eChapters

[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.

The pH is defined as negative logarithm of hydrogen ion concentration or the log of the reciprocal of the hydrogen ion concentration (Sorenson, 1906).

Principle

A glass electrode in contact with hydrogen ions of the solution acquires an electric potential which depends on the concentration of hydrogen ions. This is measured potentiometrically against some reference electrode which is usually a calomel electrode. The potential difference between glass electrode and calomel electrode is expressed in pH units.

Two electrodes are used in the determination of pH. One is reference electrode which provides a standard voltage and is usually a saturated calomel electrode which has two layers of saturated solution of KCl and mixture of solid HgCl₂ and Hg. The outer tube is usually 5-15 cm long, 0.5-1 cm in diameter. The mixture of solid HgCl₂ + Hg paste is contained in an inner tube that is connected to the saturated KCl solution in the outer tube by means of small opening. The resistance developed by this type of electrode is 2000-3000 Ohms.

The outer electrode is glass electrode that consists of a tube enclosing a lead wire made up of Ag coated with AgCl. This wire is again enclosed in a wax insulation. To the tube at the bottom is attached a glass bulb made up of a special kind of glass which is sensitive to hydrogen ions. The thickness of the glass membrane varies from 0.03 to 0.1 mm and has a resistance of 50 to 500 mega Ohms.

When these electrodes are dipped in solution, the saturated solution of KCl comes out of reference through small holes and forms an invisible ionic bridge between electrodes through which current passes. The hydrogen ions are absorbed by glass electrode and depending upon the amount of hydrogen ions present in the solution, an electric potential develops between electrodes. This potential difference is measured in terms of pH units by suitable Galvanometer.

13.1 Introduction

Eutrophication, means an increase in chemical nutrients — typically compounds containing nitrogen and phosphorus in an ecosystem. It may occur on land or in water. The term is however often used to mean the resultant increase in the ecosystem’s primary productivity (Fig. 13.1), in other words excessive plant growth and decay and even further impacts, including lack of oxygen and severe reductions in water quality and in fish and other animal populations.

Successful irrigation development requires careful evaluation of soil and land characteristics before irrigation is introduced or expanded. This chapter deals with the principles and criteria used to evaluate land for irrigation and determine its suitability for sustained agricultural production. Important soil and land characteristics considered include surface-soil texture, particle-size class of the subsoil, coarse fragments, soil depth, permeability, salinity, exchangeable sodium percentage, slope and drainage. These factors determine the ability of land to store and transmit water, support root growth and withstand potential problems associated with irrigation. The chapter introduces land irrigability classification and explains the overall capability index (Ci), including its calculation and interpretation. Subclasses are considered to identify specific limitations affecting irrigated agriculture. The chapter further discusses land suitability classification and the structure used for assessing suitability. Physical condition of soil is included as an important component of land evaluation. By integrating soil, water and landscape characteristics, the chapter provides a systematic basis for identifying suitable land, recognizing limitations and planning sustainable irrigation development.

Abstract

The paper presents an approach of selecting suitable areas for artificial groundwater recharge structures through remote sensing and integrated terrain analysis by statistical method. The study area “Ayyar basin” is an aquifer system of gneisses and charnockite litho-units in Tiruchirappalli district, Tamil Nadu. The area has witnessed a steady decline in groundwater table. Hence, the scope for artificial groundwater recharge was studied in this area with the help of Tamil Nadu State Council for Science and Technology (TNSCS&T).

10.1 Evapotranspiration (ET = Evaporation + Transpiration)

Evaporation is a diffusive process by which water from natural surfaces, such as free water surface, bare soil, from live or dead vegetation foliage (intercepted water, dewfall, guttation etc) is lost in the form of vapour to the atmosphere. It is one of the basic components of hydrologic cycle.

