eChapters

Criterion for essentiality of plant nutrients

Arnon’s (1954) criteria for essentiality of elements for plant growth:

1. The plant must be unable to grow normally or complete its life cycle in the absence of the element,

2. The element is specific and cannot be replaced by another and,

3. The element plays a direct role in metabolism.

6.1. PLANT WATER AND MINERAL NUTRITION

Plant water

Water form the major constituent of living (cells) things and the cells originated in a highly aqueous medium and all the vital processes of the life are carried out in it. Besides, water predominately acts as a source of hydrogen to plants and is released by the photolys is of water during photosynthesis.

In living tissue, water is the medium for many biochemical reactions and extraction process. Inorganic nutrients, photosynthesis, bases and hormones are all transported in aqueous solution. Soil nutrients are available to plant roots only when it get dissolved in water. It is essential for life and plays a unique role in virtually all biological process.

Water absorption

Plants absorbed water through root hairs which are in contact with soil water and form a root hair zone a little behind the root tips.Root hairs are tubular hair like prolongations of the cells of the epidermal layer of the roots. When roots elongate, the older root hairs die and new root hairs are developed so that they are in contact with fresh supplies of water in the soil.

Mechanism of water absorption

1. Active absorption of water : In this process the root cells play active role in the absorption of water and metabolic energy released through respiration is consumed active absorption may be of two kinds.

Introduction

Research accomplishments on mentioned findings showed that the quality of community voice like access is familiarized for agricultural revamp index that adapted the charge to findings at the lower like as the antecedence to analyze a number of deficiencies of complete analysis works in a specific area. Firstly, the accomplishments arise to be alloyed and diverse. Secondly, with the agricultural achievement of a span afflict decidedly by its natural, institutional and technological characteristics (which alter broadly an allocation of states), absolute analysis absorption abundantly at the accompaniment like and the change of basal up and micro-level planning emphasizing the issue. Thirdly, there is an absence of studies on agricultural achievement at the disaggregate like in the accompaniment excepting a few that does put up with are bedfast to the community set up and are based on an actual leap amount of variables accouterment periods up to the original since the year 2000. Besides a lot of changes in agriculture pattern, irrigation coverage, agriculture intensity, fertilizer consumption, boilerplate measurement of operational backing and allotment of agricultural workers accept taken abode in agriculture during the contemporary years. These changes knowledge accept afflict the agricultural achievement of districts abnormally and causeless to say they could not accept been grasped in the absolute studies. There is appropriately a charge for advantageous these analysis gaps and adorning the absolute literature. The present findings are an apprehensive advance in the management and administration to apperceive of the ITKs attainable and its role in alteration over agricultural production. In adjustment to access the acknowledgment of the farmers apropos the ITKs uses in agriculture, the analysis agenda developed with a proforma that accomplished in advised and basic villages in altered agro-ecological regions through the activity centers. Farmers’ social contact and acceptance of ITKs practices were attempted in the findings and recorded for an all-important symbol the abstracts to quantify the ITKs role in present-day agriculture.

Introduction 
The preceding chapter elucidated the concepts of potential and achievable crop production, highlighting the significant gap that often exists between a crop‘s theoretical maximum yield and what is realized in the field. While genetic potential and optimal climatic conditions define the upper limits, the vast majority of agricultural systems globally operate under less-than-ideal circumstances. Among the most pervasive and impactful constraints on crop productivity are moisture (water) and nutrient limitations. These two factors, either individually or in complex interaction, are frequently the primary drivers of the yield gap, preventing crops from expressing their full genetic potential and significantly impacting farm profitability and regional food security. Water, as the universal solvent and a direct participant in photosynthesis and countless metabolic processes, is indispensable for plant life. However, its availability in agricultural systems is highly variable and often insufficient. From the rainfed fields dependent on increasingly erratic rainfall patterns to irrigated lands facing dwindling water resources, moisture stress – encompassing both drought and, paradoxically, waterlogging – poses an immense challenge. Drought alone accounts for a substantial portion of global crop losses, directly affecting plant physiological functions, growth, and ultimately, yield. Conversely, excessive moisture can lead to anaerobic soil conditions, nutrient leaching, and root damage, equally debilitating for crop performance. Parallel to moisture, the availability and judicious management of essential plant nutrients are foundational to productive agriculture. Plants require a suite of macro- and micronutrients for healthy growth, enzymatic activity, and the synthesis of biomass. Soils, over time and with continuous cropping, often become depleted of these vital elements, necessitating external application through fertilizers or the enhancement of natural nutrient cycling processes. However, nutrient management in the field is rarely perfect. Deficiencies of

