{"id":9108,"date":"2023-04-23T10:34:40","date_gmt":"2023-04-23T08:34:40","guid":{"rendered":"https:\/\/marijuanagrowing.com\/?p=9108"},"modified":"2024-01-31T13:37:15","modified_gmt":"2024-01-31T12:37:15","slug":"soil-chapter-18","status":"publish","type":"post","link":"https:\/\/marijuanagrowing.com\/soil-chapter-18\/","title":{"rendered":"Soil – Chapter 18"},"content":{"rendered":"\n
Soilsare different\u2014very different\u2014from one another. The average organic mineral soil is made up of 45 percent mineral particles; 5 percent living and dead organisms such as bacteria, protozoa, microbes, fungi, and earthworms; and 50 percent air and water. Three major factors contribute to cannabis roots\u2019 ability to grow in a soil: texture, pH, and nutrient content (organic and mineral).<\/p>\n\n\n\n
Most gardeners look at soil in two basic ways. The first is to see it as a living, organic substance that must be nurtured in order for cannabis roots to extract the necessary nutrients quickly, efficiently, and in maximum amounts. There are large volumes of soil in outdoor gardens and in large containers placed in green\u00adhouses or indoors, and for such volumes, we can apply complete organic principles. The second way to look at soil is as a growing medium that holds chemical elements, salt-based fertilizers (nutrients), air, and water. Indoors and often in greenhouses this is the way many gardeners approach growing.<\/p>\n\n\n\n
Dirt, Soil, and Soilless Mix<\/strong> Many soils and soilless mixes used by cannabis gardeners are peat-based and are mixed with other elements.<\/em><\/p>\n\n\n\n Rocky, clayey soil is packed with nutrients, but its texture restricts air and moisture content.<\/em><\/p>\n\n\n\n Heavy clay soil is easy to spot. It clumps up readily, is difficult to work, and drains poorly.<\/em><\/p>\n\n\n\n Soil texture is governed by the size and physical makeup of the mineral particles. Proper soil texture is required for adequate root penetration, water and oxygen retention, and drainage as well as many other complex chemical processes.<\/p>\n\n\n\n \u201cSoil texture\u201d is a descriptive tool used to express mineral particle sizes and grains in sediment, and is divided into three main groups, clay, loam, and sand. Most soils are a mix of three basic soil particle sizes: clay, silt, and sand (described below).<\/p>\n\n\n\n Soil pH is a measure of the acid-to-alkaline balance. Soil life and mineral (nutrient) availability and uptake by roots are affected by soil pH levels. Every full-point change in the 0 to14 pH scale denotes a tenfold <\/em>increase or decrease. Nutrient uptake is best within a pH range of 6.0 to 6.5. Keeping the soil and water pH-balanced and within the proper range is essential to a strong, healthy cannabis crop.<\/p>\n\n\n\n Soil varies from location to location on the earth and often varies from one place to another in your own backyard.<\/p>\n\n\n\n Soil tests are remarkably inexpensive ($20\u2013$200 USD) and save medical cannabis gardeners much time and money wasted on fertilizers. Such tests also save the environment from ex\u00adcessive fertilizer pollution, including nitrates and phosphates, accumulation in the soil, and runoff in the watershed. Excess fertilizer salts wash out into the water system where they cause countless environmental and health problems. For example, home gardeners use at least ten times more fertilizer per square yard (m2) than big agribusiness farms. For every $10 USD spent on fertilizer by home gardeners, $9 USD is wasted! I recently spoke to an outdoor medical cannabis gardener who spends $3,000 USD on fertilizer annually. By applying the above information we see that 10 percent ($300 USD) worth of fertilizer is actually used and 90 percent ($2,700 USD worth of fertilizer) is washed into the soil and groundwater. The gardener could easily save $2,700 USD by invest\u00ading $20 to $200 USD in soil tests and the following recommendations.<\/p>\n\n\n\n Familiarize yourself with 2 basic types of soil analysis: base cation saturation ratio (BCSR) and sufficiency level of available nutrients (SLAN).