Title Soil Science Part-10.pdf ✅

www.iaritoppers.in Whatsapp : +91-9694095242 Page | 1 Soil Science 4 th Edition 2023-24
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 2 Important Points:  Quartz is ubiquitous in soils.  Father of soil science & pedology: V.V. Dokuchev  According to pedology, soil is a natural body.  According to Edaphology, Soil is natural habitat for plants.  When soil heated at 105 degree C to remove moisture and then come in 100% humidity is called : Saturation Point (Asked in IBPS PSB 2019)  More than 90% of the earth crust is composed of silicate minerals.  N content in Indian soils : 0.02-0.1%  Major source of N in soil: Organic matter (95-99%)  Major source of P: Apatite  Major source of K: Biotite, Muscovite, Feldspar  Major source of Ca: Dolomite, Calcite  Major source of Mg: Dolomite, Olivine  Major source of S: Gypsum, Pyrite, Organic matter  Major source of Fe: Pyrite , Magnetite  Major source of Mn: Magnetite  Major source of Boron: Tourmaline (RRB SO-2019)  Major source of Zn: Sphalerite  Major source of Mo: Olivine  Major source of Chlorine: KCl, NaCl  Lower C:N ratio promotes: Vegetative growth  Higher C:N ratio promotes: Flowering  Optimum C:N ratio = 10-12: 1  Soil is a three dimensional body having length, breadth and depth.  Minimum criteria to be an organic soil : >20% organic matter  Pedon is the smallest volume that can be called “Soil”.  Genrally, Irrigation water with EC values less than 750 micro-mhos/cm is safe for plant growth.  Generally Rabi pulses have chromosome number 2n=14 (except chickpea 2n=16)  Generally Kharif pulses have chromosome number 2n=22 (except horsegram 2n=24)  Most deficient micronutrient in Indian soil is Zn & macronutrient is N.  Argon is absent in soil.  Ratio of soild, liquids and gases in an ideal soil is 2:1:1.  Cation absorption order - Al3+ > Ca2+ > Mg2+ > K+  Anion absorption order - H2PO4 2- > OH- > SO4 2- > NO3-  Flocculation order - Al3+ > Ca2+ > H+ > Mg2+
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 3  Microorganisms in soil on the basis of number/g of soil (Normal Soils): Bacteria > Actinomycetes > Fungi > Algae  Microorganisms in soil on the basis of mass/g of soil : Fungi > Bacteria > Actinomycetes > Algae  Microorganisms in acid soils: Fungi > Bacteria > Algae > Actinomycetes  Microorganisms order in arid and semi arid (alkali) soils: Actinomycetes >Bacteria > Fungi > Algae  Nitrogen losses in low land rice (Decreasing order): Denitrification (60%) > Leaching (8-14%) > Volatilization (1-4%)  Nitrogen losses in India (Decreasing order) : Volatilization > Leaching > Denitrification  Finger millet is having highest water use efficiency: 13.4%  Often cross pollinated crops: Cotton, Sorghum, Arhar  Beusening practice is related to rice done at 30-45 days after sowing (to reduce straw and increase grain).  Seed require light for germination are known as positive photobalastic.  Rotavator is used for primary and secondary tillage implement.  Permissible limit of soil loss in India is: 12 ton/ha./year  Present rate of soil erosion in India is: 16.4 ton/ha/year  Seed rate of Bt. cotton is 1.5kg/Ha.  Cabbage is highly sensitive to Boron toxicity (<0.33 ppm).  O2 concentration in soil below 10% restricts the root growth.  Generally, Rabi pulses have chromosome number 2n=14 (except chickpea 2n=16)  Generally, Kharif pulses have chromosome number 2n=22 (except horsegram 2n=24)  Red soils have high P fixation capacity.  pH of peat soil is 3.9 so it is suitable for paddy cultivation.  Potash Mica – white mica , also known as muscovite mica.  Magnesium Mica - Biotic Mica , Also known as Black Mica.  White mica is more resistant to weathering than Black Mica.  Recommended N:P:K for oilseed is 4:1:4  Recommended N:P:K for legumes is 1:2:1  Recommended N:P:K for cereals is 4:2:1  NPK ratio which is generally followed in India : 6.5: 2.5:1  Region of soil subjected to the influence of the plant roots is known as Rhizosphere.  Furrow slice : first 15 cm layer of land which is ploughed for cultivation.  Furrow slice weight: (Oven dry weight of 1 ha. land with 15 cm. depth, 2.25 x 106 kg ha-1 )  Surface soil : Top 0-15 cm. or 0-25 cm. soil  Sub-surface soil: Relatively compact yellow colour soil layer below surface soil.
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 4  Total N content of soil ranges from <0.02 % in subsoil to > 2.5% in peats.  Nutrient require for biological N fixation is Molybednum.  Erosion caused by excessive grazing , deforestration is called anthropogenic erosion.  Erosion avoiding crops: Cowpea, Groundnut, Lobia, Grasses.  Adiabatic lapse rate: Temperature changes as air rise or falls, 10 degree per km.  Precuersor of ethylene is Methionine.  Fertilizer use efficiency of N-Fertilizer: 30-60%  Fertilizer use efficiency of P-Fertilizer: 20-30%  Fertilizer use efficiency of K-Fertilizer: 50-60%  Highest consumption of Phosphorus in pulses.  Soil solarisation increases the soil temperature by 10-15°C.  Most appropriate months for soil solarisation are: April-June  Fertilizer control order (FCO) came in 1985.  Diffusion is the predominant process of soil aeration. More than 90% gaseous exchange in soil takes place by diffusion and rest by mass flow.  Most outstanding crop for green manuring is Sunhemp.  Nutrient needed for peg formation in groundnut is Calcium.  Common crop in paira and utera system is lathyrus.  Fertiliser Association of India (FAI) was established in 1955 with the objective of bringing together all concerned with the production, marketing and use of fertilizer.  Most of legumes fulfill their 75% nitrogen requirement through root nodule (symbiosis).  Mode of germination in pulses: a) Rabi pulses shows hypogeal kind of germination in which cotyledons remain in soil (except rajma). b) Kharif pulses shows epigeal kind of germination in which cotyledons emerge out from soil (except arhar).  Chairman of National Commision for farmers- Dr. M.S. Swaminathan  Microorganisms which grow at temperature below 10°C are known as psychrophiles.  Microorganisms which grow between 10-40°C are known as Mesophiles.  Microorganisms which can tolerate temperature above 45°C are known as Thermophiles.  Negative logarithm of H+ ions in soil is known as pH. The term was given by Sorensen.  A unit change in pH of soil represents a 10 folds change in H+ and OH- ions activity.  Saline soils are also known as Luni (Rajasthan), Thur(Punjab), and Reh(Gujarat).  Sodic soils are also known as Kallar (Punjab), Ussar(UP) and Kshar(Gujarat).  The process of increase in the nutrients of waters and resultant spurt in algal productivity is called eutrophication. It is responsible for aging of lakes.