1.1. WEATHER AND TILLAGE

Weather : A state or condition of the atmosphere at a given place and at a given instant of time'

Climate : The generalized weather or summation of weather conditions over a given region during comparatively longer period

Meteorology : Greek word “Meteoro” means 'above the earth's surface' (atmosphere) and “logy” means “indicating science”. Branch of science dealing with that of atmosphere is known as meteorology

Agricultural meterology : Branch of applied meteorology or a branch of agriculture as it deals with agriculture

Coordinates of India : 8^o N and 37°N latitude; 68°E and 98°E longitude

Coordinates of Tamilnadu: 08°05' N and 13°35' N latitude; 76°15' E and 80°20' E longitude

Hydrosphere - water portion of the earth

Lithosphere - solid portion of the earth

Atmosphere - gaseous portion of the earth

Atmosphere : It is the colourless, odourless and tasteless physical mixture of gasses, which surrounds earth on all

4.1. PESTS OF FIELD CROPS

Insect pests are the major constraints limiting agricultural productivity growth. It is estimated that herbivorous insects eat about 26 percent of the potential food production. Emerging problems of insecticide and disease resistance, secondary pest outbreak and resurgence further add to the cost of plant protection. Annual crop losses due to insect pests and diseases in India are estimated to be 18 percent of the agricultural output. Main causes of emerging pest and disease are favourable prevailing weather condition, absence of natural enemies, abundant food supply, use of pesticides, use of fertilizers and irrigation.

PESTS OF RICE

Borers and Defoliators

Large quantities of crop residues are produced and if properly used, they can provide cost effective means for supplying organic matter, plant nutrients and improved soil health. The highly lignocellulosic nature of crop residues indicate their potential role in maintaining soil organic matter and enriching the soils with N-rich microbial biomass resulting from decompositions. However, their indiscriminate handling often burning leads to decline in soil health, air pollution and overall loss. Since most crop residues find use as feed and fuel, efficient recycling of the remaining amount can have very significant and positive effect.

Large quantities of crop residues are produced and if properly used, they can provide cost effective means for supplying organic matter, plant nutrients and improved soil health. The highly lignocellulosic nature of crop residues indicate their potential role in maintaining soil organic matter and enriching the soils with N-rich microbial biomass resulting from decompositions. However, their indiscriminate handling often burning leads to decline in soil health, air pollution and overall loss. Since most crop residues find use as feed and fuel, efficient recycling of the remaining amount can have very significant
and positive effect.
The data regarding five major crops are shown. Even after use of some of them as animal feed they offer a great opportunity of using them back in to the soils which are hungry for organic carbon and other matters. Practice of Crop Residue Burning
The problem of collection and transport of crop residue and the short timebetween harvesting of one crop and making the farm free for the second crop has led to the harmful practices of crop residue burning. If instead of burning it, the residues can be incorporated into soils, a host of heterotrophic microorganisms bring about minor discharge of carbon and other elements contained in plant residues. A large increases in beneficial soil microbial populations and organic carbon can be achieved

Rice-wheat (RW) is the major cropping system occupying about 10.5 mha in the IGP of India. It contributes more than 60% of the foodgrains to the central pool. With shrinking land resources and burgeoning population, the RW system will be under pressure to produce more grain output per unit area in the coming decades. Meeting this challenging task requires sustainable management of soil, water and plant nutrient resources. High yields of the irrigated RW system result in production of huge quantities of crop residues. Total production of crop residues in Punjab is about 47.2 mt which includes paddy straw, wheat straw, cotton sticks, sugarcane leaves, maize stalk, and other oilseeds and pulse residues (Beri and Gupta, 2003). Wheat and rice straw constitutes more than 70% ofthe crop residues produced in the country. Paddy straw alone constitutes more than 50%. Cotton and sunflower residues are generally used as fuel. Sugarcane trash (leaves) is generally burnt in-situ or used as fuel after collection from the field. Increasing constraints of labour and time have led to the adoption ofmechanized farming in the highly intensive RW cropping system. Approximately 91% ofthe total rice area is mechanically harvested, while 82% of the total wheat area is mechanically harvested. Traditionally, wheat and paddy straws have been removed from the fields for use as cattle feed and for several other purposes such as livestock bedding, thatching material , for houses, and fuel. While more than 80% ofwheat residue is collected by the farmers after combine harvesting and often fed to animals, paddy straw is considered poor feed for animals due to its high silica content.

