There is a natural aluminosilicate in nature with effects of molecular sieving, adsorption, ion exchange and catalysis. This natural substance is called zeolite with the synthetic zeolite also known as molecular sieves. Before we proceed to detailing further, Zeolites have been found to have no negative effects on nature hence use of Zeolite in gardening and farming is considered organic as per various standards and has its own set of benefits
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There is a natural aluminosilicate in nature with effects of molecular sieving, adsorption, ion exchange and catalysis. This natural substance is called zeolite with the synthetic zeolite also known as molecular sieves.
Zeolite chemical composition formula: (Mn+) 2/nO • Al2O3 • xSiO2 • pH2O, M represents a metal ion (usually Na in the artificial synthesis), N represents a metal ion valence, x represents the number of moles of SiO2, also known as silica to alumina ratio, p represents the number of moles of water. The most basic structure of the crystalline zeolite backbone is the tetrahedra SiO4 and AlO4, through the binding of common oxygen atoms to form crystals with three-dimensional network structure. This combination forms, constitutes cavities and channels of molecular level and uniform pore size. Owing to the different structures and different forms, “cage” shaped holes can be divided intoα, β, γ, hexagonal prism and faujasite.
Zeolites are hydrated aluminosilicate minerals made from interlinked tetrahedra of alumina (AlO4) and silica (SiO4). In simpler words, they’re solids with a relatively open, three-dimensional crystal structure built from the elements aluminum, oxygen, and silicon, with alkali or alkaline-Earth metals (such as sodium, potassium, and magnesium) plus water molecules trapped in the gaps between them. Zeolites form with many different crystalline structures, which have large open pores (sometimes referred to as cavities) in a very regular arrangement and roughly the same size as small molecules.
There are about 40 naturally occurring zeolites, forming in both volcanic and sedimentary rocks; according to the US Geological Survey, the most commonly mined forms include chabazite, clinoptilolite, and mordenite. Dozens more artificial, synthetic zeolites (around 150) have been designed for specific purposes, the best known of which are zeolite A (commonly used as a laundry detergent), zeolites X and Y (two different types of faujasites, used for catalytic cracking), and the petroleum catalyst ZSM-5 (a branded name for pentasil-zeolite).
Properties of Zeolites
- Zeolites are very stable solids that resist the kinds of environmental conditions that challenge many other materials. High temperatures don’t bother them because they have relatively high melting points (over 1000°C), and they don’t burn.
- They also resist high pressures, don’t dissolve in water or other inorganic solvents, and don’t oxidize in the air.
- Since they’re un-reactive and based on naturally occurring minerals, they’re not believed to have any harmful environmental impacts.
- The most interesting thing about zeolites is their open, cage-like, “framework” structure and the way it can trap other molecules inside it.
- Zeolites can exchange other positively charged ions for the metal ions originally trapped inside them (technically this is known as cation exchange) and, as Cronstedt found over 250 years ago, they can gain or lose their water molecules very easily too (this is called reversible dehydration).
Conventional open-pit mining techniques are used to mine natural zeolites. The overburden is removed to allow access to the ore. The ore may be blasted or stripped for processing by using tractors equipped with ripper blades and front-end loaders. In processing, the ore is crushed, dried, and milled. The milled ore may be air-classified as to particle size and shipped in bags or bulk. The crushed product may be screened to remove fine material when a granular product is required, and some pelletized products are produced from fine material.
There are over 200 synthetic zeolites that have been synthesized by a process of slow crystallization of a silica-alumina gel in the presence of alkalis and organic templates. Many more such structures could theoretically be made. In addition to variations in structures, zeolites can also be made with a variety of other atoms in them to make them chemically interesting and active. Some examples of the so-called heteroatoms that have been incorporated include germanium, iron, gallium, boron, zinc, tin, and titanium. One of the important processes used to carry out zeolite synthesis is sol-gel processing. The product properties depend on reaction mixture composition, pH of the system, operating temperature, pre-reaction ‘seeding’ time, reaction time as well as the templates used. In sol-gel process, other elements (metals, metal oxides) can be easily incorporated. The silicalite sol formed by the hydrothermal method is very stable. The ease of scaling up this process makes it a favorite route for zeolite synthesis.