Likewise transpiration is a process by which water is lost in the form of vapour through plant surfaces, particularly leaves. In this process water is essentially absorbed by the plant roots due to water potential gradients and it moves upward through the stem and is ultimately lost into the atmosphere through numerous minute stomata in the plant leaves. It is basically an evaporation process. However, unlike evaporation from a water or soil surface, plant structure and stomatal behaviour operating in conjunction with the physical principles governing evaporation modify transpiration.

Thus, evapotranspiration is a combined loss of water from the soil (evaporation) and plant (transpiration) surfaces to the atmosphere through vaporization of liquid water, and is expressed in depth per unit time (for example mm/ day). Quantification of evapotranspiration is required in the context of many issues:

The geologists of the Indian subcontinent have all along been of the opinion, that, the southern part of the Indian Peninsula is a stable shield area. But, the recently acquired IRS-1A image of June, 1988 vividly displays spectacular geomorphic anomalies suggesting that this part of the Indian subcontinent is prone to earth movements. In order to unearth more evidences on such earth movements / neotectonism in Tamil Nadu, the IRS-1A image of Coromandel coast of Tamil Nadu was analysed ( Fig. 1).

OBSERVATIONS

• The IRS-1A image conspicuously displays three contrasting morphotectonic domains in the study area marked by the western undissected Tertiary upland (Vallam upland), central highly dissected Tertiary upland (Pattukottai -Mannargudi upland) and the eastern Cauvery delta (Fig 1 and 2). These three domains are separated by two conspicuous N-S trending lineaments (E and F, Fig.1 and 2) namely the Tanjavur - Avadaiyarkovil lineament in the west and Kumbakonam -Muttupet lineament in the east.
• In addition, two more E-W trending lineaments (G and H, Fig.1 and 2) are also observed trifurcating the undissected Vallam upland into three blocks.
• Along these lineaments, especially the Tanjavur -Avadaiyarkovil and Kumbakonam -Muttupet lineaments, the rivers show conspicuous drainage anomalies in the form of drainage deflection, drainage compression etc., wherever they transect the lineaments.

Agriculture has progressed from labour-intensive traditional practices through mechanization and the Green Revolution to precision agriculture and Agriculture 5.0. This chapter traces that historical development and identifies limitations associated with conventional farming, including inefficient resource use, environmental degradation and weak adaptability. It explains how GPS-guided machinery, sensors and precision technologies prepared the foundation for intelligent systems. Artificial neural networks, deep learning and fuzzy logic now process data from IoT devices, UAVs and satellites to support automated irrigation, crop monitoring and soil analysis. The chapter emphasizes that integrating human knowledge with computational power is increasingly essential for global food security, sustainability and climate resilience.

Modern farm planning involves nonlinear, discontinuous and multi-objective problems that conventional optimization methods may not solve effectively. This chapter examines Genetic Algorithms, Particle Swarm Optimization and Differential Evolution for improving agricultural resource allocation. These nature-inspired techniques can simultaneously address crop yield, water use, fertilizer application, environmental effects and financial viability. Their integration with deep-learning forecasts and crop-simulation systems enables more realistic optimization. Multi-objective evolutionary algorithms identify Pareto-optimal alternatives, allowing decision-makers to balance productivity and ecological sustainability. The chapter also emphasizes explainable artificial intelligence, economical implementation and farmer usability as necessary conditions for transferring evolutionary optimization methods from experimental research to practical farm management.

Exchanges sodium (Na+) is animportantparameter forsalt affected soils. This is estimated by extraction with ammonium acetate and then measuring the extract inflamephotometer.

Reagents

1. Neutral normal ammonium acetate solution (1 N CH₃COONH₄ of pH 7): Dissolve 77.09 g of ammonium acetate in distilled water and make up the volume to one litre. Adjust the pH of the solution to 7 with ammonia solution or acetic acid.
2. Standard solution of Na (500 mg/L Na): Dissolve 1.271 g of NaCl in distilled water and make up the volume to one litre.
3. Working standard solution of Na (100 mg/L): Dilute 200 ml of 500 mg/L stock solution to 1000 ml.

