Search the Community
Showing results for tags 'npk'.
Found 3 results
Nitrogen Potassium Potassium in Plants and Soils. The Importance of Potassium CropNutrition - The Importance of Potassium Potassium (K) is an essential nutrient for plant growth and is classified as a macro-nutrient due to significant amounts of K being taken up by plants during their life cycle. This compilation is designed to instill the basic understanding of potassium (K) nutrition of plants, how it reacts in soils, and what it dows for the plants, and how it effects efficient crop production and quality. Not all plants uptake the same amount of potassium such as corn silage and alfalfa will uptake and remove from the soil far greater amounts of potassium than say grain crops. Understanding this aspect is vital as to better design a nutrient plan for crops but this is largely true of all macro-nutrients and crop types. Depending on the amount of available K and exchangeable K and your plants needs you may need to add K to your fertilizer nutrient plant. The total amount of K in soils often exceeds 20,000 ppm (parts per million). Almost all of this K is held in the structural components of soil minerals and is not available for plant uptake. Due to the differences in plant/crop type and the effect of weathering of these materials the amount of K supplied by soils varies. Therefore, the need and amounts for K in a fertilizer program varies. The Potassium Cycle Univ of Wisconsin Integrated Pest and Crop Management Soil Moisture factors on available K Dry soil or low soil moisture. Approximately 78% of the plants K needs are taken up by the roots. Higher soil K levels relieves some of the nutrient stress associated with drought. K alleviates the effects of both moisture deficit and excess on the crop and counteracts the yield reductions due to either. Low K in the soil can reduce plant uptake of potassium during dry/drought conditions. Soil moisture increased from 10% to 28% can increase potassium uptake by 175%. Too high soil moisture and cold soils will reduce oxygen availability and restrict the uptake of K. (wet roots) Too high soil moisture can also work to leach away available potassium to the plant. Irrigation can play a role in leaching K in sandy and mucky type of soils. Soil Temperature & PH for Potassium Optimum soil temperature for uptake is 60-80°F. Low temperature will restrict plant growth and the uptake rate of available K. Early planting can reduce the uptake of K. Increasing K may be a viable option. High available K levels will increase K plant uptake at low temperatures. Phosphorous and Potassium are typically high in rooting/starting fertilizers for this reason as together they greatly assist root growth. Low PH conditions and acidic soils Higher competition for CEC sites at a lower PH. Low ph can be a cause for potassium deficiency in crops while having sufficient K quantities of K in the soil. Correct PH conditions or limed soils. Enables more K to be held in CEC and also reduces leaching. Illustration of K in soil (organic particles are negatively charged.) https://extension.psu.edu/programs/nutrient-management/educational/soil-fertility/managing-potassium-for-crop-production Potassium is held in soils in 3 states; soil solution, exchangeable/fixed, and mineral. Soil solution - Usable to plants. Potassium (K) is taken up by plant roots only from the soil solution. K in solution is a small fraction of the total K in soil. The soil solution is replenished with K from other sources in the soil to be usable by plants. That replenishment comes primarily from readily available, “exchangeable” K. Exchangeable or Fixed K Exchangeable K, like other positive charged ions such as magnesium (Mg), calcium (Ca), and aluminum (Al), is loosely held in soil by an attraction to the negative charged surfaces of soil particles, this is similar to magnets on a refrigerator. This is not held strongly and can be leached. The amount of exchangeable K in the soil is dependent on the soil's cation exchange capacity or (CEC). When K is added to soil it occupies negative charged sites on soil particles by “kicking off,” or exchanging with, other positive charged ions. The creates a reserve of K in the soil waiting for a place in the soil solution to become available. As plant uptake occurs, K is released from these sites to the soil solution. The amount held in reserve and how much is released in soil solution is directly dependent the proportion of the CEC sites it occupies. The amount of exchangeable K is related to the amount of K available to the crop and the crops uptake. Clay type and Iron levels in the soil affects K availability. As Fe3+ is reduced K can be trapped between clay layers for smectite With illite K will be released. Soil testing for potassium. Soil test measures K in soil solution and exchangeable K. Take soil test at same time each year. Is very important to test annually and regularly for sandy and organic soils due to leaching. When dried the type of clay particles/minerals can affect the amount of K available. Soil heavy in micas release K during freeze and dry cycles at higher rates. Soils with low mica and high quantities of exchangeable K are less affected by freeze thaw. Time of soil sampling in regards to wet and dry cycles can affect the soil test. Spring, summer, fall and winter will show different levels. The factors of weathering, plant uptake and soil clay and mineral make up are all factors that can alter exchangeable K. It is not advised to input high K on sandy and mucky soils in the fall due to leaching aspects. By spring most will be leached away. Mineral - Not usable and very slowly released The majority of K in soil is held more tightly, trapped, or as part of the structure of soil minerals. approximately 90-98% of total soil K is found in this form. Feldspars and micas are minerals that contain most of the K and plants cannot use the K in this form. These forms, called nonexchangeable K, are