Substantial loss ofplant nutrients (especially N and S) and organic carbon occurs during burning of crop residues, with important implications to soil health. About 40% of the N, 60-85% of the K, 30-35% of the P, and 40-50% of the S absorbed by rice remains in the vegetative parts at maturity. One tonne of paddy straw contains approximately 6-7 kg of N, 1.0-1.7 kg of P₂O₅ and 14-25 kg K₂O. Apart from huge loss of precious plant nutrients, burning of crop residues depletes soil health. Air pollution from stubble burning also impacts human and animal health both medically, and by traumatic road accidents due to restricted visibility. In view ofthe serious problems associated with the residue burning, new ways are being sought to efficiently utilize the huge amount of surplus residues produced in the country.

11.1 Biomass

Globally, all agricultural countries have promoted the use of biomass sources for many household applications and biomass energy generation. Biomass is defined as the bio residue available from the sum of crop production, agricultural waste, vegetation, forestry waste and organic waste. Biomass is a renewable source of energy and contains a complex mixture of carbon, nitrogen, hydrogen, and oxygen. Various biomass resources are available in different parts of countries and are classified based on their availability. The broad classification of biomass energy is in three formats; residue of agricultural crops, energy plantations, and municipal and industrial waste. Agriculture residues are organic materials produced as the byproduct from processing and harvesting of agriculture crops. 

Indian crop production system excels in front of several biophysical adversities commonly known as biotic and abiotic stress.  Water is the principal factor limiting crop yield and about 2/3 of total cultivated landing India comprise of Dry land agriculture primarily under rainfed conditions with no or limited water supply system.  The Indian production systems are dominated by cereals, primarily rice maize, sorghum, pearl millet other coerces and fine cereals leguminous (urd bean, mung bean, peanut) and oil yielding crops during kharif and  wheat barley chickpea, lentil and forage legumes in rabi  season.  The production systems are generally characterized by cereal/legume mixed-cropping dominated by maize, millet, sorghum and wheat. The major constraints in both regions to crop production are low soil fertility, insecure rainfall, low-productive genotypes, low adoption of improved soil and crop management practices, and lack of appropriate institutional support. choice of crop  is important but selection of right varieties is utmost  important because  varieties which have proven excellent in irrigated or high rainfall areas are generally not suited for limited irrigated conditions.

Introduction

Through the use of both art and science, crop breeding is the process of enhancing significant agricultural plants for the benefit of humanity. Crop breeders attempt to improve the productivity and nutritional value of our food, f iber, pasture, and industrial crops via their efforts. In order to meet the needs of a growing global population with rising dietary demands, crops are essential. Additionally, the activity of crop breeders contributes to the improvement of environmental protection.

Since the beginning of agriculture, farmers have been selecting plants for desirable characteristics such as bigger seeds, more flavourful fruits, and other desirable characteristics. This method is known as plant breeding. In today’s world, the breeding of plants is a collaborative effort between scientists and farmers.

Different techniques are used by plant breeders, depending on the manner of reproduction of crops. This process is known as self-fertilization, and it occurs when pollen from one plant fertilizes the reproductive cells or ovules of another plant. There is a phenomenon known as cross-pollination, in which pollen from one plant can only fertilize another plant. For example, runners from strawberry plants are an example of asexual propagation, in which the new plant is genetically identical to its parent plant. Apomixis, also known as self-cloning, is a process in which seeds are created asexually and their offspring are genetically identical to their parents. When it comes to developing appropriate breeding and selection strategies, the mode of reproduction of a crop is the decisive element. This is because the genetic makeup of the crop is determined by the mode of reproduction. Additionally, it is necessary to have knowledge of the way of reproduction in order to artificially manipulate it in order to produce enhanced varieties. The only breeding and selection strategies that are appropriate for a crop are those that do not disrupt the crop’s natural condition or guarantee that it will remain in that form. The imposition of self fertilization on cross-pollinating crops results in a significant decrease in the performance of such crops for several reasons, including those listed above.

Introduction

The crops, its significance along with its classification has got paramount importance in agricultural heritage. A crop is a plant or animal product that can be grown and harvested in an area with a target to earn profit or achieve subsistence. Crop may refer either to the harvested parts or to the harvest in a more refined state (husked, shelled, etc.). Most crops are cultivated in agriculture or aquaculture.

A crop is usually expanded to include macroscopic fungus (e.g. mushrooms), or alga (alga-culture) at the point of origination. Most crops are harvested as food for humans or livestock (fodder crops) or to get raw materials for agro-based industry. Some crops are gathered from the wild collection (including intensive gathering). The important non-food crops include horticulture, floriculture and industrial crops. Horticulture crops include plants used for other crops (e.g. fruit trees, grown single or in orchard). Floriculture crops include blanket plants, houseplants, flowering garden and pot plants, cut cultivated greens, and cut flowers. Industrial crops are produced for clothing (fiber crops), bio-fuel (energy crops, algae fuel), or medicine (medicinal plants).

