Soil Salinity, Sodicity, Waterlogging and Reclamation MCQs 2026

Among the listed crops, the crop usually regarded as sensitive to salinity is

1. ABarley✓
2. BCotton✓
3. CBean✓
4. DSugar beet✓

Soil salinity refers to the presence in the root zone of excessive

1. ASoluble salts✓
2. BExchangeable aluminum only✓
3. COrganic residues only✓
4. DClay minerals only✓

Among common field crops, the crop generally considered relatively salt tolerant is

1. ABean✓
2. BBarley✓
3. COnion✓
4. DCarrot✓

The most common laboratory measure used to assess soil salinity is

1. ACation exchange capacity only✓
2. BElectrical conductivity of the saturation extract✓
3. CPermanent wilting percentage✓
4. DBulk density of dry soil✓

Soil sodicity is mainly a problem of excessive

1. ANitrate nitrogen in soil solution✓
2. BCalcium carbonate in parent material✓
3. CExchangeable sodium on the soil complex✓
4. DOrganic carbon in surface soil✓

A typical saline soil has ECe greater than 4 dS/m, ESP less than 15 and pH usually

1. AAbove 10.5✓
2. BExactly 7.0 always✓
3. CBelow 4.0 always✓
4. DBelow 8.5✓

A sodic soil is commonly characterized by ESP above 15 and soil pH usually

1. AGreater than 8.5✓
2. BLess than 5.0✓
3. CExactly neutral✓
4. DControlled only by rainfall✓

A saline-sodic soil generally has both ECe greater than 4 dS/m and

1. AOrganic carbon greater than 10 percent✓
2. BESP greater than 15✓
3. CpH less than 4.5 always✓
4. DNo exchangeable sodium✓

Sodium adsorption ratio of irrigation water is calculated from sodium relative to

1. ANitrogen and phosphorus concentrations✓
2. BBoron and chloride concentrations only✓
3. CCalcium and magnesium concentrations✓
4. DCarbon and sulfur contents✓

A white crust on the soil surface in arid irrigated fields usually indicates accumulation of

1. AHumus only✓
2. BIron oxide only✓
3. CFresh clay minerals only✓
4. DSoluble salts✓

Poor infiltration and surface sealing in sodic soils are mainly caused by

1. ADispersion of clay particles by sodium✓
2. BExcess gypsum flocculation✓
3. CHigh sand content only✓
4. DLow soil pH from sulfuric acid✓

The amendment most commonly used for reclaiming sodic soils is

1. AUrea✓
2. BGypsum✓
3. CMuriate of potash✓
4. DRock phosphate✓

Gypsum improves a sodic soil because calcium from gypsum replaces exchangeable sodium and the sodium is then

1. AConverted into nitrogen gas✓
2. BChanged into clay mineral permanently✓
3. CLeached out with percolating water✓
4. DAbsorbed by chlorophyll molecules✓

Leaching of saline soils means applying good quality water to move salts

1. AInto the seed bag✓
2. BOnly onto leaf surfaces✓
3. CBack to the soil surface✓
4. DBelow the active root zone✓

Effective drainage is essential in salinity reclamation because it removes

1. ASalt-laden percolation water from the soil profile✓
2. BAll clay minerals from the field✓
3. COnly insects from plant roots✓
4. DAll organic matter from topsoil✓

Waterlogging in agriculture means the crop root zone is saturated long enough to cause

1. AExcess oxygen around roots✓
2. BOxygen deficiency around roots✓
3. CComplete absence of soil water✓
4. DInstant phosphorus fixation only✓

A common cause of waterlogging in canal-irrigated areas is seepage combined with

1. AExcessive slope and runoff only✓
2. BVery deep groundwater always✓
3. CInadequate natural or artificial drainage✓
4. DAbsence of irrigation canals✓

Capillary rise from a shallow saline water table causes salinization by carrying salts toward the surface where water

1. AFreezes permanently✓
2. BTurns into nitrogen✓
3. CBecomes organic matter✓
4. DEvaporates✓

The primary reclamation practice for saline but non-sodic soils is

1. ALeaching with good quality water and drainage✓
2. BAdding only urea fertilizer✓
3. CCompacting the soil surface✓
4. DRemoving all crop residues✓

After applying gypsum to a sodic soil, the displaced sodium must be removed mainly by

1. AFoliar spraying of micronutrients✓
2. BLeaching through the profile✓
3. CHarvesting green fodder only✓
4. DKeeping the field dry forever✓

Residual sodium carbonate in irrigation water evaluates the hazard caused by carbonate and bicarbonate reducing soluble

1. ANitrogen and sulfur✓
2. BBoron and zinc✓
3. CCalcium and magnesium✓
4. DCarbon dioxide and oxygen✓

Irrigation water with high residual sodium carbonate tends to increase soil sodicity because it precipitates calcium and magnesium as

1. ANitrates✓
2. BChlorides✓
3. CSulfates only✓
4. DCarbonates✓

The high pH of sodic soils is largely associated with hydrolysis of

1. ASodium carbonate✓
2. BCalcium sulfate✓
3. CPotassium nitrate✓
4. DFerric phosphate✓

Rice tolerates flooded conditions better than many upland crops because its plants develop

1. ADeep woody taproots only✓
2. BSalt glands on leaf margins only✓
3. CNo root respiration requirement✓
4. DAerenchyma for internal oxygen movement✓

Subsurface tile drainage is installed mainly to

1. ALower the water table✓
2. BIncrease exchangeable sodium percentage✓
3. CStop all rainfall infiltration✓
4. DApply nitrogen fertilizer✓