<\/p>\n\n\n\n Base cation saturation ratio is commonly used by organic farmers and market gardeners in many countries. The results of BCSR testing provide the actual amounts of nutrients in soil. The goal of BCSR testing is to achieve a balanced ratio of nutrients. The methodology uses Mehlich 3 extraction with different testing parameters. The BCSR soil-test\u00ading method is supported by the National Sustainable Agriculture Information Service (ATTRA).<\/p>\n\n\n\n Standard soil tests provide information for some or all of the following: Get a BCSR soil analysis ($110\u2013$150 USD) from Earthfort, http:\/\/earthfort.com\/lab services.html<\/a>.<\/p>\n\n\n\n Also known as Index (UK) system, SLAN is used by the majority of uni\u00adversities, farmers, and big agribusinesses worldwide. The results of this type of test provide plant-available nutrient levels in a well-known range, ensuring neither a deficiency nor an excess. The methodology uses ammonium acetate extraction.<\/p>\n\n\n\n Standard SLAN soil tests provide some or all of all of the following and many include recommendations to improve soil nutrient content. An optimum range for each reading and amendment and fertilizer recommen\u00addations are also included in many soil tests. For a little more money many labs include an easy-to-read graph.<\/p>\n\n\n\n SLAN Soil Test Labs<\/strong><\/p>\n\n\n\n Logan Labs, LLC: Least expensive soil tests I have found. Basic test $20 USD. www.loganlabs.com<\/a><\/p>\n\n\n\n A&L Western Laboratories, Inc.: Excellent service at a reasonable price. https:\/\/al-labs-west.com\/<\/a><\/p>\n\n\n\n Spectrum Analytic, Inc.: This lab does everything and also shows a sample soil test. www.spectrumanalytic.com<\/a><\/p>\n\n\n\n Regardless of the type of test you choose, BCSR or SLAN, follow soil collection and submission guidelines to the letter. Gardeners living in a state or country that sanctions medicinal cannabis can send tests to local labs and request recommendations for cannabis. Medical gardeners who do not live in such a state can send their soil samples to any soil test lab but are advised not to mention the target crop.<\/p>\n\n\n\n Excellent sites to learn more about soil:<\/strong><\/p>\n\n\n\n \u2022 Soil and Health Library provides free e-books, mainly about holistic agriculture, holistic health, and self-sufficient homestead living. https:\/\/soilandhealth.org<\/a><\/p>\n\n\n\n \u2022 Soilminerals.com provides complete information on garden soil minerals, nutrients, trace minerals, fertilizers and amendments for all gardens, farms, lawns, orchards and greenhouses. www.soilminerals.com<\/a><\/p>\n\n\n\n \u2022 University of Idaho, College of Agriculture offers a short course in soil and plant diagnostics. www.webpages.uidaho.edu\/~bmahler\/s44603.pdf<\/a><\/p>\n\n\n\n \u2022 Acres USA is North America\u2019s oldest magazine covering commercial-scale organic and sustainable farming. www.acresusa.com<\/a><\/p>\n\n\n\n \u2022 National Sustainable Agriculture Information Service (ATTRA) manages projects that promote self-reliance and sustainable lifestyles that include sustainable and renewable energy, energy conservation, resource-efficient housing, sustainable community development, and sustainable agriculture. www.attra.ncat.org<\/a><\/p>\n\n\n\n \u2022 Jorge Cervantes Presents Marijuana Growing. Check our site, which includes a forum for updates and current discussion! www.marijuanagrowing.com<\/a><\/p>\n\n\n\n \u2022 Google <\/strong>William A. Albrecht, PhD, a famous agronomist who pointed out the direct relationship between soil fertility and human health. www.google.com<\/a><\/p>\n\n\n\n Analyzing plant tissue for nutrient accumulation and utilization is common among professional farmers and green\u00adhouse growers. The tests cost less than $40 USD and help growers fine-tune fertilizer application. A small investment in periodic plant tissue analysis will lower fertilizer bills and increase yields, often substantially. Legal medicinal can\u00adnabis gardeners are also able to request plant tissue analysis from agricultural laboratories within states and countries that sanction medical cannabis.<\/p>\n\n\n\n Soil tests measure nutrient levels that are potentially available for uptake by roots.<\/p>\n\n\n\n The test is normally performed before planting, and it does not measure the actual concentration of nutrients inside of plants. For example, nitrogen is often deficient in plants even though it may be readily available in the soil. A tissue analysis, on the other hand, will provide current data to make timely decisions.