Preface The book which deals with cropping systems in detail. The topics covered in this book are in an order, which helps in a better understanding of the concept and will serve as a ready reckoner for the undergraduate and post graduate students. The concepts presented are not so elaborative, but are in the form of gist which helps students to grasp more within a short period of time. Simple usage of English and concepts explained with examples are the key features of this book. Agronomical calculations are clearly indicated step by step, which leads to furthermore absorption of the concept. Cropping systems being one of the major courses in Agronomy has its own importance to play with. Not only the syllabus covered helps to clear course exams of undergraduate and postgraduate but also help in clearing many competitive exams, in which the present topic will play a crucial role. Features Efforts have been made to describe principles and practices of cropping systems in a systematic and comprehensive manner. Book also contains brief general topics about importance of cropping systems for getting higher yield and measures to overcome productivity. The latest aspects about, indices for land use, for different cropping systems and for sustainability in crop production. This book serves as study material in the classroom and as a quick reference material for preparation of examinations. The authors warmly acknowledge their indebtedness to authors of books from which most of material has been freely drawn for compilation.

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 unit which possess a group of interacting components, operating together for a common purpose, capable of reacting as a whole to external stimuli. It is unaffected directly by its own outputs and has a specified boundary based on the inclusion of all significant feedbacks. For example, the human body is a system-it has a boundary (skin) enclosing a number of components (heart, lungs) that interact (the heart pumps blood to the lungs) for a common purpose (to maintain and operating the living body). Ecosystem: Any collection of organisms that interact or have the potential to interact along with the physical environment in which they live form an ecological system or ecosystem. Ecosystems are not static entities but, they are dynamic systems with characteristic pattern of energy flow, nutrient cycling and structural change. Agro ecosystem: Agro ecosystems are ecological systems modified by human beings to produce food, fibre or other agricultural products. Like the ecological systems, agro ecosystems are structurally and dynamically complex. But their complexity arises from the interaction between socio economic and ecological processes. Crop system: An arrangement of crop population that transform solar energy, nutrients, water and other inputs into useful biomass that produce food, feed, fuel and fibre. Crop system comprise of soils, crop, weed, pathogen and insect subsystems. The crop can be of different species and variety, but they only constitute one crop system if they are managed as a single unit. Cropping systems: It is defined as the order in which the crops are cultivated on a piece of land over a fixed period of time. Cropping system is the way in which different crops are grown. In the cropping systems, sometimes a number of crops are grown together or they are grown separately at shorter intervals in the same field.

The main objective of any cropping system is to utilize available resources efficiently viz., land, water, solar radiation by maintaining stability in production in order to obtain 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 By increasing area under cultivation By increasing the productivity per unit area of the crop But two more dimensions are added to modern agriculture To increase the production per unit time To increase the production per unit space In the traditional cropping systems, mixtures and rotations were developed by the farmers over years of experience by trial and error to suit specific ecological and sociological conditions to attain yield stability, whereas modern scientific cropping has three pillars viz.

Multiple cropping includes both inter and sequential cropping systems and here the main objective is to utilize the available resources effectively in a given environment. Number of indices are available for assessing land use and the yield advantage of crop mixtures compared to pure stands. These indices not only reflect the difference in criteria used to appraise advantages often encompassing aspects of quality or values as well as yield, but also reflects the different reasons for which an assessment is made. Rotational intensity (RI): Crops are grown in a recurring sequence on the same piece of land with sufficient diversity and intensity. Crop rotations to control erosion/ to improve or maintain soil fertility and to manage weeds, insects and disease. Lower values of rotational intensity indicate mono cropping and higher values of rotational intensity indicates more rotation.

In sustainable agriculture the word sustain is derived from the Latin word sustinere (sus-from below and tinere-to hold), to keep in existence or maintain, implies long term support or performance. As it pertain to agriculture, sustainable describes farming system that are capable of maintaining their productivity and their usefulness in society indefinitely. Such system should be resource conserving, socially supporting, commercially competitive and environmentally sound. Systems approach is essential for understanding sustainability and it gives us tools to explore the interconnections between farming and other aspects of our environment and sustainability implies at the following, Meeting the basic needs of all people and giving this priority over meeting the greeds of a few Keeping population densities if possible below the carrying capacity of the region Adjusting consumption patterns and the design and management of systems to permit the renewal of renewable resources Conserving, recycling and establishing priorities for the use of non- renewable resources Keeping environmental impact below the level required to allow the systems unaffected to recover and continue to evolve. Various definitions have been provided for what constitutes sustainable agriculture ranging from the narrow focus on economics or production to the incorporation of culture and ecology. Wendell Berry has simply said A sustainable agriculture does not deplete soils or people.

Classifications of cropping systems Depending on the resources and technology available, different types of cropping systems can be adopted on farms and which are as below. Mono cropping /single cropping: Mono cropping refers to growing only one crop on a particular land year after year or practice of growing only one crop in a piece of land year after year. Example, growing only crops during kharif in rainfed areas and this is due to lack of irrigation facilities and crops depend on rainfall alone.

Various types of cropping systems are practiced in a farm or region. They should be evaluated to find out their stability and relative advantages in yield. Again, comparisons may be made with reference to land use efficiency, biological potential and economics. Following are the important indices for assessment of competition and yield advantage: 1. Relative yield total (RYT): The oldest establishment measure of the yield advantage of crop mixtures is the Relative Yield Total. The RYT index was designed as a measure of the extent to which various crop components shared common resources, rather than as a direct measure of yield advantage.

