✅American society of Agronomy was founded as early as 1907.
✅Agronomy is essentially an applied science.
✅Basic sciences are those which reveal the facts or secrets of nature and comprise subjects like Chemistry, Physics, Mathematics, Botany, Zoology, Economics, etc.
✅Applied sciences are those in which the theories and laws propounded in basic sciences are applied to problems in agriculture and other fields.
✅A person who is expert in Agronomy is known as Agronomist,
✅Soil consists of mineral matter, organic matter, water, air and living organisms.
✅Soil has three dimensions viz. length, breadth and depth.
✅A vertical section of the soil through all it’s layers and extending into parent rock is
known as soil profile.
✅Important minerals are-feldspar, quartz, hornblende, mica, pyrites, zeolite, apatite, gypsum, etc.
✅90% of earth’s surface is formed from Igneous rock which contain 60% feldspar, 17% hornblende, 12% quartz,4% mica and 7% others. They supply all plant food elements, except the most important element viz Nitrogen.
✅Physical weathering is called disintegration while the chemical weathering is called
decomposition.
✅Physical Weathering is mechanical process. Temperature and water, heating and cooling, wetting and drying, rainfall, winds, grasses and shrubs split rock, animals like rats, rodents, termites, ants, cultivation by man are chief factors of physical weathering
✅Chemical weathering changes the nature and composition of soil. No chemical weathering is possible without the presence of water. Chemical weathering is accelerated when CO2 gets dissolved and temperature is increased. The principal agents are solution, Hydration, Hydrolysis, oxidation and reduction, carbonation, etc.
✅In Carbonation CO2 dissolved in water forms carbonic acid.
✅Weathering is destructive process, soil formation is a constructive process resulting in a soil profile.
✅Soil=C + PM + R + P and A +time
Climate + Parent material + Relief (Topography) + Plant and animal + time,
S-F(C, Pm, R, t, o..d)
✅Accumulation of lime near the surface of soil due to less rainfall, process is called
calcification. Soils are alkaline.
✅In heavy rainfall areas, calcium is more or less completely leached, and Fe and Al are concentrated near soil surface, process is called laterization. Soils are acidic in nature. They poor in fertility, specially P and K.
✅Granite rock is slow to weather and soils from it is not very productive. Lime stone
develop dark colored and productive soil.
✅Climatic conditions are more important in soil formation than parent material.
SOIL PROFILE DIAGRAM
✅A00 – Undecomposed organic debris.
✅A0 – Partially humified organic matter.
✅A1- Dark coloured- higher content of humus well mixed with mineral matter
✅A2 – Light in colour- maximum leaching
✅A3- Transitional more like A than B; sometimes absent.
✅B1- Transitional more like B than A; sometimes absent.
✅B2- Usually deeper coloured, maximum accumulation of clay minerals, Fe and organic matter.
✅B3- Transitional to C
✅C- Weathered soil parent material; horizons of accumulation of CaCO3 and CaSO4
occur in this zone.
✅D- Bed Rock (Parent material.)
✅Al+A2+A3= Zone of Eluviation (A Zone); B1+B2+B3 Zone of Illuviation (B
Zone). A and B combines called Solum.
✅Solum plus parent material sometimes referred as regolith.
✅In nature, no profile occurs which has all these horizones.
✅No two profiles are exactly alike.
✅Types of soils – (1) Rad Soils (2) Laterites and lateritic soils (3) Black soils (4)
Alluvial soils (5) Forest and hill soils (6) Desert soils (7) Saline and alkaline soils (8) Peaty and marshy soils.
✅Red soils are light textured with porous and friable structure and there is absence of lime kankar and free carbonates. They have neutral to acid reaction and are deficient in N, humus, phosphoric acids and lime.
✅Laterites and lateritic soils- Red to Reddish yellow, low inN, P, K, lime and magnesia; found in situ under high rainfall, excessive leaching of bases and silica from parent rock. Laterization process is occur.
✅Black soils – Also called Indian Regurs. The black colour is variously assigned to the
presence of titaniferous magnetite, organic compound of Fe and Al, Accumulated humus and colloidal hydrated double iron of alluminium silicate.
Soils are deficient in N, Phosphoric acid and organic matter but rich in K, Ca and Mg.
They have minerals are montmorillonite.
✅Alluvial soils- In all states along river sides. They are usually productive but many are
✅Forest and hill soils occur at high elevations as well as at low rainfall where rainfall is deficient in N, humus and P. sufficient to support trees. These are shallow, steep, stony and infertile.
✅Desert soils- low in N and organic matter but have a high pH, subjected to wind erosion.
✅Peaty and marshy soils are black coloured, heavy and highly acidic.
✅Maharashtra state was divided into 4 by topography
1) Costal areas along west coast
2) Sahyadri hill ranges
3) Deccan Plateau
4) Eastern plains
✅Soils of Maharashtra have divided into 6 groups.
1)Black soils
2)Red Soils
3) Lateritic soil
4)Alluvial soils
5)Forest and hill soils
6) Saline-alkali soils
✅Black soils-have good potash content, medium in Pand low in N and organic matter
✅Clayey soils with clay content 50-60%, mildly alkaline, PH=7.2-8.5, CEC-50 me/
100gm soil, predominant cation is calcium, dominant clay mineral is montmorillonite.
The characteristic darker colour is mainly due to the clay-humus complex and
presence of titaniferous magnetic compounds. Depth is from few to 60 cm and may classed as-
(1) Shallow black soils found on the ridges
(2) Medium black soils as intermediate
(3) Deep black soils in low laying situations.
In pedological languages, such three depth phases are known as toposequences.
✅Eight land capability classes are indicated by Roman numbers from I to VIII . The first 4 classes are suitable for cultivation, of which class I is the best, while class II to IV becomes progressively inferior for growing crops and needs different kinds of soil
conservation measures before bringing them under agricultural crops. Class V to Vl are primarily not suited for cultivation but should be maintained under natural vegetation of forest or grasses. Class eight lands, e.g. are mainly suited for wild life maintenance or for watershed protection.
Read More-
- Basics of Silviculture
- Agriculture History of India
- Silvicultural System of Concentrated Regeneration
- Coppice System of Silviculture
- Branches of Horticulture
