Agrometeorological Data Collection, Analysis and Management
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Agrometeorological Data Collection, Analysis and Management ICAR Sponsored Training Program for Technical Officers 25th July to 6th August 2016 Lecture Notes Editors P Vijayakumar, AVM Subba Rao and MA Sarath Chandran All India Coordinated Research Project on Agrometeorology ICAR-Central Research Institute for Dryland Agriculture Santoshnagar, Hyderabad – 500 059 Citation: Vijayakumar P, Subba Rao AVM and Sarath Chandran MA. 2016. Agrometeorological Data Collection, Analysis and Management. Central Research Institute for Dryland Agriculture, Hyderabad- 500 059. 152p. Editors P Vijayakumar AVM Subba Rao MA Sarath Chandran Agrometeorological Data Collection, Analysis and Management ICAR Sponsored training program for technical officers 25th July to 6th August 2016 CONTENTS Lecture Topic Speaker Page Basic Concepts of Agrometeorology B.V. Ramana Rao 1 Monsoon: Concept and its Features VUM Rao 7 Measurement of Solar Radiation BV Ramana Rao 15 The importance of monitoring weather parameters in GGSN Rao 18 crop insurance schemes Agroclimatic indices and their application P Vijaya Kumar 26 Crop -Weather Relationships P Vijayakumar 40 Crop Water Requirements AVM Subba Rao and MA 51 Sarath Chandran Agroclimatic Database Management System AVR Kesava Rao and 62 Suhas P Wani Statistical Analysis of Agromet Data including BMK Raju 68 Rainfall Probability Weather elements influencing plant disease Suseelendra Desai 85 Micro-level Agromet Advisory Services H Venkatesh 92 Water Balance by Thornthwaite & Mather And FAO GGSN Rao 97 Methods Computations of Drought Indices GGSN Rao 102 Crop Micrometeorology Diwan Singh, Anil Kumar 114 and Surender Singh Application of GIS & Remote Sensing tools in Kaushalya Ramachandran 125 Agriculture Mitigation and Adaptation Strategies for Climate Suhas P Wani 139 Change through Integrated Watershed Management Impact of climate change on insect pests M Srinivasa Rao 144 Acknowledgements It is a great privilege for us to express our profound sense of gratitude to Indian Council of Agricultural Research (ICAR), New Delhi for its funding the Training Program on ‘Agrometeorological Data Collection, Analysis and Management’ during 25 July to 6 August 2016. The encouragement and guidance received from Dr Ch Srinivasa Rao, Director, CRIDA is acknowledged with thanks. We express our sincere thanks to all the resource persons from different parts of the country and also the scientists from CRIDA for their efforts in providing lecture notes. We are also thankful to Shri IR Khandgonda, A Mallesh Yadav, D Harini, O Bhavani, VM Sandeep, VP Pramod, V Narasimha Rao, P Pani and K Vijayalakshmi and for their technical and secretarial assistance. P Vijayakumar AVM Subba Rao MA Sarath Chandran Basic concepts of Agrometeorology B.V. Ramana Rao Retd. PC (AICRPAM), CRIDA Life demands food. The production of food depends upon four factors namely Plant and genetic material, Weather, Soil and Water Many other factors like management practices, size of the holding and enterprising nature of the farmer may also contribute to the success or failure of agricultural production. But weather plays a more decisive role. The farmer will have very little control on the weather. Weather will influence the agricultural production through its effects on soil chemistry and physics, plant growth and development, yield and yield components and in every phase of animal growth and production as well. So, the basic philosophy of agricultural meteorology is to make use of the science of meteorology in the interest of food production. Agricultural meteorology can be broadly defined as the science which deals with the interaction between the atmosphere and the plants and farm animals. Therefore, the aim of agricultural meteorology is to make use of all the products of meteorological services including Historical data base, which can be analysed for crop planning, soil and water management strategies, identification of extreme weather events that might cause decline in productivity and evaluate the climatic shifts including inter seasonal and intraseasonal variability of weather factors trends, if any that might provide clues on climate change and if possible the impact of such variability on crop production. Long, medium and short range weather forecasts issued by the meteorological department for taking decisions in crop planning and management, impact of changing weather conditions on biotic interferences to the crop growth and guide the extension officials and farmers from time to time. Global weather parameters like El Nino, Southern Oscillation etc which may have severe effect on seasonal climates within different agroclimatic regions and their impact on crop production. 