generally either unavailable or only slowly available. Not viable to depend on this for plant use. Mineral K is not, typically measured as part of the soil test procedure. Decomposing organic matter in soil contributes little K. K is a soluble nutrient that leaches quickly from fresh crop residue, manure and sandy soils. However organic matter is important to K fertility because it provides many negative charged sites for holding exchangeable soil K. Finding this balance or fertilizing management with the your nutrient plan is vital for healthy plants. Union Break! Alex Clare - Alex Clare - Open My Eyes End of Union Break! Potassium in Plant Growth Potassium directly assist the plant to with stand stressful conditions and builds a stronger resistance to disease and plays a role in nearly every facet of crop production. Photosynthesis, control of plant N, formation of new proteins and tissues, and strength of cell walls and stalk tissues are all influenced directly by K nutrition. K is associated with movement of water, nutrients, and carbohydrates in plant tissue. K is involved with enzyme activation within the plant which affects protein, starch and adenosine triphosphate (ATP) production. The production of (ATP) regulates the rate of photosynthesis. The main value of K to crop plants is in times of stress. Full and balanced nutrition in all essential nutrients maintains a plant’s vigor and reduces its vulnerability to stress. Potassium, role in a plant’s defense, which is primarily preventative. Resistance of some varieties to stresses of disease, temperature, or moisture is related to a greater ability to take up soil K. Plant disease requires at least two conditions An infection point or entrance and a favorable environment for development. Resistance to both the incidence and the severity of disease is conferred by K through alleviating these two conditions. In some plant species, wounds, which are potential entrance sites for infection, heal more rapidly when the plant is supplied with adequate K. Even if higher numbers of disease organisms are present, plants nourished with sufficient K are less affected because of greater plant integrity. Even if disease is able to enter the plant the development of disease in a plant is affected by its K levels. When K is deficient, production of proteins and tissues stops and production materials accumulate, thus providing an ideal environment and food source within the plant for disease to develop. Potassium also helps to regulate the opening and closing of the stomata which regulates transpiration which is the exchange of water vapor, oxygen, and carbon dioxide. If K is deficient or not supplied in adequate amounts, growth is stunted and yield is reduced. For perennial crops such as alfalfa, potassium has been shown to play a role in stand persistence through the winter. Other roles of K include: Increased root growth and improves drought resistance Maintains turgor; reduces water loss and wilting Aids in photosynthesis and food formation Reduces respiration, preventing energy losses Enhances translocation of sugars and starch Produces grain rich in starch Increases protein content of plants Builds cellulose and reduces lodging Helps retard crop diseases Potassium Management In evaluating a fertility program analyzing the K soil test trend over time gives a perspective that is more important than the level at any one given time. Maintaining the level within the optimum range over time is the goal. The response to added K can also be predicted somewhat by anticipating stresses to the crop. If the crop is planted in a poorly drained field, or conversely, a drought field, moisture stress is likely, and so is a response to added K if soil levels are even borderline low. Managing K fertility for a corn grain/alfalfa hay rotation is a matter of extending your perspective from the K requirement of the present crop to the requirement of the next crop as well. A profitable response to added K is most likely when soil test levels of K are low. Within the optimum range, nutrient availability will not limit growth. Soil test levels are thus put into the context of the rotation. Potassium can be stockpiled during the corn years of a rotation in anticipation of the large requirement by alfalfa later in the rotation. Applying manure to supply nitrogen to corn will likely supply K in excess of what the corn crop generally removes. But because the concentration of K in the soil solution is low, and because it is held by the CEC, there is little potential for this nutrient to be lost through leaching, particularly in heavier soils of high CEC. The little leaching that does occur provides K for subsoil uptake by the deep-rooted alfalfa crop. In this case, soil test K levels may exceed the optimum during the corn years of the rotation, but for the rotation overall they should be around optimum on the average. Potassium soil test levels for corn-alfalfa rotation during which manure was applied in corn years to build up K for hay crop requirements. The need for increasing or reducing potassium in a fertilizer program can be determined by conducting and analyzing plant analysis data and soil testing. Soil testing is the most reliable predictor of this need. Calculations of K2O recommendations for a soil of CEC=10 at three initial soil potash levels and for three crops. Penn State Extension For most soils, this adequately predicts K availability however in some soils, the mineral K (which is not usually measured) supplies a significant amount of K to the crop, and thus the test based on the exchangeable and solution K does not fit the situation. This is most likely to occur with soils containing high amounts of the illite and vermiculite types of clays. The clue may be that there is little change in soil test K when K removal is expected to be large, or conversely (because the reaction is reversible), little change in soil test K level when K is added. Once this is a known factor this aspect can be accounted for in your nutrient management plans. This is not a common scenario. Reduced potassium in soils reasoning over time. Not sufficiently replacing potassium after crop harvest and rotations. Cost of potassium fertilizer. Minerals in soils. Soil minerals in K cannot replenish K to account for plant uptake. Is true for deep rooted plants to bring up K but the amount is not sufficient. Adjusting K in the soils Soil buffering capacity Less K is needed to adjust PPM levels. 