<\/p>\n\n\n\n Plant tissue analysis also helps ensure plants are not overfertilized. High concentrations of nitrogen, in particular, may affect human health because excess nitrates can convert to nitrites while being digested in the gut. Nitrates may react with other compounds to form nitrosamines that may be carcinogenic.<\/p>\n\n\n\n Fine-tuning fertilization programs, including micronutrient levels, is much easier when accurate information from analysis of plant tissue is available. Micro\u00adnutrients are required in minute amounts, and an overdose could easily stunt a crop or significantly diminish yields. Hydroponic gardeners, who do not have soil tests at their disposal, find plant tissue analysis especially useful.<\/p>\n\n\n\n Plant tissue analysis often takes 1 to 2 weeks when a specimen is sent to a laboratory. When crops are grown for 10 to 12 weeks total, this might be 10 percent of the plant\u2019s life. But, nitrogen tests* can be completed on the spot with a handheld meter in the garden, and results are available immediately.<\/p>\n\n\n\n *A chlorophyll concentration meter measures chlorophyll content index (CCI) in foliage and the nitrogen content is extrapolated from this data. One molecule of chlorophyll contains four nitrogen atoms.<\/p>\n\n\n\n A soil test and the proper organic amendments before planting saved this gardener hundreds of dollars in fertilizer.<\/em><\/p>\n\n\n\n To feel its texture, pick up a handful of moist outdoor soil and rub it between your fingers. Heavy clay soil will feel slick and greasy. Sandy soil feels grainy and rough. Silty soil will feel soft and spongy and be dark in color.<\/p>\n\n\n\n Pick up a handful of moist potting soil and gently squeeze it to feel the texture. The soil should barely stay together and have a sponge effect when you slowly open your hand to release the pressure. Potting soils that do not fulfill these requirements should be thrown out or amended.<\/p>\n\n\n\n The cation exchange capacity (CEC) of a growing medium is its capacity to hold cations that are available for uptake by the roots. The CEC is the number of cation charges held in 3.5 ounces (100 gm or 100 cc) of soil and is mea\u00adsured in milliequivalents (mEq) or cen\u00adtimoles\/kg on a scale from 0 to 100. A CEC of zero means the substrate holds no available cations for roots. A CEC of 100 means the medium always holds cations available for uptake by roots. Growing mediums that carry a negative electrical charge are the best.<\/p>\n\n\n\n Cation exchange capacity is a calculated value that estimates the ability of a soil to attract, hold, and exchange cation elements; CEC values are reported in milliequivalents per 100 grams of soil (mEq\/100 gm). Soil-sample testing labo\u00adratories report a value for the CEC. Use the CEC numeric value on your report and then compare the number to the graph below to find your soil type.<\/p>\n\n\n\n High-CEC soils hold more nutrients and water. But soils with high levels of clay (and high CEC readings) allow little room for oxygen and can slow root growth and nutrient uptake. If acidic, high-CEC soils also require more lime to buffer and lower pH.<\/p>\n\n\n\n Nutrients take more time to leach out of high-CEC soils.<\/p>\n\n\n\n Low-CEC soils hold nutrients poorly, which requires more frequent irrigation and lower volumes. These soils have a low capacity to retain cations. Add humus-based amendments to acidify and balance low-CEC soils.<\/p>\n\n\n\n Nutrients must be dissolved in (water) solution in order to be absorbed by roots. When dissolved, they are in a form called \u201cions.\u201d This means that they have electrical charges. An electrical charge is either positive (+) or negative (-). For example, table salt, sodium chloride (NaCl), becomes 2 ions when dissolved: sodium (Na+) and chloride (Cl-). The sodium ion with a positive (+) charge is called a \u201ccation,\u201d and the chloride ion with a negative (-) charge is called an \u201canion.\u201d In chemistry, oppo\u00adsites attract and likes repel one another. In ionic form, nutrients are attracted to opposite charges\u2014positive attracts negative and vice versa.