Microbes (fungi, bacteria or viruses) are rarely referred to as crops. Animals raised for human or animal consumption are referred to as livestock and microbes as microbiological cultures. Microbes are not typically grown for food itself, but are rather used to alter food (e.g., for production of citric acid, fermenting yogurt, soya sauce and so on). The importance of a crop varies greatly by region. Crop production depends on the availability of arable land and is affected in particular by yields, macroeconomic uncertainty, as well as consumption patterns; it also has a great incidence on agricultural commodities’ prices. The importance of crop production is related to harvested areas, returns per hectare (yields) and quantities produced. Crop yields stands for harvested production per unit of harvested area for the particular crop i.e. products. In most of the cases yield data are not recorded, but are obtained by dividing the production data by the data on area harvested. The actual yield that is captured on farm depends on several factors such as the crop’s genetic potential, the amount of sunlight, water and nutrients absorbed by the crop, the presence of weeds and pests infestation. These indicators are presented for wheat, maize, rice and soybean. Crop production is measured in tons per hectare, in thousand hectares and thousand tons.

Agricultural systems are complex, and understanding this complexity requires systematic research under shrinking agricultural research resources. Field experimentation can only be used to investigate a very limited number of variables under a few site-specific conditions. The crop growth simulation models simulate crop growth, development and yield taking into account the effects of weather, genetics, soil water, carbon and nitrogen, planting, irrigation and fertilizer (e.g. Nitrogen, Phosphorus) management. Ofthe many factors that potentially affect the growth of plants, the two that are most responsive to management are water and nitrogen. It is therefore not surprising that most crop models include routines to handle responses to water and nitrogen. Less frequently do models attempt to describe limitations due to other soil constraints (Probert and Keating, 2000). In the context of integrated nutrient management, the performance of a crop model depends mainly on its ability to adequately describe the release of nutrients from diverse inputs and their uptake by the crop.

Origins and genesis of a crop simulation model

Crop simulation model approach was started near about 50 years ago, in early 1960s when early simple crop models were developed for estimation of transpiration and photosynthesis. The first step towards crop modeling was the development of simple models to estimate light interception and photosynthesis (Loomis and williams, 1963; De wit, 1965 and Duncan et al., 1967). There are many crop growth simulation models. Some are more generic in nature while others are built for specific purposes. Most of these models simulate crop growth and soil processes using daily time steps. All models are developed with some assumptions and hypotheses, and all have strengths, weaknesses and limitations for appropriate application. Well-known crop modelling groups across the world include IBSNAT/IFDC (International Benchmark Sites Network for Agro technology Transfer/International Fertilizer Development Centre) in USA, WAU/AB-DLO (Wageningen Agriculture University/Centre for Agro-biological Research) in the Netherlands, and APSRU (Agriculture Production Systems Research Unit) in Australia. The IBSNAT project was initiated in 1982, and over the past 20 years it has developed more than 15 models, including CERES (Crop Estimation through Resource and Environment Synthesis) Rice and CERES Wheat, which are available either as stand-alone models or within the DSSAT (Decision Support System for Agrotechnology Transfer) shell (Uehara and Tsuji, 1993).

5.1 Introduction

A Crop Simulation Model is a mathematical model which describes crop growth and development processes as a function of environment, soil conditions, and crop management. Simulation model is a schematic representation which works on set of underlying assumptions, equations and algorithms, closely replicating the behaviour of the agricultural systems. A crop growth simulation model predicts the harvestable yield. Apart from this final state of crop production, the model also provides a host of quantitative information about major processes involved in the various stages of crop development. The information covers each component of the crop such as leaves, stems, roots and harvestable products as they change over time, including the changes in soil moisture and nutrient status.

An increase in the population, demands an increase in agricultural production with available resources. Efficient management of available resources under varying weather conditions is important for increasing agricultural productivity. Besides that, the emphasis of agricultural production changes from quantity to quality and sustainability (Aggarwal et al., 2000). Solution of these new challenges lies in understanding the interaction of the numerous elements affecting the plant growth and generating a crop growth model. This extremely complicated information needs to be processed and interpreted on a spatial scale. Information technology which has unleashed new frontiers in data analysis and automation is the driving force behind this model generation. These powerful computer programmes simulate the crop growth or yield of crops under various management regimes and provide near real time information to help farmers to make strategic decision in the management of their crops.

