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OF AGRONOMY development of crop and its growing period based on temperature and/or day length. They are used to quantify the rate of crop growth in terms of radiation interception, water use and nutrient supply which moderate harvest index, when the crops experience stress condition. The basic information required to b... | Agricultural_studies.pdf | Agri life sciences |
on soil N content and rate of availability to the roots. Thus, physical place of N in the visibility of root system and transformation is important. Phenological model These models predict the crop development from one growth stage to another. The prediction is generally based on the accumulated heat limits. Mechanisti... | Agricultural_studies.pdf | Agri life sciences |
information on intermediate steps like daily weight of different plant parts, which is verified through experimentation. The model acts like a real crop be gradually growing leaves, stems, roots etc., during a season. In other words, simulation is the process of using a model dynamically by following a system over a ti... | Agricultural_studies.pdf | Agri life sciences |
contains descriptions of distinct processes such as leaf area expansion, tiller production etc. Crop growth is a consequence of these processes. D. Uses of Crop Weather Modeling The models can be used as a research tool in planning alternative strategies for cropping, land and water management practices for a range of ... | Agricultural_studies.pdf | Agri life sciences |
in CO2 from 180 ppm to 350 ppm. The earth’s atmosphere has never been free of change (in its composition, temperature, self-cleaning ability). Due to change in atmosphere, the world is warming, climatic zones are shifting; glaciers are melting and sea level is rising. B. Climate Variability The temporal changes in weat... | Agricultural_studies.pdf | Agri life sciences |
El-Nino events, the strongest of the last century is estimated to have affected 110 million people and cost the global economy nearly US $ 100 billion. Statistics compiled from insurance companies for the period 1950-1999 show that major natural catastrophes that are mainly weather and climate related caused estimated ... | Agricultural_studies.pdf | Agri life sciences |
ENSO phenomena • Anthropogenic causes of climate variation in green house gases and aerosols. D. Effects of Climate Change The increase in concentration of CO2 and other green house gases are expected to increase the temperature of the earth. Crop production is weather dependant and any change will have major effects o... | Agricultural_studies.pdf | Agri life sciences |
activities increase carbon dioxide, methane, nitrous oxide, chlorofluorocarbons (CFC) etc., which lead to increase in temperature and sea level rise. These gases, which are in traces, cause environmental perturbations (disturbances) such as green house effect (global warming), stratospheric ozone depletion, acid deposi... | Agricultural_studies.pdf | Agri life sciences |
about 10 to 30 miles straight up. From the beginning of time, the ozone has blocked the sun’s most dangerous ultraviolet rays from reaching us. It continues to do so even today. Each ozone molecule is made up of three small oxygen atoms that act like a safety net to catch most of the UV rays and keep them from getting ... | Agricultural_studies.pdf | Agri life sciences |
ozone layer. One chlorine atom can break apart more than 100,000 ozone molecules. 236 A TEXTBOOK OF AGRONOMY Other chemicals that damage the ozone layer include methyl bromide (a pesticide), halons (used in fire extinguishers), and methyl chloroform (a solvent used in industrial processes). As methyl bromide and halons... | Agricultural_studies.pdf | Agri life sciences |
greenhouse gases. We can do this by carpooling, using more efficient cars or electrical cars, not purchasing aerosol products and by getting our air conditioners serviced annually. Another simple way to help is to turn off electrical appliances when they are not being use. This will reduce the amount of electricity bei... | Agricultural_studies.pdf | Agri life sciences |
because El-Nino occurs around Christmas time each year when the water of the Peruvian coast warm slightly. In every 3–6 years, the water becomes unusually warm. ‘El Niño’ is now used more widely to refer to this abnormal warming of the ocean and the resulting effects on weather. ‘El Niño’ is often coupled with ‘Souther... | Agricultural_studies.pdf | Agri life sciences |