6 to 7 pounds per acre will adjust 1 PPM. Less time is needed for a change to occur to raise or lower soil k levels. Crop removal of potassium Alfalfa by the ton K removal 180 lbs Corn silage by the ton K removal 160 lbs corn grain by the bushel K removal 46 soybean by the bushel K removal 63 wheat by the bushel K removal 23 Suggested management practices for K vary with each crop. Top dress applications are appropriate for perennial crops such as alfalfa and grasses. For soybeans, broadcast applications incorporated before planting are most effective. For corn and wheat either banded or broadcast applications can be used Broadcast rates can be reduced by one half if banded applications are used for these crops. This management practice does not reduce yields but results in a savings of fertilizer dollars. For crops (alfalfa and corn silage examples) that use lots of potassium and for soils with low potassium amounts. Soil test and monitor these soils often to ensure proper levels and availability. Top dress potassium. No till or reduced tillage crop systems - These crop systems can cause compaction and reduced soil temperature which leads to less K availability. Soil test and monitor these soils often to ensure proper levels and availability. Top dress potassium. Too high Potassium High potassium in forage crops can be problematic to farm animals. Dairy cows can get milk fever for example. Consider the potassium levels in the soils and how it relates to your plants and farm animal dietary needs. Decrease in uptake of other nutrients can result with too high K in the soils. Potential nutrient pollution of surface water through erosion of the nutrient-rich soil. Potassium is not a problem pollutant, but when soil K levels are built up by applying manure, soil phosphorous levels are also likely to be high. Reducing soil K in soils is to keep removing it, typically by utilizing crops with a high K requirement, without continued application. Can cause a depression of magnesium (Mg) uptake by cool season grasses. This can lead to grass tetany, a potentially fatal condition for ruminant animals. Its effects are related to nitrogen fertilization, low soil temperatures, and animal physiology. Grass, especially in fertilized pasture, accumulates K during the period of lush growth in May and early June, but Mg (magnesium) uptake is hindered by soil temperatures below 60 degrees F. Grazing cattle get a high K diet that increases their need for Mg, This results in a nutrient imbalance in the animals. Guarding against grass tetany involves pasture and animal feed management. The potential for this condition is greatest in pastures composed totally of cool season grasses. Legumes accumulate Mg, even at soil temperatures below 60 degrees F. High K forages can also result in increased incidence of milk fever if these forages are fed to dry cows. Union Break! Overheard - Flow End of Union Break! Potassium Deficiency LDSPrepper - POTASSIUM DEFICIENCY IN PLANTS: Symptoms & Treatment With a K deficiency the seasonal duration of leaf photosynthesis is shortened, transport of nutrients and sugars within the stem is hamstrung, plant integrity is compromised, starch formation is hindered, and use of nitrogen is limited. K is mobile and shows on older leaf growth. At the bottom leafs of the plant. The plant will take K from the lower leaves and transport them to the top leaf growth. Classic signs are a yellowing or chloro-sis from the leaf tip then around the leaf edges Can be spots to streaks of yellow or white depending on plant type. Research and understand the K deficiency for your crops and plants as various difference can be illustrated. Leaves already showing deficiency symptoms cannot be restored by adding K. Yield potential yield has already been reduced by the time the deficiency symptoms appear, and the plant has become more susceptible to the effects of other stresses. Yield and quality of the crop is directly affected. If insufficient K is available, characteristic symptoms of deficiency are likely to be evident during rapid crop growth. Photo Examples Romaine Lettuce Lettuce Rice Corn on the Cob Corn Leaf Potassium Application Gary Pilarchik (The Rusted Garden) - Understanding Garden Potassium: What it Does, Greensand, Banana Peels & Other Forms Organic options for Potassium Compost - Especially with adding banana peels. Usable to the plant immediately. Easily leached. Wood Ash - Hard wood ash 5 gallon bucket will treat about 1000 square feet. Can be added to compost to boost potassium levels of the compost. Caution - will raise PH levels. Kelp Meal and seaweed - Dry or Liquid form Easily available to the plants. Greensand - Mined from ancient sea beds. Can be used as a fertilizer or used in compost. Muriate of Potash (potassium chloride) Contains chlorine which is harmful to soil microbes. Sulfate of Potash Similar to muriate of potash but generally more expensive Does not contain chlorine and is safe to soil microbes. Not all sources of sulfate of potash is truly organic. Sul-Po-Mag - A variation of potash, sulfate of potash-magnesia A natural version is langbeinite Is water soluble and immediately available to the plant Can leach Generally is not used unless you need sulfur and magnesium. Granite Dust Is very slow potassium and tract mineral release. Not a sufficient source of potassium on its own. Can be added to compost piles. Manure Potassium Manure is a K resource present on most farms. However, K concentration