eChapters

13.1. Soil survey and soil mapping

Refers to study and mapping of soils in the fields.

Process of classifying soil types and other soil properties in a given area and geo-encoding such information.

Draws information on geomorphology, theories of soil formation, physical geography, analysis of vegetation and land use patterns.

Primary data for the soil survey are acquired by field sampling and by remote sensing.

Remote sensing principally uses aerial photography (Illuminating the object/ target with pulsed laser light and measuring the reflected pulses with sensor), but LiDAR ( Light Detection and Ranging) and other digital techniques.

Major 2 types of erosion (i) soil erosion and (ii) wind erosion

2.1. Soil erosion

Detachment of soil particles from the surface • Transportation by water, wind, ice or gravity.

1.1. Watershed development

Refers to the conservation, regeneration and judicious utilization of all the resources viz., land, water, vegetation, animal and human within a particular watershed in integrated manner.

Water drainage area on earth’s surface from which runoff, due to precipitation, flows into a single to a larger stream, a river, a lake or the ocean.

1.2. Concept of watershed management

Planning and design of soil and water conservation structures such as bunds, waterways, overflow structures, water harvesting structure.

3.1. Land use classification

3.1.1. Classes

Capability class is the broadest category in the land capability classification system.

Class codes 1, 2, 3, 4, 5, 6, 7, and 8 are used to represent both irrigated and non-irrigated land capability classes.

Class 1: Soils have slight limitations that restrict their use.

Class 2: Soils have moderate limitations that reduce the choice of plants or require moderate conservation practices.

Class 3: Soils have severe limitations that reduce the choice of plants or require special conservation practices or both.

1.1. Status of irrigation in Tamil Nadu

Geographical area of 13 million hectares is ranked eleventh in size among the Indian states.

Net area sown is about 6 million hectares.

3 million hectares or 50% get irrigation facilities.

3.1. Ground water development

3.1.1. Rain water harvesting

Collecting and using precipitation water from a catchments surface.

Extensive rain water harvesting apparatus existed 4000 years ago in the Palestine and Greece.

In ancient Rome, residences were built with individual cisterns and paved courtyards to capture rain water to augment water from city’s aqueducts.

As early as the third millennium BC, farming communities in Baluchistan and Kutch impounded rain water and used it for irrigation dams.

4.1. Water Use Efficiency (WUE)

An efficient irrigation system implies effective transfer of water from the source to the field with minimum possible loss.

To identify the nature of water loss and to decide the type of improvements in the system.

Evaluation of performance in terms of efficiency is prerequisite for proper use of irrigation water.

Term moisture stress is generally applied to the stomata opening and transpiration increases with time until they close due to high temperature.

5.1. Causes of moisture stress in plants

Main reason is extent of transpiration which is affected by leaf size and composition, size and distribution of stomata on leaf, atmospheric humidity, temperature, wind velocity and day length.

High atmospheric temperature due to intense sun and increased transpiration causes closure of stomata and wilting of leaves even, if soil moisture content is not limiting.

This deficit is made up during night due to decreased transpiration.

In plants, moisture content decreases either due to increased transpiration or reduction in absorption or both.

6.1. Quality of irrigation water

Asia per capita water availability has fallen by around 80 per cent during last five decades.

Suitability of waters for a specific purpose depends on the types and amounts of dissolved salts.

Some of the dissolved ions such as NO₃ are useful for crops.

Word manure derived from French word ‘Manoeuvrer, means to manipulate, to work, to produce crop.

2.1. Sources of organic wastes

Cattle shed wastes-dung, urine and slurry from biogas plants.

Human habitation wastes-night soil, human urine, town refuse, sewage, sludge and sullage.

Poultry litter, droppings of sheep and goat.

Slaughter house wastes-bone meal, meat meal, blood meal, horn and hoof meal, fish wastes.

Byproducts of agroindustries-oil cakes, bagasse and press mud, fruit and vegetable processing wastes.

4.1. Physiological disorders in field crops

Identification of physiological disorders in agricultural crops

1.1. Types of energy

1.1.1. Potential energy

Stored energy and the energy of position (gravitational).

1.1.2. Kinetic energy

Energy in motion - the motion of waves, electrons, atoms, molecules and substances. It exists in various forms.

4.1. Tractor

Self propelled power unit having wheels or tracks for operating agricultural implements and machines including trailers.

Tractor engine is used as a prime mover for active tools and stationary farm machinery through power-take off (pto) or belt pulley.

