled since bird (and bat guanos) can carry spores that cause human respiratory disease, so please wear a mask when handling bird and bat guanos and fresh foul waste.
Poultry Manures (1.1-1.4-0.6) - are often simply chicken shit mixed also with the droppings of other domesticated birds including duck droppings, pigeon poop, and turkey turds. They are "hotter" than most animal droppings, and in general they can be treated like chicken shit.
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Animal Manures vary by species, and also depending of how the animals are kept and manures are collected. Urine contains a large percentage of nitrogen and potassium. This means that animals boarded in a fashion where urine is absorbed with their feces (by straw or other similar bedding), can produce organic compost that is richer in nutrients.
Cattle Manure (0.6-0.2-0.5) - is considered "cold" manure since it is moister and less concentrated than most other animal shit. It breaks down and gives off nutrients fairly slowly. Cow shit is an especially good source of beneficial bacteria, because of the complex bovine digestive system. Cow digestion includes regurgitation (cows chew their "cud") and a series of stomachs, all evolved to help cows more fully digest grasses. Since cow manure is more fully digested, it also is less likely to become a source of weed seeds than some other manure. Depending on your location, many sources of cattle manure can be from dairy cows. Recent expansion in the use of bovine growth hormones to increase milk production certainly could become a concern for organic farmers trying to source safe cattle manures. The healthier the cow, and the healthier the cow's diet, the more nutrients its manure will carry.
Goat Manure (0.7-0.3-0.9) - can be treated in a similar fashion to sheep dung or horse shit. It is usually fairly dry and rich and is a "hot" manure (therefore best composted before use).
Horse Manure (0.7-0.3-0.6) - is richer in nitrogen than cattle or swine manure, so it is a "hot" manure. A common source of horse manure is rural stables, where owners usually bed the beasts very well. Horse manures sourced from stables, therefore, may also contain large amounts of other organic matter such as wood shavings or straw with manure mixed in. Some sources of mushroom compost contain large quantities of horse manure and bedding in their mix. So from one standpoint, horseshit's use in herb growing is already fairly well documented. Horseshit, because it is hot, should be composted along with other manures and higher carbon materials, and in some cases wet down, to prevent it from cooking too hot and fast which destroys potential plant nutrients. As is true with all the different manures, healthier, well maintained animals will produce more nutritious and better balanced fertilizer. Since horses are usually well tended, this means horse manure from stables is usually a pretty good source for those in search of shit. Unfortunately, horse crap also contains a higher number of weed seeds than other comparable manure fertilizers.
Pig Manure (0.5-0.3-0.5) - is highly concentrated or "hot" manure. It is less rich in nitrogen than horse or bird crap, but stronger than many of the other animal manures. Swine crap is wetter overall than other mammal manures, and is often stored by farmers in the form of liquid slurry, that is mostly water. When allowed to dry, hog shit becomes a very fine dust, which can be a lung irritant. Pig shit is less likely to have nutrients "burn off" in the compost pile than horse manure, but is best used when mixed and composted with other manures and/or large quantities of vegetable matter.
Rabbit Manure (2.4-1.4-0.6) - is the hottest of the animal manures. It may even be higher in nitrogen than some poultry manures. As an added bonus it also contains fairly high percentages of phosphates. Because of it's high nitrogen content, rabbit crap is best used in small quantities (as a light top dressing or lightly mixed into soil) or composted before use. An excellent fertilizer by itself, some folks combine rabbit hutches with worm farms to create what is a potentially very rich source of nutritious worm castings. As with other animal manures, healthier animals fed a nutritious diet will produce a superior manure fertilizer.
Sheep Manure (0.7-0.3-0.9) - is another hot manure similar to horse or goat manure. It is generally high in nutrients and heats up quickly in a compost pile because it contains little water. Sheep and goat pellets, because they are lighter, are easier to handle than some other manures. Sheep shit contains relatively few weed seeds but more organic matter than other animal manures. As a side note, sheep farming is generally more destructive to the environment than cattle farming (or many other grazers). Sheep have a "split lip" allowing them to graze closer to the ground, so they tend to strip grass bare to the root. This heavy grazing kills many grasses, leaving earth more prone to destructive erosion. While it’s hardly considered environmentally friendly, cattle grazing is less heavy on the land than sheep farming.