6.0 General

No lessons can be drawn without the experiences of the past. In fact, much of engineering, rather all sciences have developed in bits and pieces from the experiences of the past. The engineers by and large have never become wiser in one day. They have become wiser slowly and slowly with their own experiences and from the experiences of past engineering works. Wisdom lies to gain wisdom from experiences/draw lessons from the marvellous engineering works constructed so far. It helps us in a direction for further development of technological skills.

Here an effort is made to draw lessons from experiences of the canals constructed in the past.

 There are several aspects of such experiences. A few important aspects of studies are:

 (i) Internal hydraulic sections of the canal with respect to discharge, topography, stability of side slopes, type of lining, operation and maintenance problems and their solutions etc.

 (ii) Design of canals banks (embankment) with respect to discharge, depth of flow, depth of cutting /filling, below/above natural ground level, type of soil, topography, operation and maintenance, drainage of banks etc.

 (iii) Canals aesthetics and arboriculture

 (iv) Other utility/service of canal such as multi-objectives of hydropower, irrigation, drinking/industrial water supply, social needs of recreation, forests etc.

Abstract

It has been established beyond doubt that the drainage architecture and the fluvial histories of river systems give excellent indications not only on the surficial lithology but also on the ongoing morphotectonic processes of the planet earth. Among the various drainage patterns, the ‘eyed drainage’ pattern is considered to be one of the most significant anomalies and such ‘mega eyed’ drainages interpreted from IRS-IA imagery in some of the major river systems in Tamil Nadu, Indian Peninsula, are found to signify ongoing tectonic movements in an otherwise seismically inert shield area.

Soil microorganisms (Flora & Fauna) are just like higher plants depends entirely on soil for their nutrition, growth and activity. The major soil factors which influence the microbial population, distribution and their activity in the soil

Several environmental conditions affect the density and composition of the microflora and frequently alter their activities in soil. Primary factors include soil moisture, aeration, temperature, pH, organic matter and inorganic fertilizers. Lesser variables are the secondary factors, which include crop rotation, season, soil depth, cultivation practices etc.

I. Primary Factors

Soil moisture

Soil moisture is one of the important factors influencing the microbial population. Water is the major component of protoplasm; an adequate supply must be available for vegetative development of organisms. But, when it becomes excessive, proliferation is suppressed due to limitation in gaseous exchange and lowers the availability of O₂ supply creating an anaerobic environment. Most of the organisms prefer a moisture percentage between 20 and 60 per cent. Many bacteria and fungi can adjust themselves to different moisture conditions. Under dry conditions, the bacteria may form spores that can resist the drought conditions. The fungi may sporulate or form chlamydospores to tide over adverse conditions. The protozoans also may form cysts and can survive under dry conditions. Actinobacteria are the chief group of organisms that prefer dry conditions. It is believed that the concentration of nutrients is diluted and also the aeration is very much limited at moisture and hence only the anaerobic and microaerophilic organisms can develop better.

Factors for deterring the Fertilizer Schedule are two factor

Soil Supplying Power: Growing different crops during different seasons alters the soil nutrient status, estimated by soil analysis at the beginning of the season. The soil supplying power increases with legume in rotation, fertilizer application and addition of crop residues. The available nitrogen and potassium in soil after groundnut are higher to initial status of the soil. But after pearl millet, only potassium status in the soil is improved and no changes in P.

Nutrient Uptake by Crops: The total amount of nutrients taken by the crops in one sequence gives an indication of the fertilizer requirement of the system. The balance is obtained by subtracting the fertilizer applied to crops that nutrient taken by the crops.

Residual Effect of Fertilizers: The extent of residues left over in the soil depends on the type of fertilizer used. Phosphatic fertilizer and FYM have considerable residue in the soil, which is useful for subsequent crops. The residues left by potassium fertilizers are marginal. Legumes add nitrogen to the soil in the range of 15 to 20 kg/ha. The amount of nitrogen added depends on the purpose. Green gram grown for grain, contributes 24 and 30 kg N respectively to the succeeding crop. Inclusion of leguminous green manures in the system add 40 kg to 120 kg N/ha. The availability of phosphorous is also increased by incorporation of green manure crops.

