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Tips for Your Indoor Plants During the Winter
Something that should be clear to us is that the winter season is rarely ideal for growing plants outdoors. Of course, unless you live in a warm and tropical area where the climate is fairly stable and the sun is hot practically all year round.
Luckily there are plants that can live and even thrive indoors. As long as we know how to protect them from the cold and give them the proper care, they will stay beautiful until the weather warms up again and we can return them to the balcony or terrace. Here are some useful tips.
Where to put them in winter
Whether they are plants that live inside your house all year round, or that you have brought them indoors to protect them from the winter cold, where you place them is of the utmost importance. Since you must not only protect them from inclement weather, but also choose a place where they can thrive for several months.
Find them a place away from the heating, since these devices tend to overheat the environment and reduce the little humidity that exists in the air in the interior spaces. Most ornamental plants are tropical species, so they prefer places with certain levels of humidity such as the kitchen or bathroom.
Also be sure to place them away from open doors or windows, where very cold breezes are constantly blowing in. Ideally, keep them at a fairly constant temperature.
What kind of light do they need?
The ideal place to place them should have good light above all. Ideally, it should be filtered natural light coming through the windows. But if the days are too cloudy and dark, give them a little help with some artificial light.
Many plants can survive for some time in poor light, but you will surely notice a decline. This does not mean that they are dying, but that they have stopped the production of new leaves to rest and adapt to the new environmental conditions. Once the weather changes they will start to recover quickly.
When to water them
One of the most common mistakes when we take plants indoors is in the matter of watering. Indoor plants need to be watered very differently from those we keep outdoors, especially during the winter time.
A rule to follow is the following: the less sun and heat, the lower the risks. When we water our plants, they usually absorb only a portion of the water in the soil. The rest tends to evaporate with the light and heat provided by the sun, or passes into the deeper layers of the ground.
In the case of potted plants and indoors, the water tends to be kept in the ground longer, as it evaporates less easily. Then watering too much, the only thing that will do is create pools of water that will end up rotting the roots of your plants.
What about fertilizer
When the winter time comes the weather gets colder and the days shorter. Plants know this, so they take the opportunity to take a break in the production of branches, leaves and flowers. Therefore they do not need additional food, as the fabric factory will be closed for a while.
The ideal is to fertilize in the times of greatest sun, which go from spring to autumn. If you fertilize in times of cold and little sun, you will stimulate the plants to produce tissues without enough sun to develop. Then these can come out somewhat atrophied and even burn with the cold.
When to take them outside
Once the sun begins to warm up, the days get longer and you know that there will be no more frosts in the garden, it is time to take your plants out to the balcony or terrace. This usually happens in early to mid spring.
Remember that your plants have been indoors for a few months with little sunlight. So the ideal is to remove them gradually. That is, place them in a place with good but filtered light, not under direct sunlight.
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Provides the drainage cacti need to flourish; ready to use; pH balanced
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This product measures 4 quarts
How to choose the soil?
The soil is used by most gardeners, both as a substrate for potted plants and for growing in the ground. But what is it made of? Why use potting soil? And above all, how to choose? In fact, there is a wide range of potting soil at all price points and under a large number of different names, making it difficult to navigate at times. Here are some benchmarks to see more clearly and choose the best flooring for your intended use.
Definition of potting soil
Potting soil is a growing medium. It consists mainly of peat and composted plant debris (leaves ...). To improve the structure, topsoil and other organic materials (wood fibers, composted bark, manure ...) can be added. Other elements can come to complete it to give it specific qualities:
Fertilizer: provides nutrients that contribute to the good start of the plantations. Mineral materials: they are designed to retain water (clay) or to lighten the soil and improve aeration (sand, perlite, vermiculite).
What is soil for?
For potted plantings , potting soil is often the only growing medium and is used as is. Aerated, it allows a good development of the root system, promotes a good anchorage of the plant, limits the suffocation of the soil and, therefore, the rotting of the root. Optimally transports water and nutrients to the plant. Finally, thanks to the various elements it contains or is enriched, it stimulates the growth of the plant.
For crops in the ground , in the garden, the supply of soil is at the level of the planting hole. The soil is used as is or mixed with the garden soil. Its use can serve two different purposes: to improve the nutritional qualities of the soil, which is depleted as crops grow, and / or to improve the soil. There is talk of an amendment when it comes to modifying the structure of the soil, such as improving the ability of a sandy soil to retain water and nutrients or, conversely, lightening a heavy clay soil.
What potting soil to choose according to its use?
The first criteria in choosing a potting soil is the use for which it is intended. Depending on whether you want to plant, seed, transplant, cut, or repot, you will not use the same soil. Also, for some types of plants, a specific soil is needed.