South central pacific and Darwin in North Australia, which represents the northern part of the Indian Ocean. The positive SOI denotes high pressure over the central pacific and low over Indonesia, North Australia and Northern Indian Ocean. Above average rainfall is expected over India and Indonesia and North Australia ... | Agricultural_studies.pdf | Agri life sciences |
the end of 1972 as series of catastrophic events in different parts of the world drew attention to their possibility of global teleconnection in weather, the monsoon off 1972 was poor-severe drought in Northern Africa. Around the same period of this are abnormal current of warm waters off the coast of few in the Easter... | Agricultural_studies.pdf | Agri life sciences |
farmer, soil refers to the cultivated top layer (surface soil) only, that is, up to 15–18 cm of the plough depth. Soils widely vary in their characteristics and properties. Understanding the properties of soils is important (1) for optimum use they can be put to and (2) for best management requirements for their effici... | Agricultural_studies.pdf | Agri life sciences |
Normally the proportion is 50:25:25, but this may vary from soil to soil. In some occasions, liquid or gaseous phase may be absent. For e.g., in water logged soil, air is not present; similarly in desert dry sandy soils, water is not present. SOILS 239 Components of Soil Soil consists of four major components. They are... | Agricultural_studies.pdf | Agri life sciences |
has been derived. The rock fragments are disintegrated and broken portion of the massive rocks, from which regolith through weathering, the soil has been formed. These materials are usually very coarse and the minerals are extremely variable in size. The primary minerals viz., quartz, biotite, muscovite (dominates coar... | Agricultural_studies.pdf | Agri life sciences |
chelate, due to chelate formation between organic matter and various metals; the availability of these metallic elements will be increased. • It contributes to cation exchange capacity in soils. • It reduces soil erosion; shades the soil and keeps the soil cooler. (c) Soil water Soil water plays a very significant role... | Agricultural_studies.pdf | Agri life sciences |
During rainy season, water replaces air from the soil pore spaces, but as soon as water leaves by downward movement, surface evaporation, and transpiration etc., air gradually replaces the water, as it is lost form the pore spaces. Soil air contains various gases like CO2, very small amounts of O2 and N etc. Generally,... | Agricultural_studies.pdf | Agri life sciences |
1-5% by weight in different soils. Normally in tropics, red soil contains less than 1% and heavy soil up to 2%. (c) Chemical compounds The chemical components of soils are made of silica and silicates. It varies from profile to profile; generally the larger particles contain more silica content and finer particles cont... | Agricultural_studies.pdf | Agri life sciences |
pore spaces enclosed by soil matrix are shared by soil-air and soil-water. As the amount of one increases, that of the other decreases. Table 5.1. Composition of Soil and Atmospheric Air (%) Air O2 CO2 N2 Soil air 20.05 0.25 79.20 Atmospheric air 20.97 0.03 78.03 5.2 PROPERTIES OF SOIL 5.2.1 Physical Properties of Soil... | Agricultural_studies.pdf | Agri life sciences |
sand 1-0.5 mm Medium sand 0.5-0.25 mm Fine sand 0.25-0.1 mm Very fine sand 0.1-0.05 mm Silt 0.05.0-0.002 mm Clay < 0.002 mm Out of these systems, the textural classification based on size of soil particles is commonly followed in India. Based on the proportion of sand, silt and clay particles, classification was made a... | Agricultural_studies.pdf | Agri life sciences |
when wet and hard when dry, high water holding capacity (WHC), relatively high nutrient holding capacity, slow movement of water and air, hardier for workability of implements and slow release of water to plants with poor drainage are its important features. (c) Silt It contains 80% silt and less than 12% of clay. Medi... | Agricultural_studies.pdf | Agri life sciences |
(i) Stones and gravel If stones and gravels are present < 10 percent, it reduces evaporation, facilitates good drainage, and results in easiness for the workability of tillage and intercultural implements. If stones and gravels are present > 10 percent, Soil will be too open and loose; It permits rapid drainage; It red... | Agricultural_studies.pdf | Agri life sciences |
of organic and inorganic soil colloids. The binding or cementing materials are: Iron or Aluminium Hydroxide and decomposing organic matter. The names of soil structures based on their shapes are: 1. Platy, 2. Prismatic, 3. Columnar, 4. Blocky, 5. Cloddy, 6. Granular, 7. Crumb, 8. Single grain, and 9. Massive. SOILS 245... | Agricultural_studies.pdf | Agri life sciences |