"There are, in Cuba, a great number of caves providing a considerable supply of the richest fertilizer. In these caves, where bats shelter, a fertilizer has accumulated, a true guano, the result of a mixture of solid and liquid excrement, the remains of the fruit that fed the animals, and their own carcasses. All these materials, sheltered from the sun, air and rain, form a rich mix of nitrogenous, carbonaceous and saline elements. They contain uric acid, ammonium urate, nitrates, phosphates and calcium carbonate, alkaline salts, etc. The huge quantity of guano amassed in some caves can be explained by the number of beasts that have sheltered there for so many years".
Alvaro Reinoso - "Ensayos sobre el cultivo de la caña de azúcar", ("Essays on sugar-cane cultivation"), Havana - 1862
Bat and seabird guanos are some of the most wonderful, extraordinary, versatile, naturally occurring organic fertilizers known to man. They are not considered to be a renewable resource, and they are sometimes mined in an environmentally destructive fashion, so environmentally conscious growers sometimes avoid guanos.
Bat Guano - Bat guano is found as deposits in some caves that have been inhabited by these little flying mammals. Bat crap can sometimes also be found in smaller quantities in other places bats inhabit (old or abandoned buildings, trees, etc.). Bat guano has many horticultural uses. Its presence can help to guarantee efficient soil regeneration. When used as a fertilizer or tea, bat crap fosters abundant harvests of a high quality, making it an invaluable agricultural fertilizer for producing outstanding organic herbs, fruits, and vegetables. Many dedicated organic farmers insist that bat guano brings out the best flavors in their organic herbs. The bottom line is bat guano has many excellent properties that give it great value for growing an organic product of the highest quality. It may very well be possible to justify the boast that bat guano is "superior to all other natural fertilizers".
Bat Guano consists primarily of excrement of bats (no surprises there - eh?) It also contains the remains of bats that lived and died in that location over many long years. Bat guano is usually found in caves, and bats are not the only residents. Therefore, bat guano almost certainly contains the remains and excrement of other critters such as insects, mice, snakes and (gasp!) even birds. And, guano is by no means just collected excrement and animal remains, as guano ages it can undergo a array of complex decomposition and leaching processes.
The fertilizer quality of any particular bat guano depends on variety of factors. These can include: the type of rock in which the guano cave formed, the feeding habits of the bat species producing the guano, the guano’s age, and the progress of mineralization in the guano (which undergoes an endless transformation through chemical and biological processes). Guano can appear in a wide range of colors including white, yellow, brown, hazel, gray, black, or red, but color does not indicate or influence its quality.
One of the factors that can determine the fertilizer quality of bat guano is the dietary habits of the different bat species who inhabit a cave. Some bats are vegetarian, eating primarily fruits. Other bats are carnivorous; their diet usually consists of insects and similar small critters. As an example, the specific form of nitrogen in guano will depend on the feeding habits of the bats living in the caves. Bats that feed on insects eject fragments of chitin, the main component of insects' exoskeletons. Chitin resists decomposition, and contributes a long lasting form of nitrogen that appears in many older guano deposits. Obviously, chitin from digested insect remains is not likely to be found in any quantity in the guano of fruit eating bats.
Even a cave’s location will effect the composition of guano deposits found within. Different chemical reactions during the actual cave making process result in different nutrient characteristics in the various guanos. Over time, guano combines in various ways with the actual rock and minerals from the bedrock of their region. Ultimately, minerals may be deposited throughout layers of guano by a variety of means. Minerals that have been dissolved in water filtering through porous rock from above can fortify guano deposits as they drip from cave ceilings. In caves where water filters through the guano, soluble elements will likely be washed out, so the composition of the guano changes in other ways as well.
In addition to minerals deposited by leaching water, another factor in guano composition is the huge amount of particulates that fall from the cave ceilings and walls where the bats sleep and hibernate. The release of their liquid excrement at high-pressure pounds cave walls, and the physical presence of the bats as they constantly flit about, both combine to cause erosion. Chemical reactions caused by the bat crap (as well as many natural cave making processes), also work to break down cave ceilings and walls. All of these factors result in an invisible rain of minute solid mineral particulates. All of these mineral particulates are mixed into the copious quantities of bat crap (and other matter) deposited on the floor. As a result, bat guanos have a wide range natural / organic source mineral nutrients that are immediately available for plants, called chelates.
