Preface The rainfed agriculture distributed approximately ¾th of global crop lands, is expected to respond to climate change and human population growth and these responses may be especially pronounced in water limited areas. Because the environmental conditions that support rainfed agriculture are determined by climate, weather, and soil conditions that affect overall and transient water availability, Indian Agriculture is being described even today as a gamble of the monsoon and every year fate of farmers oscillate with the behaviour of monsoon. Different types of droughts of varied intensities experienced at a different growth stages viz., early, mid and end season drought are the common feature of the rainfed ecosystem. In this publication entitled “Rainfed Agriculture-Principles and Practices” an earnest attempt has been made to include various issues related to Rainfed Agriculture viz. soil and water conservation, drought management strategies, rain water harvesting, crops and cropping system for dryland agriculture, conservation agriculture, climate-smart agriculture and watershed management as per the recommendation of fifth Dean's Committee of Indian Council of Agricultural Research has been presented. The subject matter is both narrative and critical. Illustrations have been added to make the subject matter more clear. Authors are highly indebted to the contributions of the various reviews through their books, monographs, periodicals and reports, especially of AICRPDA, Bangalore centre reports from which liberally research data has been drawn to demonstrate the worthiness of dryland technology in this textbook. The authors are pleased to express their gratitude for encouragement to all the colleagues and students of department of agronomy.

The term Rainfed agriculture is used to describe farming practices that rely on rainfall for water. It provides much of the food consumed by poor communities in developing countries. In India, about 52% of total net sown area comes under rainfed lands. Rainfed crops account for 48 per cent area under food crops and 68 per cent under non-food crops. India ranks first among the rainfed agricultural countries of the world in terms of both extent and value of produce. Due to population pressure on agricultural lands, the poverty is concentrated in rainfed regions. The climate in India’s rainfed regions is characterized by complex climatic deficiencies, manifested as water scarcity for rainfed crop production. The climate is largely semi-arid and dry sub-humid with a short (occasionally intense) wet season followed by long dry season. Rainfall is highly unreliable, both in time and space, with strong risks of dry spells at critical growth stages even during good rainfall years. The fluctuations are due to numerous factors affecting the monsoonal climate including the atmospheric circulation and strong links to El-Nino Southern Oscillation (ENSO) phenomenon in the Pacific Ocean. Rainfed areas in India are highly diverse, ranging from resource rich areas to resource-constrained areas. Some of the resource rich areas are highly productive and have experienced widespread adoption of technology. However, most of the areas are resource constrained and dry areas. In the resource constrained and dry areas, the farming is a survival mechanism rather than a growth oriented activity. Rainfed agriculture is practiced under a wide variety of soil type, agro-climatic and rainfall conditions ranging from 400 mm to 1600 mm per annum. Rainfed Crops are prone to breaks in the monsoon during the crop growth due to water stress. This water stress may be due to variability of rainfall, delay in sowing, diversity in crop management practice and variability of the soil type. The prolonged breaks can result in partial or complete failure of the crops.

With renewed interest in rainfed agriculture during 1970s, both the national (AICRPDA and CRIDA) and international institutions (ICRISAT) have studied several aspects of rainwater management. Recommendations have been made after their through testing both at the research Stations and on farmer’s fields. Initially these technologies were accepted by the farmers because of the pursuation by the Scientists and the incentives, but many of them are forgotten once the support is withdrawn. It is now time for us to examine whether the technologies themselves were weak or certain components were missing malfunctioning of the software may be due to a bug right from the beginning or it entered into the system at a later stage. It is also possible that we neglected certain critical inputs which became major constraints making the system defunct. Whatever the reason it should be identified and set right if the technology has to continue as tool for tackling the challenges of rainfed agriculture. Main constraints of dry land agriculture to enhance the productivity are classified as follows:

Soil is the top layer of the earth surface in which plants can grow, consisting of rock and mineral particles mixed with decayed organic matter and having the capability of retaining water. Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Earth’s body of soil, called the pedosphere, has four important functions

Meteorology is defined as the branch of science concerned with the processes and phenomena of the atmosphere. It is also defined as the climate and weather of a region. The word meteorology is derived from two Greek words: Meteor and logus. Meteor means event occurring above the earth surface and logus means to study. Meteorology is science deals with the physics, chemistry and dynamics of atmosphere and also their direct and indirect effects upon the earth surface, oceans and thereby life in general. Climatology: Climatology is scientifically defined as weather conditions averaged over a period of time. Different regions of the world have different characteristic climates which determine the crops of any region. Climatology is derived from Greek word ‘klima’ – place/zone or slope of the earth and logs is study. It discovers, describes and interprets the climate on the basis of causes and long term effects on variation in regional and global climate. Climatology is the science which studies average condition of weather or the state behavior of the atmosphere over a place or region for a long period of time. Agrometeorology: Agrometeorology is the study of weather and use of weather and climate information to enhance crop production. Agrometeorology is defined as the branch of meteorology that deals with relationship between weather and climate on crop, livestock production and soil management.