When the units are thin, they are called laminar. The platy is often inherited from the parent Single grain Blocky Platy Rapid Rapid Moderate Moderate Slow Slow Granular Prismatic Massive 246 A TEXTBOOK OF AGRONOMY materials. In addition, frost, fluctuating water table, compaction and this layering of different texture... | Agricultural_studies.pdf | Agri life sciences |
as granular and it is less porous, and (b) crumb, when the granules are especially porous. II. Classes of soil structure: Each primary structural type of soil is differentiated into five size classes based on the size of the individual peds. They are as follows: • Very fine or very thin • Fine or thin • Medium • Coarse... | Agricultural_studies.pdf | Agri life sciences |
is associated with tilth of soil. The permeability of water and air into the soil and penetration of roots are influenced primarily by soil structure. It is the determining factor for the soil porosity, bulk density, etc. Hence it directly plays a role on water retention, permeability, etc. SOILS 247 There are two dist... | Agricultural_studies.pdf | Agri life sciences |
compaction and use of soil conditioner may be tried for better soil structure management. D. Soil physical properties with reference to volume–weight relationship This relationship can be simply explained through a schematic diagrams as indicated below: Fig. 5.4 Schematic diagrams Va – Volume of air Vw – Volume of wate... | Agricultural_studies.pdf | Agri life sciences |
equal volume of water and hence known as real specific gravity or true specific gravity which is more than or equal to particle density. Wt. of unit volume of soil solid Wt. of an equal volume of water 5.2.1.6 Apparent Specific Gravity (ASG) It is the ratio of weight of unit volume of dry soil including pore spaces to ... | Agricultural_studies.pdf | Agri life sciences |
65% depending upon the bulk density. (b) Volume wetness Relative water content expressed in volume basis of water and soil Volume of water in soil Vw Total soil volume Vt = = Vw Vw Vs Va = + + Degree of saturation Represents to the volume of water present in the pore spaces. Vw Vw Degree of saturation Va Vw Vp = = + Th... | Agricultural_studies.pdf | Agri life sciences |
enclosed container having big particles is less than that of small particles. The size of individual pores is highly important for the movement of water in soil than the percentage of total pore space in soil. For example, percentage of pore space is high in clay soil, which contains more micropores where water movemen... | Agricultural_studies.pdf | Agri life sciences |
alone excluding of pore space is taken for consideration. Porosity is the comparison between the volume of pores to the total volume of soil i.e., including pore space is given consideration. Hence this index has certain advantage and accuracy over porosity. Capillary and non-capillary pores The soil pores are also cla... | Agricultural_studies.pdf | Agri life sciences |
and pore spaces in equal proportion. 5.2.2 Soil/irrigability Classification Soil is the reservoir for water in retaining and supplying the soil moisture to plant growth. The periodical recharging of water in soil pore spaces can be made either by irrigation or rainfall. The recharged water has to be supplied to plant s... | Agricultural_studies.pdf | Agri life sciences |
into 5 classes as I to V for the purpose of irrigation, survey and mapping as follows. Group I It is indicated in green colour in soil mapping. The soil has the characteristic features of: • Good available moisture holding capacity • Low water table • Low salts either soluble or exchangeable • No soil crust and pan for... | Agricultural_studies.pdf | Agri life sciences |
salt content (0.5%) • low moisture supplying capacity • low internal permeability. Group V It is indicated in dark green colour. 252 A TEXTBOOK OF AGRONOMY • The soil is shallow in depth • Total soluble salt and exchangeable sodium percentage is high (more than 25%) • Stony impervious layers • Severe crust and pan form... | Agricultural_studies.pdf | Agri life sciences |
extreme deficiencies or limitations with soil respect to drainage, topographic undulations even though it is suitable for irrigation. Class IV • Some lands in this may be costly to irrigate but due to intensive cropping the returns are adequate. • The reclamation cost will be high in some lands. • Yields of crops are v... | Agricultural_studies.pdf | Agri life sciences |
