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.