Another large component of bat guano deposits is the “fauna” within, the great collection of microorganisms that work as decomposers. Their main function is to accelerate the process of breaking down organic matter in the guano. These beneficial bacteria populations work to increase the guano’s wealth of essential nutrients, and can provide their own benefit to gardeners as a soil innoculant.
Once bat guano is deposited, it begins and endless process of transformation. From fresh deposits, nitrogen is the essential element that is usually released first. This is partially as ammonia, with its characteristic strong smell, which is omnipresent in fresh guano. The rest of the nitrogen oxidizes and forms nitrates that are often dissolved and leached by water. The phosphorus contained in guano comes partly from bat excrement, but is generally from skeletal remains (it may also come from mineral elements in the cave.) Many of the decomposition processes work to concentrate phosphorous levels in bat guano deposits as they age, and this provides some of guano’s greatest value to gardeners. Potassium is often the least represented of the three essential macro-elements, due to the solubility of its compounds, which are usually washed out of guano deposits by natural cave conditions.
During decomposition the actual proportion of the different fertilizer components of the guano change. As the guano breaks down, the levels of organic matter, nitrogen, and potassium will fall. At the same time, the relative levels of calcium, phosphates, sand, and clay levels will rise. The actual excrement and remains of bats are the main source of the elements nitrogen, phosphorus and potassium in guano. The organic compounds in the excrement contain sulphur, phosphorus, and nitrogen. After decomposition and oxidation, these combine to form sulphuric, phosphoric, and nitric acids.
Over time, those acids react with mineral elements from cave rock to form a variety of mineral salts - including sulphates, phosphates, and nitrates. Leaching washes out most of the soluble compounds including the nitrates, sodium, and potassium compounds. At the same time, the insoluble phosphates and sulphates build up in larger proportions. These include calcium phosphate, iron phosphate, aluminium phosphate and calcium sulphate. .
As we have already said, bat guano is an ecological fertilizer, obtained naturally from the excrement and physical remains of bats living in caves. This product is rich in nutrients, outclassing all other existing organic fertilizers, with a better balance of essential nutrients (N-P-K), a wealth of micro-organisms and much higher levels of organic matter. Its chemical and biological composition vary according to the bats' feeding habits, type of cave, age of guano, etc.
A great variety of different agrochemical analyses have been carried out on bat guanos through the years. All the different analysis show that the nutrient and micro-organism content of bat guanos are high, but it varies according to the type of guano. Because the chemical, physical and biological composition of bat guano (and other organic fertilizers) will naturally vary, it is impossible to set a specific single value for any nutrient. The table below is copied from internet research and is a summary of the variety of results obtained from bat guano analyses.
Source: Omar Páez Malagón, January 2004
Total Nitrogen(N) 1.00-6.00%
Phosphorus Oxide (P2O5) 1.50-9.00%
Potassium Oxide (K2O) 0.70-1.20%
Calcium Oxide (CaO) 3.60-12.0%
Magnesium Oxide (MgO) 0.70-2.00%
Iron (Fe) 0.70-1.50%
Copper (Cu) 0.20-0.50%
Manganese Oxide (MnO) 0.40-0.70%
Zinc (Zn) 0.40-0.65%
Sodium (Na+) 0.45-0.50%
Organic matter (OM) 30-65% pH (in H2O) 4.3-5.5
Ratio C/N 8-15/1
Humidity (Hy) 40-30%
Total humic extract 25-15.00%
Microbial flora 30 - 45x107 u.f.c./ gr
These values are not always uniform, but provide useful data for calculating doses of nutrients or micro-organisms and analyzing the product's physical properties for agricultural or industrial use. These indicators are for intermediate guano, in the natural state of transition between fresh guano and old or fossil guano. Source: Omar Páez Malagón, January 200
seabird guano-contains an equivalent percentage of plant nutrients,helps bind soil particles,aids in nitrogen fixation and greatly enhances beneficial bacteria. A great all around nutrient with quite a history.The most famous of all seabird guano's was that used by the inca's,the word guano actually originated from Quichua, language of the Inca civilization and means "the droppings of sea birds".The guano was collected on the rainless islands and coast of Peru.Where the atmospheric conditions insured a minimal loss of nutrients,leaving the Legendary fertilizer of the Incas.Seabird guano can be used as an soil amendment or as a tea at 1-2tbsp per gal.Bcause of its balanced npk ratio,an average of 10-10-2.5,seabird guano can be used as a base when making tea's (throught out the grow)
Green Manure is a crop grown for the purpose of supplying the soil with nutrients and organic matter. It is called a “cover crop” when the green manure is grown for the added purpose of reducing soil erosion. Green manures are usually legumes or grasses, and they are grown with the simple intent that they will be turned back under the soil. Cover crops and green manures are certainly cost effective for large-scale farmers, but many backyard gardeners have no idea how simple and effective they are to use. And, as we mentioned earlier, they do offer a “manure” option for growers who choose vegan organics.