<\/p>\n\n\n\n Soil chemistry can become very com\u00adplex, and it is beyond the scope of this book to dig deeply into the subject. For more information on the subject, check www.marijuanagrowing.com<\/a>.<\/p>\n\n\n\n This soilless mix is super dry but light and powdery. It holds a lot of water and air at the same time.<\/em><\/p>\n\n\n\n This handful of soil has everything necessary for strong plant growth.<\/em><\/p>\n\n\n\n This is very heavy clay soil. It is great for making pottery but horrible as garden soil.<\/em><\/p>\n\n\n\n Use this table to estimate the CEC of your soil:<\/p>\n\n\n\n This list shows different growing mediums\u2019 ability to hold positive charges that are ready for root uptake. Note the zero CEC of perlite and rockwool. Roots must be constantly bathed in nutrients. Other mediums do not provide a constant flow of nutrients and the CEC regulates the ability to hold a positive charge to make nutrients available for root uptake.<\/p>\n\n\n\n This cutaway drawing shows how roots penetrate the soil. Note: There must be enough air trapped in the soil to allow biological activity and absorption of nutrients.<\/em><\/p>\n\n\n\n Clay soil <\/strong>consists of very small, flat mineral particles that have a strong negative ionic charge. In fact, the negative electrical charge often ties up calcium, magnesium, potassium, and sodium in clay soil. Minute mineral particles pack tightly together, especially when wet, causing very slow drainage. Roots penetrate clay soil slowly, and damage from waterlogging is more common. Clay soil has little or no space for oxygen, the lack of which slows nutrient uptake. Clay soil can be very difficult to till; it is often extremely heavy when wet and is known to clump up.<\/p>\n\n\n\n Amend clay soil with compost, manure, gypsum, etc. (See Organic Soil Amendments later in this chapter for a complete list.) Incorporating compost, manure, or other organic amendments in the fall is one of the best ways to improve clayey and poor-quality soils. Raised beds are also an excellent option to combat clay soil. Till clay soil when it is damp and workable, and add manure, compost, or both.<\/p>\n\n\n\n The hard, clayey, rocky soil above is packed with nutrients but restricts root growth and water drainage. Plants shown here are in sunken beds to conserve moisture.<\/em><\/p>\n\n\n\n Sandy soil<\/strong> boasts the largest particles that permit good aeration and drainage. Drainage can be too fast if particles are too big. The texture of sandy soil is somewhat gritty depending upon the size of its mineral particles. Sandy soil is easy to cultivate and warms quickly in the spring, but low water-retention rates mean that frequent watering is necessary. Amend sandy soil with compost and organic matter to help it retain water more evenly.<\/p>\n\n\n\n Silty soil<\/strong> is very fertile. It is composed of fine organic particles and minerals such as quartz. Silty soil is granular, like sandy soil, but it has more nutrients and offers better drainage. When silty soil is dry it has a smoother texture and looks like dark sand. This type of soil can hold more moisture and can at times become compacted. It offers better drainage and is much easier to work with when moist.<\/p>\n\n\n\n Soils are seldom all clay, all sand, or all silt. They are a combination of different types. This table demonstrates the different percentages of soil combinations.<\/p>\n\n\n\n Beautiful peat-rich soil is ideal for planting. This greenhouse and the field in the foreground produce nice, big gardens of medicinal cannabis.<\/em><\/p>\n\n\n\n Loam soil<\/strong> is made up of sand, silt, and clay. Loam is considered by many to be the perfect soil. Its texture is often gritty, yet it retains plenty of air and water and drains well because of its different-sized particles. Depending upon its makeup, loam can range from heavy (clay) to light (sandy).<\/p>\n\n\n\n Peat (bog) soil<\/strong> is formed by the accumulation of dead and decayed organic matter. Found in rainy, marshy areas, the decomposition of organic matter in peat soil is blocked by soil acidity. Few nutrients are present even though peat soil is rich in organic matter. Peat soils are prone to waterlogging, so for best results, they must be mixed with other soils and compost before cannabis is planted.