Garden Safe Rooting Hormone (93194), Case Pack of 1

 Garden Safe Rooting Hormone (93194), Case Pack of 1

• PROMOTES ROOTING: Rooting hormone grows new plants from cuttings.
• GROW CUTTINGS: Works with most popular home, garden and greenhouse varieties.
• ROOT NEW FAVORITE PLANTS: Helps African violets, roses, poinsettias, philodendrons, geraniums, coleus, woody ornamentals and more grow from cuttings.
• APPLY TO CUT ENDS: Moisten the plant cutting, stir the cut end in powder, remove excess rooting hormone and plant.
• ACTIVE INGREDIENT: Indole-3-butyric acid, similar to the root hormone that naturally occurs in plants.

Soil improvement

Farmers know that healthy soil is necessary to achieve a good harvest. Many farmers enrich the land with natural fertilizers such as manure (from animals), green manure (from plants), and compost. Natural fertilizers are healthier for soil, plants, water, air, and people than chemical fertilizers, and they produce all the nutrients plants need for free or at a very low cost.

To know the grounds

Soil is a mix of sand, sediment, clay, and organic matter (for example, insects, bacteria, green leaves, decaying plants, and compost). The ratio of each component and the farming methods you apply will affect the soil's texture (coarse or fine), its fertility (how rich it is to grow), and its structure (how the soil sticks together). A soil with good texture and fertility gives air, water, nutrients and roots room to move freely. This improves the land's ability to support crops and resist erosion.

Furthermore, soils can be alkaline (also called "basic" or "sweet") or acid (also called "sour"). The "pH" of the soil (whether it is sweet or sour) can be determined by testing or simply testing whether the taste is sweet or sour. Most plants grow best in soils that are neither too sweet nor too sour. Specific nutrients are added to further sweeten or sour the soil. Adding organic matter tends to improve all soils.

Using heavy equipment to plow, remove, or dig, the soil can be compacted (pressed to the point that there is no space or air left). It is difficult for water or plant roots to enter compacted soil. It is also difficult for plants to get the nutrients they need if the soil is compacted.

To prevent the soil from compacting, remove the foreign matter and stir the soil when it is not too wet or too dry, but wet as when squeezing a cloth. Many farmers stir the soil as little as possible, add manure and crop debris, and use methods such as planting holes or green manure to loosen the soil for planting.

Chemical fertilizers may be helpful now, but hurt later

Chemical fertilizers are costly for both the farmer and the land because they damage the land, pollute the water and create the need to buy more chemicals. The letters NPK usually appear on the fertilizer bag, which represents the main nutrients that plants need (N is Nitrogen, P is Phosphorus and K is Potassium or Potash). Chemical fertilizers have concentrated (very strong) amounts of these chemicals. If these concentrated nutrients run off from the grounds into groundwater and rivers and aqueducts, the water
becomes dangerous to drink, wash and bathe.

The biggest problem for developing crops with chemical fertilizers is that farmers who use them frequently stop adding organic matter such as manure to the soil, and as a consequence the soil quickly loses its nutrients and becomes compact, which results in to pest problems, poor harvests, loss of water, and increased dependence on chemical fertilizers. If you use chemical fertilizers, it is important to also add natural fertilizers.

Learning about soils

Purpose: This activity serves to show how different agricultural practices affect the land.

Duration: 3 hours.

Materials: Scraping tools, 3 boards or cardboard, water, paper and pencil or marker.

Choose 3 parcels of agricultural land that have been used for different uses. For example, choose a cornfield or dry rice field, a kitchen garden or home garden, and a lot that has been used as pasture for many years. The lots should be within walking distance of each other to be able to walk from one to the other.

• With a group of farmers, go to each of the locations. Cross from top to bottom, observing all the factors that could affect the terrain. What indications allow us to determine the use that has been given to the land? Are there signs of erosion? (for example, are there ravines, rocky or bare places, richer soil at the foot of the hill than at the top?) Do the plants look healthy?
• Talk to the farmers of each of the fields to find out what practices they have applied during the last 5 to 10 years. Do the group's observations match what you learned from the farmers?
• Dig a small hole 50 cm deep in each plot. Cut one of the walls of the hole vertically and evenly. With a flat shovel or a long machete cut a 3 cm wide slice of this wall and place it carefully on a board or flat surface. Label the sample to identify where it came from.
• When you have taken the soil samples from the 3 locations, take them to the meeting place where the group can examine them. What are the differences between the different samples? Look carefully for differences in color, texture, structure, odor, and the presence or absence of worms and insects. You may be able to taste a little of each soil to compare the pH. Is it sweet or sour? Have each person pick up some soil from the different samples. Put some water on each sample and see if it is sticky, rough, smooth, or cracks.
• Discuss which differences may have been caused naturally by wind and weather, and which by land use.

Taking into account the knowledge of the people, the directions in this book, and information from other sources, discuss possible measures to protect or improve the land where you want to farm. These measures may include the use of natural fertilizers , protecting the land against erosion , applying sustainable grazing practices and other agricultural practices.