The susceptibility and vulnerability of crops to diseases are critical factors that determine the impact of disease outbreaks on agricultural productivity and food security. Crop diseases can have devastating effects on crop yields, quality, and marketability, resulting in significant economic losses for farmers and the agricultural industry as a whole. The susceptibility of crops to diseases refers to the inherent characteristics of the crop that make it more or less prone to infection by a particular diseasecausing agent. This can include factors such as the crop’s genetic makeup, its physiological state, and its environmental conditions. For example, some crop varieties may have a natural resistance to certain diseases, while others may be more susceptible due to their genetic characteristics. Vulnerability, on the other hand, refers to the degree to which a crop is exposed to disease-causing agents and is unable to withstand or recover from disease outbreaks. This can include factors such as the crop’s location, climate, soil type, and farming practices. For example, crops grown in areas with high disease pressure, inadequate soil moisture, or poor farming practices may be more vulnerable to disease outbreaks. Understanding the susceptibility and vulnerability of crops to diseases is essential for developing effective disease management strategies. By identifying the factors that contribute to a crop’s susceptibility and vulnerability, farmers and agricultural experts can take proactive measures to prevent or mitigate disease outbreaks. This can include using disease-resistant crop varieties, implementing integrated pest management practices, and adopting sustainable agricultural practices that promote soil health and biodiversity. In this chapter, we will explore the concept of susceptibility and vulnerability of crops to diseases in more detail, including the factors that contribute to these phenomena and the strategies that can be used to manage and mitigate disease outbreaks. By understanding the complex interplay between crops, diseases, and environmental factors, we can develop more effective and sustainable approaches to disease management that promote agricultural productivity and food security.
4.1 Factors Determining Susceptibility
The susceptibility of crops to diseases is determined by a complex interplay of factors, including genetic, physiological, and environmental factors. Genetic factors play a crucial role in determining the susceptibility of crops to diseases. Some crop varieties may have a natural resistance to certain diseases, while others

Introduction

The literary meaning of voyage is a long journey by water or air to a distance place. The crop voyage means the introduction of different crops from outside and movement of the crops originated in India to abroad. India is one of the mega agro-biodiversity countries of the world. Many plant species have been domesticated here. The agro-biodiversity of the indigenously domesticated higher plant species was further enriched with introduction of exotic crops since ancient times, as reflected by the presence of American cereals such as maize and amaranths, African cereals such as pear millet and sorghum, West Asian legumes such as field pea, grass pea and chickpea, and Chinese proso millet and buckwheat in the archeological remains and/or in ancient Indian agriculture writings. Most of these crops have acclimatized and adapted to diverse ecological conditions offered by the Indian Sub-continent to such an extent that many appear natural to the land, and have thrown enormous genetic diversity, making India either a secondary center of diversity for crops such as pearl millet, sorghum, maize, amaranths, cowpea, niger, safflower, muskmelon, pumpkin, chilies and others or regional center of diversity for crops such as barley, grain amaranth, buckwheat, pearl millet, foxtail millet, chickpea, bottle gourd and others. All details of crop voyage has already been discussed in the relevant topic of discussion (Chapter 8) on “Journey of agriculture and its development from past to modern era.”

The Crop Weather Calendar (CWC) is arguably one of the most practical and indispensable tools developed within agricultural meteorology. It transcends simple weather data by synthesizing comprehensive information about a specific crop’s entire life cycle with the historical climate patterns and recommended agricultural practices for a particular geographical area, typically an agro-climatic zone or even a district. More than just a timetable, it serves as a strategic blueprint that guides farmers and agricultural professionals toward optimized, resilient, and sustainable farming (Fig. 4.1).Imagine it as a detailed annual planner for a specific crop, where every entry is backed by decades of climate data and agronomic research. 4.2 Crop Weather Calendar: A Deeper Dive