1.1. Plant breeding

An art and science, deals with ways and means to change the genetic architecture of plants so as to attain a particular objective.

For ensuring food security, it is important to breed and develop new varieties that are high-yielding, pests diseases and drought resistant or regionally adapted to different environments and growing conditions.

4.1. Synthetic varieties

Produced by crossing in all combinations, a number of lines that combine well with each other.

Done for both biotic and abiotic stresses.

Biotic stresses are disease and insect pests.

Abiotic stresses are drought, salt, flood, heat, cold, etc.

12.1. Variety release

Superior cultivars are to be purified by breeder and tested for genuiness in 7 generations.

Then, they are forwarded to MLT after RYT, RRYT, PYT and CYT in respective research station.

Based on results of the MLT, strain is forwarded to Adaptive Research Trials (ART).

3.1. GM or transgenic crop

Plant that has a novel combination of genetic material obtained through the use of modern biotechnology.

GM crop contains a gene(s) that has been artificially inserted instead of plant acquiring through pollination.

In 1994, Calgene’s delayed ripening tomato (Flavr-Savr) is first GM food crop.

3.1. Seed generation system

Seed multiplication is nothing but production of a particular class of seed from specific class of seed up to certified seed stage.

5.1. Seed village

Compact area approach in which the whole village is involved in seed production.

Concept is a win-win model (Deepak Mullick)

Semiochemicals are chemical substances that mediate communication between organisms.

Classified into pheromones (intra specific semiochemicals) and allelochemicals (inter specific semiochemicals).

2.1. Types of plant diseases

2.1.1. Types of infection

1. Localized diseases

4.1. Physical methods

Employed for reduction or elimination of primary inoculums that may be present in seed, soil or planting material.

1.1. Weeds

Plants that are unwanted in a given situation and may be harmful, dangerous or economically detrimental.

Weed invasion ranked second to habitat loss in causing biodiversity decline.

Major threat to both the productivity of land and water and integrity of natural ecosystems.

2.1. Based on life span

2.1.1. Annual weeds

1.1. Farm business management

Concerned with resource allocation.

Useful to impart knowledge and skill for optimizing the resource use and maximizing profit.

Classification of the farming systems based on following criteria

Available natural resources, include water, land, grazing areas and forest; climate especially altitude; landscape including slope; farm size, tenure and organization.

Dominant pattern of farm activities and household livelihoods, include field crops, livestock, trees, aquaculture, hunting and gathering, processing and off-farm activities.

6.1. Management of important farm resources

Factors of production are land, labour, machinery, equipments and buildings.

9.1. Risk

Situation in which one knows both possible future and probability outcomes.

4.1. Definition

Kohls and Uhl refer to expansion of firms by consolidating additional marketing functions and activities under a single management.

Establishment of wholesaling facilities by food retailers and setting up of another plant by a milk processor.

15.1. Minimum Support Price (MSP)

MSP are announced by GOI at beginning of sowing season for certain crops on basis of recommendations of CACP.

MSP is price fixed by GOI to protect producer - farmers against excessive fall in price during bumper production years.

Guarantee price for their produce from the Government.

Objectives are to support farmers from distress sales and to procure food grains for PDS.

16.1. World Trade Organization (WTO)

Only global international organization dealing with rules of trade between nations.

Location: Geneva, Switzerland

Established: 1 January 1995

Created by: Uruguay Round negotiations (1986-94)

Membership: 164 members representing 98% of world trade

Budget: 197 million Swiss Francs for 2018

Secretariat staff: 625

Head: Roberto Azevêdo (Director-General)

17.1. Fruit Products Order (FPO), 1995

Promulgated under Section 3 of Essential Commodities Act, 1955.

For regulating sanitary and hygienic conditions in manufacture of fruit, vegetable products.

Mandatory for all manufacturers of fruit, vegetable products to obtain a license under this order.

4.1. Information and Communication Technology

Refers to technologies that provide access to information through telecommunications.

Similar to IT, but focuses on communication technologies.

Includes the Internet, wireless network, cell phones, and other communication medium.

7.1. Sriniketan Project (1914)

Shri Rabindra Nath Tagore in 1914 established a rural reconstruction institute at Sriniketan involving youth from a group of 8 villages.

Maintained a demonstration farm, a dairy and poultry unit, an outdoor clinic, a department of cottage industries and a village school.

Villages were expected to approach these agencies through village workers who lived in villages to obtain solution of their more pressing problems.

Scheme of land development and tree plantation were given due importance.