Climatic classification is the method of identifying climatologically homogenous regions. The systematic study of climate and its analysis and processing, which is referred as climatology plays an important role in national weather, planning activities and decision making in human activities. Iso climatic regions are those regions which have same climatic conditions. Specific objectives of climatic classification To identify the climates for transfer of production technology developed at particular center. To provide adequate indices of moisture availability for successful crop production in drylands. To quantify the risk levels associated with production constrains to agriculture production.

Soil is a living, dynamic ecosystem that nurtures plants. Soil is responsible for Sustaining plant and animal life below and above the surface, Regulation water and fertilizer/pesticide runoff, Storing and cycling nutrients. But, the natural soil balance was disturbed by man due to agricultural activities to get food. The intensification of agriculture leads to soil erosion, which leads to creation of unproductive soils. In agriculture, soil erosion refers to the wearing away of a field’s topsoil by the natural physical forces of water and wind or through forces associated with farming activities such as tillage. As a result of improper cultivation practices, deforestation and overgrazing aggravates the problem of soil erosion. Globally soil erosion has reached a level that endangers the sustainable supply of food for the growing global population. It already threatens food production and ecosystem service delivery and therefore, there is a pressing need to address this threat. This is especially true in India where, in a total area of 328 million hectares (m ha), 121 m ha is undergoing soil degradation, 68% of which is attributed to water erosion. Water erosion rates range from 5 t ha–1 yr–1 in dense forest regions to rates in excess of 80 t ha–1 yr–1 where erosion is most severe, such as in the Shiwalik mountainous region. India’s average soil loss has been estimated to be 15t ha–1 yr–1; however, given the limited coverage of measurements, this should be treated with caution. In the light of the serious threat that soil erosion poses in the country, there is a pressing need for a systematic nationwide assessment of land degradation due to erosion using appropriate techniques. The area under ravine soil erosion is highest in UP to a tune of 12.30 lakh hectares and lowest in Maharashtra to a tune of 0.20 lakh hectares

Improving water use efficiency or enhancing agricultural water productivity is a critical response to growing water scarcity, including the need to leave enough water in rivers and lakes to sustain ecosystems and to meet the growing demands of cities and industries. Rainfall is the main source of water for the existence of life on the earth. Timely onset of rainfall and its distribution during the crop growing season determine the success of agriculture and food production. Unfortunately, the human life has hardly any control over nature and prevailance of delayed onset of monsoon and dryspells during different stages of crop growth are commonly observed in the dryland agriculture. Drought is a weather-related natural disaster which makes greater impact on food production and it reduces life expectancy and the economic performance of large regions or entire countries. Drought is a recurrent feature of the climate. It occurs in virtually all climatic zones, and its characteristics vary significantly among regions. Drought differs from aridity in that drought is temporary; aridity is permanent characteristic of regions with low rainfall. Drought is related to a deficiency of precipitation over an extended period of time, usually for a season or more. This deficiency results in a water shortage for some activity, group or environmental sector. Drought is also related to the timing of precipitation. Other climatic factors such as high temperature, high wind and low relative humidity are often associated with drought.