varies by water and bedding content. Manure nutrient analysis is the only sure way to manage amounts of applied manure nutrients. Potassium in animal manure is almost totally dissolved in the liquid fraction, so it is important to conserve this portion of the manure. As long as liquid is not lost, handling and surface or incorporated application do not affect K content or availability. If a soil sample is taken after manure application, then the available manure K will be reflected in the soil test level and recommendations. If, however, manure is applied after soil sampling, then manure K should be subtracted from the recommendations on the soil test report. Manure K is immediately available and may be considered a 1:1 substitute for K fertilizer. Manure Moisture (%) K2O (lbs/ton) Variation (%) Cattle 85 10 36 Pigs 91 11 53 Poultry 30 30 39 The average K content of various animal manures. Fertilizer Potassium Potassium chloride (KCl), called muriate of potash is the most common fertilizer form. It is a highly water soluble salt with a K2O analysis of 60 to 62 percent. Processing differences result in two common chemical qualities, identifiable as red and white muriate of potash. Because the difference is of no consequence to the plant, deciding which to use should depend on the basis of cost per unit of K. The K analysis of a fertilizer material is given as the percentage of K2O (potash) for the material. There is no actual K2O in fertilizer, but this is the accepted and legal reporting form. Potassium recommendations are reported as lbs of K2O per acre on a soil test report. The units of potash (K2O) can be converted to potassium (K) by multiplying lbs of K2O by 0.83. For the opposite conversion, multiply lbs of K by 1.2 to get lbs of K2O. Is incompatible with tobacco. Potassium sulfate, with a K2O analysis of 50 percent, also supplies sulfur, but this is generally inconsequential since sulfur is rarely limiting for agronomic crops. Solution fertilizers may use KOH as the K source. KOH has a high K2O analysis, 70 percent, the K is no more available to the crop than if KCl were applied. Fertilizer solutions made with KCl may not be clear, but that is not a disadvantage from the plant’s perspective. As a salt, K has the potential to injure plant roots. Whether this becomes a problem depends on the rate of fertilizer or manure, especially poultry manure applied and its placement relative to plant roots. Rainfall dilutes and leaches the salts in soil, reducing the risk of injury. Because starter fertilizer is placed, by design, near seedling roots, this practice has the greatest potential for root injury. You can avoid injury by reducing the rate or by placing the fertilizer farther from the seed. Recommendation by Penn State is that total nitrogen plus K2O should not exceed 70 lbs per acre when the fertilizer is placed 2 inches over and 2 inches down from the seed row, and less if placed closer. Except in low K soils, there has been little consistent benefit from banding K as a part of the starter application and, therefore, it may be best not to include K in starter fertilizer. Summary In soil fertility we are concerned with crop response. We want to apply nutrients, K in this case, where we are most likely to get a profitable return. We have seen that crop response to K may be more indirect than direct. Effects will be an increased response to nitrogen and improved resistance to disease, drought, and cold temperatures, and may, therefore, depend on growing season conditions. In soil testing, we have a good, though not perfect, indicator of probable response to K. Soil testing partnered by good crop records enables management to make it effective. Then, by knowing the yield per field, growing conditions, problems, soil K level, and other factors, you can make decisions, based on realistic information for your crops and fields that will project into the coming years. This is important when you rotate crops in a field, especially when those crops, like corn and alfalfa, have very different K requirements. Managing nutrients makes better use of limited finances. Manure needs to become a primary concern in nutrient management, because it is a readily available nutrient carrier on most farms. Potassium needs to be used wisely to ensure an adequate supply for your crops, but not oversupplied in “insurance applications.” Recommendations: Test soil regularly, at least every three years or when changing crop. The soil test reports the amount of available K and the K2O required, if any, to bring soil level up to optimum and offset crop K removal. Evaluate the fertility program for each field by looking at the trend, over time, of the soil test levels in relation to the optimum range. Plan ahead within a rotation to supply K for the crop with the larger requirement. Reduce soil erosion with soil and water conservation practices, Do not stockpile nutrients in fields prone to erosion. Conserve the liquid portion of the manure with bedding or leak proof storage to conserve the manure K. Have farm manure analyzed for its nutrient content. Apply manure uniformly and at a known rate as part of a planned nutrient management program. Remember, quality in gets quality out. Evaluate the need for K in a starter fertilizer relative to soil test levels. At optimum or higher K levels, a response to starter K is unlikely. Keep rate of K used in starter low, or keep K away from the seed to avoid salt injury to seedlings. Keep good crop records and include input amounts, measured yields, and production costs. Managing Potassium for Crop Production (PDF) - Penn State Extension Credits: CropNutrition http://www.extension.umn.edu/agriculture/nutrient-management/potassium/potassium-for-crop-production/ https://extension.psu.edu/programs/nutrient-management/educational/soil-fertility/managing-potassium-for-crop-production Univ of Wisconsin Integrated Pest and Crop Management Alex Clare Gary Pilarchik (The Rusted Garden) Overheard LDSPrepper https://www.todayshomeowner.com/organic-sources-of-potassium-for-your-lawn-or-garden/ NRateliffVEVO School of Life congratulations for learning about Potassium in soils and plants Links Nitrogen Potassium A proud cultural healing and life compilation.