the force of attraction between molecules of different substance. That is the force of attraction between solid surface (soil mass) to liquid surface (soil water). A thin film of water is held in soil particles due to this adhesive force. B. Cohesion Cohesion is the force of attraction between molecules of same substan... | Agricultural_studies.pdf | Agri life sciences |
water column To convert the soil moisture tension to equivalent atmosphere, the above conversion ratio can be used. 254 A TEXTBOOK OF AGRONOMY But here, there is no real vertical pressure of water column. Hence, it can be stated as suction or negative pressure. Hence, soil moisture tension of one atmosphere is approxim... | Agricultural_studies.pdf | Agri life sciences |
the unavailable form of water. This condition mostly occurs at permanent wilting point stage or dry condition. 2. Capillary water This is the next stage after attaining hygroscopic water, with reference to soil-water relationship. In this stage there is relatively better thick film of water around the soil particles an... | Agricultural_studies.pdf | Agri life sciences |
tension. Due to the surface tension, the liquid tries to move tangentially along the water surface. This movement is called capillary water movement and the available water to plant is decided by the capillary water, which will be the function of pore space, which again depends upon the soil texture, structure and orga... | Agricultural_studies.pdf | Agri life sciences |
a specific language, which is a shorthand impression on the nature of the soil profile. • It helps the soil scientists to remember the soil properties very easily. • It easily establishes the relationship between soil individuals. • It predicts the soil behaviour with reference to the purpose for which put into. • It i... | Agricultural_studies.pdf | Agri life sciences |
in Indo-gangetic alluvial soils of Uttar Pradesh and West Bengal. In Assam, old alluvium at hills is more acidic than the new alluvial soils along the riverbanks, which are often neutral or alkaline. In general alluvial soils are low in N except in Brahmaputra valley where they are moderate. Alluvial soils are found in... | Agricultural_studies.pdf | Agri life sciences |
are: • formed from granites, gneiss and other metamorphic rocks either in-situ or from decomposed rock materials • with Argillic subsurface horizon • Occur in semi-arid tropics • Light textured, friable, absence of lime and CaCO3 and low contents of soluble salts • Kaolinite with an admixture of illite clay minerals • ... | Agricultural_studies.pdf | Agri life sciences |
productive under water supply • Dominantly illitic with smaller amount of kaolinite, chlorite, vermiculite 5.4.6 Tarai Soils (Mollisols) Tarai soils are derived from the materials washed down by the erosion of mountains (alluvial origin). Characteristics • Hard clay, coarse sand and gravel (parent material) • Relativel... | Agricultural_studies.pdf | Agri life sciences |
pH: > 8.5; EC: < 4d Sm-1 ; ESP : > 15. Use gypsum (CaSO4 2H2O) as amendment for reclamation of sodic/alkali soils. Iron pyrites, (FeS2) bulky organic manures (especially green manures) and crop residues which produce weak organic acids are also used for reclamation. Crops having tolerance are grown in the soils. (i) To... | Agricultural_studies.pdf | Agri life sciences |
heavily leached and therefore, poor in basic elements and plant nutrients. Their pH ranges from 6.6-8.0. Calcium is the important exchangeable cation in these soils. They are neutral to slightly alkaline in reaction. 5.5.1 Black Soils or Vertisol About 18 lakh ha occurs in all districts except Kanyakumari and Nilgiris.... | Agricultural_studies.pdf | Agri life sciences |
higher elevation. They are rich in humus and plant nutrients and strongly acidic in reaction. Soil acidity increases with elevation. 5.5.3 Alluvial Soils or Entisols It covers an area of more than 18 lakh ha in all districts except Madurai, Dindugal. The soils are river alluvium, Coastal alluvium and eroded soils. Rive... | Agricultural_studies.pdf | Agri life sciences |
marine deposits are similar to Cauvery alluvium in their alternate layers of clay, silt and sand but exhibit influence of sea indicated by the presence of shells and bleached sand. They are poor in nitrogen and available phosphorus but rich in potash and lime. Some of them also contain salts. 5.5.4 Peaty Soils Peaty so... | Agricultural_studies.pdf | Agri life sciences |
moderately well developed sub soil. 260 A TEXTBOOK OF AGRONOMY The soils are cultivated with sorghum, groundnut, cumbu, pulses and tapioca. Under irrigated condition, groundnut, maize, onion, tapioca etc. Poor in lime N, P, rich in Kaolinite clay minerals, CEC 10-15 c.mol(p+)kg−1. 5.5.8 Ultisols Area 36, 499 ha occur i... | Agricultural_studies.pdf | Agri life sciences |