<\/p>\n\n\n\n Chalky soil<\/strong> is very alkaline in nature and is often packed with rocks. It is prone to dryness, and in summer chalky soil consumes much water and fertilizer. This soil also locks up iron and magnesium due to its high pH activity.<\/p>\n\n\n\n Alkali soils <\/strong>are packed with sodium carbonate, which is detrimental to cannabis growth. The farmland around my hometown is plagued with alkali soil. Many other regions in the world also suffer from alkali soil; the pH hovers around 8.5 and higher. Alkali salt is so abundant in many places that it appears as white powder that cakes up on the surface of soil. Alkali soils also significantly slow water absorption.<\/p>\n\n\n\n To “purge” alkali salt from soil, farmers cultivate with a tractor or tracked vehicle equipped with 30- to 36-inch (76\u201391 cm) “ripping bars.” Tilled fields are flood-irrigated with a foot (30.5 cm) or more of water to drive the alkali salts deep into the soil, beyond the depth of most roots. The salts rise to the surface over time, and the process is repeated every few years as needed.<\/p>\n\n\n\n Outdoor cannabis gardeners plagued with alkali soil should grow in large containers and amend the alkali soils with acidic elements, including peat moss. Use as little alkali soil in the container as possible, and before planting, leach the alkali soil heavily with water to wash out unwanted salts.<\/p>\n\n\n\n This soil pyramid demonstrates the diversity of most soils.<\/em><\/p>\n\n\n\n A simple pH chart shows the range in which most nutrients are available in soil.<\/em><\/p>\n\n\n\n Potential hydrogen (pH) is a scale from 0 to 14 that measures the concentration of either hydrogen (H) ions or hydroxide (OH) ions. Zero is the most acidic, 7 is neutral (also known as base), and 14 is the most alkaline. Every full-point change in the logarithmic pH scale signifies a tenfold increase or decrease in acidity or alkalinity. For example, soil or water with a pH of 5.0 is 10 times more acidic than soil or water with a pH of 6.0. Water with a pH of 5.0 is 100 times more acidic than water with a pH of 7.0. With a tenfold difference between each full point on the pH scale, accurate measurement and control are essential to ensure nutrient availability.<\/p>\n\n\n\n Cannabis grows best in soil with a pH from 6.5 to 7.0. Within this range cannabis can properly absorb and process all necessary available nutrients most efficiently. If the pH is too low (acidic), acid salts chemically bind nutrients (or, more correctly stated, the ion form changes in valence, or charge). The plant then only takes up a certain charged ion such as phosphate, the plant-available form (H2PO4 -) converts to the unavailable form HPO4 2- on pH rise and achieves equilibrium at pH 7.2, and the roots are unable to absorb the nutrients. An alkaline soil with a high pH causes nutrients to become unavailable. Excess unused nutrients in soil also cause toxic salt buildup that limits water intake by roots. It can also make some elements available at toxic levels when pH drops below 5.4!<\/p>\n\n\n\n The pH of soil mixes is very important because it dictates the ability of specific pH-sensitive bacteria. But I have experimented and irrigated well-managed organic soil with 8.0 pH water and higher. Once the rich organic soil absorbs the water, the soil life buffers the pH and it reverts back to 6.5 after a few minutes!<\/p>\n\n\n\n Hydroponic nutrient solutions perform best in a lower pH range than for soil. The ideal pH range for hydroponics is from 5.8 to 6.8. Some gardeners run the pH at lower levels and report no problems with nutrient uptake.<\/p>\n\n\n\n Measure pH with a litmus paper, a liquid pH reagent test kit, or electronic pH meter, all of which are available at most nurseries. When testing pH, take 2 or 3 samples and follow\u2014to the letter\u2014instructions supplied by the manufacturer. Soil test kits measure soil pH and primary nutrient content by mixing soil with a chemical reagent solution and comparing the color of the solution to a chart. Novice gardeners often have a difficult time achieving accurate measurements. Comparing the color of the soil\/chemical mix to the color of the chart is often confusing. If you use one of these kits, make sure to buy one with good, easy-to-understand instructions, and ask the sales clerk for exact recommendations on using it.