Green manure (from plants) and cover crops

For the green manure those plants are used that serve to fertilize the earth. These same plants are used to protect crops and smother herbs. Many plants serve both tasks and are therefore known by both names, "green manures" and "cover crops."

Many of the green manures are from the legume family (plants with seeds in pods, for example peas, beans and tamarind trees). Legume plants add nitrogen to the soil. If you start a bean plant, or look at the root of a tree, you will see small balls that form at the roots. These little balls retain nitrogen from the air and put it in the soil to make it more fertile.




Green manures offer many advantages:

• They cover the land, protecting it from erosion and helping to retain water.
• They add organic matter to the soil, making it more fertile.
• After using green manure for many years, it is easier to work the soil.
• There are no labor or transport costs because green manures grow right in the field where they will be used.
• When grown with other crops, they control weeds and insect pests.

Green manures have other uses besides improving the land. Some produce food, for example oats, amaranth, rye, and beans. Others produce fodder for animals, for example alfalfa and clover. Plants like Sudan grass and others in the mustard family ward off crop diseases. Trees used as green manure can be used for firewood.


Three common uses of green manure

• Grow it alongside major crops such as corn, millet, and cassava (manioc).
• Sow the green manure plants when the soil is to rest (fallow); one year of fallow with green manure improves the soil and removes weeds just like a five year fallow without green manure.
• Grow it during the dry season, after harvesting the main crop.

The best cover crop is a mix of plants. A grain that grows quickly into a tall plant could add organic matter to the soil, while a bean crop will add nitrogen and cover the soil at the same time. Talk to other farmers in the region to find out what's best for their land.

Dead cover (mulch)

It is best to keep the land covered, even during the growing season. Dead cover is understood to be any element that is used to cover farmland. Dead mulch, or mulch, helps retain water, controls weeds, and prevents erosion. Plant debris, such as corn stalks, bean stalks, or grasses, are best suited to produce dead mulch since they can simply be left to rot in place and thus add organic matter to the soil. Herbs can be used in the same way, but must be cut before they produce seeds, to prevent regrowth.

The dead cover should not be more than 10 cm thick. Too thick mulch can hold in too much moisture and cause plant disease.

Manure

Manure gives the plants all the necessary nutrients, and over time improves the texture, structure and fertility of the soil. Chemical fertilizers, on the other hand, give crops only 2 or 3 nutrients and do not improve the soil.

Care must be taken when composting manure. If used too much, too many nutrients could accumulate in the soil and water sources could also be contaminated. Fresh manure also contains germs that can cause disease. Don't put fresh manure near drainage ditches, rivers, streams, or aqueducts. Always wash your hands and wash your clothes thoroughly after handling manure.

Fertilization with human waste

Human urine can become fertilizer and feces, after proper treatment, can add organic matter to the soil. However, human waste contains dangerous microbes and can cause disease if not managed properly ( Chapter 7 explains how to safely use human waste to improve crop yields).

Compost (organic compost)

Compost, or compost, is a natural fertilizer made from food waste, crop residues, herbs, and manure. By adding it to the soil, its nutrients can be returned to it. However, since it would be very difficult to produce enough compost for an entire plot, compost is generally applied in small plots.



Compost can be applied in different ways:

• Put a shovel full of compost in the bottom of the hole before planting a fruit tree.
• Mix a handful of compost with the soil from the hole when sowing the seeds.
• Spread a layer of compost on top of the soil before turning.
• When the plants are growing, put a circle of compost around their stem. If it is a tree, the diameter of the circle should be approximately equal to the edge of the tree's shadow at noon. Cover it with a little soil. The plant will feed slowly, as the water carries the nutrients to the roots.

Compost tea (liquid organic compost)

Compost can be used to make a liquid compost for plants to help control pests. Wrap some compost in a piece of cloth and tie it together creating a beanbag. Put it in a bucket of water for 7 to 14 days. When the water turns brown, remove the sachet and spread the remains of the compost on the grounds. Sprinkle or water the water ("compost tea") on the leaves of the plants. Be sure to wash your hands after handling this water.

Other methods of adding nutrients to the soil

Other materials can be added to change the pH and add nutrients to the soil. Limestone, wood ash, and ground bones and shells lower the acidity of the soil, while dry leaves and pine needles raise it. Sugarcane that has been left to rot for at least a year and dried, ground coffee pulp add nutrients. In this way crop residues can be used as fertilizers.

Land improvement helps control weeds

All organic soil improvement methods such as green manure, compost, and cover crops also serve to control weeds. When the soil is healthy, herbs in small amounts do not affect crop yields.


Herbs can also be controlled if the plants are planted closely together so that there is no room for the weed, and if the animals are allowed to eat the weed. Crops native to the area tend to resist damage from local grasses better. After many years, locally developed crops adapt to the climate, herbs and pests, and survive better than other crops or other varieties of the same crop.