climate Salt affected soil are mostly formed in arid and semi arid regions where low rainfall and high evaporation prevails. (c) Ground water If ground water contains large amounts of water soluble salts, irrigation of such water leads to accumulation of salts in soil. (d) Ocean or seawater Seawater enters into the lan... | Agricultural_studies.pdf | Agri life sciences |
Restricted drainage is another factor that usually contributes to the soil salinization and may involve the presence of a high ground water table. C. Characteristics • When the soil contains excess of sodium salts while in clay complex still contains preponderance of exchangeable calcium. • The salts usually present in... | Agricultural_studies.pdf | Agri life sciences |
saline soil the soluble salt concentration in soil solution is very high and as a result osmotic pressure of the solution is also very high. As a result of which the plant growth is affected due to wilting and nutrient deficiency. Salt content more than 0.1% is injurious to plant growth. (b) Osmotic pressure (OP) Osmot... | Agricultural_studies.pdf | Agri life sciences |
with the same amount of salt may be just a normal soil in which the yields of even sensitive crops would not be affected. The US Salinity Laboratory has developed the concept of saturation percentage which depends on texture of soil and that is used for characterizing saline soil. E. Reclamation In saline soils, reclam... | Agricultural_studies.pdf | Agri life sciences |
EC × × = where LR – Leaching requirement in percentage Ddw – Depth of drainage water in inches Diw – Depth of irrigation water in inches ECiw – EC of irrigation water (dSm-1) ECdw – EC of drainage water (dSm-1) If the soil is not free draining, artificial drains are opened (or) tile drains laid underground to help in w... | Agricultural_studies.pdf | Agri life sciences |
becomes the dominant cation in the soil solution. In arid regions as the solution becomes concentrated through evaporation or water absorption by plants, the Ca2+ and Mg2+ are precipitated as CaSO4, CaCO3 and MgCO3, with a corresponding increasing of sodium concentration. When the Na+ concentration is more than 50% of ... | Agricultural_studies.pdf | Agri life sciences |
2 Na SAR Ca Mg 2 + + = + 264 A TEXTBOOK OF AGRONOMY (Na+, Ca2+, Mg2+ are concentrations in saturation extract in me.l-1). The value of SAR can be used for the determination of exchangeable sodium percentage (ESP) ( ) ( ) 100 0.0126 0.0147 SAR ESP 1 0.0126 0.0147 SAR − + ≈ + − + The following regression equation is also... | Agricultural_studies.pdf | Agri life sciences |
is not impaired. While removing exchangeable sodium, the presence or absence of calcium carbonate in the soil has to be taken into consideration. If the soil has no reserve CaCO3, the addition of CaSO4 (Gypsum) is necessary. (b) Gypsum Requirement (GR) The main principle for the reclamation of sodic soil is to replace ... | Agricultural_studies.pdf | Agri life sciences |
from soils by leaching is presently practicing, but the leached salts have been washed into groundwater or streams, making those water more salty. Due to use of such water the soils are further subjected to salt problems. With this view, a new concept in managing soils has been developed and that is known as precipitat... | Agricultural_studies.pdf | Agri life sciences |
to a certain extent and the cracks allow more easy percolation of water. Both these processes hasten the removal of sodium salts and wash them to deeper layers. (d) Prevention • Avoid excess water table by following judicious water management practices • Ensure free and efficient drainage • Flooding of land with large ... | Agricultural_studies.pdf | Agri life sciences |
exchangeable sodium and soluble salts. A. Genesis/origin These soils are formed as a result of the combined process of salinization and alkalization. If the excess soluble salts of these soils are leached downward, the properties of these soils may change markedly and become similar to those of sodic soil. As the conce... | Agricultural_studies.pdf | Agri life sciences |
of break down of H-clay under alkaline condition is known as “solodization”. 5.7 SOIL PRODUCTIVITY CONSTRAINTS 5.7.1 Physical Constraints The following are the physical constraints. • Highly permeable soils • Impermeable soils (slowly permeable) • Crusted soils • Subsoil hard pan • Fluffy paddy soils 1. Highly permeabl... | Agricultural_studies.pdf | Agri life sciences |
cement have been found to arrest the higher rate of nutrient and water losses in sandy soils. This technology is costly. • Compaction technology The soils should be ploughed uniformly. About 24 hours after a good rainfall (or) irrigation, the soil should be rolled 10 times with 400 kg stone roller of 1 m long (or) an e... | Agricultural_studies.pdf | Agri life sciences |