<\/p>\n\n\n\n If using litmus paper, collect samples that demonstrate an average of the soil. Place the samples in clean jars, and then moisten the soil samples with distilled water that has a pH of 7.0. Place 2 pieces of the litmus paper in the muddy water. After 10 seconds, remove 1 strip of litmus paper. Wait a minute before removing the other one. Both pieces of litmus paper should register the same color. The litmus paper container should have a pH-color chart on the side. Match the color of the litmus paper with the colors on the chart to get a pH reading. Litmus paper will accurately measure the acidity of the substance to within a point or less. The pH readings will not be accurate if altered by water with a high or low pH, and the litmus paper could give a false reading if the fertilizer contains a color-tracing agent.<\/p>\n\n\n\n For an accurate pH test with an electronic pH meter:<\/p>\n\n\n\n Litmus paper is relatively expensive and is fairly accurate.<\/em><\/p>\n\n\n\n Mix water with a chemical in liquid pH reagent test kits.<\/em><\/p>\n\n\n\n This simple N-P-K and pH reagent soil test kit is inexpensive and easy to use.<\/em><\/p>\n\n\n\n Electronic pH meters are economical and convenient. Also, remember to check the pH of irrigation water. See chapter 15, Meters, for complete information on electronic pH meters.<\/em><\/p>\n\n\n\n Lime amendments will raise pH and lower acidity, but too much lime can burn roots and make nutrients unavailable. If you need more than 1 full point of pH adjustment, check with local farmers, nurseries, or agricultural agencies for recommendations on lime application.<\/p>\n\n\n\n Lime application differs based on soil type. Some guidelines are:<\/p>\n\n\n\n As a rule of thumb, add 1 to 2 pounds (0.5\u20130.9 kg) of dolomite lime to each cubic foot (0.03 cm\u00b3) of soil.<\/p>\n\n\n\n Lowering alkaline levels is somewhat easier than raising the acid level. If your soil is too alkaline, you can reduce soil pH by 1 point by applying:<\/p>\n\n\n\n 1.2 ounces (34 gm) of finely ground rock sulfur per square yard (90 cm\u00b2) for sandy soil.3.6 ounces (100gm) per square yard (90 cm\u00b2) for other types of soil.<\/p>\n\n\n\n *1 cubic yard is equivalent to 27 cubic feet (1 m\u00b3 is approximately equal to 106 cm\u00b3, and 1 cubic yard is approximately equal to 105 cm\u00b3).<\/p>\n\n\n\n Well-decomposed sawdust, composted leaves, and peat moss are effective amendments for acidifying soil and reducing pH levels.<\/p>\n\n\n\n When planting, add 1 cup of fine dolomite lime to each cubic foot (1 ounce per gallon [30 ml per 4 L]) of planting medium to stabilize the pH and provide calcium and magnesium.<\/em><\/p>\n\n\n\n Dolomite lime is an essential additive for most garden soils and soilless mixes.<\/em><\/p>\n\n\n\n Gypsum is rich in calcium and works wonders in cannabis gardens.<\/em><\/p>\n\n\n\n Agricultural lime<\/em><\/p>\n\n\n\n The most common way to raise pH both outdoors and indoors is to incorporate lime into the soil (see descriptions below of different kinds of lime). Other materials that raise soil pH include pulverized eggshells, clam and oyster shells, and wood ashes, all of which have a high pH. Both eggshells and oyster shells decompose extremely slowly and are not recommended. Wood ashes, with a pH of 9.0 to 11.0, are easy to overapply. They are also soluble and wash from soil quickly. Wood ashes from fireplaces are often adulterated with contaminants that are not plant-friendly.<\/p>\n\n\n\n Cannabis is a well-known accumulator plant that takes in heavy metals and sequesters toxins in vacuoles, which are impermeable. The heavy metals remain toxic. Cannabis was planted around Chernobyl, the toxic nuclear site in Russia, to absorb toxic radioactive heavy metals.<\/p>\n\n\n\n Agricultural Lime (aka Aglime, agricultural limestone, or garden lime) is made from pulverized limestone or chalk. Calcium carbonate is the active component, but it may also include calcium oxide, magnesium oxide, and magnesium carbonate. Aglime raises pH and ads calcium and possibly magnesium and trace nutrients. Aglime is usually available in larger particle sizes and takes much longer than finer grades to affect soil pH.