Introduction 
Building upon our foundational understanding of how weather intrinsically shapes crop development, from the micro-scale physiological responses to the broader patterns revealed by Indigenous Technical Knowledge, we now transition to a chapter dedicated to a highly practical and actionable synthesis of this critical interrelationship: Crop Weather Calendars. These calendars are far more than mere chronological charts; they represent systematically organized and dynamic compilations of meteorological information meticulously integrated with precise crop-specific data, designed to serve as an indispensable guide for optimizing agricultural practices. In this chapter, we will embark on a comprehensive exploration of Crop Weather Calendars, moving beyond the often informal or culturally embedded ecological calendars previously discussed. We will delve into how these powerful tools systematically integrate historical weather patterns, which involves analyzing longterm meteorological data to establish reliable averages and identify probabilities of specific weather events, such as the typical onset of monsoons, average frost dates, or periods of peak solar radiation. They also incorporate real-time meteorological data, bringing in current weather observations to track actual conditions against historical norms and initial forecasts. Furthermore, Crop Weather Calendars utilize future weather forecasts, drawing on short-, medium-, and long-range meteorological predictions to anticipate upcoming conditions (Fig.12.1). This integrated weather information is then critically aligned with the precise phenological stages of a given crop cultivar, recognizing that a crop’s sensitivity and requirements vary significantly throughout its life cycle. Our exploration will detail the essential components that constitute a robust crop weather calendar, including the identification of crucial growth periods, pinpointing the most sensitive and influential developmental stages of the crop like germination, tillering, flowering, and grain filling, where weather impacts are most pronounced. It also involves the establishment of weather thresholds, which means defining the optimal, critical, and damaging ranges of key weather

Variation in field crops between years is associated with many factors. This is mainly due to weather, soil and management factors. There is complex reaction of weather variables among themselves as well as with other factors. Therefore, many attempts were made to study the effect of weather variable on crop yield through simulation modeling.

Climate, soil, input and management factors influence the crop yield. Weather is the most important natural input that affects the agricultural production and productivity. The agricultural activities starting from the land preparation to harvest and post-harvest storage are greatly influenced by the weather. The effects of weather on crops may be direct such as those of precipitation, solar radiation, humidity, temperature, etc., or indirect such as those of pest, diseases, weed competition, etc. Thus, the success or failure of a crop is determined by the prevailing weather conditions. Although influence of weather conditions on yield is well established, the quantitative assessment is not always straight forward and simple. The quantitative assessment of the effect of weather on crops is an important application of agrometeorology. The relationship between weather and crop production has been understood through crop weather modelling and study on this aspect through a systematic approach started a century ago. The aim of developing crop weather models is to ensure better utilisation of resources and hence a more environmental friendly and sustainable agriculture.

A model is a schematic representation of the conception of a system or an act of mimicry or a set of equations, which represents the behaviour of a system. Its purpose is usually to aid in explaining, understanding or improving performance of a system. Agricultural models are mathematical equations that represent the reactions occurring within the plant and the interactions between the plant and its environment. However, it is a difficult task to represent any system completely in mathematical terms because of the complexity of the system. Universal models do not exist for the agricultural systems and agricultural models are built for specific purposes and the level of complexity is accordingly adopted. Different models are developed for different subsystems and several models may be built to simulate a particular crop or a particular aspect of the production system. Crop weather models may be defined as a simplified representation of the complex relationships between weather or climate on one hand and crop performance such as growth, yield or yield components, on the other hand by using mathematical and/or statistical techniques

Plant competition is a powerful force for the elimination of some weaker plants. Plants require nutrients, water, light, Oxygen and Carbondioxide for their growth and development. Weeds compete with the crop for growth factors and the competition is maximum at the early growth stages of the crop. But the competiting ability of the weeds becomes practically nil as soon as the crops attain maturity. Weeds need more nutrients and water than the crop plants. The weeds in general grow faster and shade the crop plant if they are not controlled at proper time and afterwards interfere in the growth of crop plant. Weeds have allelopathic effect on crop growth. Some weeds excrete certain chemicals into the soil which inhibit the germination and growth of other plants in their vicinity and the phenomenon is called allelopathy. Allelopathy is defined as the direct or indirect harmful effects of one plant on another plant through the production of chemical compounds that escape in the environment.

1.1 Weather Parameters

The atmosphere is a gaseous component surrounding the earth as an integral part and its interaction with ocean (water bodies), other planets of the solar system and land (Earth) generates one physical product namely weather elements (temperature, pressure, wind, humidity, precipitation, etc.,) and these form the weather and climate of the Earth. The process of generation of weather and climate of the region is purely natural and cannot be modified by the human being. But they can do adaptation to the existing climate and weather for their sustainable life. The weather can be defined as day to day change in the atmosphere in terms of heat and moisture exchange, while the climate is average of long period weather covering larger area or a region.

The particular climate of a region dictates/permits the genesis of a particular bio-organism in that domain and this selected organism’s growth and multiplication are triggered by the prevailing weather of that particular climate. Hence weather parameters of the atmosphere are very important to human being and other organisms of the Earth. The details on weather elements are given in question and answer section of this book (Annexure-I)

There are some weeds which prefer to in crop field and some of them have a distinct association with some crops.