When crops are grown in either intercropping or sequential cropping interaction between different component crops occurs which is essentially a response of one species to the environment as modified by the presence of another species is commonly referred to as interference or interaction. The interaction are classified into three groups Competitive interaction: One species may have greater ability to use the limiting factor and will gain at the expense of the other and this is called competitive interaction or when one or more growth factors are limiting, the species that is better equipped to use the limiting factor(s) will gain at the expense of the other and this is called competitive interaction. Non competitive: If the crops are grown in association and the growth of either of the concerned species is not affected, such type of interaction is called non competitive interaction or if resources (growth factors) are present in adequate quantities, as a result of which, the growth of either of the concerned species is not affected, then it is non-competitive interaction or interference. Complementary: If one species is able to help the other, it is known as complementary interaction or if the component species are able to exploit growth factors in different ways (temporal or spatial) or if one species is able to help the other in supply of factor (like legumes supplying part of N fixed by symbiosis to non-legumes), it is complementary interaction or interference and also referred to as Annidation.

The stability of yield is an important characteristic to be considered when judging the value of a cropping systems when compared to others cropping systems. Here, we focus on multiple cropping and how this agroecological practice can be used to increase the sustainability of crop production. Strip, mixed and relay intercropping can be used to increase crop yields through resource partitioning and facilitation. In addition to achieving greater productivity, diversifying cropping systems through the use of strategic cropping systems will increase yield stability, reduce weeds, pests, disease and improve soil health. Several multiple cropping systems are already implemented in industrialized agricultural landscapes, including mixed intercropping with perennial grasses and legumes as forage and relay intercropping with winter wheat and red clover. Because multiple cropping systems will provide numerous benefits, researchers should be clear about their objectives and use appropriate methods so as not to draw spurious conclusions when studying multiple cropping systems. In order to advance the practice, experiments that test the effects of multiple cropping systems should use standardized methodology and researchers should report a set of common criteria to facilitate cross-study comparisons. Multiple cropping systems with two or more crops appears to be less common with annuals than perennials, which is likely due to differences in the mechanisms responsible for complementarity. One area where intercropping with annuals in industrialized agricultural landscapes has advanced is with cover crops, where private, public and governmental organizations have harmonized efforts to increase the adoption of cover crop mixtures.

Crop diversification refers to the addition of new crops or cropping systems to agricultural production on a particular farm taking into account of the different returns from value-added crops with complementary marketing opportunities. Major driving forces for crop diversification Crop diversification provides better conditions for food security and enable farmers to grow surplus products for sale at market and thus obtain increased income to meet other needs related to household well being. Crop diversification enable farmers to gain access to national and international market with new products, food and medicinal plants. Diversification from the monoculture of traditional staples are important for nutritional benefits of farmers in developing countries and can support a country to become more self reliant in terms of food production. Diversification also manages price risk and compared to monoculture techniques. For diversification crops generally consists of more sustainable natural resources and again, diversified farms are usually more economically and ecologically resilient.

The crop production is affected by the plant type, climatic condition, soil type and management factors. The production of the plant might be increased by changing plant type and increasing the grain filling period under certain climatic condition where management and soil factors are not limited. There is a direct relationship between the plant type and crop yield because the orientation and number of leaves play an important role in carbon fixation (photosynthesis). Again any variety/cultivar will contribute 21-25 per cent to the total yield of any crop in general. In recent years due to development of photoinsensitive varieties and hybrids which are more fertilizer responsive and high yielding varieties lead to increase overall production in the country. Plant ideotypes Refers to plant type in which morphological and physiological characteristics are ideally suited to achieve high production potential and yield reliability. The concept of ideotype was given by Donald in 1968 and he illustrated that there should be minimum competition between the crops and crop must be competent to compete with weeds. Ideotype is defined as a biological model which is expected to perform or behave in a predictable manner within a defined environment. On the basis of environment, Donald and Hamblin (1976) identified two forms of ideotypes that is isolation ideotypes and competition ideotypes. Isolation ideotypes are suitable for mono/single cropping and competition ideotypes are suitable for mixed cultivation.

Agriculture is the most important sector in India in terms of the population dependent on it. Although agriculture now accounts for on 14 per cent of GDP, it is still main source of livelihood for the majority of the rural population. Rapid growth of agriculture is critical for development of rural economy and viable development of rural economy will leads to overall development of country. Diversification in agriculture is need of the hour, any cropping system comprising crops with varied maturity period, crop canopy and high yielding potential is need for an average farmer. Again cropping systems depending upon the soil type, total rainfall and arrival of monsoon in the region. Low cost technology is essential for reducing financial burden on farmers and to increase production on sustainable manner.

An area with similar soil, climatic conditions and resource availability resulting in similar type of crops and cropping systems. Ex. Rice based cropping system, Ragi based cropping system, Wheat based cropping system, Cotton based cropping system etc. Efficient cropping zone: An analysis of productivity efficiency of crop was made by Kanwar (1972) using relative yield index (RYI) and relative spread index (RSI). A zone where both yield and spread indices are maximum that is above 90 per cent is called most efficient and in case of indices below 90 is the least efficient zone of a crop.