* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Soil Basics - Hampshire Farm Landscaping
Survey
Document related concepts
Entomopathogenic nematode wikipedia , lookup
Soil horizon wikipedia , lookup
Plant use of endophytic fungi in defense wikipedia , lookup
Soil erosion wikipedia , lookup
Surface runoff wikipedia , lookup
Arbuscular mycorrhiza wikipedia , lookup
Soil respiration wikipedia , lookup
Human impact on the nitrogen cycle wikipedia , lookup
Canadian system of soil classification wikipedia , lookup
Soil compaction (agriculture) wikipedia , lookup
Crop rotation wikipedia , lookup
Terra preta wikipedia , lookup
No-till farming wikipedia , lookup
Soil salinity control wikipedia , lookup
Soil food web wikipedia , lookup
Soil contamination wikipedia , lookup
Transcript
1. The Symbiotic Decay-Nutrition (Continued on next page) Cycle The soil works as a dynamic plant-growing system. Good soil is rich in organic matter and microbes that, together with the atmosphere, precipitation and sunshine, provide all the needed elements and conditions for strong plant growth. Plants are known to need at least 16 elements to live, grow and reproduce (See Table 1). Recent research has shown that most plants also require very small amounts of nickel, and some plants require silicon. Like animals, plants need a certain balance of nutrients, not just the nitrogen (N), phosphate (P) and potassium (K) that we typically associate with plant foods. And like animals, plants need different amounts of the various nutrients at different life stages. How does the soil supply these nutrients in the right balance, and how can we improve soil properties to maximize plant health and vigor? Table 1. Typical Elemental Plant Composition (%) Oxygen Carbon (from air) Hydrogen Nitrogen Potassium Calcium Sulfur Phosphorus 45 44.0 6.0 2.0 1.1 0.6 0.5 0.4 Magnesium Manganese Iron Zinc Chlorine Boron Copper Molybdenum 0.3 0.05 0.02 0.01 0.01 0.005 0.001 0.0001 In the real world of crop and pasture management, two things are very important to maintaining soil health, and therefore plant vitality: the decay cycle (by which organic matter is recycled to recover critical elements), and supplemental provision of nutrients, usually via some kind of fertilizer. Decay of organic matter that enriches the soil is a cycle – there must be organic matter present to decay, and there must be microbes present to cause the decay. Organic matter, plants and microbes have a symbiotic relationship; organic matter enriches the physical attributes of the soil by holding water, warming appropriately but not baking in the sun as barren soil would, and providing a food source for the soil microbes. The microbes breakdown the organic matter and make elemental nutrients available to the plants. And the plants provide shade to prevent excessive soil warming (which would be detrimental to the microbes) and provide a continuous supply of organic matter through fallen leaves, dead grass blades, seed husks, etc. The addition of complex chemical and biological compounds to the soil via decay substantially enriches the physical, chemical and biochemical complexity of the soil and helps to maintain the proper pH (6.0 to 6.8) that allows for a healthy balance of microbial life. Use of a natural fertilizer such as the Bradfield products contributes to this provision of organic matter and nutrients. This symbiotic development of a nutrient cycle results in healthy plants with deep, extensive root systems that are better able to absorb nutrients and water from the surrounding soil. Use of a straight chemical www.bradfieldorganics.com 1. The Symbiotic Decay-Nutrition (Continued from next page) Cycle fertilizer interrupts this symbiotic cycle by 1) not contributing organic matter; 2) depressing natural fixation of nutrients by bacteria living in the soil and in nodules found on the roots of plants; 3) disrupting the balance of nutrients available to the plant (much as oversupply of one nutrient may disrupt absorption of another in animals); and 4) interrupting the normal progress of the decay cycle. Over time, this results in plants suffering from malnutrition and inadequate root development, thus increasing the need for extraneous provision of fertilizers. Nutrient needs are relatively small at the beginning of a crop’s or pasture’s growth, then increase dramatically during peak vegetative growth and during seed production. If soil is healthy and the decay cycle is progressing normally, last year’s residues will be digested and their nutrients released and available to the plant at about the time the plant is approaching its peak needs. Anything that interrupts or slows the cycle can result in inadequate nutrition when the plant most needs it. Healthy soils have far larger amounts of nutrient elements than crops need, but most of this total soil nutrient supply is unavailable to plants. Most of the nutrients in soil are initially “tied up”, their molecules chemically bound in mineral particles, or in the complex organic molecules in humus or the bodies of soil organisms. These nutrients can be made available through natural processes: weathering, the action of precipitation and temperature changes; plant root release of acidic substances (hydrogen ions and organic acids); microbe release of acids and chelating substances; and microbial decay of organic matter. In a healthy, biologically active soil, these natural release mechanisms can often meet much of a plant’s nutrient needs. Indeed, natural nutrient release is one reason that biological farmers can reduce their fertilizer inputs after several years. Farmers using inorganic