Nitrogen Potassium Plant Nutrition Nitrogen Nitrogen, a basic and standard plant food. However the idea of a "food" can be problematic for some gardeners when it comes to managing as we humanize the subject of supplying the plants with nutrition. I will discuss plant nutrition more like building materials for a construction job. As a gardener it is your job to supply the materials as needed. If you send to much or to less it causes problems from uptake to use to storage. If you care what you will get from your garden. Be competent, diligent and not impulsive. Carbon and Nitrogen Carbon is obtained by plants mostly by C02 and thus is how in part plants can grow hydroponically and in soils of various stages. Nitrogen type, growth speed vs transpiration rates will effect the internal carbon of the plant. A balance of nitrogen to internal carbon with yield is the ideal goal. In plants this carbon is often stored in the pith sections. As a plant develops it uses and stores more nitrogen during the vegetative period and will relocate nitrogen from lower leaves later in bloom when needed. Increasing nitrogen in bloom to account for nitrogen deficiency can extend the bloom to harvest period and offer a sub par harvest. Early Growth Considerations Before we begin to consider applying fertilizers we need to consider a few things but essentially we want to consider plant transpiration and nitrogen volatization and mineralization in the soil and media. Environment with considerations to Temperature & humidity in terms of vapor pressure density for your crop area. Dry and Wet conditions. Root structure of plants Feeding plants that have proper roots will ensure the plants can store enough nitrogen for the blooming stages. Most of the nitrogen for the plants needs will be taken up and stored in the roots in the vegetative stage and reaching correct to optimum levels is important of yield goals. The plants will make many chemical reactions and create many substances that all pretty much have other important uses in the plant. Having early deficiencies with nitrogen can cause problems later in the grow on a variety of fronts. Root structure and metabolism can lead to differential accumulation of nitrogen. This happens when environmental or other reasons growth is slowed due to transpiration and assimilation issues. Also can occur from uneven watering of the soil media. This is a negative as it concentrates nitrogen in areas you do not want it and can extend a harvest. Input of nitrogen in bloom stage can create new growth if concentrations are too high. Generally keep Phosphorous and nitrogen in the correct ratio for the applicable plant stage. Types of Nitrogen Nitrate Nitrogen Must be converted prior to use internally in the plant. Nitrogen can be leached easily from soils and medias. More humid climates tend to have poorer nitrogen soils due to leaching. + charge (type of nitrate can fluctuate in + value) This can effect PH of the media. The plant will release a - ion for a + Ion. This build up in the media can alter the PH of the media depending on a variety of factors. Molybdenum is needed to convert nitrate to ammonia to be use in the plant. Nitrogen metabolism takes place in roots and the leafs (shoots). Respiration and transpiration rates affect the plants ability . Environment, EC, plant stage and media conditions are all factors. The assimilation of nitrate is an energy-consuming process, using the equivalent of 15 mol of adenosine triphosphate (ATP - is energy from photosynthesis) for each mole of nitrate reduced (16). Storing nitrate is not toxic. Nitrate can be made mobile. Ammonia Nitrogen Ammonia nitrogen can be used by the plant immediately when foliar fed. Ammonia nitrogen can be assimilated twice as fast as nitrate. Ammonia is broken within 3 days to a few weeks depending on temperature and PH of media by biolife and turned into nitrite. Ammonia in high concentration can stop the nitrogen cycle. Nitrogen cycle Water logged media can remove the soil bacteria and ammonium increases becomes toxic to your plant. Ammonia has a negative - charge. This can effect PH of the media. The plant will release a - ion for a + Ion. This build up in the media can alter the PH of the media depending on a variety of factors. Ammonia nitrogen has a high energy requirement. The assimilation of ammonia requires an additional five ATP per mole. In roots, as much as 23% of the respiratory energy may be used in nitrate assimilation compared with 14% for ammonium assimilation (17). Ammonium is toxic at even low concentrations and must be metabolized into organic combination. Consequently, ammonium metabolism for detoxification may deplete carbon reserves of plants much more than nitrate accumulation. Glutamine synthetase an enzyme created via several processes nitrate reduction but is necessary for ammonia absorption. Part of domino effect of problems if deficiencies shut down. An in part reason why a nutrient is typically made up of a nitrate and ammonia %. The plant will go into phytotoxic conditions if Glutamine Synthetase is reduced or prevented. Their are several parts of ammonia with in the plant assimulation process but each process makes an enzyme or amino acid that is used in another process. Nitrogen Aspects Their are many enzymes, amino acids, and other types of chemicals made during the internal processing of the different states of internal nitrogen use. Some of these products and/or their % may indicate stress factors or assist in other functions of the internal plant processes in terms of making the process function in some detoxification way. Detecting these signals can assist in future planning. It is important to understand that concept as I will