Miracle-Gro 3002510 Shake 'N Feed Tomato, Fruits and Vegetables Continuous Release Plant Food Plus Calcium

 Miracle-Gro 3002510 Shake 'N Feed Tomato, Fruits and Vegetables Continuous Release Plant Food Plus Calcium

• Contains natural ingredients to feed microbes in the soil
• Specially formulated with micronutrients to help plants grow strong and produce more fruits and vegetables versus unfed plants
• Feeds up to 3 months
• Calcium helps form stronger cell walls, producing better quality and longer-lasting fruits and vegetables. Plus, it helps prevent disorders in edible crops commonly associated with calcium deficiency.
• For use in ground and in containers
• Now contains natural ingredients that helps feed and nourish above and below soil, for even better quality and longer lasting fruits and vegetables versus unfed plants

SOIL ELEMENTS ESSENTIAL FOR PLANTS

Summary.

• 1. Criteria of essentiality.
• 2. Absorption of nutritive elements by plants.
• 3. Classification of nutritional elements.
• 4. Conclusions.

SUMMARY

Current knowledge about plant organisms makes it possible to ensure that almost all of them are composed of only three fundamental elements, which are C, H and O. Plants obtain both carbon and oxygen directly from the air by photosynthesis, while the Hydrogen comes directly or indirectly from soil water. Plants, however, are incapable of living solely on air and water, requiring chemical elements that, generally, are provided at the expense of mineral substances in the soil. It is interesting to note that these elements, which plants obtain from the soil, are the ones that commonly limit the development of crops. Plant growth, except for exceptional circumstances, such as drought, low temperatures, abnormal soils or diseases,

1. ESSENTIAL CRITERIA

These essential criteria were established by Arnon and Stout in 1939 and are listed below:

• 1. An element cannot be considered essential unless its absence makes it impossible to complete the vegetative or reproductive stages of its life cycle.
• 2. The deficiency must be specific to the item in question, and can only be avoided or corrected by providing it.
• 3. The element must be directly involved in the nutrition of the plant, regardless of its possible effects on the correction of unfavorable chemical or microbiological conditions of the external environment.

Although these criteria have been accepted as valid and fully applied to all living things, some researchers consider that the second criterion is not totally correct. For example, molybdenum is required for N fixation by bacteria of the genus Azotobacter sp . However, in some species of this genus molybdenum can be substituted for vanadium. Another example is sodium, which is not considered essential for all plants, but its presence has been shown in practice to increase yield in many crops. Therefore, from an economic point of view, sodium should be considered an essential element.

2. ABSORPTION OF NUTRITIVE ELEMENTS BY PLANTS

Only a small part of each nutrient present in the soil is available to plants (2%). The rest (98%) appears in forms not assimilated by plants, that is, it is firmly linked to the mineral fraction and organic matter, being inaccessible as long as it is not affected by the decomposition processes. These occur slowly, over long periods, and the nutrients are released gradually.



Plants absorb the nutrients contained in the air and in the soil through the leaves and roots. CO 2 , a source of carbon and oxygen, is absorbed through the stomata of the leaves, while the other nutrients are generally absorbed from the dissolution of the soil through the roots .

Plants absorb nutrients through the numerous root hairs that young roots have, which are continually renewed, since they have a life of a few days. These root hairs secrete acidic substances that help to solubilize difficultly soluble compounds, such as phosphates and carbonates. In this solubilization action the CO 2 produced by the respiration of the roots also intervenes .

The nutritive elements that plants absorb from the soil come from rocks (except in the case of N, which comes from the air), which slowly degrades into soluble compounds. These compounds dissociate in soil water into positive ions (cations) and negative ions (anions), and in these forms they are assimilated by plants (photo 1). The ions can be free in the soil solution or can be adsorbed by the colloidal particles of the same. The anions and a small part of the cations are contained in the soil solution, while most of the cations are adsorbed on the colloidal complex. The ions adsorbed by the colloidal particles can be absorbed directly by the roots or, more frequently, pass first into the soil solution, from where they are absorbed by the roots. When an ion passes from solution to the plant, another ion passes from the complex to solution, in order to maintain a proper ion concentration.

In general, the amount of macronutrients that plants need to absorb in order to develop their life cycle is significantly higher than that of micronutrients. In this way, it is explained the fact that the absorption of macroelements by crops can represent a significant amount compared to the reserves of said elements contained in the soil. This shows the need to add manures and fertilizers to most agricultural soils (photo 2).