sources of fertilizer typically find that they must increase application rates year after year in order to sustain reasonable crop growth. For optimal plant health and production, your soil needs sufficient organic matter (2 to 3% minimum), adequate moisture, a proper balance of all nutrients (not just N, P and K), and high biological activity in order to provide an appropriate balance of nutrients and encourage plants to have strong root systems by which to absorb these nutrients. Bradfield products act as a part of the symbiotic cycle to provide natural sources of nutrients in a base of organic matter to feed the soil, not just the plants! REFERENCES Zimmer, Gary. 2006. Soil Basics: How It Works. Acres U.S.A. www.answers.com/topic/CNO-cycle Harrison, John Arthur. The Nitrogen Cycle: Of Microbes and Men. www.visonlearning.com/library/module_viewer.php?mid=98&l=&c3 www.bradfieldorganics.com 2. Water Uptake (Continued on next page) Plants need water as part of their cells. Indeed, plant tissue is about 80 to 90% water. This water is the substance in which the various molecules and ions that perform metabolic activities (such as photosynthesis, food transport, cell maintenance, growth and reproduction) are dissolved and transported. Water is also the substance in which the soil’s nutrients are dissolved and carried into the plant. Plants are constantly losing water via “transpiration” through thousands of tiny pores (“stomata”) in the leaves and by leakage of root exudates through the tips of the roots. Plants do have some ability to regulate the size of their stomata and slow down water loss, but obviously water must be continually provided to the plant by absorption through the roots to maintain optimal health. The constant movement of water upward from the roots to the leaves serves to carry nutrients from the soil to all parts of the plant and to help cool the leaves during hot weather. Plants vary in their water needs – while a cactus will lose only microscopic amounts of water in a day, a corn plant may lose up to two quarts! In the soil, water fills pore spaces between soil particles. In moist soil, about half of the total soil water is able to be absorbed (“available water”) and about half is too tightly held on soil particles to be used (“unavailable water”). The composition of the soil is a major factor in availability of water to plants. Soils with a high clay content hold a higher percentage of the total water as unavailable water, but their total water supply will be considerably larger than sandy soils. High clay soils are also subject to compaction, which can impede the development of strong, deep root systems. Sandy soils will be short on total water-holding capacity and may not have the humus content necessary to support nutrition and water provision needed by many plants. Use of fertilizers such as Bradfield products that contribute organic matter to soils can increase the available water and reduce the compaction of clay soils and increase the total water capacity and nutrient content of sandy soils. Salts in soils also affect root water uptake. The higher the salt level, the more difficult it is for the plant to draw water from the soil. Excessive use of inorganic, high-salt fertilizers (such as potassium chloride or ammonium nitrate) can increase salt levels so high that plant growth is negatively impacted. Use of natural fertilizers avoids this salt build-up and maintains water availability. The faster the rate of transpiration from the leaves, the faster the plant must draw water through the roots to keep up. Plants need much more water when weather is sunny, humidity is low, or the wind is strong. Under these conditions, if the soil’s supply of available water is low, either due to low capacity or low availability, plants will begin to wilt. This is one reason why a soil’s structure and humus content are so www.bradfieldorganics.com 2. Water Uptake (Continued from next page) important: to improve water movement and availability. Inorganic fertilizers do nothing to enrich the organic matter or humus content of a soil and therefore do nothing to improve the supply of water to plants. Indeed, the potential for salt buildup will result in a negative impact on available water over time. A soil rich in organic matter will not only be optimal for water availability, it will encourage growth of dense, deep root systems that are better able to withstand periods of water shortage. Use of natural Bradfield fertilizers helps to build soil organic matter, ultimately resulting in stronger, healthier plants! REFERENCES Zimmer, Gary. 2006. Soil Basics: How It Works. Acres U.S.A. Transport in Plants. www.biologymad.com/PlantTransport/PlantTransport.htm www.bradfieldorganics.com 3. Ions, Nutrition and all that “Scary” Chemistry (Continued on next page) Nutrients that are held on soil particles yet are available to plants for use are called “exchangeable nutrients”, meaning they can be easily exchanged between the soil particle and the plant root. These nutrients are in the form of “ions”, atoms or molecules that have an electrical charge. Ions with a positive charge are called “cations”; those with a negative charge are “anions”. Common nutrients are shown here in the form in which they are available to plants: Positive ions Potassium Calcium Magnesium Iron Copper Zinc Manganese Nickel Negative ions Nitrogen Phosphorus Sulfur Boron Molybdenum Chlorine The very small colloidal particles in soil, clay and humus have a large surface area covered by many negative electrical charges. Cations are attracted to and held by these negatively charged colloids (positive and negative charges attract – similar charges repel). Anions are mainly found free in the soil solution (the water between the soil particles). Clay particles generally have a flat, angular shape, while humus particles are irregular and lumpy. Humus particles have much more surface area and can hold about three times as many nutrients as clay particles. Scientists have a means of estimating a soil’s fertility by determining its cation exchange capacity (CEC). The CEC is only an estimate of a soil’s ability to hold major cations (calcium, magnesium and potassium), but it has proven to be a fairly accurate estimate of soil fertility. The CEC of various soil types and humus is shown in Table 1; note that the more clay and humus a soil has, the greater its ability to store nutrients. Thus, it is valuable to enrich clay soils with organic matter such as that found in the Bradfield natural fertilizer products to enhance their nutrient-holding ability. www.bradfieldorganics.com 3. Ions, Nutrition and all that “Scary” Chemistry (Continued from next page) Table 1. Cation Exchange Capacity of Soil Types Soil Texture Sands Sandy loams Loams, silt loams Clay loams Peat Clays Humus CEC 1–5 5 – 10 5 – 15 15 – 30 10 - 30 over 30 100 – 300 Now, remember that while a soil may be able to hold a lot of nutrients, those nutrients must be available to the plant to be useful. A soil may have a great capacity to store nutrients but may be depleted of available nutrients from many years of growing plants with little or no supplemental fertilization or organic matter recycling. Under these circumstances, the negatively charged sites on the soil colloids that normally bind nutrient cations such as calcium, magnesium and potassium, will become filled with positively charged hydrogen ions. This meets the need of the negative site to bind with a positively charged ion, but it does nothing for the plant. Indeed, as hydrogen ions pile up, the soil’s pH drops, becoming more acidic, which is a sign of nutrient-poor soil. “Liming” a soil to increase its pH is really a matter of replacing hydrogen ions with needed nutrients. The material used for liming should be designed to replace those nutrients specifically missing, so having soil thoroughly tested for elemental composition is important for proper restoration. Enhancing a soil with natural fertilizers such as the Bradfield products, which directly provide nutrients as well as organic matter that supports microbial growth and provides colloidal binding sites, can help to prevent excessive soil acidity in the first place. Proper fertilization with an organic matter- containing fertilizer will help to maintain the physical characteristics of soil that are so necessary for optimal soil fertility and superior plant health. REFERENCES Zimmer, Gary. 2006. Soil Basics: How It Works. Acres U.S.A. MicroSoil: Cation Exchange Capacity. www.microsoil.com/CEC.htm Cation-Exchange Capacity. Tree Fruit Soil and Nutrition. Washington State University. soils.tfrec.wsu.edu/webnutritiongood/soilprops/04CEC.htm www.bradfieldorganics.com 4. Who are these Microbes, and what are they doing in my Soil? (Continued on next page) Strong, healthy soil is critical to anyone who has planted anything for any reason. Without it, your chances for success are pretty poor. But what makes one soil support abundant, vigorous plant life while another seems to produce only sickly plants and weeds? Let’s start with soil structure, which has an important impact on transport of nutrients from soil to plants. There are three main types of soils. Sandy soils are composed of large, loose particles that drain easily. Sandy soils will never compact, but they are also poor repositories for water and nutrients. Unless sufficiently amended and maintained, sandy soils will support only the hardiest of plant life. At the other end of the spectrum are clay soils. Clay soils are composed of very small particles that are sticky when wet. They have a lot of valuable surface area for adherence of nutrients and retain water very well, but they compact very easily and may be lacking in the air spaces that allow movement of water and nutrients, thus limiting their availability to the plant. In between sandy and clay soils lie the loamy soils. These soils are actually a combination of sand, clay and organic matter. They resist compaction but retain enough water and nutrients to support plant life when well-managed. The good news is that both clay and sandy soils can be made more like loamy soils with the proper care and amendments. All plants require 16 essential elements, and many require a few more. They get carbon, hydrogen and oxygen from the air and water, the availability of which is directly related to the structure of the soil they are growing in. Loamy soils with good aggregate structure and adequate porosity allow plenty of air and water to reach plant roots. But no soil, regardless of structure, will support vigorous plant life and deliver enough of the other 13 or 14 essential elements unless it is teeming with the billions of microbes that are necessary for maintaining soil health and supporting vegetative growth. Just what do soil microbes do? The list is impressive: • • • • • • • • Increase availability of phosphorus, potassium and other nutrients Deliver nitrogen Break down organic residues Increase soil aeration Improve water penetration and retention Increase naturally occurring organic acids that stimulate root growth Improve delivery of multiple nutrients to plant roots Inhibit pathogens How do microbes do all this? Soil microbes exist in the “rhyzosphere”, the area of