• Very high clay content and bulk density • Poor drainage, hydraulic conductivity and infiltration rate due to higher proportion of pores • Temporary water logging of the soil develops oxygen stress in root zone • Development of salinity with poor drainage • High soil pH and calcareousness may promote ammonia volatiliz... | Agricultural_studies.pdf | Agri life sciences |
along the slope (or) across the slope with drainage furrows in between broad beds. • The productivity of sodic clay soils can be increased to a significant extent through use of gypsum and agricultural grade iron pyrites. • Long term application of organic manures along with chemical fertilizer under well aerated condi... | Agricultural_studies.pdf | Agri life sciences |
iron plough which goes up to 45 cm depth, thereby shatters the hard pan in the subsoil. • The field is to be ploughed with chisel plough at 50 cm interval in both the directions • Chiseling helps to break the hard pan in the subsoil • Farm yard manure (or) press mud (or) coir pith at 12.5 t/ha is to be spread uniformly... | Agricultural_studies.pdf | Agri life sciences |
under the impact of rain drops. The quantity of dispersed soil increases with the increase in drop size, drop velocity and rainfall intensity. The hydration of aggregates causes a disruption through the process of swelling and explosion of entrapped air. The fine fractions go into the suspension, which may either enter... | Agricultural_studies.pdf | Agri life sciences |
of seeds/hill may be adopted for small seeded crops. • sprinkling water at periodical intervals may be done wherever possible. • resistant crops like cowpea can be grown. • most of the red and laterite soils are poor in organic matter and therefore deficient in nitrogen. Organic manures and use of biofertilizers holds ... | Agricultural_studies.pdf | Agri life sciences |
roots and the yield of crops is adversely affected. Remedial measures • The irrigation should be stopped 10 days before the harvest of rice crop. • After the harvest of rice, when the soil is under semi-dry condition (proctor moisture level), compact the field by passing 400 kg stone roller or on empty drum filled with... | Agricultural_studies.pdf | Agri life sciences |
Acid forming fertilizers and soluble salts The use of ammonium sulphate and ammonium nitrate increases soil acidity. For (e.g.), ammonium ions from (NH4)2 SO4 when applied to the soil replace calcium ions from the exchange complex and the calcium sulphate is formed and finally leached out. (NH4)2SO4 NH4 + SO4 Ca SO4+ O... | Agricultural_studies.pdf | Agri life sciences |
oxides of iron and aluminium. Under favourable conditions they undergo stepwise hydrolysis with the release of H+ ions in the soil solution and develop soil acidity. Aluminium in the development of soil acidity Hydrogen ion contribute soil acidity directly while aluminium ions do so indirectly through hydrolysis. In aq... | Agricultural_studies.pdf | Agri life sciences |
0 + H+ B. Kinds of soil acidity Soil acidity may be of two kinds viz., 1. Active acidity, and 2. Potential/reserve/exchange acidity. Adsorbed H (and Al) ions ⎯⎯→ Soil solution H (and Al) (potential/exchange/reserve acidity) ←⎯⎯ (Active acidity) (a) Active acidity Active acidity may be defined as the acidity developed d... | Agricultural_studies.pdf | Agri life sciences |
Fe2+ respectively and toxicity of these elements develops. Due to such toxic effects, a physiological disease of rice is found in submerged soils, which is popularly known as “browning disease”. (c) Toxicity of Aluminium (Al) Al toxicity in soils affects pant growth in various ways: • It restricts the root growth. • It... | Agricultural_studies.pdf | Agri life sciences |
tobacco, blights of potato etc. E. Amelioration of soil acidity One of the most important feasible management practices is the use of lime and liming materials to ameliorate the soil acidity. (a) Lime requirement It may be defined as the amount of liming material that must be added to raise the pH to some prescribed va... | Agricultural_studies.pdf | Agri life sciences |
water and calcium ion from limestone is left to undergo cation exchange reactions. The acidity of the soil is, therefore, neutralized and the percent base saturation of colloidal material is increased. (b) Why gypsum is not considered as liming material Gypsum, on its application dissociates into Ca2+ and SO4 2− CaSO4 ... | Agricultural_studies.pdf | Agri life sciences |