1 Agricultural Climatology: The agricultural production potential primarily depends upon the availability of moisture in the soil through precipitation (water received over the soil from the atmosphere either in solid or liquid form) and the soil moisture storage capacity which depends upon the clay content and depth of the soil. The other important factor is the thermal regime. The growth and development of the crops is generally believed to take place when the mean daily temperatures are above 5°C. In tropical regions, the mean daily temperatures are much higher than 5°C throughout the year and therefore crops can be grown round the year, if water is available. In high altitude locations and in the interior regions beyond tropics, the mean daily temperatures will be less than 5°C during the winter season and therefore arable crop production is restricted to warm weather season only. Therefore, the agricultural climates all over the world are classified based on the two parameters i.e., the moisture regime and thermal regime. Crop growth and development: The distinction between crop growth and development can be recognized by the fact that growth represents the increase in weight and volume of the total plant or various plant organs while development represents the consecutive phenological stages through which it passes. The two processes, growth and development are inter related. The factors influencing crop production can be divided into three major groups: (i) Yield defining factors like radiation. (ii) Yield limiting factors like water availability and nutrients. (iii) Yield reducing factors like weeds, pests and diseases. Phases of crop growth: Generally, the crops can be considered to pass through important phases which can be distinguished from each other clearly under ideal conditions. (i) During the first phase, the crop consists of individual plants which do not shade each other and the growth rate increases. A major part of the assimilates is invested in leaf growth and the increase in leaf area is proportional to the solar radiation intercepted. The plant weight increases at constant rate when water is not a limitation. 2 (ii) During the second phase, crop covers the soil completely and growth rate is constant if there is no limitation of water. A major part of the dry matter accumulation during the phase depends upon the growth rate and duration of the phase. (iii) The crop is maturing and the growth rate is decreasing The major environmental factors influencing phenological development are temperature and day length. The crops have a threshold temperature below which no growth takes place. By summing the daily temperatures above certain the threshold value (base temperature) during a particular phase, the number of thermal units (sometimes referred as degree days) required for completion of the phase can be obtained. The fraction of thermal units made available to the crop compared to the thermal units required for a particular phase will provide a numerical value of the development stage. Starting from the date of sowing, the first phase covers germination of seeds, emergence of seedlings and vegetative phase. The second phase covers fifty per cent flowering, grain formation and grain filling stages. The third phase covers physiological and harvest maturity stages. Potential Evapotranspiration: Evaporation of water takes place from the soil as ‘soil evaporation’ and the leaves of the plants as ‘transpiration’. The combined loss of water due to evaporation from soil and transpiration from the crop is called ‘Evapotranspiration’. The water loss due to evapotranspiration depends upon the ‘water availability’ to the plants through soil moisture storage, rainfall and or irrigation. Therefore Penman (1948) introduced the concept of ‘potential evapotranspiration’ (PET) which is defined as the maximum amount of water that can be lost through evapotranspiration from short grass covering the entire soil when water is not a limiting factor. He developed a mathematical expression which is popularly known as Penman’s method for computing the potential evapotranspiration using weather data such as temperature, wind speed, vapour pressure deficit, radiation etc. At many of the places, the data required for estimating the potential evapotranspiration may not be available. Therefore, Thornthwaite (1948) also developed a formula to calculate the potential evapotranspiration using temperature data. Later Monteith improved the Penman’s equation for more reliable estimation of PET which is now widely used as Penman-Monteith’s equation. 3 Crop water requirement (ET0): The actual amount of water required by the crop for evapotranspiration is called water requirement of the crop. The water requirement of the crop depends upon what is known as Leaf Area Index (LAI) i.e., the leaf