Use in Gardening/Farming
In agriculture, zeolite is used as a soil treatment. If previously loaded with ammonium, the zeolite can serve a similar function in the slow release of nitrogen. Zeolites can also act as water moderators, in which they will absorb up to 55% of their weight in water and slowly release it under the plant’s demand. This property can prevent root rot and moderate drought cycles. Zeolite has also been added to chicken food: the absorption of water and ammonia by the zeolite made the birds’ droppings drier, less odoriferous and hence easier to handle.
Following are the uses of Zeolites in Gardening and Farming
- It acts like a soil conditioner and can help retain more water in soil, 100 grams of Zeolite can hold 80 grams of water and can release it easily to plants.
- Zeolites also have been observed to store nutrients and release them slowly. Hence they can be used with singular fertilizer.
- They can be mixed with soil during soil preparation phase.
- In pots they can be lined at the bottom of pot so that draining water can be absorbed and nutrients escaping can be recovered.
- They can also be used to line the bottom of the lawn bed just prior to laying of soil, this can help your lawn to become more efficient in terms of water and nutrients.
- Zeolites can help in absorbing water which is released to plants easily.
Use in Composting and worm beds
Composting is a process that converts organically bound nitrogen to ammonium nitrate and ammonia, both of which are plant-accessible nutrients.
Methane and nitrous oxide are two greenhouse gases produced during the composting process. Scientists have concluded that both gases are more potent than carbon dioxide.
zeolite has two methods of holding cations such as ammonium. The first method is by absorption, made possible by the mineral’s high surface area and porosity. The second method is by cation exchange.
Zeolite can sequester nitrates, sulphates, and hydrogen ions, which can prevent methane and nitrous oxide production during the composting process.
Addition of zeolite helps in following ways;
- It absorbs escaping Nitrogen and thus helps in increasing the Nitrogen percentage in the final product.
- It enables final product to absorb more water thus improving the water efficiency.
- Bad odor can be absorbed with the help of Zeolites, thus making the process more hygienic.
- Above points hold true for Worm bins as well. Zeolites are non-toxic to Worms.
Zeolite as Soil Amendment
The unique attributes of this natural resource acts like a powerful mineral sponge, it is dense yet highly porous with a molecular sieve structure. Water is absorbed, drawn in, and collected by the tiny zeolite granules, once blended into soil it creates space for root aeration. Since the molecule is of a negative molecular charge and pH neutralizing it holds moisture longer than soil, clay, sand perlite, coco-coir, etc. while also buffering the soil and deterring root-rot.
In agriculture, horticulture and farming zeolite is used widely as a slow-release carrier of fertilizers and as a soil buffering and aerating agent. Zeolite’s unique characteristics allow it to adsorb macro and micro nutrients, with a porosity size ranging from 4 – 7 angstroms. More specifically the natural variety of zeolite clinoptilolite has a particular nutrient release curve that enables the mineral to adsorb nutrients and hold on to them well enough to withstand leaching by way of water runoff, but at the same time lightly enough that the plant roots can draw the nutrients back out.
Zeolite’s unique crystalline lattice structure contains millions of pores and channels allowing oxygen to flow in and out of the mineral while also trapping and storing the oxygen. Zeolite improves the availability of oxygen to the roots and the aeration of the soil in general helping to prevent anaerobic bacteria, stagnation and root-rot.
Reduces Fertilizer requirements
While nitrogen stimulates plant growth, it contributes to water pollution; up to 70 percent of nitrogen contained in fertilizers is lost to the environment. Zeolite is an all natural product that improves fertilizer quality and productivity while withholding toxins from the environment.
Using Zeolite will cut fertilizer and water costs by holding the nutrients and water in the root zone until the plant is ready to utilize them. Thereby requiring less fertilizer and water to be applied. This promotes good stewardship of the land by reducing pollution brought on by fertilizers leaching to the groundwater or running off into surface water sources. Zeolites, when used properly, can yield some impressive results in regards to faster germination times, faster growth rates, larger plants, crop yields and reduced fertilizer and water applications.
Zeolite has a high CEC that enables a greater loading of plant nutrients such as nitrogen & micronutrients. The nutrients are held in the growth zone and are plant accessible but not water-soluble. Reduces nitrogen fertilizer requirements as a large portion of nitrogen fertilizers leach through the growth zone and into the aquifer. Zeolite will hold nitrogen and prevent the pollution of the water table by nitrates and nitrites. Zeolite prevents compaction, increases infiltration, and helps the aeration of deep root systems due to its high surface area and porosity. Zeolite is 100% natural for organic operations and when composted with manure, it becomes a natural fertilizing system.