plant pathogens, e.g., Club root disease of Cole crops can be reduced by liming • Liming increases the efficiency of different fertilizers especially N and P fertilizers. (d) Over liming If liming materials are applied over and above its requirement then it is called over liming. (e) Effects of over liming When excessi... | Agricultural_studies.pdf | Agri life sciences |
sulphates particularly salt water, accumulate sulphur compounds, which in poorly aerated soils are bacterially reduced to sulphides. Such soils are not usually acidic when first drained in water. When the soil is drained and then aerated, the sulphide (S2) is oxidized to sulphate (SO4) by a combination of chemical and ... | Agricultural_studies.pdf | Agri life sciences |
disease that prevents rice plants roots from absorbing nutrients. C. Management Maintaining the reduced condition of flooded (anaerobic) soil inhibits acid development. (a) Controlling water table If a non-acidifying layer covers the sulphuric horizon, drainage to keep only the sulphuric layer under water (anaerobic) i... | Agricultural_studies.pdf | Agri life sciences |
development schemes. It is also useful to delineate agricultural, forestry wastelands etc. At town level, soil survey reports are of immense use for town planning or locating areas for residential building, roads, parks, waste disposal sites, other sanitation facilities etc., In an agro climatic region, soil survey hel... | Agricultural_studies.pdf | Agri life sciences |
of soil survey are numerous. A few important applied practical objectives are listed below. • To delineate cultivated soils, problem soils (such as saline soil, saline-alkali and alkali, water logged, drained soils, coarse and heavy textured soils and wastelands. • To identify areas prone (subject) to wind and water er... | Agricultural_studies.pdf | Agri life sciences |
series or Some boundaries association of are checked most soil series inferred Detailed low 1:10,000 1 100 m 1 per ha Phases and soil Almost intensity all boundaries are checked High intensity 1:5,000 0.25 50 m 4 per ha Phases and soil All boundaries series are checked Each type can be distinguished by the scale of map... | Agricultural_studies.pdf | Agri life sciences |
field. Using the map again, the entire area is traversed to note physiographic relationship. Wherever necessary and whenever available cross section of road cuts, dug well, open quarries are examined visually, the soils are examined with augers. The broad soil series and its associations are demarcated on the map and l... | Agricultural_studies.pdf | Agri life sciences |
photographs. The density of observation will vary. Chapter 6 Seasons and Systems of Farming Season is defined as “part of the year during which a distinguished type of weather prevails”. Season is a period in a year comprising few months during which the prevailing climate does not very much. Growing season for a crop ... | Agricultural_studies.pdf | Agri life sciences |
follows: (i) Cold weather period (winter) : January–February 280 A TEXTBOOK OF AGRONOMY (ii) Hot weather period (summer) : March–May (iii) South-West Monsoon period : June–September (Rainy season) (iv) North-East Monsoon period : October–December 6.1.1 Characteristics of Seasons A. Winter or Cold weather The weather pr... | Agricultural_studies.pdf | Agri life sciences |
the middle of October and later starts falling rapidly. The rainfall received during the period is about 33% of annual rainfall except in Tamil Nadu and Coastal Andhra Pradesh where the annual rainfall received during this period is more than 55% half of it with occasional cyclones. The sky is clear in northern India. ... | Agricultural_studies.pdf | Agri life sciences |
June–July planting 6.1.3 Agronomic Concepts of the Growing Seasons Agronomically the growing season can be defined as the period when the soil water, resulting mainly from rainfall, is freely available to the crop. This condition occurs when the water consumed by the crop is in equilibrium with rainfall and water stora... | Agricultural_studies.pdf | Agri life sciences |
period There are four types of growing period. 1. Normal: In this type, rainfall is in excess during the humid period. At the end of the pre-humid period when precipitation is higher than the 0.5 PET sowing the crops are taken up. This type of growing season is prevalent in semi arid tropics. 2. Intermediate type: The ... | Agricultural_studies.pdf | Agri life sciences |
This may favourably influence the yield. In India, four cropping seasons have been identified by IMD in dry farming areas. Table 6.1. IMD seasons S.No Name of the season Duration Water need Crops from rainfall 1. Short duration Up to 10 weeks 75% Very short duration crops 2. Medium duration 10-15 weeks 75% Medium durat... | Agricultural_studies.pdf | Agri life sciences |