Experiment on paddy, sugarcane and cotton were undertaken.

9.1. Rural Sociology

Science of rural society.

Study of sociological life in rural setting to discover their conditions and tendencies and to formulate principles of progress.

A.R. Desai: Rural Sociology involves the study of human relationships in rural situations.

10.1. Social value

Ideas which help an individual to discriminate whether a particular object or behaviour is good or bad, desirable or undesirable.

Norms: Times rules which govern the action

Normative behavior: People are expected to behave in accordance with the values held by the individual.

S.C. Dood defined the value as “desiderata” i.e., anything desired or chosen by someone, sometime.

Value may be considered as attitude-related attribute that are projected upon people, objects and situations.

12.1. Women in Agriculture

Women are actively involved in various agricultural activities.

Principle

Standard solutions are the solutions of accurately known concentrations. There are two types of standard solutions viz., primary and secondary.

A known quantity of the substances is dissolved in a volumetric flask and the volume is made upto the mark. Standard solutions prepared in this way are known as primary standard. This method can be used for preparation of standard solutions of substances which satisfy the following conditions.

More often, if the reagent is not a primary standard, a secondary standard solution must be prepared. The chemical is dissolved and made up or diluted to the desired concentration and then it is standardized against a primary standard or against another reliably known secondary standard solution. Such solutions are called as secondary standard solutions.

Soil is analyzed to know the nature of soil, to classify and advocate to farmers about the peculiarities of the soils and how much of fertilizers should be applied for better crop production.

A composite soil, of course, can not be moved to into a laboratory. The value of the laboratory work depends upon care in sampling. Each soil sample needs to be a fair representative of the specific area or horizon worth sampling.

If the sample is to be a representative of an area, it is necessary to take large number of samples spread over the area, pool them and sub-sample it so as to get a sample of desired size. For soil survey work, samples are collected from a profile which is typical of the soil of the surrounding area.

Principle

When water is ponded inside the concentric metallic rings driven into the soil, the rate of recession (fall) of the water level, or the rate of water withdrawn from a supply source used to maintain a constant head of water on the soil surface, gives the infiltration rate of the soil.

During infiltration of water into the soil, appreciable lateral movement of water may also occur. To avoid the error due to this lateral movement, two concentric rings are used. Equal heights of water are to be maintained in both the rings. The infiltration is measured in the inner ring only. The rate of water intake per unit area varies markedly with the size of the rings and the depth of the soil to which they are driven into. Infiltration rate studies are preceded by the profile, initial soil moisture and any other problems of the region in which the soil is located.

[Titrimetric/ Walkley and Black (1934) Method]

Introduction

The role of soil organic matter, in relation to soil fertility and physical conditions, are widely recognized. The organic matter is the source of plant nutrients which are released inassimilable forms during microbial degradation. A major proportion of N (95 – 99 % of the total), P (33 – 67 % of the total) and S (75 % of the total) in soils occur in organic combinations, which mineralize to release the nutrients in inorganic forms to be used by plants. Nevertheless, it serves as a reservoir of plant nutrients, in promoting water storage, and in regulating microbial activity.

The organic matter content of a soil varies from 0.344 % in very sandy arid soils to more than 86 % in Peats and Mucks. Soil organic matter contains 5 % N, and 0.5 % each of P and S, thereby, having a N:P:S ratio of 10:1:1. The organic matter content of a soil is estimated by the amount of organic carbon (C) present, as this element represents, on an average, 52 – 58 % of the organic matter, and the C:N ratio is 10 – 15. In the sub-soil, the average organic carbon amount is 36 – 44 % (40 %), and the C:N ratio is < 8. In order to find out the amount of humified organic material, the organic carbon content is multiplied by 1.724, which represents the ratio between the humus and the organic carbon (100/58) and is known as the ‘von Bemmlen factor ’.

The organic matter content of soils is estimated from the organic carbon, determined by using the ‘Titrimetric method / Walkley and Black method. The Titrimetric determination, also known as the ‘wet-digestion method’ involves a rapid titration procedure for the estimation of organic carbon content of soils.

[Alkaline Permanganate / Subbiah and Asija (1956) Method]

Introduction

Nitrogen (N) is found in the arable horizon of the soil, mostly in organic material. In the soil solution, organic N is gradually transformed into ammoniacal (NH₄ ⁺), nitrite (NO₂ ^–) and nitrate (NO₃ ^–) nitrogen by microbial processes. Organic-N is, in itself, of very little use to plants, as it can not be absorbed as such. It is, therefore, necessary to estimate the different forms of mineralized or available N. The NO₃ ^–_N and NO₂ ^–-N together, hardly, exceed 1 % of the total N in normal soil.