<\/p>\n\n\n\n Calcitic lime<\/strong> is calcium, CaCO3. Lime is calcium, calcium carbonate. Calcitic lime is just calcium, CaCO3. Dolomite lime, on the other hand, is calcium and magnesium, CaMg(CO3)2. If soil needs magnesium, apply dolomite lime. But many soils contain an adequate level to an abundance of magnesium but insufficient calcium and therefore require calcitic lime. Granular and coarse lime reacts slowly in soil. Apply lime to soil in the fall so that it has time to react. If applied in the spring it will not change pH for several months.<\/p>\n\n\n\n Dolomite lime<\/strong> (calcium magnesium carbonate, CaMg(CO3)2) stabilizes pH and adds calcium and magnesium. As long as it is thoroughly mixed into the soil, it is difficult to overapply. Dolomite has a neutral pH around 7.0 and does not raise the pH beyond 7.4, the upper range for carbonates. It stabilizes the pH safely. Compensate for acidic soil by mixing dolomite with soil before planting. It will buffer the pH, keeping it stable when applying mild acidic fertilizers. Dolomite does not prevent toxic-salt accumulation caused by impure water and fertilizer buildup. A proper fertilizer regimen and regular leaching helps wash away toxic salts. When purchasing, look for dolomite flour (powder), the finest fast-acting dustlike grade available. Coarse dolomite could take a year or more before it affects soil pH. Mix dolomite flour thoroughly with the growing medium before planting. Improperly mixed, dolomite will stratify, forming a cake on the soil surface or a subterranean layer that burns roots and repels water. Lime is sold as a grade of fineness with a sieve size of 10 to 100. When using different grades, the amounts are also adjusted, since 3000 pounds of coarse lime may equal 1000 pounds of a fine grade.<\/p>\n\n\n\n Hydrated or slaked lime<\/strong> (calcium hydroxide, Ca(OH)2) contains mainly calcium and might contain magnesium. It is improperly referred to as hydrated lime and is actually hydroxide of lime. As the word hydrated implies, this lime is water-soluble. Hydrated lime is more caustic (quickly burns skin) than quicklime and is usually made by adding water to burnt lime, forming a hydrate. It absorbs water readily from the air, and as a result becomes increasingly difficult to handle. Fast-acting hydrated lime alters pH quickly, but the results last about 2 weeks and it is caustic enough to burn skin. If you decide to use it, be very careful. Mix it thoroughly with warm water, and for fast results apply small amounts with each watering. At most, use a mix of 0.25 cup (6 cl) hydrated lime and 0.75 cup (18 cl) dolomite lime. Any larger quantity will toxify soil and stunt or kill plants.<\/p>\n\n\n\n Hydrated lime is immediately available, whereas the slower acting dolomite buffers the pH over the long term. My favorite use of hydrated lime is for a garden room fungicide. Sprinkle it on the floor and around the room. It also is used as a fungistat, killing fungus on contact.<\/p>\n\n\n\n Quicklime<\/strong> (calcium oxide, CaO) is made by burning rock limestone in kilns. This highly caustic lime should never be used in the garden. Quick-lime reacts with water, yielding slaked (calcium hydroxide) lime. Organic certification agencies prohibit the use of quicklime. Although fast-acting, the effect is short lived and it does not have the buffering abilities of dolomite lime.<\/p>\n\n\n\n Gypsum<\/strong> (calcium sulfate, CaSO4\u00b72(H2O) is the \u201cmagic ingredient\u201d in many soil mixes. It is an amendment, conditioner, and fertilizer. Gypsum lowers the pH of sodium-rich soils and lowers the level of exchangeable sodium. It can also raise soil pH, albeit slowly. Here is a great link about gypsum: www.usagypsum.com\/agricultural<\/a> gypsum.aspx. See chapter 12, Outdoors, and chapter 13, Case Studies, for more information.<\/p>\n\n\n\n Do not mix fast-acting hydrated lime and fertilizer.<\/strong> At best, acidic fertilizers will cancel the effects of lime. For example, urine is slightly acidic. When it is dispersed into a toilet that was recently cleaned with bleach, which is very alkaline, it results in an unpleasant odor and neutralizing reaction. The same is true with fertilizers.<\/p>\n\n\n\n To raise pH 1 point, add 3 cups (65 cl) of fine dolomite or agricultural lime to 1 cubic foot (30 L) of soil. An alternate fast-acting mix would be to add 2.5 cups (590 cl) of dolomite and 0.5 cup (12 cl) of hydrated lime to one cubic foot (28.3 L) of soil.