The proportion of macronutrients extracted by the harvests can represent practically all of the stocks in the soil, while in the extraction of micronutrients from the soil, these quantities never represent such a high proportion of the total but, in general, only represent a small percentage of the total amount existing in a soil. This means that, with few exceptions, deficiencies should not appear in terms of crop nutrition, and yet this is not the case. It must be taken into account that, due to their characteristics, microelements generally have low mobility derived from conditioning factors, which is why they are not easily assimilated by plants. This, together with the influence of cultivation techniques and the characteristics of the cultivated species,



There are numerous factors inherent to the environment (soil and climate) that influence the greater or lesser degree of absorption of nutrients. These factors include the following:

1. Soil texture.

Soils with fine textures have a greater external surface, so the agents that alter their structure have a greater possibility of action: 1g of colloidal clay presents an external surface 1,000 times greater than that presented by the same amount of coarse sand.

2. Soil pH .

For certain pH values, some assimilable elements are transformed into their non-assimilable forms, due to the fact that they become part of the insoluble compounds. For example, iron in a basic medium results in an insoluble hydroxide. On other occasions volatile compounds are produced, which are lost as they escape into the atmosphere; such is the case of ammonium fertilizers, which in basic soils produce ammonia, part of which is lost to the atmosphere when the fertilizer is added to the soil surface.

3. Interactions between ions.

On some occasions there are interactions between two ions, which make it difficult or easier to absorb one of them. Antagonism occurs when one of the ions tends to inhibit the absorption of the other, especially when the concentration of one of them increases. This is the case, for example, of potassium-magnesium antagonism, where the higher concentration of potassium causes a deficient assimilation of magnesium. Synergism occurs when one of the ions favors the absorption of the other, as occurs, for example, with nitrogen and potassium.

4. Climate.

The factors that most influence absorption are temperature and humidity. As the temperature increases, the absorption increases, due to a greater biochemical activity, until it reaches an optimum level, above which it progressively decreases until it stops. At low temperatures, the opposite occurs since biochemical activity is hampered and solubility in the soil decreases. Similarly, it happens that as humidity increases there is an increase in the absorption of nutrients.

3. CLASSIFICATION OF NUTRITIVE ELEMENTS

Currently it is admitted that higher plants can contain up to 60 elements, of which 16 of them (C, H, O, N, P, K, Ca, Mg, S, Fe, Mn, B, Mo, Cu, Zn and Cl) are considered essential for their normal development while another 4 (Na, Si, Co and V) are considered only essential for some of them (figure 1). All these elements perform very important functions in plants, and when they are present in insufficient quantities, serious alterations can occur and their growth can be significantly reduced.

Of the 16 essential elements, the first 3 are supplied mainly by air and water, while the remaining 13 are supplied by the soil. These nutritive elements supplied by the soil can be classified into macro- and microelements, depending on whether the plants need to absorb relatively large or small amounts of them. As macroelements, N, P, K, Ca, Mg and S should be highlighted and as microelements, trace elements or trace elements essential for plants are Fe, Mn, B, Mo, Cu, Zn, and Cl.



MACRONUTRIENTS: Primary elements (N, P and K) and secondary (Ca, Mg and S).

Macronutrients are the necessary elements in relatively abundant quantities to ensure the growth and survival of plants. The presence of a sufficient quantity of nutritive elements in the soil does not by itself guarantee the correct nutrition of the plants, since these elements must be found in molecular forms that allow their assimilation by the vegetation. In short, it can be said that a sufficient quantity and adequate availability are essential for the correct development of the vegetation.

Within these, it is possible to distinguish between primary elements (N, P and K) and secondary elements (Ca, Mg and S).

1. Primary elements.

In most crops, the needs of the plants are higher than the existing reserves in assimilable form of the elements in the soil, so it is necessary to make contributions through the use of compost and fertilizing substances. The primary elements are considered to be N, P, and K.

- Nitrogen (N) .

The processes of combining N with another element are called nitrogen fixation and are carried out, in nature, thanks to the action of certain microorganisms and the electrical discharges that take place in the atmosphere. However, the amount of fixed N is usually small compared to what plants could use. About 99% of the combined N in the soil is contained in organic matter. Organic N, included in large and complex molecules, would be inaccessible to higher plants if it were not previously released by microorganisms. Microbial activity gradually breaks down complex organic materials into simple inorganic ions, which can be used by plants. How quickly crops would potentially be able to use N, it usually exceeds the speed with which it is released. Consequently, the amount of N available in the soil is usually relatively very small.

- Phosphorus (P) .

Unlike N, which can be incorporated into soils through biochemical fixation by microorganisms, P does not have such microbial support since it comes only from the decomposition of the bedrock that takes place during the weathering process. The amount of total P in the soil, expressed as P 2 O 5 , rarely exceeds 0.50% and can be classified as inorganic and organic. Inorganic P is supplied by the weathering of minerals such as apatite Ca 5 (PO 4 ) 3F and to a lesser extent it can be part of the silicate chain where it replaces silicon, or found in newly formed minerals. Organic P is of great importance for soil fertility because certain organic compounds are an indirect source of soluble forms. Humus and other types of non-humid organic matter are the main source of organic P in the soil.

- Potassium (K).

