Salinity & pH: 2 critical concepts for each farmer!
2+2 best practices to regulate soil salinity and pH.
By AgriSC Scientific Team
THE SALINITY PROBLEM THROUGH THE AGES
Irrigation of agricultural land has caused problems since ancient times, as the need for drainage was only recently understood. Indeed, this often led to reduced soil productivity and, consequently, the decline of civilizations that developed based on agriculture. A characteristic example was the Sumerians, an ancient Mesopotamian people. The Sumerians irrigated their fields on a large scale in the Diyala River region, causing salting (the presence of salt in their areas) in 2400 BC.
SALINITY: WHAT IS IT, AND WHAT CAUSES IT?
Irrigation water, whatever its quality, contains dissolved mineral salts, the concentration and composition of which depend on the origin of the water. For example, water from snowmelt or reservoirs contains fewer salts than groundwater in coastal areas or from treated wastewater. Therefore, if the quantity and quality of water entering the ground are not adequately controlled, high concentrations of salts (salinity) will be observed.
WHY IS SALINITY MEASUREMENT IMPORTANT?
Salinity certainly is a fundamental concept for the farmer, affecting plant nutrition. Depending on its value, it can reduce or even inhibit the intake of nutrients. This is because it reduces the plants’ water potential and water availability. For this reason, techniques have been developed to measure and quantify salinity, calculated as total dissolved solids (TDS) or electrical conductivity (EC) more quickly.
ELECTRICAL CONDUCTIVITY: WHAT IS IT, AND HOW IS IT MEASURED?
Pure water is a poor conductor of electricity, but its conductivity, i.e., its ability to conduct electricity, increases with dissolved salts. EC electrical conductivity can be measured in both soil samples and aqueous solutions. It is beneficial in hydrofertilization as it can guide fertilizer deficiency or surplus. Electrical conductivity is measured with special instruments called conductivity meters, and the units of measurement are called deciSiemens per meter (dS/m).
WATER HARDNESS: WHAT IS IT, AND HOW IS IT TREATED?
The hardness of water is related to the presence of salts, especially calcium carbonate or calcite. Hard water is a severe problem for any cultivator, as it blocks irrigation pipes, causing significant damage. This problem can be corrected by adjusting salinity and removing Ca++ and Mg++ ions.
pH: WHAT IS IT, AND HOW IS IT MEASURED?
pH indicates the degree of acidity/alkalinity of the soil, irrigation water, or nutrient solution and is a crucial determinant of growth in any crop. The pH of a nutrient solution is essential for plant nutrition because it determines the solubility and availability of nutrients to plants. The pH is measured with special instruments called pH meters, and the scale ranges from 0 (very acidic) to 14 (alkaline), with a neutral value of 7.
WHAT ARE THE BEST PRACTICES TO ADJUST SALINITY AND pH?
In addition to controlling the quantity and quality of water required for each irrigated crop, we suggest the following:
TO ADJUST THE SALINITY OF THE SOIL
Improving soil porosity is an easy solution to regulate and manage soil salinity. This is achieved by enriching organic matter, manure, compost, etc. Proper soil treatment can also prevent water accumulation in places and improve drainage conditions.
FOR pH ADJUSTMENT
Adjusting pH in practice is complex and should be done carefully and in consultation with a specialist. The addition of limestone or calcium nitrate to acidic soils and Sulphur or ammonium sulfate to alkaline soils are some indicative solutions. In alkaline soils, pH can also be corrected by adding organic fertilizers.
BIBLIOGRAPHY
- Poulovasilis, A. (2010). Introduction to Irrigation. Athens: Embryo Publications.
- Brandy, C.N and Weil, R.R. (2015). The nature and properties of soils. Athens: Embryo Publications.
If you are in an agronomy business, own an agronomy shop, and are seeking a collaboration opportunity with AgriSC, fill out the form below. Our team will respond promptly!