Reverse osmosis systems for agriculture
Reverse osmosis systems for agriculture is used to cope with the salinity of irrigation water and to prevent the loss of agricultural production and the deterioration of land and soil. The most important achievements of Reverse osmosis systems for agriculture are reducing salinity, preventing soil sodiumization, eliminating toxic elements of plants and reducing the anionic composition of water.
Reverse osmosis systems for agriculture causes the salinity of water to decrease and, due to sodium depletion, reduces the sodium absorption, which in the long run prevents the dryness of soil and land. Increasing the sodium content of the soil due to the use of saline water gradually causes the soil dispersion phenomenon. Irrigation with salt water also reduces the amount of crop production that can be eliminated by water treatment.
Reasons for using Reverse osmosis systems for agriculture Reverse osmosis systems for agriculture is important because the use of salt water in agriculture, in addition to the decline in the production of the product, also reduces the useful physical properties of the soil, which means that the land is drying. The most important goals of agricultural water treatment are to deal with the following problems:
• Increased salinity or total salts concentration in water
• Sodium content or sodium concentration in water than other cations
• Anionic compounds of water, especially high concentrations of carbonates and bicarbonates
• High concentrations of boron or other toxic elements for plant growth
The effect of salt on the growth of osmotic plants. Because water is absorbed from the root growth medium in the form of a solution of water and soil, increasing salt results in increased osmotic solubility, and water molecules hardly separate from the solution and enter the root.
In agricultural water treatment, the pH or acidity parameter of irrigation water is not used as a qualitative criterion because the soil is a pH balancer. Except in areas where agricultural water treatment is used as drip irrigation.
In water treatment, toxic elements such as boron and lithium are removed from the water. It should be noted that when the compounds are added to the soil, a significant portion of it is absorbed by the particles of the soil and a small amount of it enters the soil solution. In the case of lithium, the concentration of these ions also causes burns of leaves. Today, due to industrial pollution, water contains many toxic elements that increase the importance of using agricultural water treatment.
Basic concepts of Reverse osmosis systems for agriculture In Reverse osmosis systems for agriculture, salinity or electrical conductivity is determined by measuring the electrical resistance of the two electrodes that are immersed in parallel in a solution. With increasing salinity or the concentration of water salts, the electrical conductivity increases linearly. The salinity unit in agricultural water treatment is mmho / cm.
The percentage of exchangeable sodium or ESP is an important criterion for Reverse osmosis systems for agriculture to describe the physical and structural conditions of the soil. Estimates of the amount of sodium exchangeable (ESP) and sodium adsorption (SAR) values can be estimated from the degree of plant resistance to sodium or the destruction of the agricultural soil structure, for example in ESP, more than 15 soil will be lost and water penetration will be difficult. In such a situation, the use of agricultural water purification is essential in sweetening irrigation water.
Soil type and necessities of Reverse osmosis systems for agriculture The soil texture is classified by the size of its constituent particles into three groups:
• Sandy soil with particles larger than 0.02 mm
• Silt soil with particles between 0.002 mm and 0.02 mm
• Clay with particles smaller than 0.002 mm
Soil particles have a negative charge. The smaller the size of the particles of the dust, the higher the specific surface and, because of its negative charge, absorbs cations. Conventional soils have about 70% calcium, 25% magnesium and 3% potassium ion, but saline soils have significant amounts of sodium ion. To avoid soil salinization, the use of desalinating water is essential for irrigation of the cultivated area.
In general, water treatment is important because if the ions absorbed by soil particles are of a bivalency type such as calcium and magnesium, the soil will have a good physical property, but continuous irrigation with saline water will replace monovalency ions such as sodium with these ions.
It is enough that at least 10% of the absorbed cations of the soil particles are of sodium type, then the soil loses its structure due to the dispersion of particles and its permeability decreases.
The importance of Reverse osmosis systems for agriculture in irrigation is important because in the event of continuous use of salt water, the soil is dispersed and generally loses its structure. Soil dispersion is an irreversible phenomenon and causes permanent loss of land.
The less the soil texture, such as clay, the more its ability to degrade the soil structure, and the use of an agricultural water purifier will be more necessary for irrigation.
Decreasing water salinity by water treatment Water salinity reduces agricultural production. High salinity causes burns at the margins of the plant, the lack of uniformity of growth in the field and the change of color to dark blue in green leaves. Experience has shown that the maximum absorption of water by roots from the soil are from places where there is less salinity. Because most of the water needed is obtained from the upper part of the root development area.
Reverse osmosis systems for agriculture is important because the amount of the product will decrease if the amount of irrigation water reaches a certain amount. Increasing the amount of salt to reduce the crop and eventually zeroing the crop yields. Agricultural water treatment costs are insignificant in comparison to long-term crop yields.
The effect of salinity on many plants is evident when the plant is exposed to salt for a long time. Moreover, the plant's resistance to salinity also depends on the question of which plant is at what stage of growth.
Salt control methods in Reverse osmosis systems for agriculture Water absorption by the plant and surface evaporation cause the salt to move to the surface of the soil, but if excess water is given to the ground or used by Reverse osmosis systems for agriculture methods such as reverse osmosis, to move the water downwards and some salts of the soil along with it, it comes out of the root. In brief, the methods of using saline water are as follows:
• Cutting the gap between irrigation
• Pick the right plant
• Soil washing
• Irrigation before planting
• Selection of seed placement
• Change the irrigation method to rainy or droplet methods
• Agricultural water treatment by methods such as reverse osmosis or land ionization
• Use of chemicals such as gypsum