K is, perhaps, the mineral element that is found in the highest proportion in plants and is relatively frequent in rocks. Regardless of the K that is added as a component of various fertilizers, the K present in soils comes from the disintegration and decomposition of rocks that contain potassium minerals. Along with this mineral K should be included that from the decomposition of plant and animal remains. Unlike P, K is found in relatively large amounts in most soils. In general, its content as K 2Or it ranges from 0.20-3.30% and depends on the texture. In sodium soils, it varies between 2.50-6.70%. The clayey fraction is the one with the highest K content, so clay and silty-clayey soils are richer than silty-sandy and sandy soils, also taking into account that the variation in K content is influenced by the intensity of losses due to crop extraction, leaching and erosion.

2. Secondary elements.

The amounts of these elements present in the soil usually cover the needs of the crops, so, in general, it is not necessary to make contributions of any kind to the soil. This group of elements includes Ca, Mg and S.

- Calcium (Ca).

The Ca present in the soil, apart from being added as fertilizer or amendment, comes from rocks and minerals in the soil, and its total content can vary widely. In soils considered non-limestone it ranges between 0.10 and 0.20%, while in limestone it can reach up to 25%. In general, it can be said that Ca comes from the weathering of minerals. These materials are so common that most soils contain enough Ca to cover much of the plant's needs.

- Magnesium (Mg).

Mg is a chemically very active element, but it does not appear by itself as a free element in nature, but is distributed in mineral form. According to various estimates, its average content in the earth's crust can be around 2.30% while in the ground it is close to 0.50%.



MICRONUTRIENTS

They are called micronutrients, those essential elements for plants to complete their life cycle, even if the necessary amounts of them are very small. The total content of micronutrients in the soil is a function of the starting material and the edaphological processes. Those elements whose total concentration in the soil is normally less than 1000 mg / kg are called trace elements. Within this group we can include micronutrients (Cu, Mn and Zn), essential for plants and animals in low concentration, but which can become toxic when reaching certain levels. The exception among them is in Fe, which is a micronutrient but not strictly a trace element.

- Iron (Fe).

Despite its abundance in soils and rocks, it is one of the most deficient micronutrients. Fe is the fourth most abundant element in the continental crust after O, Si and Al, constituting around 15% by weight of the earth's crust. It is, by far, the most abundant microelement in soils, either as a mineral constituent or in the form of oxides and hydroxides. However, in soils with horizons enriched in organic matter, Fe appears mainly in the form of chelates. Its content in temperate soils usually varies between 1 and 5%. In isolated cases, values ​​close to 10% can be found. In the soil, the Fe content fluctuates in the range of 0.20 to 5%, in an order of magnitude similar to that of the underlying rock.

- Copper (Cu).

Cu is one of the most important essential elements for both plants and animals; however, excessive amounts of it can produce toxic effects. Among the different types of igneous rocks, Cu prevails in the basalts. In sedimentary rocks it is more abundant in shales. In general, its abundance in basaltic rocks is higher than in granitic ones, and very low in carbonate rocks.

-Manganese (Mn) .

The Mn present in soils is mainly caused by the decomposition of ferromagnesic rocks. It is a microelement similar to Fe, both in its chemistry and in its geology and very abundant in the lithosphere. In rocks, the Mn content varies between 350 and 2000 mg / kg. The content in the soil shows considerable variations, but normally fluctuates between 20 and 800 mg / kg. However, and as in the case of Fe, these total contents cannot be considered as an indication of its availability to plants since there are many factors that affect its absorption.

- Zinc (Zn).

Zn is a widely distributed element that is found in small but sufficient amounts in most soils and plants. The amount of Zn that can be found in a soil depends directly on the nature of the bedrock. There is, however, an important aspect that needs to be highlighted in relation to the useful Zn in soils and that is that the superficial part of many of them, which corresponds to the upper horizons, always contains more Zn than the lower horizons. It is believed that this fact is due, on the one hand, to the fact that plant residues, upon being deposited on the surface of the soil, provide after their decomposition, a certain amount of the element; on the other hand, Zn does not present a downward migration in the profile, as occurs with other elements,

4. CONCLUSIONS

Water and dissolved nutrients, which are normally absorbed by the roots, can also be absorbed by the leaves. Foliar applications are effective especially when the plant needs some nutrients immediately, such as: Fe, Zn, Mn, Cu and Mo. When the soil contains an excessive amount of essential elements in a form assimilable by plants, normal development of these can be seriously affected. In general, there are usually no problems in this regard with macroelements, but there may be problems with some microelements, where there is a narrow margin between optimal and toxic levels.

