Soil science important points to know for jrf\srf

Very very important concepts and points in soil science. Must read before you appear for exams. Probable questions included

Ø  N in Indian soils == 0.02-0.1 %
Ø  NH4 + gets fixed n crystal lattice
Ø  Scab of potatoes, Pox of sweet potato, black rot of tobacco are favoured by neutral to alkaline soils.
Ø  major form of absorbed Boron ==> H3BO3
Ø  iron deficiency occurs at conc below 50 ppm
Ø  Iron deficiency common in crops grown in calcareous or alkaline soils
Ø  Zinc deficiency occurs at conc. below 20ppm
Ø  Molybdenum is essential for Nitrogenase and Nitrate reductase enzymes
Ø  The metal component of Urease enzyme is == Nickel
Ø  Soils with highest CEC is è Vermicullite (120-150 cmo/Kg)
Ø  The negative charge on 2:1 type clays is both pH dependant and pH independant.
Ø  Lyotropic series è Strength of cation adsorption by clay == Al >Ca> K=NH4+ >Na
Ø  The cec of organic soils is of the range == 50-100 meq/100g
Ø  Base saturation = (Total bases/CEC) * 100

Ø  The weight of 1 acre of soil at 6 inch height is 2*10^6 lbs
Ø  Nutrients are absorbed by plants in three mechanisms mass flow, diffusion and root expansion.
Ø  The only nutrient that entrs the root by all three mechanisms is Zinc
Ø  Diagnostic soil horizons are termed as == Epipedons
Ø  Laterization is the process of removal of Silica from the profile with simultaneous deposition of sesquioxides
Ø  Podzolisation is the removal of sesqioxides and deposition of silicates
Ø  Acidic soils are those formed by weathering of rocks with more than 65% SiO2
Ø  The amount of nitrogen in soils same as that of the atmospheric Nitrogen content ie, 78%
Ø  the most dominant salt in alkali soils is Na2CO3
Ø  The elements present in porphyrin ring of chlorophyll are Mg and N2
Ø  Entisols refer to the young soils
Ø  Ultisols refer to old soils
Ø  The chelated iron most suitable for calcareous soil is == EDDHA
Ø  Apparatus used to measure the soil plasticity ==Atterbergs apparatus
Ø  Apparatus used for measurement of soil aggregation == Yoders apparatus
Ø  Beckett put forward the concept of Q/I relationship, high availability of K at high PBC
Ø  Readily available forms of K to plants is only 0.1-2.0% of total k in soil
Ø  CEC of mica is 0
Ø  Percentage of Sulphur in Potassium sulphate is 17%
Ø  Sulphur content in soil is determined by reagent Calcium chloride
Ø  Micronutrints like Fe, Zn, Mn, Cu are done using reagent DTPA
Ø  Imbalance of Molybdenum causes disease called molybdenosis in cattles
Ø  Aluminium toxicity is prominent in acid soils with ph less  than 5
Ø  Soils with poor soil conditions are == Sodic soils
Ø  ESR= Exchangeable Na/ Exchangeable Ca+Mg
Ø  Concept of Leaching requirement was put forth by Shoemaker
Ø  leaching requirement = ECiw/ECdw
Ø  Vertical horizons of soil are called Profile
Ø  Solum comprises of the soil horizons A,B, E
Ø  Regolith comprises of horizons A,B, C
Ø  Organic soils have 50%  by volume and 20% by mass of organic matter
Ø  Most resistant primary mineral is == Quartz
Ø  Least resistant primary mineral == Olivine
Ø  Soil order formed from volcanic ash and ejecta == Andisols
Ø  Andisols are dominated by == allophone
Ø  Ultisols are soils with very low fertility
Ø  Entisola are highly fertile alluvial soils
Ø  Lowest category of soil classification == Series
Ø  A soil mus have minimum of 35% clay to be called as clay soil
Ø  Soil structure in grasslands == Spheroidal
Ø  The gravitational potential of in soil is always positive
Ø  Elements used in Newtons moisture meter == Radium, Americium, Beryllium
Ø  Magnesium in octahedral sheet == Trioctahedral
Ø  Aluminium in octahedral sheet == Dioctahedral
Ø  The humus fraction which is light coloured == Fulvic acid
Ø  The water holding capacity of humus is 4-5 times that of silicte clays, so they  are used to improve soil property
Ø  CEC of humus is2-3 times as that of clay



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