Terreaux for plantation
Universal Soil - In theory, universal potting soil should be suitable for all kinds of uses except plants with special needs. It can be a good option if you are looking to modify the soil in your garden.
Horticultural soil : it is a soil rich in humus and organic matter (manure, algae ...). Contrary to what its name suggests, it is a very versatile soil, suitable not only for planting flowers and flowering shrubs, but also in the vegetable garden and garden. It is suitable for both pots and field crops, but not for plants with special needs.
Vegetable soil : it is a soil enriched in organic manure and manure. It is generally used in organic farming.
Terreau pots and planters: is a potting soil designed to have strong water retention and to limit watering.
Green Soil Plants: It is an aerated soil that promotes rooting of plants to allow them a harmonious growth.
Some plants have special needs, which absolutely require the use of suitable soil: they are heather or acidophilic plants (azaleas, rhododendrons, hydrangeas, camellias ...), cacti and succulents. Orchids and citrus.
Heather earth : it is an acid soil, which can be composed of pure earth (true heather earth), or simply a mixture of various elements (peat, pine bark ...) making the potting soil acidic.
Cacti terrines and succulents: sand and pozzolana are part of its composition, for a very light and draining potting soil.
Soil orchids: it is also a very airy soil, rich in bark and pozzolana or perlite.
Citrus soil: it is a soil rich in clay, which retains enough water while being light and flexible. Enriched with nutrients more specifically for citrus, it promotes their growth and fruiting.
Soil Roses, Geranium Potting Soil - Roses and geraniums don't really need specific potting soil. Rose potting soil or potting soil geraniums are good organic materials enriched in vegetables. You can use a rose potting soil for all the flowers in your garden and a geranium potting soil for all of your flower boxes.
Soil for seedlings, cuttings and pots.
The soil for sowing and cuttings is a healthy soil, particularly fine and light, which favors the success of planting and cuttings. It can be used for both types of operations, even if it is not expressly mentioned in the name "cuts". This potting soil can also be used to transplant flower or vegetable seedlings after planting. The soil pot is a pot soil adapted to pot all potted plants, green or flower, except those with specific needs.
How to recognize a potting soil?
Good quality potting soil is dark in color. It must be flexible to the touch and homogeneous. Large badly decomposed elements are, on the contrary, the mark of a mediocre soil. Finally it must be easily wet and retain water.
For the rest, read the labels! Depending on the type of compost you are looking for, some mentions are quality compromises: presence of manure, organic fertilizer, rooting stimulator ... On the contrary, unless they are specific uses, a soil very rich in bark and wood fiber. less interesting because it is grosser and less decomposed.
The mention "usable in organic agriculture" is an advantage, guaranteeing the absence of any chemical product in the soil.
In general, avoid very cheap land. They can simply serve to improve the structure of your soil, especially if you already regularly compost it.
Good soil, often the only substrate for potted plants, is the guarantee of good rooting while promoting optimal water and nutrient intake to the roots. It is worth choosing carefully, always in accordance with the intended use!
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Prepare and fertilize the garden
The vast majority of garden plants need a fertile soil , since it is their primary source of nutrients, and at the same time and with a good capacity to retain water and drain properly at the same time.
Prepare the ground and fertilize the soil in your garden
Land preparation is essential for your ornamental plants to develop well, especially if it is in the ground, but also if you use substrates in bags ready to use in pots and planters. The addition of organic fertilizer during the preparation of the flowerbeds and flowerbeds at the beginning of spring or autumn for sowing or planting, will restore the fertility and physical qualities that it has lost with your previous plantings and will make it available to the new ones. You plant the food and conditions they need to grow healthy and strong. This way they can provide you with an abundant and beautiful flowering.
STEP 1 How to prepare the garden soil
Step 1.1: Remove weeds and clean the land
Remove the pine bark or aggregates that you used to mulch the soil with the previous crop. Eliminate the remains of annual and biannual plants that have already completed their cycle, and the perennials (or perennial herbaceous) that you have decided to discard, as well as any weeds that have emerged.
Weeds appear all year round. Remove them periodically, you can help yourself with a rake to remove the remains of vegetation and roots.
Step 1.2: Prepare the soil for planting
Till the ground to a depth of 20 centimeters if you are going to sow. If you are going to plant developed specimens, take into account the height of the root ball to deepen what is necessary. Use a hoe or shovel. If the extension is large, you should use a motor hoe. Try not to affect the root zone of the plants that will remain in place (perennials, shrubs). You must turn the soil and break up the clods to get a soft and loose substrate where the roots of the plants can expand easily.
Step 1.3: Make a background fertilizer
Intermix the soil with organic matter (mulch, compost, worm castings, composted horse manure), you will recover the nutrients that have been lost with the previous crops and the new plants will have the necessary food to develop. You will also improve the structure and texture of the soil, fluffing those of the clay type, which tend to compact, and agglutinating the sandy ones. This is what is called a background subscriber.