Green manures improve soil in a variety of ways. Green manures add significant amount of organic matter into the soil. Like animal manures, the decomposing of green manures works to enhance biological activity in the soil. Green manures can also diminish the frequency of common weeds, and when used in a crop rotation, they can help to reduce disease and pests. When turned under, the rotting vegetation supports beneficial bacterial populations. As those decomposers do their work, nutrients stored by the cover crop are returned to the soil.
Alfalfa roots regularly grow to depths of five feet or more, soybeans and clover can reach almost as deep. Since their roots go deeper than folk would commonly cultivate with a rototiller or plow, a green manure crop can bring subsoil minerals up to where even shallow rooted plants can reach them. Green manures also help to improve overall soil structure, because those deep reaching roots leave behind minute channels deep into the soil. When these deep roots decay, they provide organic matter that promotes long-term soil building.
Except for buckwheat (a member of the rhubarb family) and rapeseed (related to the cabbages), all commonly used green manures are either legumes or grasses. Rye and oats are two good examples of grass family members that are commonly used as green manures. When we think of legumes, beans and peas are the “classics” which come to mind, but the legume family also includes relatives such as clover and alfalfa. Members of the legume family can be particularly valuable as green manures, due to their ability to “fix” nitrogen from the atmosphere.
In the legume family, a very specific type of bacteria works in league with plant roots. These microorganisms, called nitrogen fixing bacteria, form nodules on the plant roots where they work in a form of partnership with their host. Functioning in concert with the plant roots, nitrogen fixing bacteria transform atmospheric nitrogen (which plants otherwise can’t use), into ammonia, which plant roots can easily absorb.
If one of these plants is uprooted, the small nodules become visible as white or pinkish bumps the size of a large pinhead. The more nodules visible the better, since more nodules equals more nitrogen fixed. To assure that enough of these bacteria are present, commercially sold legume seeds are often treated with a bacterial innoculant. Make sure to get the appropriate innoculant for your specific legume crop if it’s necessary to inoculate your own soil or legume seed stock.
Each kind of legume requires a specific species of bacteria for effective nitrogen fixation, and each innoculant works for only a few species. It’s usually possible to buy an innoculant mix designed for all peas, snap or dry beans, as well as lima beans. Soybeans will require their own specific innoculant. A totally different innoculant will be needed to serve the needs of the vetches (as well as fava beans.) Still another nitrogen fixing bacteria will work with all the true clovers, but sweet clovers will require yet another innoculant.
With careful stewardship, a legume cover crop can enrich the soil with enough nitrogen to supply most of the following years crop nitrogen needs. Commonly used legumes for cover crops include: alfalfa; fava, mung and soy beans; a whole variety of clovers; cowpeas and field peas; common or hairy vetch; the lupines; and finally our favorite name among the legume cover crops - Birdsfoot trefoil.
Although the grasses and other non-legumes do not have the ability to fix nitrogen from the atmosphere, they still provide all the other benefits of green manures. Other non-legume crops grown for green manure include; barley, bromegrass, buckwheat, millet, oats, rapeseed, winter rye, ryegrass, grain sorghum, and wheat.
Seed for cover crop and green manures doesn’t need to come from fancy little packets at the garden center. Purchase grass and legume seeds by the pound, if you can, to save money. Farm and agricultural supply centers, what we call “feed & seed” stores, usually offer the most economical source. If your garden area is small, a single pound of seed may go a long way. With the smaller seeds, a pound could be expected to last through a couple of plantings. The larger seeds of legumes, like beans and peas, don’t store as well, so it’s advised to purchase them fresh annually.
The use of green manures and cover crops is relatively simple, the primary necessity being the time to grow the plants. Some preplanning is always helpful to make sure the correct crop is selected to best meet the grower’s needs. So, for example, if enriching soil nitrogen levels is a goal, then it’s best to choose a cover crop from the legume family due to their ability to fix nitrogen.
