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Syllabus: 45. Soil Science NET ARS SMS Exam 2025

Unit 1: Soil genesis, classification, survey and land use planning

Concept of land, soil and soil science. Composition of earth crust and its relationship with soils; Rocks, minerals and other soil forming materials; Weathering of rocks and minerals; Factors of soil formation; Pedogenic processes and their relationships with soil properties; Soil development; Pedon, polypedon, soil profile, horizons and their nomenclature. Soil Taxonomy - epipedons, diagnostic subsurface horizons and other diagnostic characteristics, soil moisture and temperature regimes, categories and criteria for soil classification systems. Soil mineralogy and clay minerals - classification, structure, composition, properties, genesis, transformation and identification techniques, role in plant nutrition, interaction with humus, pesticide and heavy metals. Interpretation of soil survey data for land capability and crop suitability classifications, Macro-morphological study of soils. Land evaluation and land use type concept and application. Application and use of global positioning system for soil survey. Soil survey - types, techniques. Soil series - characterization and procedure for establishing soil series, benchmark soils, major soils of India and soil correlations. Study of base maps: cadastral maps, toposheets, aerial photographs and satellite imageries. Use of geographical information system for preparing thematic maps.

Unit 2: Soil Physics

Soil physical constraints affecting crop production. Soil texture - textural classes. Soil structure - classification, soil aggregation and significance, soil consistency, soil crusting, bulk density and particle density of soils and porosity, their significance and manipulation. Soil water - retention and potentials. Soil moisture constants. Movement of soil water - infiltration, percolation, permeability, drainage and methods of determination of soil moisture. Darcy's law. Thermal properties of soils, soil temperature, Soil air - composition, gaseous exchange, influence of soil temperature and air on plant growth. Soil erosion by water, wind - types, effects, mechanics. Rain erosivity and soil erodibility. Runoff - methods of measurement, factors and management, runoff farming. Soil conservation measures, soil conservation in special problem areas. Characterization and evaluation of soil and land quality indicators; Causes of land degradation; Management of soil physical properties for prevention/restoration of land degradation; Identification, monitoring and management of waste lands; Land use - land cover mapping and land use planning using conventional and remote sensing techniques; Concept of watershed - its characterization and management. Remote sensing and geographic information system in precision farming.

Unit 3: Soil Chemistry

Chemical composition of soil; Soil colloids - structure, composition, constitution of clay minerals, amorphous clays and other non-crystalline silicate minerals, oxide and hydroxide minerals; Crystallography, space lattice, coordination theory; Solubility and ionic products: computation and mineral formation, Charge development on clays and organic matter; pH- charge relations; Buffer capacity of soils. Soil organic matter fractions, clay organic interaction. Elements of equilibrium thermodynamics, chemical equilibria, electrochemistry and chemical kinetics. Inorganic and organic colloids - surface charge characteristics, diffuse double layer theories, zeta potential stability, coagulation/flocculation, peptization, electrometric and sorption properties of soil colloid. Soil organic matter - fractionation, clay-organic interactions. Cation exchange - theories, adsorption isotherms, Donnan-membrane equilibrium concept, clay-membrane electrodes and ionic activity measurement, thermodynamics, anion and ligand exchange - inner sphere and outer-sphere surface complex formation, fixation of oxyanions, hysteresis, sorption-desorption of oxy-anions and anions. Nitrogen, potassium, phosphate and ammonium fixation in soils and management aspects. Quantity/intensity relationship and nutrient availability. Chemistry of acid, salt-affected soil, Chemistry and electrochemistry of submerged soils and management aspects, geochemistry of micronutrients. Basics of radioisotopes - radioactivity, monitoring radiation and isotopic techniques.

Unit 4: Soil Fertility

Essential elements in plant nutrition; Nutrient cycles in soil; Transformation and transport of nutrients (Macro and micro nutrients) in soil; Manures and fertilizers; Fate and reactions of fertilizers in soils; Chemistry of production of different fertilizers; Slow release fertilizers and nitrification retarders; Quality control of fertilizers. Soil fertility evaluation - soil testing, plant and tissue tests and biological methods; Common soil test methods for fertilizer recommendation; Soil test-crop response correlations; Integrated nutrient management; Use of isotopic tracers in soil research; Nature, properties and development of acid, acid sulphate, saline and alkali and their management; Lime and gypsum requirements of soils, lime potential; Irrigation water quality - EC, SAR, RSC and specifications. Fertility status of major soil groups of India. Concept and application of soil health and soil quality.

Pollution: types, causes, methods of measurement, standards and management. Heavy metal toxicity and soil pollution; Chemical and bio-remediation of contaminated soils; Soil factors in emission of greenhouse gases; Carbon sequestration in mitigating greenhouse effect; Radio-active contamination of soil.

Unit 5: Soil Microbiology

Soil biota, soil microbial ecology, types of organisms. Soil microbial biomass, microbial interactions, unculturable soil biota. Microbiology and biochemistry of root-soil interface Phyllosphere. Soil enzymes, origin, activities and importance. Soil characteristics influencing growth and activity of microflora. Microbial transformations of N, P, K, S, Fe and Zn in soil. Biochemical composition and biodegradation of soil organic matter and crop residues. Humus formation. Cycles of important organic nutrients, microbial transformations of pollutants in soil. Soil genomics; xenobiotics; Biodegradation of pesticides, organic wastes and their use for production of biogas and manures. Biofertilizers - definition, classification, specifications, method of production and role in crop production.

Unit 6: Analytical chemistry in soil

Concept of chemical analysis, Solution reactions, titrimetric analysis, concept of standard solution, Indicators: theory and applications. Methods of soil analysis - particle size distribution, bulk and particle density, moisture constants, Modern methods of soil, plant and fertilizer analysis. Flame photometry and inductively coupled plasma optical emission spectroscopy; Spectrophotometry - visible, ultra-violet and infrared; Atomic absorption spectrophotometry; Potentiometry and conductimetry; X-ray diffractometry; Mass spectrometry; Geiger Muller counter, solid and liquids scintillation counters.

Unit 7: Statistics

Experimental designs for pot culture and field experiments; Analysis of Variance (ANOVA) and Covariance; Statistical measures of central tendency and dispersion; Correlation and regression; Tests of significance - t and F tests; Computer use in soil research.

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