<\/p>\n\n\n\n Soils with a pH above 7.0 are generally considered alkaline and must be lowered to accommodate robust cannabis growth. Use sulfur in the form of iron sulfate or magnesium sulfate to lower pH. Sulfur is readily available at nurseries or garden centers in geographic areas with high-pH soil. Do not confuse \u201celemental sulfur\u201d (iron sulfate and magnesium sulfate) with sulfur used as a \u201cplant nutrient.\u201d Aluminum sulfate is often recommended because it lowers pH instantly as it dissolves in the soil. Cannabis can tolerate very little aluminum. Do not use aluminum sulfate. Other acids in liquid, crystal, and powder form can be used to lower pH, but they kill soil life in organic soil and are not advised. See chapter 23, Container Culture & Hydroponics, and chapter 20, Water, for more information.<\/p>\n\n\n\n
Dirt is found under your fingernails. Soil is mineral-based and best employed to grow cannabis in fields, planting beds, and very large containers. Soilless mixes are best for growing cannabis in small containers\u2014indoors, outdoors and in greenhouses. The dynamics of small containers are not the same as in large containers, planting beds, or Mother Earth.<\/p>\n\n\n\n
\n\n\n\nSoil Tests<\/h2>\n\n\n\n
\u2022 calcium
\u2022 magnesium
\u2022 potassium
\u2022 sodium
\u2022 phosphorus
\u2022 sulfur
\u2022 chlorine
\u2022 minor elements
\u2022 trace elements<\/p>\n\n\n\n
\u2022 pH
\u2022 ECe (dS\/m)
\u2022 NO3-N (ppm)
\u2022 NH4-N (ppm)
\u2022 PO4-P (ppm)
\u2022 potassium (ppm)
\u2022 magnesium (ppm)
\u2022 calcium (ppm)
\u2022 sodium (ppm)
\u2022 SO4-S (ppm)
\u2022 zinc (ppm)
\u2022 manganese (ppm)
\u2022 iron (ppm)
\u2022 copper (ppm)
\u2022 boron (ppm)<\/p>\n\n\n\nPlant Tissue Analysis<\/h2>\n\n\n\n
Soil gardeners are able to test soil, which gives them an idea of which nutrients may be lacking. They can use subsequent plant tissue analysis to concentrate on determining amounts of specific elements and how those elements are utilized by plants.<\/p>\n\n\n\nTexture and Types of Soil<\/h2>\n\n\n\n
SOIL<\/th> MIN.<\/th> MAX.<\/th><\/tr> <\/td> CEC<\/td> CEC<\/td><\/tr> sand<\/td> 1<\/td> 4<\/td><\/tr> sandy loam<\/td> 5<\/td> 8<\/td><\/tr> silt loam<\/td> 8<\/td> 20<\/td><\/tr> clay loam<\/td> 20<\/td> 40<\/td><\/tr> clay<\/td> 40<\/td> 80<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n CEC of popular growing mediums measured in mEq\/100 grams<\/h3>\n\n\n\n
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NAME OR TYPE OF SOIL<\/th> PARTICLE DIAMETER LIMITS<\/th><\/tr> <\/td> USDA Classifi cation<\/td><\/tr> clay<\/td> Less than 0.002 mm<\/td><\/tr> silt<\/td> 0.002\u20130.05 mm<\/td><\/tr> very fi ne sand<\/td> 0.05\u20130.1 mm<\/td><\/tr> fine sand<\/td> 0.1\u20130.25 mm<\/td><\/tr> medium sand<\/td> 0.25\u20130.5 mm<\/td><\/tr> coarse sand<\/td> 0.5\u20131 mm<\/td><\/tr> very coarse sand<\/td> 1\u20132 mm<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n Other Soils<\/h3>\n\n\n\n
Soil pH<\/h2>\n\n\n\n
Measuring Soil pH<\/h3>\n\n\n\n
Adjusting Soil pH<\/h3>\n\n\n\n
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Raising Soil pH<\/h3>\n\n\n\n
Guidelines to raise soil pH from 5.5 to 6.5 in different types of soil:<\/th><\/tr> Soil Type<\/td> kg\/m2<\/td> lb\/yd2<\/td><\/tr> clay<\/td> 0.9<\/td> 1.67<\/td><\/tr> sand<\/td> 0.7<\/td> 1.29<\/td><\/tr> silt<\/td> 0.8<\/td> 1.47<\/td><\/tr> organic<\/td> 1.1<\/td> 2.03<\/td><\/tr> peat<\/td> 1.7<\/td> 3.13<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n POUNDS OF ELEMENTAL SULFUR NEEDED TO LOWER THE PH OF A LOAM SOIL TO A DEPTH OF SIX INCHES<\/th><\/tr> Current pH<\/th> <\/td> Desired pH<\/th> <\/td> <\/td> <\/td> <\/td><\/tr> lb per 100 ft2<\/td> kg per 9.3 m2<\/td> 6.5<\/td> 6<\/td> 5.5<\/td> 5<\/td> 4.5<\/td><\/tr> 8<\/td> 3.62<\/td> 3<\/td> 4<\/td> 5.5<\/td> 7<\/td> 8<\/td><\/tr> 7.5<\/td> 3.4<\/td> 4<\/td> 3.5<\/td> 4.5<\/td> 6<\/td> 7<\/td><\/tr> 7<\/td> 3.17<\/td> 1<\/td> 2<\/td> 3.5<\/td> 5<\/td> 6<\/td><\/tr> 6.5<\/td> 2.94<\/td> <\/td> 1<\/td> 2.5<\/td> 4<\/td> 4.5<\/td><\/tr> 6<\/td> 2.72<\/td> <\/td> <\/td> 1<\/td> 2.5<\/td> 3.5<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n Lowering Soil pH<\/h3>\n\n\n\n