tie that in later in advanced growing writing when talk about making changes via stress by altering hormone and auxin levels. This is important in Plant Tissue Testing. (Not THC or CBD but for analysis of growth and deficiency) Nitrogen and other NPK % can affect internal plant signals and alter its growth condition based on those signals. Higher Phosphorous than nitrogen signals flowering aspects in some plants. Longer flowering tropical plants will use nitrogen over a longer period of time but you generally fertilize similar for each period of growth. Generally only the length of the development periods is different. Ammonia and Nitrate nitrogen % of a recipe can be used to help regulate PH in regards to some medias. Optimal Nitrogen Use When we think of optimal we think we can open up a book or jump on the device known as the internet and find our answer. Their is no true answer that you seek like that. You can find ranges but the answer you seek is unique and complicated to be that simple. Optimal comes from environment, overall nutrition, plant management, competence and diligence. Nitrogen is very difficult to determine for yield as the plants are not visibly showing when they are at their "sufficiency" or optimum for yield and is known as critical concentration. Continued use of nitrogen will accumulate to toxicity. The gap from sufficiency to toxicity can vary from large to small. With a nutrient supply in which all elements except nitrogen are held at a constant high level, The concentration of nitrogen within the plant should increase with growth and yields, with increases in nitrogen supply. Nitrogen concentrations in leaves are often not correlated with increased growth and yields. Green color of leaves does not indicate optimum or even wholly problematic levels. Changes and timing of nitrogen levels can affect harvest time periods. Nitrogen concentrations will diminish in leaves, stems, and roots as the plants mature but added nitrogen will go to the plant tissues and become concentrated. Levels vary by the time of day in regards to the daily life function of the plant. In morning or when light starts about 2 hours after. Testing The only way to truly determine absolute nitrogen optimum for your plants is via plant tissue testing. For small farms this may not be large factor but for medium and large farm operations this difference can be a noticeable saving when adjusted for yield and cost efficiency. With this information precise nutritional formulas can be developed for specific locations with respects to its specific environment and plants. Tested plant material should be collected at same light conditions and time of day and location of plants. leaf from same exact location on several plants per section for example. The use of information on internal concentrations of nitrogen in plants should not be directed toward forecasting of yields as much as it should be used in assessing how yields can be improved by fertilization in reference to other nutritional issues. In part this is due to still many factors to come with the growing period that can affect. Field yields rarely give book yields until a farmer is experienced and competent. Generically you want to reduce nitrogen as the plant wants to start to add weight to fruit or when flower truly bloom and no longer make buds but concentrate on the flowers. If nitrogen uptake and assimilation is deficient during its stages of early development it will be problematic. It is common for people to over nitrogen accumulate toxic levels which can be more problematic than under feeding. Testing is only valid for the location and time period of each specific garden or farm. Environmental, overall nutrition, management system, water frequency and type of nitrogen form makes your test unique to you. Same crop, same size, same fertilizer but different location will equal different tests. Their is no golden number from a book, what you search for is the capability of "your" environment, plant, nutrition and you! Deficiencies I have not seen better than the site grow weed easy illustrate and explain deficiencies so I wont try. Deficiency: http://www.growweedeasy.com/nitrogen-deficiency-cannabis Toxicity: http://www.growweedeasy.com/nitrogen-toxicity-cannabis The identification of a problem is the easy part, addressing is easy enough but understanding the reason for the deficiency is important to ensure the issue is not repeated. Generically speaking, nitrogen deficiency (not toxicity) often will not overly affect yield when only occurring in bloom but is illustrative of potential problems in transport (environmental stress? if current but often is result of earlier deficiency). In terms of yellow plants ensure optimal P and enhance the limited photosynthesis you can to keep transport energy levels up more so than healthy plant. Yellowing of leaves is not always caused by nitrogen deficiency but often is a common affect. The reasons for a nitrogen problem is not always easy to pinpoint. The following should lead you to the cause but understand deficiency and other problems are often in a domino effect. Ensure to thoroughly understand the cause and how to prevent again. If only fix the visible issue you potentially will see issues again. Be diligent with this. Check environment records, Temperature (highs and lows and at period of growth) Humidity Light distance Clean Air C02? OZ near plants? Check nutritional records, Check amounts and frequency of feeding Check timing issue after a particular feed? If soil based. Review recipe and ensure the % of nitrogen cycle breakdown is correct and all accounted for. Annotate when you notice the issue and try to determine its starting period of time. Next grow with similar soil make up either add fertilizers at that point next grow or Adjust soil recipe increasing or decreasing the % and types of nitrogen as applicable. Check growth period and ensure the nutritional recipe was correct. Sometimes after an incorrect