Crop: Plants grown in association, sown (or planted) and also harvested by human being, are collectively known as crop.
Crop plants have some economic values and there is an interaction or competition among the plants.

What is Crop?
Crop refers to plants sown and harvested by man for economic purposes. 
Cropping Seasons: There are three main seasons and two sub seasons.
1. Rainy or Kharif Season – Main characteristics of the Kharif season are 
    ·    It starts from June and spreads to September.
    ·    There is high temperature and high humidity.
    ·    More than 2/3^rd of annual rainfall is received in a year.
    ·    In the beginning, days are longer than nights while days and nights are equal when season ends. 
    ·    Important crops grown are maize, rice, sorghum, Moong, Urd, groundnut, cowpea, soybean etc. 

1.1. Cropping pattern

Yearly sequence and spatial arrangement of crops or crops and fallow on a given area.

1.2. Cropping seasons in India

1.2.1. Kharif season: Southwest monsoon

Crops - Rice, cotton, jute, jowar (sorghum), bajra (pearl millet) and redgram (Pigeon pea).

Terms associated with cropping and farming systems are:

1. Cropping system: is an important component of a farming system. It represents cropping pattern used on a farm and their interaction with farm resources, other farm enterprises and available technology which determine their makeup.
2. Cropping pattern: means the proportion of area under various crops at a point of time in a unit area. It indicates the yearly sequence and spatial arrangement of crops and fallow in an area.
3. Cropping scheme is a plan according to which crops are grown on individual plot of a farm during a given period of time with the object of obtaining maximum return from each crop without impairing soil fertility. Thus a cropping scheme is related to the most profitable use of resources, land, labour, capital, and management.
4. Multiple cropping: Growing two or more crops on the same piece of land in one calendar year is known as multiple cropping. It is intensification of cropping in space and time dimensions. It includes intercropping, mixed cropping and sequence cropping.
5. Quadruple cropping: Growing of four crops in a year in sequence.
6. Competition effect: Competition of intercropped spp. For light, nutrients, water, carbon dioxide, and other growth factors.
7. Complementary effect: Effect of one component on another which enhances growth and productivity.

In agriculture, the ideal management practices were developed for individual crops through regular research and feedback received from the farmers. However, farmers are growing various crops in different seasons based on their adaptability to a particular season.

System is a set of principles or procedures according to which management is done; it is an organized scheme or method. A system is a group of interrelated or interacting elements (crops or livestock) that act according to a set of rules to form a unified whole.

Cropping systems are designed to mimic nature and bring diversity into our farming system. The cropping system should provide enough food for the family, fodder for cattle and generate sufficient cash income for domestic and cultivation expenses.

The objective of any cropping system is efficient utilization of all resources viz., land, water and solar radiation, maintaining stability in production and obtaining higher net returns. The efficiency is measured by the quantity of produce obtained per unit resource used in a given time. The objective of traditional agriculture was to increase the production by two means:

a) By increasing area under cultivation.

b) By increasing the productivity per unit area of the crop.

Growing more than one crop in sequence or simultaneously as a mixed crop is an ancient practice. In Indian Vedas, there is a mention about double cropping. In early periods, the objective to adopt sequential cropping practices was to reduce the risk of total crop failure due to uncertain monsoon and to have a variety of produce to meet food requirement of farmer’s family, fodder to animals and to meet his cash requirements. Other benefits of yield increase was due to complementary effects of the component crops in improving the soil fertility, spreading the labour requirement throughout over a period of time and to reduce damage caused by weeds, pests and diseases were only incidental.

Multiple cropping in simple terms refers to the practices that increase production in a unit area of land through two or more growing crops simultaneously. The importance of intensive cropping in sustainable agriculture has been well understood by the agricultural scientists of late and there has been surge of interest in the research community to explore these complex systems in detail and to see what can be learnt from the farmers in our quest to make cropping system more sustainable progress made in the past through intensive research carried by the various agricultural universities, ICAR, research institutes/ coordinated research projects and international research institutes such as IRRI, ICRISAT, IITA and CIMMYT, it has shown that and more efficient utilization of the natural resources is possible by suitably modifying the present cropping systems in the various regions of the world.

The present cropping intensity in India is 136 per cent. There is a great prospect for increasing the cropping intensity both in irrigated and rainfed areas. In many irrigated areas, cropping intensity can be increased to 200-300 per cent. There is good scope to increase cropping intensity to 180-200 per cent with proper policies and technology options in rainfed conditions also.

A system is a set of components that are interrelated and interact among themselves. A system may be natural, social or artificial. Natural systems consist
of all the materials both physical and biological and are independent of human beings. Our role in relation to natural systems is to try to understand these
systems and make use of them as per our needs. 