Use substrates in ready-to-use bags, containing compost for the first weeks. This will save you the work of preparing the ground.
Step 1.4: Prepare the soil for the next planting
Smooth the surface with a rake to make it even. Wait at least 15 days before sowing or planting.
If your garden bed is large, we recommend using a motor hoe to till it. It will be easier and you will save time. These handy tools can be electric or gasoline-powered.
STEP 2 Planters and pots
The different types of containers for growing ornamental plants in a patio or terrace - pots, planters, drawers, with and without a water reserve - are easily filled with substrates in bags.
Step 2.1: Provide nutrients to the soil
Place a layer of gravel at the bottom of the container to ensure good drainage and avoid puddling at the root level. Fill it with universal or special substrate for the type of plants you want to plant, ensuring that it is loose and without lumps. These specific substrates already include compost, so you won't need to add mulch. Leave two fingers between the surface of the substrate and the edge of the mount.
If you have already cultivated before in the substrate present in the container, it is not necessary to renew it completely. Remove the remains of the previous crops and remove the soil with a hoe until it is very loose and soft. Spread a light layer of compost and weave it around. You can also add new substrate.
Step 2.2: Work the soil before planting Smooth the surface with the rake. You can sow the seeds or plant the specimens immediately. Once the plants are in place, add substrate around it and tamp it down with your fingers.
Step 2.3: Water generously So that the seeds or plants settle well in the substrate and any remaining air pockets disappear. In the case of plants, this step is important so that the substrate is well adhered to the root ball.
Planters, especially those made of autoclaved wood, can function as small grow boxes, ideal for placing in a corner. They usually carry a geotextile bag inside to contain the soil and preserve the wood, or spacers to isolate crops.
STEP 3 A substrate for each type of plants
The different types of containers for growing ornamental plants in a patio or terrace - pots, planters, drawers, with and without a water reserve - are easily filled with substrates in bags.
Choose the right substrate
At LEROY MERLIN you will find universal or specific substrate bags for different types of crops, ready to use. They are quality products, 100% organic, free of seeds, weeds and heavy metals, and with the ideal degree of porosity for growing, so it is always kept fresh, that is, neither too wet nor dry.
- Universal substrates: you can use them for all types of plantations. There is also a universal substrate with hydrogels, which allow optimizing irrigation water, and light ones, weighing 50% less than usual, thanks to the presence of peat in their composition.
- Specific substrates: there are substrates specially formulated for:
Designed to be less prone to gnats (Contains no compost or bark, which are known to shelter fungus gnats)
Contains coconut coir, which holds and releases water and helps soil easily re wet
For use in containers
Soil to cultivate - useful tips for preparing the soil
Today we want to talk to you a little about the preparation and care of the land before proceeding with the planting of the plants. As you already know, the land must be fertile enough to ensure proper plant development, so you should not miss our advice.
Practical tips for preparing farmland
Before fertilizing, you must know the type of soil you have in the garden. If it is a soil with excess nutrients, this can be as harmful as its absence.
Fertilize and fertilize the land for cultivation
These cases lead to alterations in plant growth, reduced product quality, loss of natural sources of raw materials and water-soluble minerals such as potassium, magnesium, nitric nitrogen, which fall into groundwater instead of remaining in soil.
Types of manures and fertilizers
In order to live and grow, plants need not only water and carbon dioxide, but also nutrients. They can only absorb dissolved minerals, so we must provide them with access to them.
Select the appropriate fertilizers for the terrain
Sometimes we can guess that there is a lack of nutrients by looking at the appearance of the plant and especially in the way it develops.
How to prepare the garden soil
Amateur gardeners when it comes to fertilizing must choose the right product since the shelves of specialized stores present many products.
Tips on how to grow plants in the garden
Each group of plants has at least one type of special fertilizer, as some of these plants have specific needs. But sometimes it can be a mistake to be guided by the ads, it is good to know the individual needs of each species.
Tips for preparing the soil for planting
Nitric nitrogen contained in the soil cannot be stored, and the rain pushes it into the deeper layers of the soil, where it threatens the quality of groundwater.
Tips for preparing the farmland
Our advice is to fertilize organically as much as possible. This means that you recycle the nutrients present in nature's cycle. Mineral fertilizers should be used when plants suffer from a serious lack of nutrients.Prepare the land with compost and fertilizers
Next we are going to see the ten most important types of fertilizers. Compost is not a fertilizer and soil adjuvant, it contains nutrients. Humus improves the structure of the soil. Mature compost contains an average of 0.3% nitrogen, 0.1% phosphorus and 0.3% potassium. Depending on the composting material, these concentrations vary.