Introduction
Farm mechanization represents a pivotal shift in agricultural practices, marking the transition from traditional, labor-intensive methods to modern, technologydriven farming systems. This chapter explores the various dimensions of farm mechanization, highlighting its critical role in enhancing agricultural productivity, ensuring food security, and addressing the challenges of global warming. The chapter begins by examinin65g the different types of agricultural machinery and equipment used in modern farming. This includes tractors, plows, harvesters, seeders, and other essential tools that have revolutionized the way crops are cultivated, harvested, and processed. The mechanization of these processes has significantly increased efficiency, reduced labor costs, and improved the overall productivity of agricultural systems. Precision farming and remote sensing are discussed as integral components of modern farm mechanization. These technologies enable farmers to optimize the use of resources such as water, fertilizers, and pesticides, thereby increasing yields while minimizing environmental impacts. Key components of precision farming, such as GPS-guided machinery, soil sensors, and aerial imaging, are explored in detail, along with their applications and benefits. The chapter also delves into machinery management and maintenance, emphasizing the importance of regular upkeep and proper management of farm equipment. Effective machinery management ensures the longevity and reliability of agricultural machinery, reduces downtime, and lowers operating costs, all of which contribute to more sustainable and profitable farming practices. Farm mechanization is highlighted as a crucial factor in enhancing food security. By increasing the efficiency and scalability of food production, mechanization plays a vital role in meeting the growing global demand for food. The chapter discusses how mechanization extends growing seasons, improves crop quality, and diversifies crop choices, thereby contributing to a more stable and resilient food supply. The impact of farm mechanization on global warming is also a key focus of this chapter. While mechanization has led to increased productivity, it has also contributed to greenhouse gas emissions and other environmental challenges. The chapter explores strategies for mitigating these impacts, including the adoption

1.1 Introduction

Water is the basis of all forms of life. It supports life system not only to the plants but also to all other animals. The embryo from the conception till birth floats in the liquid medium. Cell, the basic unit of life, contains as high as 95- 98% water. Cellular metabolism is controlled by content of water. Majority of this water requirement of the crops is met from different forms of precipitation. However, when the water requirement is not fully met from precipitation, then growth of the crops is affected. This results in reduction of yield of the crops. The reduction in yield depends on the amount of scarcity of water requirement of the crops. Water requirement of crops depend on many factors. It depends on the type of crops, irrigation schedules practiced, soil texture, position of groundwater table below the effective root zone of the crop and management practice followed in crop cultivation. The pulses, oilseeds, vegetables which are also otherwise termed as dry land crops need less water compared to rice which is a water loving crops and perennial crops like sugarcane and banana.

Water requirement of crops is partly met by the upward flux of groundwater. The capillary rise of shallow water table in the form of upward flux helps in meeting the water requirement of crops to some extent. The upward flux depends on the type of the soil, effective root zone depth of the crop, depth of water table below effective root zone depth of the crop and potential gradient of soil moisture suction. The residual soil moisture helps in supporting water requirement of crops also. The heavy soil like clay has more moisture retention capacity than the light soils like sandy soil. The residual soil moisture held in clay soil is released slowly and supports soil moisture to the crops for a longer period than the sandy soil which has less soil moisture retention capacity. After meeting the water requirement of crops from all sources including different forms of precipitation, ground water contribution by capillary rise and residual soil moisture, if there is any shortage of water, then this shortage should be met from other sources which is called as irrigation.

12.1 Introduction

Farm ponds are used for multipurpose including as a viable source for supplemental irrigation to rainfed crops, a good place of entertainment, a vital place for wild life habitats, livestock and fish and aquatic plants. Like any other structure, the farm pond needs regular repair and maintenance for effective operation. The purpose of construction of the pond will be fruitful and the life span of the pond will be enhanced if proper care and maintenance are taken. In this chapter some salient discussions on care and maintenance of the pond are mentioned.