The available N in soil refers to a fraction of the total N which is converted into forms accessible to the plants. This constitutes, on an average, only 0.5-2.5 % (rarely 5 %) of the total N in a soil at any given time. Nitrogen is, generally, absorbed by plants as NO₃ ^–, under oxidized environment (upland condition), and as NH₄ ⁺, under reduced condition. NO₂ ^– is sometimes, detectable, but the amount is, generally, very small vis-a-vis NH₄ ⁺ or NO₃ ^– and, hence does not warrant its determination. The sum total of NH₄ ⁺ and NO₃ ^–- N is smaller than the total N, which becomes available to plants and the difference being attributed to the mineralization of the organic N, during the crop growth cycle.

(Neutral Normal Ammonium Acetate Method)

Introduction

The total potassium (K) content of a soil varies from 0.05 to 2.5 %. The total K is distributed in mineral form (lattice – K, 90-98 %), fixed non-exchangeable or temporarily retrograded K (1-10 %) and exchangeable plus water soluble K (1-2 %). Exchangeable K represents an average of 2 – 15 % of the sum of exchangeable bases and 1 – 3 % of the total capacity for cation exchange. The K concentration in the soil solution is on an average 0.08 – 3 meq/litre. Both water soluble and exchangeable K are most accessible to the plant. Available K can, thus be separated into that, immediately available, which is water soluble and exchangeable, and that, potentially available or fixed. The neutral normal ammonium acetate extract contains both water soluble and exchangeable K. K extraction by this extractant is considered as a suitable index of K availability in most soils, based on crop response correlation study. Thus, the K extracted by this method is equated as the available K.

[Shoemaker, Mc Lean and Pratt (SMP) Method, 1961]

Introduction

For proper plant growth, the soil should have a pH between 6.5 and 7.5, though there are certain plants which can grow satisfactorily at low pH, for example, tea, and at high pH, for example, sugar beet. In India, acid soils are located mostly in Eastern, Southern and South Central parts though some soils, at higher elevations, in North India are acidic.

In order to achieve maximum yield and sustained productivity through efficient soil management practices, it is essential to lime an acid soil, as it has considerable influence on soil environment, besides correcting soil acidity.

Several methods have been proposed to determine the lime requirement of acidic soils, to raise the pH around 6.5. The soil pH value alone, however, is not a good criterion for lime recommendation, because of variations in the exchange acidity of soil, and the nature of crops which may not require as high as this pH to produce maximum yield. Of these various methods proposed, the Shoemaker / SMP method was found satisfactory.

The recent trend of liming is to use it as a fertilizer rather than as amendment so as not to disturb heavily the natural environment while ensuring sustained productivity.

[Schoonover (1952) Method]

Introduction

Sodic (Alkali) and Saline-Sodic soils are characterized by the presence of large amounts of sodium, as high as 15% or more, on their exchange complex. As a result of this, the pH of soils increases beyond 8.0, causing nutritional imbalances, elimination of soil organic matter, deterioration of soil physical condition, etc., besides affecting the soil biotic community. Gypsum (CaSO₄. 2H₂O) is commonly used for the management of such soils, when applied in right amounts and size.

Principle

A given weight of soil is equilibrated with a known amount of Ca solution, and the amount of Ca, left in the solution is determined by EDTA titration. The difference between the amount of Ca added and the Ca left in the solution, gives the amount of Ca exchanged. In practice, gypsum of about 1/3 of the value, obtained by this method, is satisfactory in most cases.

Various physical, chemical and biological factors interdependently affect the fungal colonization or production of the mycotoxin. Physical factors such as temperature, relative humidity and insect infestations create ideal environment for fungal colonization and mycotoxin production. Stresses such as drought, an increase in temperature, and an increase in relative humidity may selectively alter colonization and metabolism of mycotoxigenic fungi and thus alter mycotoxin production (Russell et al., 1991). Cool and damp weather favours the germination of the sclerotia and thus ergot alkaloid formation in fescue and ryegrass.

Biological factors are categorized into intrinsic factor such as fungal species, strain specificity, strain variation and instability of toxigenic properties. Interaction between the toxigenic fungal species and substrate affect the fungal colonization and mycotoxin production. Some plant species are more susceptible to colonization and some resistant plant species may also get infestation due to favourable environmental conditions.