Grow a home garden in the garden
If there is manure in the compost, it will increase the nitrogen and phosphate composition. Potassium is supplied again from bird droppings. Compost, however, contains many elements and raises the pH of the soil. Therefore, plants that are sensitive to limestone and lime must be fertilized with compost.Tips for preparing the ground for a vegetable garden
Cow manure is not for sensitive noses, but it is a very good concentration of organic fertilizer of active nutrients. It improves the long-term structure of the soil, as the straw and other fibers turn into humus.
Prepare the soil for sowing spices
It is important that the fertilizer is mature and that the best quality is dark manure. There are special nozzles that disperse the cow manure over a larger area.Tips for gardening at home
Horn shavings are another type of compost made, literally, of horns and hooves of slaughtered animals. In Germany most farm animals have horns but this raw material is imported mainly from South America.
Prepare the land before sowing
When it is ground to a very fine powder, the horn flour is obtained. If you plant trees, shrubs or roses, immediately pour a handful of this flour into the places where it is dug.Tips for planting flowers in the garden
The compost is considered complete fertilizer because it contains all the necessary nutrients for the soil fertility and plant nutrition. The ideal dose is 75 g. for 150 g. per square meter.
Original ideas for planting flowers in pots
In combination with soluble fertilizers, the blue colored crystals are suitable for all types of ornamental plants for balconies and in pots or in the garden. They act fast and should only be used when there is a great need for nutrients. Keep in mind that it is often necessary to put a smaller dose than what is printed on the package.
Ways to measure minerals and soil pH
The concentrated liquid manure is mainly used to fertilize potted plants. Depending on their nature, the offer is greater: from nitrogen-rich for orchids to phosphate-rich, ideal for balcony flowers. It is mandatory to buy a branded product.
Fertilize the soil to plant in the garden
Most liquid fertilizers work from the ground. During the growing season in flower pot and balcony plants, fertilization takes place in a period of two weeks. It is better to be a little prudent and put less than indicated to avoid misfortunes. First of all, fill halfway with water, put the manure, and then fill the rest with water.
How to grow home garden plots
The fertilizers for the field are fertilizers that adjust to the needs of the lawn. These are long-term fertilizers, that is, substances in which they are not released immediately.
Advice and special care for the earth
Patentkali are low-chloride fertilizers and are particularly suitable for vegetables, fruit trees, ornamental trees and herbaceous perennials.Preparing the garden soil for planting
Plants such as tomatoes, potatoes and root crops can be fertilized with Patentkaliy. In all other plants, it is important to do it in September so that the potassium best serves the young shoots before winter to be more sustainable and to create the characteristic brown bark.
Ways to fertilize the soil
Magnesium sulfate or bitter salt contains 16% magnesium, which is used only in acute lack of nutrients in the soil. Magnesium is an important component of chlorophyll. It is suitable especially for coniferous plants.
Types of fertilizers for the earth
Some spruce trees planted in sandy soils often have the needles that are yellowish or tinged brown, and then they begin to fall. If you have a fir or pine tree in the garden, first check for pests such as aphids or some fungi.
Practical tips for growing plants
Superphosphate fertilizers have a high content of nutrient phosphate. One of the three essential nutrients for healthy plant growth, phosphate can be applied in a high concentration with a fertilizer to plants ranging from houseplants to agricultural crops.
Prepare the ground for planting plants
There are several different types of this fertilizer that have been created for different needs. The three different types of superphosphate fertilizers are distinguished by the amount of phosphate in them.
How to plant plants in the garden
Simple superphosphate is the mildest grade, containing between 16 and 20 percent phosphate. It is available in liquid form or in a dry formula, both of which are used just as effectively by plants.
Tips for planting plants in fertile soil
Also known as normal superphosphate fertilizer, dicalcium superphosphate is the next grade, containing 35 to 38 percent phosphate part, depending on the mix and brand.
Ways to prepare the ground for planting
The strongest version of triple superphosphate fertilizers is phosphate. Also known as concentrated superphosphate, it is typically combined with another type of compost to be applied as a compound.
Types of minerals for plants
Triple superphosphate is most often used in an agricultural setting or with cash crops; There are several processes used to create this type of fertilizer, and in most cases, it is available as a granular form.
Ideas on how to fertilize arid land
All three types of superphosphate are generally made from a naturally occurring substance called rock phosphate.
Gardening in the garden
While this can be applied as a compost in its raw form, putting it through chemical reactions to create other types of fertilizers has been found to make it more effective.
Helpful tips for planting plants
We hope you enjoyed this article, we will return very soon with more useful tips and landscape trends, we are waiting for you.
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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.
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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.
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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.