Miracle-Gro Indoor Plant Food Spikes, Includes 24 Spikes - Continuous Feeding for all Flowering and Foliage Houseplants - NPK 6-12-6

Miracle-Gro Indoor Plant Food Spikes, Includes 24 Spikes - Continuous Feeding for all Flowering and Foliage Houseplants - NPK 6-12-6

• Easy-to-use fertilizer for all indoor plants including ferns, spider plants, pothos, and croton
• Houseplant fertilizer spikes feed continuously for up to 2 months
• When used as directed, plant food spikes are safe to use on all indoor, potted plants
• Plant food spikes are filled with the micronutrients that indoor plants need
• Indoor plant care made simple; enjoy vibrant potted plants in your home, office or business

Nutrients present in the soil

Although twenty chemical elements have been identified in most plants, it has been found that only sixteen are actually necessary for proper growth and complete maturation of plants. These 16 elements are considered essential nutrients. Carbon, oxygen and hydrogen, make up most of the dry weight of plants, these elements come from atmospheric CO2 and water. Next in quantitative importance are nitrogen, potassium, calcium, magnesium, phosphorus and sulfur that are absorbed from the soil.

The most important elements for plant growth are macronutrients (nitrogen, phosphorus and potassium) and they should be supplied to plants through fertilizers, mesonutrients (calcium, magnesium and sulfur) and micronutrients or trace elements (iron, manganese, boron , zinc, copper and molybdenum) which are generally present in the soil in sufficient quantities and are needed by plants in lower doses.


The following table shows the functions of these elements in plants and their deficiency symptoms:

• Nitrogen (N)    Stimulates rapid growth; favors the synthesis of chlorophyll, amino acids and proteins.    Stunted growth; yellow color on the lower leaves; weak trunk; light green color.
• Phosphorus (P)    Stimulates root growth; favors the formation of the seed; participates in photosynthesis and respiration.    Purple color on lower leaves and stems, dead spots on leaves and fruits.
• Potassium (K)    Accentuates vigor; provides resistance to diseases, strength to the stem and quality to the seed.    Darkening of the margin of the edges of the lower leaves; weak stems.
• Calcium (Ca)    Constituent of cell walls; collaborates in cell division.    Deformed or dead terminal leaves; light green color.
• Magnesium (Mg)    Component of chlorophyll, enzymes and vitamins; collaborates in the incorporation of nutrients.    Yellowing between the nerves of the lower leaves (chlorosis).
• Sulfur (S)    Essential for the formation of amino acids and vitamins; gives the green color to the leaves.    Upper leaves yellow, growth stunted.
• Boron (B)    Important in flowering, fruit formation and cell division.    Dead terminal buds; Top leaves brittle with folding.
• Copper (cu)    Component of enzymes; collaborates in the synthesis of chlorophyll and in respiration.    Terminal buds and dead leaves; teal color.
• Chlorine (Cl)    It is not well defined; collaborates with the growth of roots and shoots.    Wilting; chlorotic leaves.
• Iron (Fe)    Catalyst in the formation of chlorophyll; component of enzymes.    Chlorosis between the veins of the upper leaves.
• Manganese (Mn)    Participates in the synthesis of chlorophyll.    Dark green on the veins of the leaves; chlorosis between the nerves.
• Molybdenum (Mo)    It helps with nitrogen fixation and protein synthesis.    Similar to nitrogen.
• Zinc (Zn)    Essential for the formation of auxin and starch.    Chlorosis between the veins of the upper leaves.

Therefore, the correct development of a crop will depend on the nutritional content of the soil on which it grows. But the amount of nutrients to add to the soil does not depend only on the chemical state of the soil but also on factors such as the local climate, physical structure, the existence of previous and present crops, microbiological activity, etc. Therefore, only after a technical and economic evaluation, it is possible to choose the appropriate amount of fertilizer to add. The steps to follow to get a rational subscriber are the following:

1. Make an analysis of the soil to know the richness in fertilizing elements and to be able to adopt the most convenient subscriber formula.
2. Choose the appropriate fertilizer, using the one that has a balance similar to the needs of the soil expressed in the analysis.
3. Apply, according to the needs of the crop and the level of nutrients, the quantities necessary to obtain an optimal production.

Nitrogen in the soil.

Nitrogen is a fundamental element in plant matter, since it is a basic constituent of proteins, nucleic acids, chlorophylls, etc. Plants absorb it mainly by roots in the form of NH4 + and NO3-. Nitrogen allows the development of the vegetative activity of the plant, causing the elongation of trunks and shoots and increases the production of foliage and fruits. However, an excess of nitrogen weakens the structure of the plant creating an imbalance between the green parts and the woody parts, being the plant more sensitive to attack by pests and diseases.

More than 95% of the nitrogen in the soil is in the form of organic matter, the fraction of which is less susceptible to rapid decomposition is humus. Inorganic nitrogen is fundamentally as NH4 +, of which only a small part is in the soil solution and in the exchange sites, since it nitrifies quickly, the rest is in a difficult-to-change form forming part of the silicates.

The amount of nitrogen available to plants depends on the balance between mineralization (conversion of organic nitrogen into mineral nitrogen, either by aminization, ammonification or nitrification) and immobilization (opposite process). This mineralization depends, among other factors, on the temperature of the soil, being very active at high temperatures.

Phosphorus in the soil.

