IRON TOLERANCE LIMITS IN IRRIGATION WATER

A few of these with toxic effects of trace elements mg/1 at concentrations of less than in water, and the elements in the soil solution. The majority of this toxic heavy metal trace elements is classified by all practitioners. Some of them are presented in very small amounts for plants (Fe, FR, Zn, mn, co and Mo) which is needed, while in some it is not necessary. However, for all plants and animals at high concentrations or doses the mentioned chemicals can be toxic. Some of these elements are not found naturally in water and soil. But as a result it has an access to water sources of industrial pollution.

Classification of irrigation waters according to their resistance to Bor minerals

* Example: Walnut, Lemon, Fig, Apple, Grape and Bean
** Example: Barley, Wheat, Corn, Oats, Olives and Cotton
*** Example: Sugar Beet, Clover, Bean, Onion, Lettuce and Carrot

Calcium And Magnesium-Bicarbonate Related Concentration
If irrigation water contains high concentrations of bicarbonate in the soil solution. it becomes more concentrated, calcium and magnesium as carbonate precipitation is following. In this case, if calcium and magnesium in the soil solution are reduced, and thus increase the rate of sodium, as a result, sodium ions and sodium loss become dominant.
It varies according to the type of resistance of plants to bicarbonate ions. Sometimes that will cause substantial losses and even in low osmotic concentrations toxic effects can be seen.

Classification of irrigation waters according to persistent sodium carbonate content

The classification value of the electrical conductivity

In this system considered the close relationship between the salt concentration in the water conductivity, electrical conductivity is divided into four main categories according to the values.
1.Class: less salty water (Ci – electrical conductivity the value of 0-250 microsiemens/cm)
Soil salinity of this water for irrigation without causing problems for each plant and is appropriate and can be used. The very low permeability soils that occur spontaneously under normal irrigation conditions except for clearing problem.
2. Class: middle-salty waters (C2 – 250-750 the value of the electrical conductivity microsiemens/cm)
Moderately salt tolerant plants, this water is easily used. Salt-sensitive plants should be given a wash.
3.Class: high saline waters (C3 – 750-2, the value of the electrical conductivity.250 microsiemens/cm)
Continuous use of this water in the case of regular washing is made to avoid the problem of salinity and the implementation of the program requires special tillage. Drainage should not be used on soils that are not good. However, salt-tolerant plants can be used to irrigate.
4.Class: very high saline waters (C4 – 2.250 the value of the electrical conductivity microsiemens/cm, more than one)
This water is not suitable for irrigation under normal conditions

Sodium according to classification:

Sodium adsorption ratio of irrigation water is taken into consideration. From this direction the effect of sodium on soil physical properties may be changed based on the classification. However, the physical properties of the soil that can damage plants which are sensitive to sodium concentration less than sodium even in the presence of sodium in the tissues may be harmed as a result of the accumulation.
1. Class (SAR = 0-10): low-sodium water (S1)
This is appropriate for each soil and each plant of water and sodium loss occurs before they can be used for irrigation. However, sodium sensitive crops such as stone fruit trees and avocados should be provided more careful watering.
2. Class (SAR = 10-18): medium-sodium water (S2)
This water permeability can be used in a variety of light textured and organic soils. Heavy textured soils with high cation exchange capacity, especially under low soil washing can be used under the conditions and in the absence of jips.
3.Class (SAR = 18-26): a high-sodium water (S3)
These waters generally have high permeability, sandy soils low in total salt concentration are used. Wash with plenty of organic matter and proper drainage such as the addition of some specific tillage program is implemented, unless the use of water is inconvenient. Gypsum-containing soils may be able to use.
4.Class (SAR >26): very high-sodium water (S4)
Generally this water is not suitable for irrigation. However, if the total salt concentration is low, high amounts of soluble calcium, by giving importance to wash soils, chemical reclamation of gypsum and similar materials together, it may be able to use under the given condition.