In general crop is an organism grown or harvested for obtaining yield. Agronomically crop is a plants cultivated for economic purpose.

Classification of Crops

Classification is done to generalize similar crop plants as a class for attaining better understanding of them. Field crops are classified in the following ways.

1. According to range of cultivation
2. According to the place of origin
3. Botanical classification
4. Commercial classification
5. Economic / Agricultural / Agrarian classification
6. Seasonal classification
7. Classification based on ontogeny

The occurrence of periods of water deficit for crop production, referred to as climatic drought, is commonly observed and leads to low water availability for crops. Besides climatic drought, crop water stress may also result from low levels of plant available water in the soil profile due either to the existence of physical barriers to water infiltration (e.g., surface sealing) or to soil chemical or physical limitations to plant root growth and root water uptake. Drought resulting from such factors will be referred to as edaphic drought since it is caused by soil specific conditions rather than by limited rainwater supply, and can occur even under conditions of sufficient and well-distributed rainfall. Finally, even where water is very scarce, particularly in the driest areas, a surprisingly small proportion of the available water is actually transpired by the crop. Non-productive losses include surface runoff, deep drainage, evaporation from the soil surface and deep cracks, and transpiration by weeds. Dry land farming is a system of crop cultivation depending on rainfall as the only source of moisture and the technologies refers to the cropping pattern/ rotation and agronomic practices adjusted and adopted in accordance with the moisture regime. The crops selected should have short duration, deep root system, erect leaves, moderate tillering and photosynthetically efficient.

Rainfed farming has a distinct place in the Indian agriculture, occupying 67 % of cultivated area contributing 44 % of food grains to our national food basket, supporting 40% of human and 65% of livestock population. The system is characterized by resource poor farmers, poor infrastructure and low investment in technology inputs. Even when full irrigation potential of the country is realized, 50% of the net sown area is continued to be rainfed. The important problems encountered in rainfed areas are unfavorable weather, limited choice of crops and varieties, low cropping intensity and unstable productivity. The research work done by the net work of AICRPDA (All India Co-ordinate Research Project for Dryland areas) centres and SAUs (State Agricultutal Universities) indicated that the production in rainfed environment could be enhanced by 200 % compared to the productivity of farmers’ field by adopting improved cropping systems and agro techniques.

Crowdsourcing is a concept that involves obtaining information, ideas, or services from a large group of people, often through an online platform. This approach has become increasingly popular in recent years, particularly with the rise of social media, mobile devices, and other digital technologies. In the context of agriculture, crowdsourcing can be used to collect data on various aspects of farming, such as crop yields, soil conditions, and weather patterns. This data can be used to provide farmers with valuable insights and advice on best practices for farm management. One of the key benefits of crowdsourcing in agriculture is that it allows farmers to share knowledge and expertise with each other. By pooling their collective knowledge and experience, farmers can gain a better understanding of the challenges and opportunities facing their industry, and develop more effective strategies for overcoming them (Fig.7.1).
For example, a crowdsourcing platform might allow farmers to share data on crop yields and soil conditions. This data could then be used to create detailed maps of soil types and conditions, which could be used to provide farmers with advice on optimal planting and harvesting schedules.
Another example of crowdsourcing in agriculture is the use of mobile apps to collect data on weather patterns. By collecting data from a large number of

Values denote the subjective significance or preferences accorded to objects, concepts, or experiences within an individual’s cognitive framework. The concept of value encompasses entities or outcomes that are desired or selected by individuals. Social values, as expounded by Green (1964), represent enduring cognitive and affective constructs pertaining to objects, ideas, or individuals within a societal context. These values are often abstract in nature and may operate at a subconscious level, embodying implicit assumptions regarding what is deemed morally and socially significant. As articulated by Young (1959), social values encapsulate abstract and subconscious beliefs regarding notions of righteousness and importance within a communal framework.

Applied agroclimatology integrates climatology with agronomy to understand and manage interactions between weather, climate, crops, soils and agricultural resources. It converts climatic observations and forecasts into practical information for sowing, irrigation, fertilizer application, pest management and harvesting. This chapter introduces agro-meteorological processes, crop-environment relationships, resource management and climate-smart decision-making. It explains how increasing temperatures, altered rainfall, droughts, floods and extreme weather threaten agricultural productivity and farmer livelihoods. Agroclimatic zoning, crop-calendar adjustment, suitable variety selection, early-warning systems and weather-based insurance are discussed as important approaches for strengthening food security, managing climate risks and developing resilient agricultural systems.