and/or too strong garden is given. Make sure you identified the correct period of plant development. This can happen during vacations or periods when focus is not on the garden. Check % of nitrate and ammonia. In hydro a reservoir fix is typically enough. In soil a flush to doing re-pot may be necessary if the soil has become acidic (not meaning PH) Check Media conditions, wet, good or dry? pest? compact/loose media? root bound? Check Stress factors Management factors Top? Tie down? Accident? Media humidity unstable? Pest Fungus/disease Root damage pesticide/fungicide? The sum total of that information should enable you to adjust your nitrogen use from general to optimal ranges. Nitrogen & Pollution Nitrogen is a necessary ingredient but is also a very polluting one due to its mobile nature. Small growers tend to not think of these aspects and thus the small farmers do play a large part in nitrogen run off issues which is currently being seen in urban settings. In the future I can see the working on regulations that will financially impact this industry and will be with merited reasons but if farmers do not incorporate correct nutritional rates the farmer actually plays a role in the altering of waters due to increase nitrogen which tends to boost algae and other unfavorable unbalanced biological growth in our environment areas. Often this is effect is unseen and largely under appreciated. Growing our own foods is like a super power in terms of survival of a species. Few creatures pull this off and with this altering comes a responsibility that humanity has not effectively embraced and thus we cause nature to suffer and only take noticed when forced via pollution effects of magnitude and/or regulatory controls which often have political slants that confuse the reduce the effectiveness of the issue. Nitrogen pollution from farming of all sizes should be taken seriously as it is a big factor largely ignored because of special interest, politics and costs. Their are and will be more emotional views of merit regarding this subject as time progresses and the issues becomes more necessary to address. I suggest looking at all views and determining best from that as facts can become blurry as politics and political operatives do their work. Some issues for farmers. Often from a financial stand point chemical nitrogen fertilizers are more cost efficient due chemical made nitrogen having a higher % and reduced cost in volume in shipping and field distribution. Generically written. Due to this view, it should be understood that a farmer may have to embrace chemical fertilizers to remain financially viable in comparison to organic fertilizers but this is only one aspect of that overall consideration but is stated to give this perspective of organic and chemical nitrogen's use in farming. Sometimes people can question a farmer fertilizer choice not realizing if they did not they would potentially put at risk the farms profit or even lose money. Union Break Mandatory Union Break! and what you do on it is your business! Nitrogen Properties and Fertilizer Use Nitrogen cycle must be understood, video describes this cycle earlier in compilation Ammonia volatilization is needed to be understood. (the changing of ammonia to nitrite and then to nitrate.) Anhydrous Ammonia (82% N) In agriculture, anhydrous gaseous ammonia is compressed into a liquid and is applied under high pressure with a special implement by injection at least 15cm deep into a moist soil. The ammonia gas reacts with water to form ammonium ions, which can be held to clay or organic matter. If the ammonia is not injected deeply enough or soil is too wet or dry, ammonia can be lost by volatilization. Anhydrous ammonia is usually the cheapest source of nitrogen, Equipment and power requirements of the methods of application are specific and high. Aqua Ammonia (21% N) Aqua ammonia is ammonia dissolved in water under low pressure. Aqua ammonia must be incorporated into land to avoid losses of nitrogen by ammonia volatilization; Is not needed to be incorporated as deeply as anhydrous ammonia. Urea (46% N) Urea is the most widely used dry nitrogen fertilizer. After application to soils, urea is converted into ammonia, which can be held in the soil or converted into nitrate. Ammonia volatilization following fertilization with urea can be substantial, and if urea is applied to the surface of the land, considerable loss of nitrogen can occur. With surface-applied urea, alkalinity of pH 9 or higher can develop under the urea granule or pellet, and ammonia will volatilize into the air. Volatilization occurs on bare ground, on debris, or on plant leaves. Urea is readily soluble in water, and rainfall or irrigation after its application move it into the soil and lessens volatilization losses. Use of urease inhibitors has been suggested to lessen the volatilization losses of ammonia from surface-applied urea. Manufactured urea is identical to urea in animal urine. Calcium nitrate urea (calurea, 34% N, 10% Ca) is a double-compound fertilizer of calcium Nitrate and urea to supply calcium and nitrogen Several derivatives of urea are marketed as slow-release fertilizers. Urea formaldehyde (ureaform, 38% N) is a slow-release fertilizer manufactured from urea and formaldehyde and is used for fertilization of lawns, turf, container-grown plants, and field crops. Urea formaldehyde is also a glue and is used for the manufacture of plywood and particle board. Dicyandiamide (cyanoguanidine) (66% N) is a nitrogen fertilizer but is used most commonly as an additive (2% of the total N fertilizer) as a nitrification inhibitor with urea. Sulfur-coated urea is a slow-release formulation (30–40% N) used as a fertilizer for field crops, orchards, and turfgrass Isobutylidene diurea (IBDU) is similar to urea formaldehyde, but contains 32% nitrogen. However, utilization of IBDU is less dependent on microbial activity than urea formaldehyde, as hydrolysis proceeds rapidly following