Soil Salinity Quiz

Salinity

• Salinity is the high concentration of dissolved mineral salts in the soil.
• Four contributing cations to salinity are Na+, Ca2+, Mg2+, and K+.
• Sodicity is a high concentration of Na+ relative to Ca2+ and Mg2+.
• Soil salinization occurs when groundwater containing salt reaches the root zone or soil surface, where evaporation leaves salt deposits.
• Common salts in prairie soils are sulfates of calcium and magnesium, along with sodium and magnesium chlorides.
• Three conditions for a salinity problem are soluble salts in subsoil or groundwater, high water tables, and plants susceptible to salt.
• High water tables contribute to salinity by carrying soluble salts into the root zone via capillary action (within 6 feet of the surface).
• Three plants susceptible to soil salinity are pulses, vegetables, and oilseeds.
• Salinity is a natural process controlled by hydrology, geology, and biological processes.
• Four types of salinity are regional, sidehill seep, bathtub ring, and irrigation.
• Regional/Artesian discharge salinity occurs when water from an aquifer is under pressure to reach the surface.
• Sidehill seep salinity happens when permeable glacial drift overlies impermeable materials, and lateral groundwater flow intersects with the surface, leaving behind salt deposits.
• Bathtub/evaporative ring salinity occurs adjacent to depressions or sloughs, with upward capillary flow concentrating salts around the sloughs.
• Irrigation salinity occurs when using poor-quality water without sufficient leaching.

Soil Salinity Management

• Leaching requirement is the amount of additional irrigation water needed to leach soluble salts out of the root zone.
• Salinity can be measured using saturated paste method or soil:water ratio method, which both measure electrical conductivity (EC) of a soil sample.
• Three methods to manage primary salinity are strategic crop choices, reduced tillage, and increased soil organic matter (SOM).
• Two strategies for secondary salinity management are strategic cropping choices and drainage strategies.
• Factors characterizing sodic (alkaline) soils include elevated sodium concentration relative to calcium and magnesium, pH above 8.5, and a high sodium absorption ratio (SAR).
• SAR is a measure of sodium relative to calcium and magnesium in a soil water extract.

Soil Organic Matter (SOM)

• SOM consists of plant, animal, and microbial tissue at various stages of decomposition.
• SOM forms from various organic matter sources like fresh residue, crop residue, root mass, and stabilized organic matter.
• SOM is crucial to soil aggregate formation, increasing porosity, protecting from erosion, and helping with water infiltration.
• Increasing SOM can be achieved through adding raw materials to the soil, reducing losses (e.g., via less tillage), and using perennial crops, continuous cropping, cover crops, manure/compost.
• C:N ratios of plant residue directly impacts N and microbial activities.

Nutrient Uptake in Plants

• Plant growth is affected by the availability of nutrients in the soil.
• Three mechanisms of nutrient movement and uptake are mass flow, diffusion, and root interception.
• Nutrients move from high to low concentration through mass flow (water flow) and diffusion.
• Active and passive uptake play a role.
• Management of nutrient movement and uptake focuses on placement strategies for active absorption.

Test your knowledge on soil salinity and its effects on agriculture. This quiz covers the definitions, causes, and types of salinity, as well as the plants that are affected by it. Dive into the science behind soil salinization and its contributing factors.