Some green manure plantings tolerate poor soil quality better than others, so some cover crops may be chosen because they tolerate particularly acidic (or alkaline) conditions. If a grower needs to break up hardpan soil and improve drainage, some cover crops grow very strong and deep roots. Such conditions call for green manures like alfalfa and birdsfoot trefoil that can thrust their roots through anything but the most dreadfully compressed soils.
As stated earlier, deep-rooted plants can also bring up essential nutrients from the subsoil. And, some do even more; they actually accumulate nutrients, concentrating them. Growing these green manures can produce a measurable (although not huge) increase in soil nutrients. Some legumes, especially red clover, can help to increase phosphorus levels. Buckwheat also increases phosphorus, as well as helping to supplement calcium. Vetches are also accumulator plants, working to increase levels of both calcium and sulfur.
Buckwheat and Rye are examples of crops often grown as green manures that also function to control weeds. Winter Rye is actually a natural herbicide; it produces chemicals that are toxic to many weed seedlings. Buckwheat works by outgrowing its weedy competitors. The large leaves of buckwheat effectively shade out many common annual weeds.
It’s also necessary to consider the seasonal needs of your garden when planning a green manure planting. Some green manures are early season crops, while others do better when planted during the heat of summer. Winter rye and winter wheat are usually planted in the late summer or fall and then turned under in the following spring.
Another key to getting the most from a green manure planting is to turn them under at the proper time. Winter cover crops of rye and wheat, for instance, should be turned under as soon as the spring soil is dry enough to work. It’s best when turning under a winter wheat to allow at least two weeks for the green manure to “work” in the soil before beginning any spring planting.
In order to assure good germination rates, it’s necessary to wait even longer for winter rye manures to be ready for replanting. A three to four week wait is suggested after turning under a winter rye crop before sowing seeds of another crop. This is due to the same herbicidal quality that makes winter rye effective in the control of weeds. In general with most grass cover crops, the best timing is to turn them under before they form mature seed.
Turning under legumes at any time will enhance the organic matter in soil and promote an active population of beneficial soil bacteria. But, to get the full benefit of a legume plantings ability to fix nitrogen, they should be allowed to grow a full season. Perennials like alfalfa, red clover, and birdsfoot trefoil can produce additional soil enriching nitrogen if allowed to grow for a second season. If allowed those two years of growth, they can be mowed multiple times, providing a high quality source of compost or material for mulching. An alfalfa cover planting can serve as a gardener’s own sure source of fresh materials for the manufacture of alfalfa teas.
Miscellaneous Wastes / Manures
this space reserved for further information on Miscellaneous Wastes / Manures
1. Earthworm Castings
2. Cricket Castings
3. Aquarium Wastewater
As we’ve stated, one of the best reasons to use manures in growing is the fact that society (as a whole) has a surplus of animal shit. The disposal or dispersal of animal wastes is a real problem for areas where large agricultural operations produce copious excesses of waste. Even Vegans who might avoid pure animal products like bone meal or blood meal, might do well to consider using manures in growing, because the use of manures is beneficial to our planet's environment.
The best advice we can give for finding good sources of shit is to look around! We suggest you simply contact people who raise the various cows, horses, pigs or chickens that make this fertilizer. If you are lucky, they'll probably let you take a load home for free. Stables are usually listed in the phone book, and state fairs and traveling circuses can also serve as great sources for free manure. For the hopelessly urban farmer, the local zoo may also offer free crap. As an added benefit, zoos can offer some pretty exotic shit, like crap from critters like lions and tigers and bears, (oh my!) Some folk claim that manure from predator species like these can help to deter garden pests, such as rabbits and deer.
If none of these manure sources are available, or if you just prefer your shit pre-packaged, just head off to the local nursery or home-and-garden center. Wal-Mart, Lowes, and Home Depot are all examples of large outlets which will carry packaged manure products, usually cow and steer crap. Often these are at least partially composted and come labeled as "humus and manure". Nowadays, even many grocery stores carries manure products like humus and manure or mushroom compost. The budget conscious shopper can often wait until late in the season when stores are "closing out" such products before winter, to grab these items at increased discounts.
Garden centers or hydro shops are usually better sources for the more exotic ingredients like worm castings and the various bat and bird guanos. Ingredients for green manures can often be found in rural animal feed stores, or other similar agricultural supply center.
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