Phosphorus is part of the nucleic acid composition, as well as reserve substances in seeds and bulbs. It contributes to the formation of buds, roots and flowering as well as lignification. A lack of phosphorus causes a stifling of the plant, slow growth, a reduction in production, smaller fruits and less expansion of the roots. Most of the phosphorus present in the soil is not available to plants and its emission in the soil solution is very slow.

Potassium in the soil.

It is always in inorganic form, and partly in reversible equilibrium between the solution phase and the easily changeable phase, depending on the temperature.

Plants differ in their ability to utilize the various forms of potassium, depending on the cation exchange capacity of the root. Legume plants have twice the exchange capacity of grasses.

Potassium acts as a cofactor in enzymatic reactions, starch metabolism and translocation, absorption of the NO3- ion, opening of stomata and protein synthesis. Potassium deficiencies can be corrected by providing organic matter (compost), mineral salts rich in potassium, etc.

SOIL ANALYSIS.

To detect possible nutritional deficiencies in a crop, three methods of analysis can be used:

• · Visual inspection of the crop to locate signs of deficiencies.  This method only identifies critical deficiencies once the damage has occurred and sometimes the observed symptoms can be unreliable. Chlorosis, for example, can be the result of a low amount of nitrogen, a feeding of a nematode, a saline or dry soil, some disease (virus) or other problems not related to the levels of nutrition of the soil .
• · Soil analysis.  They measure the nutrient levels of the soil as well as other characteristics of the same. Farmers depend on these analyzes to determine the lime and fertilizer needs of their crops.
• · Analysis of plant tissue. They measure nutrient levels only in plant tissues. This type of analysis allows detecting possible deficiencies not found in the soil analyzes.

Of the three methods described, soil analysis is the most important for most crops, especially annuals. A soil test can be done at the beginning of the season to allow the farmer to supply the necessary nutrient prior to sowing or planting. It is important to perform soil tests to determine the amount of each nutrient that is available for plant growth. From the results of these soil tests, the farmer can decide how much fertilizer should be applied to reach a sufficient level.

There are three stages to conducting a soil analysis:

• · Soil sampling. The farmer removes samples from the soil and sends them to an analysis center.
• · Soil analysis. The soil laboratory tests the sample and concludes with a recommendation to the farmer.
• · Preparation of a fertilization plan. The farmer acts according to the recommendation given by the analysis center.

Soil sampling .

The results of the analysis of a soil depend on the quality of the sample collected by the farmer at the analysis center. For this reason, the following are the recommendations to follow when taking soil samples for physical-chemical analysis:

Frequency of analysis .
The frequency of soil testing depends on the harvest and how it was grown. For most crops, collecting samples every two to three years should be sufficient. Intensive crops such as fruits or vegetables need annual sampling, and greenhouse crops perform their analyzes more often. The analysis must be carried out before sowing or planting.

Any change in harvesting practices should be preceded by a soil check analysis. For example, if a farmer intends to switch from normal to conservation tillage, a soil test should be done before the first year. A farmer who changes crops should also conduct a soil test before the new crop.

Sampling areas and number of subsamples.

The farm must be divided into homogeneous sampling plots in terms of color, texture, treatments and crops. The number of samples depends on the variability or heterogeneity of the plot. The estimate will be the more accurate the larger the number of subsamples. As a guide, it is considered appropriate to take 15 to 40 samples in each plot, doing it in a zig-zag fashion and putting all the samples in a common bag. No sample should be taken that represents an area greater than 4 hectares. It is advisable to take 10 to 20 subsamples for plots between 5,000 and 10,000 m2.

Sampling depth.
It depends on the type of crop, but in general it is always recommended to discard the first 5 cm of top soil. For most crops it is sufficient to take samples from the first 20-40 cm of the soil. In the case of grass and meadow crops the recommended sampling depth is 5 to 10 cm. On the other hand, in those crops with deep roots and fruit trees it is recommended to carry out sampling at a depth of 30 to 60 cm.

Sampling procedure.
Soil sampling tubes or augers will be used for sampling. You can also use a shovel. To do this, a V-shaped hole has to be made, cut a 1.5 cm portion of the hole wall and remove most of the sample with the blade. Each soil sample must include soil from the entire sampling depth.

Once the sampling is finished, it is recommended to mix all the samples together to obtain a homogeneous soil mix. Take approximately 1 kg of this mixture, let it dry in the air and send it to the analysis laboratory, specifying as much as possible all the data of the plot.

Sampling in greenhouses.
The fertilization program for greenhouse crops is very different from that used for extensive crops. Generally, extensive farmers rely primarily on soil nutrient reserves, such as organic nitrogen or exchangeable potassium. However, in intensive greenhouse crops, substrates are usually used to which nutrients are supplied through complex fertilization plans, in this way there is total control over the nutritional status of the plant.