soil surrounding the roots of plants. They exist in a symbiotic relationship with the plant www.bradfieldorganics.com 4. Who are these Microbes, and what are they doing in my Soil (Continued from next page) roots; microbes deliver nutrients plants need and either directly destroy pathogens or produce compounds that are antagonistic to pathogenic organisms, and plants provide microbes with amino acids and carbohydrate products of photosynthesis. Obviously, the healthier and more extensive the root system of the plant, the deeper and richer will be the rhyzosphere, and vice versa. Many microbes also derive carbon from organic matter that is broken down by bacteria, so the combination of abundant organic matter and a healthy bacterial population is essential to supporting a rich and vibrant rhyzosphere. Indeed, the microbe population in the top six inches of one acre of healthy soil has a metabolic equivalent of 10,000 humans, and each gram of soil may contain 10,000 different species of microorganisms! Many classes of microbes exist to service the soil and plant life. Bacteria serve to decompose organic matter, leaving in their wake a sticky, mucus-like substance that acts as a glue to hold the soil together in aggregates that provide soil structure with multiple spaces for movement of air and water. Some bacteria also consume many pathogens that might otherwise be able to attack plants or other beneficial microbes. Rhizobial bacteria infect the root nodules of legumes and participate in nitrogen-fixing by these plants. Fungi are responsible for delivery of a significant amount of the nitrogen that is taken up by plants. While much free solute nitrogen is absorbed directly from the soil water solution, fungi are responsible for delivery of fully one-third of the nitrogen plants need. They do this by linking soil nitrogen to carbon, moving the combined N-C molecule to the root surface, and then, just before delivery, the carbon is released and only the nitrogen is presented to the plant. Other fungi, specifically mycorrhizal fungi, are critical for phosphorus uptake and also aid in improving availability of potassium. These fungi send tiny root-like stru c t u res called “hyphae” into the soil and can bring p h o s p h o rus to a plant root from four inches away (which is miles in terms of soil nutrient provision!). Mycorrhizae also produce a substance called “glomalin”, which improves soil stru c t u re and may form as much as 30% of the organic matter in the soil. Beneficial nematodes (tiny roundworms) keep pathogenic root-eating nematodes under control. They also consume other nematodes and bacteria, thus releasing nitrogen and phosphorus into the soil, where fungi can make them available to plants. Some nematodes eat pathogenic fungi, thus helping to maintain a healthy balance of microbial life. One-celled protozoa in the soil serve as soil police squads, preying on bacteria and fungi to keep these populations under control. As with any system made of multiple components, if one portion of the population gets out of control, the system fails to function as it should. The presence of ciliate protozoa, which feed on anaerobic bacteria, indicates that oxygen is in limited supply and some soil aeration is needed. www.bradfieldorganics.com 4. Who are these Microbes, and what are they doing in my Soil (Continued from next page) Arthropods are a class of assorted creatures ranging from the microscopic to beings as large as ants, beetles and centipedes. Their general function is to break up debris and aerate the soil with their foraging. Arthropods will not be present if there is nothing to forage. Earthworms, though not really microbes, are great contributors to soil richness with their nutrient-dense castings and the aeration provided by their burrowing, and their presence is a good indication that the soil is healthy and abundant in nutrients and multiple forms of microbial life. Clearly, a soil that is barren of organic matter and microbial activity will have very limited ability to support any kind of plant life. Chemical fertilizers will only be available to plants in the form that is readily soluble in water; much will be wasted and will run off because there are no microbes to transport nutrients. Root systems will be shallow, the rhyzosphere will be thin, and soil structure will suffer. Application of large amounts of chemical fertilizers, as well as herbicides and fungicides, in an effort to feed weakening plants may even decimate what little microbial life exists, resulting in an even more sterile, barren soil. Use of organic fertilizers and amendments such as Bradfield Organics products to build soil structure and support microbial life is critical to the optimal growth of vigorous, healthy plants! REFERENCES Bago, B., P. E. Pfeffer, and Y . Shachar-Hill. 2000. Carbon metabolism and transport in arbuscular mycorrhizas . Plant Physiol. 124:949-957. Booker, Karen. 2000. Fertilizers and Soil Amendments: It’s Tricky Business. Erosion Control Feature Article, September/October. www.forester.net/ec_0009_fertilizer.html Drinkwater, L. E., P. Wagner, and M. Sarrantonio. 1998. Legume-based cropping systems have reduced carbon and nitrogen losses. Nature. Vol. 396, Nov. 19. Ellis, J. R. 1995. Mycorrhiza – An essential part of most plant root systems. Better Crops 79(1):10-11. Marschner, Horst. 1995. Mineral Nutrition of Higher Plants. (2nd ed.) Wright, S. F. 2003. The importance of soil microorganisms in aggregate stability. Proc. North Central Extension-Industry Soil Fertility Conference. 19:93-98. www.agro-K.com/organics/soil_health.htm www.bradfieldorganics.com