Open surface drains in irrigated fields are used primarily to remove

1. AOnly available phosphorus✓
2. BExcess surface and shallow subsurface water✓
3. COnly crop seeds✓
4. DOnly atmospheric nitrogen✓

Leaching requirement is the extra fraction of irrigation water needed to

1. ARaise soil pH above 10✓
2. BIncrease crop residue burning✓
3. CControl salt accumulation in the root zone✓
4. DStop evapotranspiration completely✓

Interceptor drains along canals are designed mainly to reduce

1. APhotosynthesis in nearby crops✓
2. BSeed germination in nurseries✓
3. CWind erosion from dry ridges✓
4. DSeepage moving toward adjoining fields✓

Adding organic matter to sodic soils helps reclamation by improving aggregation and

1. AWater infiltration✓
2. BSodium carbonate production only✓
3. CSoil crust cementation only✓
4. DPermanent waterlogging✓

Elemental sulfur can help reclaim calcareous sodic soils because oxidation produces acid that dissolves

1. ASodium chloride gas✓
2. BCalcium carbonate✓
3. CNitrate fertilizers instantly✓
4. DPlant cellulose directly✓

Pyrite and other acid-forming amendments aid sodic soil reclamation by generating acidity that releases

1. ANitrogen from air directly✓
2. BPotassium from irrigation water only✓
3. CCalcium from native lime✓
4. DChlorophyll from roots✓

Flooding a saline field for leaching is effective only when the soil also has adequate

1. ASodium carbonate crusting✓
2. BPesticide residues✓
3. CSeed dormancy✓
4. DPermeability and drainage✓

Brackish irrigation water is water containing appreciable amounts of

1. ADissolved salts✓
2. BOnly beneficial microbes✓
3. COnly suspended clay without ions✓
4. DOnly dissolved oxygen✓

The first physiological effect of salinity on many crops is reduced water uptake due to

1. AExcess oxygen pressure✓
2. BOsmotic stress✓
3. CAbsence of sunlight✓
4. DDirect nitrogen fixation✓

Specific ion toxicity in salt-affected soils is commonly caused by excessive sodium, chloride or

1. AOxygen✓
2. BNitrogen gas✓
3. CBoron✓
4. DSilicon dioxide✓

Salt-affected soils are commonly classified using ECe, pH and

1. ALeaf area index only✓
2. BSeed weight only✓
3. CRainfall intensity only✓
4. DESP or SAR✓

Exchangeable sodium percentage is calculated as exchangeable sodium divided by cation exchange capacity, multiplied by

1. A100✓
2. B10✓
3. C1000✓
4. D0.1✓

Sodium adsorption ratio is mainly used as an index of the sodicity hazard of

1. ADry seed lots✓
2. BIrrigation water✓
3. CStored grain✓
4. DPesticide spray droplets only✓

Hydraulic conductivity of a sodic soil usually decreases because clay particles become

1. AMagnetized✓
2. BConverted to sand✓
3. CDispersed✓
4. DSterilized✓

Gypsum requirement estimates the amount of gypsum needed to replace a desired quantity of

1. AAvailable nitrate✓
2. BSoil organic carbon✓
3. CPlant chlorophyll✓
4. DExchangeable sodium✓

During the early years after reclamation, a salt-affected field should preferably be planted with

1. ASalt-tolerant crops✓
2. BOnly the most salt-sensitive vegetables✓
3. CNo cover crops ever✓
4. DOnly deep-rooted forest trees✓

Raised-bed planting can help in waterlogged or saline fields by improving root-zone aeration and

1. AExchangeable sodium accumulation only✓
2. BSurface drainage around crop rows✓
3. CCapillary rise from groundwater only✓
4. DSoil pH above 11✓

In arid areas, a shallow water table within about one to two meters can promote salinization through

1. APermanent freezing of groundwater✓
2. BComplete absence of dissolved ions✓
3. CCapillary rise and evaporation✓
4. DConversion of salts into humus✓

Arid and semi-arid climates favor soil salinity because evaporation often exceeds

1. ASoil texture and structure✓
2. BRoot respiration and photosynthesis✓
3. CSeed size and seed rate✓
4. DRainfall and natural leaching✓

Compared with sodic soils, saline soils often have better permeability because soluble salts promote

1. AFlocculation of clay particles✓
2. BClay dispersion by sodium carbonate✓
3. CComplete pore blockage✓
4. DCementation by humus only✓

The term black alkali is commonly associated with sodic soils because sodium disperses organic matter forming dark

1. AIron rust coatings only✓
2. BSodium humate stains✓
3. CGypsum crystals only✓
4. DCalcium phosphate bands✓

The SI-compatible unit commonly used for soil electrical conductivity is

1. Akg/ha✓
2. Bcmol/kg only✓
3. CdS/m✓
4. Dpercent clay✓

Reuse of saline drainage water is safest when managed through blending, suitable irrigation scheduling and

1. AIgnoring soil salinity monitoring✓
2. BStopping drainage maintenance✓
3. CIncreasing waterlogging intentionally✓
4. DCrop salt-tolerance selection✓

Biosaline agriculture focuses on productive use of saline land and water by growing

1. ASalt-tolerant crops and forages✓
2. BOnly salt-sensitive beans✓
3. COnly crops without roots✓
4. DOnly plants under zero irrigation✓

A common reason reclamation of salt-affected land fails is applying leaching water without adequate

1. ASeed certification label✓
2. BDrainage outlet✓
3. CLeaf wax coating✓
4. DHarvest machinery✓