To carry out samplings in these crops, the methodology used in sand vegetable crops and drip irrigation will be taken as an example. For this, a point is chosen 10-15 cm from the trunk of the plant and in the direction of the drip line. The layer of sand and manure is separated and we puncture until we reach the average depth of the roots (10 cm). To do this, a cane takes samples of half a cane or a small hoe will be used. The important thing is that the soil is extracted throughout the entire drilling and in equal amounts. The amount of soil extracted (150-200 gr) must be similar in all the sampling points (subsamples). Avoid taking samples in the bands and corridors as well as in the 4-5 meters near them.

 

Soil analysis .

 

There are two methodologies to carry out an analysis of the collected soil samples. The older method uses chemical reactions that produce color changes. The exact color depends on the amount of minerals available in the soil. In the case of pH analysis, the color depends on the pH of the soil.

These simple chemical tests are very easy to perform but are unreliable. For this reason these tests based on color comparison have been replaced in laboratories by tests using modern devices such as the pH meter and the spectrophotometer. These devices quickly and accurately measure mineral amounts in soil samples.

However, laboratory results are only reliable if they have been validated on similar soils as sampled. That is, the tests should be based on studies carried out on fertilization and nutrient levels in soils similar to those of the sample soil.

Generally in the analysis of a soil the following tests are carried out:

• · Determination of the texture by means of mechanical analysis of sieving of the sample.
• · Measurement of soil organic matter.
• · Determination of pH levels by using pH meters.
• · Measurement of soluble or available phosphorus (amount of free phosphorous for plant growth) by washing the sample with an acid solution and its subsequent analysis in a spectrophotometer.
• · Measurement of exchangeable potassium.

At present, there are numerous relatively cheap electronic devices (digital pocket pH meters, conductivity and nutrient meters, etc.) that allow rapid and timely tests to be carried out on the farm in crops that require constant monitoring of the nutritional state of the soil (horticultural crops , nurseries, etc.).

ANALYSIS OF VEGETABLE TISSUES.

Plant tissue tests in combination with soil tests give a more complete view of the plant's nutritional status. In tissue analysis, analyzes are performed only on plant nutrients, rather than on soil nutrients. These analyzes are useful to determine possible nutritional problems related to micronutrient deficiencies, which are more difficult to determine in the soil.
With the analysis of plant tissues, physiopathies caused by nutritional deficiencies can be differentiated from other diseases caused by fungi, bacteria or viruses. In addition, these analyzes allow to know the competition phenomena between the different elements, which prevent the absorption of nutrients.

Nutrient levels vary considerably in different plant tissues or at different ages. For this reason, before carrying out an analysis it is important to determine the part of the plant used and the required growth stage.
Taking samples of plant material for analysis is an operation that is related to the purpose of the analysis, and is always subordinate to the judgment and good sense of the operator. However, the plant material to be analyzed must always be representative, so that it is statistically significant.

With this input approach, two sampling options can be distinguished:

• 1) Sampling of parts or whole plant.
• 2) Sampling of leaves for foliar analysis.

In both cases, the plot should be divided into sampling units. In this case, the sampling unit will be a set of plants that are visually similar, have the same vigor, the same development, are in the same type of soil, and which are practiced the same cultural techniques. The sampled plants have to be representative of the sampling unit.

When the terrain looks the same, the sampling unit should not represent more than:

• Greenhouses: 3000 m2.
• Irrigation: 10,000 m2.
• Extensive: 25000 m2.

If there is any area clearly different from the rest of the crop but very small, it is advisable not to take samples from it. In any case, the sample must be accompanied by the corresponding report prepared according to the criteria of the receiving laboratory.

Below are established a series of general rules in the collection and transport of plant tissues for analysis, although the modes of action will depend on the type of culture:

• · Use bags or other paper containers (avoid plastic).
• · If parts or a whole plant are sampled, it will be necessary to take 20 or 30 plants, paying attention that they are in the same stage of development and that they present the same morphological characteristics.
• · When sampling leaves for foliar analysis, always take the leaves at the junction with the stem, so that the laboratory receives the leaf with its entire petiole. The leaf to be sampled will be the first fully developed, with a limb and petiole (it will be the 4th, 5th or 6th starting from the apex).
• · The best time for leaf sampling is early in the morning.
• · The number of sheets to be taken must be more closely related to the representativeness of the sampling than to the amount of material needed for the analysis, since the latter is very small. Due to this, the same criterion as for soil sampling is considered valid, that is, from 10 to 20 leaves, taking more leaves the smaller they are and vice versa.
• · Do not delay delivery to the laboratory more than is strictly necessary, avoiding direct sunlight. In case of late shipment, it is advisable to put the samples in a refrigerator to slow down their metabolic activity.
• · If you have to wait a few days before sending the samples to the laboratory, it is advisable to wash them with a non-ionic detergent, such as citric acid, to avoid the influence of possible contamination on the results of the analysis. After washing, they are rinsed with distilled water and dried in the sun.
• · Do not forget the correct labeling of the samples to avoid confusion.