12.2 Maintenance Against Silting

The farm ponds constructed in medium to deep black soils are subjected to getting silted up. Hence, periodic desilting to restore the original storage capacity is required. If the pond is used for supplemental irrigation to crops, then desilting may be done once in every 5 to 10 years depending on the amount of silt getting deposited in the pond.

The breaches and rill formed in the spoil bank and shoulder bunds should be immediately repaired. The inlet and outlet structures should be maintained periodically. The silt deposited in the silt trap should be removed periodically. In areas where silt carried by the runoff is more, a vegetative filter near the inlet structure may be used. The pond may be desilted manually if it is small in size otherwise mechanical measures may be used to desilt. It is easy to desilt the pond when it is dry. A Simple and inexpensive method to desilt the pond is to stir the water of the pond and then allow the desilted water move away from the pond through the outlet (Belgaumi, et. al., 1997). Fig. 12.1shows a badly maintained pond with excess silting and weed infestation causing severe reduction of its storage capacity.

In India since ages, the dryland farmers adopted a kind of mixed farming involving traditional annual crops and livestock consisting of one or two cows / bullocks and few poultry birds. This traditional system though of small scale provided some kind of risk minimisation particularly in the years of scanty rainfall causing agricultural drought. (https://coabnau.in/uploads/1587050523_ Agriculturalheritage.pdf) Discouraged by their marginal impact on farm economy, dryland farmers switched over to the lure of ‘productive’ mono-cropping with certain commercial crops like cotton etc. The continuous mono-cropping resulted in impoverishment of soils and low crop yields which took farmers into the labyrinth of poverty.

The Fertilizer (Control) Order

The Fertilizer (Control) Order (FCO) is a set of legally enforceable executive orders issued by the Govt. of India under the Essential Commodities Act, 1955 passed by the Parliament. This order came into force in 1957, essentially to regulate the sale, price and quality of fertilizers in India. Amendments are made from time to time as per the exigencies and need of the hour and therefore a large number of amendments were made over a period of time. Consequently, after an overall review of the various provisions of the order, a revised Fertilizer (Control) Order 1985, was issued, which came into effect on September 25, 1985. The FCO consists of five Schedules comprising of different activities as mentioned in Figure 8.1, besides forms of registrations and appendices.

Schedule I comprises Part A and B. While Part A contains the specifications of different fertilizers (e.g. minimum nutrient content, maximum moisture content, range of physical parameters, maximum levels of impurities/ contaminants, etc.), that can be marketed in India (no material not performs the specifications as in the FCO cannot be sold as fertilizer), Part B lists the tolerance limits in plant nutrients and physical parameters for various fertilizers. Schedule II encompasses again two parts, with Part A describing the procedures for drawal of samples of fertilizers, and Part B describing detailed methods of analysis of fertilizers.

Schedule III encompasses four parts namely, Part-A, Part-B, Part-C and Part-D. While Part-A contains specifications of different biofertilizers, Part-B contains tolerance limits of biofertilizers, Part-C describes the procedures for drawal of sample of biofertilizers, Part-D describes the methods of analysis of biofertilizers. Schedule IV also encompasses four parts. Part-A contains specifications of organic fertilizers, Part-B contains tolerance limits of organic fertilizers, Part-C describes the procedures for drawal of sample of organic fertilizers, and Part-D describes the methods of analysis of organic fertilizers. Schedule V also contains of four parts. Part-A contains specifications of non-edible de-oiled cake fertilizers, Part-B contains tolerance limits of non-edible de-oiled cake fertilizers, Part-C describes the procedures for drawal of sample of non-edible de-oiled cake fertilizers, and Part-D describes the methods of analysis of non-edible de-oiled cake fertilizers.