dissolution of IBDU in water. Nitrogen is released when soil moisture is adequate. IBDU is used most widely as a lawn fertilizer. Its field use is to restrict leaching of nitrogen Methylene ureas are a class of sparingly soluble products, which were developed during the 1960s and 1970s. These products contain predominantly intermediate chain-length polymers. The total nitrogen content of these polymers is 39 to 40%, with between 25 and 60% of the nitrogen present as cold-water-insoluble nitrogen. This fertilizer is used primarily in fertilization of turfgrass, It has been used with other crops on sandy soils or where leaching of nitrate is an environmental concern. Ammonium Nitrate (34% N) Ammonium nitrate is a dry material sold in granular or prilled form. It can be broadcasted or side dressed to crops and can be left on the surface or incorporated. It does not give an alkaline reaction with soils; hence, it does not volatilize readily. However, incorporation is recommended with calcareous (high calcium soils) soils. Ammonium nitrate is decreasing in popularity because of storage problems, e.g., with fire and explosion. Calcium ammonium nitrate (ammonium nitrate limestone, about 20% N and 6% Ca) is a mixture of ammonium nitrate and limestone. This fertilizer is not acid-forming and is used to supply nitrogen and calcium to crops. Ammonium Sulfate (21% N) Ammonium sulfate is marketed as a dry crystalline material. It is recommended for use on alkaline soils where it may be desirable to lower soil pH. Nitrification of ammonium is an acidifying process. Ammonium sulfate can be broadcasted or side dressed. It can left on surfaces or incorporated, On calcareous (high calcium) soils watering in or incorporating is recommended to avoid ammonia volatilization Nitrogen Solutions (28–32% N) These fertilizers are mixtures of ammonium nitrate and urea dissolved in water. In the solutions, half of the nitrogen is supplied as urea, and half is supplied as ammonium nitrate. Because of the difficulties in handling, urea and ammonium nitrate should not be mixed together in dry form. The solution acts once the dry materials are applied to the soil. Ammonia volatilization may be substantial during warm weather, especially with surface application. The solutions should be watered into the soil and should not be applied to foliage. Ammonium Phosphates (10–21% N) Ammonium phosphates are important phosphorus-containing fertilizers because of their high concentrations of phosphorus and water solubility. Ammonium phosphates are made by reaction of ammonia with orthophosphoric acid (mono- and diammonium salts) or with superphosphoric (pyrophosphoric) acid Diammonium phosphate (commonly 18% N, 46% P2O5) is a dry granular or crystalline material. It is a soil-acidifying fertilizer and is useful on calcareous soils. It should be incorporated into the soil. It is a common starter fertilizer and is a common component of greenhouse and household fertilizers. Monoammonium phosphate (commonly 11% N, 48% P2O5) has uses similar to those of diammonium phosphate. Ammonium polyphosphate (10% N, 34% P2O5) is marketed as a solution. Its use is similar to that of monoammonium phosphate and diammonium phosphate. Double-salt mixtures such as ammonium nitrate sulfate (30% N), ammonium phosphate nitrate (25% N), urea ammonium phosphate (25–34% N), nitric phosphate, and ammoniated superphosphate (8% N) (152). These materials are used in the manufacture of mixed N-P-K fertilizers or for special needs in soil fertility. Organic Nitrogen Fertilizers (0.2–15% N) Most commercial varieties of organic nitrogen comes from other industry with waste plant and animal sources and are proteinaceous. Organic nitrogen is typically more costly in terms of shipping and distribution in the field. Organic materials range from less than 1 to about 15% N compared with the chemical sources. Difficult for analysis. Commercially organic fertilizers decline in usage with time. Additionally the proteinaceous by-products of food processing have higher value as feeds for poultry and livestock than as fertilizers. Demand for organic fertilizers remains, as organic farmers require these products in the maintenance of soil fertility on their cropland The value of organic nitrogen fertilizers depends on their rate of mineralization, which is closely related to their nitrogen concentration). Generally, the more nitrogen in the fertilizer, the faster the rate of mineralization. In bio farming methods such as natural farming/Korean farming microbes and fungus assist with this aspect more and that is a key ingredient to success to maintain mineralization at acceptable levels. Recap Video Summary Understanding nitrogen correctly will enable you to manage your crops successfully. By proper analysis it is possible to find your optimum nitrogen range for your unique location, plant and conditions. When volumes of fertilizer are being used this can be a good cost effective means as the luxury level plants can hold without benefit to yield or quality is a wast of resources. By understanding how to minimize leaching of nitrogen we also become better stewards of the land we have taken for our needs. Credits & Respects too Handbook of Plant Nutrition 1st edition - http://hortsci.ashspublications.org/content/42/2/422.3.full I recently learned of 2nd edition and when I have time will get and review to update as applicable in time. Handbook of Plant and Crop Stress - https://www.crcpress.com/Handbook-of-Plant-and-Crop-Stress-Third-Edition/Pessarakli/p/book/9781439813966 I recently learned of 3rd edition and when I have time will get and review to update as applicable in time. GrowWeedEasy - Website for specific negative plant states. Cornell University - BIOPL3420 - Plant Physiology - Thomas Owens xkellzzz GrowGreenerGuru grimpadre Yara International Univ of Wisconsin Integrated Pest and Crop Manageme Weed Schooling Steven Myers The Strumbellas Science with Hazel Links Nitrogen Potassium ~Hempyfan