Successful crop production both in the rainfed and irrigated ecosystems depends on timely onset of monsoon, its distribution during the crop life cycle and collection of water in various storage structures viz; tanks, reservoirs and ground water table. It is therefore important that adequate supplies of water should be developed to sustain life. Development of water supplies should, however, be undertaken in such a way as to preserve the hydrological balance and the biological function of our ecosystems. Consequently, the human endeavour in the development of water sources must be within the capacity of nature to replenish and to sustain. If this is not done, costly mistakes can occur with serious consequences. The application of innovative technologies and the improvement of indigenous ones should therefore include management of the water resources to ensure sustainability and to safeguard the source against pollution. As land pressure rise, cities are growing vertical and in country side more forest area encroached and being used for agriculture. In India small farmers depends on monsoon where rainfall is from June to October and much of the precious water is soon lost as surface runoff. While irrigation may be the most obvious response to drought, it has proved costly and can only benefit a fortunate few. There is now increasing interest in the low cost alternative-generally referred to as “Rain Water Harvesting (RWH)”. Water harvesting is the activity of direct collection of rainwater, which can be stored for direct use or can be recharged into the ground water. Water harvesting is the collection of runoff for productive purposes. Rivers, lakes and ground water are secondary source of water. In present times, we depend entirely on such secondary source of water. In the process, it is forgotten that rain is the ultimate source that feeds all these secondary sources and remain ignorant of its value. Water harvesting is to understand the value of rain, and to make optimum use of rainwater at the place where it falls.

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.

Green Revolution has increased food grain production by four fold since 1950–51 with the adoption of HYVs, intense input use, extensive tillage, burning of residues and irrigation. The intense cultivation has lead to degradation of natural resource such as soil, water, vegetation etc. In this context, globally conservation agriculture (CA) has opened a new paradigm as it has potential for higher resource use efficiency, water productivity and climate change mitigation through its key principles. Total area and percentage of total area under no tillage practised as part of conservation agriculture in different continents is given in Table 92.

Climate change is looming large on the globe. Food security is one of the key issues that inevitably needs to be resolved under the specters of climate change, particularly in the fragile ecosystems. Never before in the history has Indian agriculture been as vulnerable and uncertainty ridden as it is today. A glimpse of the dynamics of Indian agriculture reveals that it has systematically deviated away from its base environment, the prop that nourishes all biological resources. Today’s agriculture is valued against the prices it fetches from the market, especially the global market. Its contribution to human health and welfare, ecological integrity, resilience of nature etc., are grossly neglected. Agriculture in developing countries must undergo a significant transformation in order to meet the related challenges of achieving food security and responding to climate change. Projections based on population growth and food consumption patterns indicate that agricultural production will need to increase by at least 70 per cent to meet demands by 2050. Most estimates also indicate that climate change is likely to reduce agricultural productivity, production stability and incomes in some areas that already have high levels of food insecurity. Developing climate–smart agriculture is thus crucial to achieving future food security and climate change goals. The production, processing and marketing of agricultural goods are central to food security and economic growth. Products derived from plants and animals include foods (such as cereals, vegetables, fruits, fish and meat), fibers (such as cotton, wool, hemp and silk), fuels (such as dung, charcoal and biofuels from crops and residues) and other raw materials (including medicines, building materials, resins, etc.,). Production has been achieved through a number of production systems which range from smallholder mixed cropping and livestock systems to intensive farming practices such as large monocultures and intensive livestock rearing. The sustainable intensification of production, especially in developing countries, can ensure food security and contribute to mitigating climate change by reducing deforestation and the encroachment of agriculture into natural ecosystems

Watershed is defined as a natural hydrological unit that covers a specific land surface area from which runoff passes through a common outlet or area with common drainage or outlet. In simple terms, it implies a catchments or drainage basin from which water drains towards a single channel. It may extend over a few acres only or may cover thousands of acres. Watershed management is the integration of technology within the natural boundaries of a drainage area for optimum development of land, water and plant resources to meet the basic minimum needs of the people in a sustained manner. It is also defined as the development and management of watershed resources in such a manner as to achieve optimum production without deterioration of resources base or disturbing the ecological balance. It is also termed as “Resource centered technology” since it helps in assessment, augmentation and optimal utilization of all natural resources viz., land, water and vegetation, it prevents deterioration of resources and at the same time ensures sustained productivity of land to meet basic needs of people.

Strategies To Improve The Productivity Of Drylands With renewed interest in rainfed agriculture during 1970s, both the national (AICRPDA and CRIDA) and international institutions (ICRISAT) have studied several aspects of rainwater management. Recommendations have been made after their through testing both at the research stations and on farmer’s fields. Initially these technologies were accepted by the farmers because of the pursuasion by the Scientists and the incentives, but many of them are forgotten once the support is withdrawn. It is now time for us to examine whether the technologies themselves were weak or certain components were missing. Malfunctioning of the software may be due to a bug right from the beginning or it entered into the system at a later stage. It is also possible that we neglected certain critical inputs which became major constraints making the system defunct. Whatever the reason it should be identified and set right if the technology has to continue as tool for tackling the challenges of rainfed agriculture.

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