under a common management. Farming is the process of harnessing solar energy in the form of economic plant and animal products or it is the business of cultivating land, raising livestock etc. System refers to an orderly set of interdependent and interacting components none of which can be modified Fig. 6.1 A successfu... | Agricultural_studies.pdf | Agri life sciences |
for a least several weeks in each year (or) to crop growth in such soils. The water is not entirely under the control of the farmer. Wetland Farming is the practice of growing crops in soils flooded through natural flow of water for most part of the year. 2. Garden land The garden land system means the land supplied wi... | Agricultural_studies.pdf | Agri life sciences |
land Rainfed 1. Farming practices 9-12 moths 9-12 months <6 months 6-8 months (duration) 2. Source of water river, lake, wells rainfall rainfall pond/tank (800 mm/year) (800 mm/year) 3. Climate arid to humid arid to humid arid to semi-arid sub humid to humid 4. Irrigation natural flow lift irrigation -no irrigation5. W... | Agricultural_studies.pdf | Agri life sciences |
2 crops in a year are Grown, subject to the crops in a year is possible. availability of water. 8. Crop failure (risk) is expected. No chance of crop failure (no risk). Farming system Farming systems represent an appropriate combination of farm enterprises viz., cropping systems, livestock, fisheries, forestry, poultry... | Agricultural_studies.pdf | Agri life sciences |
as to make the soil into fine particles. 7.0 DEFINITION Tillage refers to the mechanical manipulation of the soil with tools and implements so as to create favourable soil conditions for better seed germination and subsequent growth of crops. Tilth is a physical condition of the soil resulting from tillage. Tilth is a ... | Agricultural_studies.pdf | Agri life sciences |
soil for easy root penetration and proliferation; • To remove other sprouting materials in the soil; • To control weeds; • To certain extent to control pest and diseases which harbour in the soil; TILLAGE 287 • To improve soil physical conditions; • To ensure adequate aeration in the root zone which in turn favour for ... | Agricultural_studies.pdf | Agri life sciences |
Tillage operations done for raising the crops in the same season or at the onset of the crop season are called as on season tillage. They are, A. Preparatory Tillage It refers to tillage operations that are done to prepare the field for raising crops. It is divided into three types viz., (i) primary tillage, (ii) secon... | Agricultural_studies.pdf | Agri life sciences |
and structural development of the soil are the objectives. 288 A TEXTBOOK OF AGRONOMY B. Inter Tillage/Inter Cultivation It refers to shallow tillage operation done in the filed after sowing or planting or prior to harvest of crop plants i.e., tillage during the crop stand in the field. It includes inter cultivating, h... | Agricultural_studies.pdf | Agri life sciences |
temperate regions where the winter is severe that makes the field unfit for raising crops. Ploughing or harrowing is done in places where soil condition is optimum to destroy weeds and to improve the physical condition of the soil and also to incorporate plant residues. (d) Fallow tillage It refers to the leaving of ar... | Agricultural_studies.pdf | Agri life sciences |
(iv) Strip tillage Ploughing is done as a narrow strip by mixing and tilling the soil leaving the remaining soil surface undisturbed. (v) Clean tillage Refers to the working of the soil of the entire field in such a way no living plant is left undisturbed. It is practiced to control weeds, soil borne pathogen and pests... | Agricultural_studies.pdf | Agri life sciences |
AFFECTING (INTENSITY AND DEPTH OF) THE TILLAGE OPERATIONS Several factors are responsible for deciding intensity and depth of tillage operations. They are soil type, crop and variety, type of farming, moisture status of the soil, climate and season, extent of weed infestation, irrigation methods, special needs and econ... | Agricultural_studies.pdf | Agri life sciences |
of tillage. Crop following rice needs repeated preparatory tillage for obtaining an ideal seedbed. Crops following tuber crops like potato require minimum tillage. Similarly crops following pulses need lesser tillage than that of following sorghum, maize or sugarcane. 7.6 DEPTH OF PLOUGHING Desirable ploughing depth is... | Agricultural_studies.pdf | Agri life sciences |
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