Irrigation Methods and Management PDF

AGEN REVIEWER 110 Irrigation - artificial application of water to the soil - it provides the moisture needed for the plant growth - provides moisture to soil - process nutrients to plants or uptake - salts breakdown to prevent soil acidity Irrigation water management - it is the determ...

AGEN REVIEWER 110 Irrigation - artificial application of water to the soil - it provides the moisture needed for the plant growth - provides moisture to soil - process nutrients to plants or uptake - salts breakdown to prevent soil acidity Irrigation water management - it is the determination and controlling of the rate of application, timing, and amount of water to be applied for optimum efficiency. - Limited resources - Small water impound system (pond) Wet & dry method -- alternate wetting - We irrigate the soil, not the plant itself. Purpose of Irrigation 1. To add water to the soil to supply the moisture essential for plant growth 2. To provide crop insurance against short-duration drought 3. To cool the soil and atmosphere 4. To wash out or dilute salts in the soil 5. To reduce the hazard of soil piping (soil pipping is the development of macropores associated with landslides and collapse subsidence) 6. To soften the tillage pan 7. To facilitate better fertilization 8. To allow easy weeding & cultivation Irrigation needs proper drainage (removal of excess water) Challenges in WM & Irrigation 1. Water scarcity & competition 2. Soil salinity & water logging (occurs when there is too much water in a plant root zone which decreases the oxygen) 3. Energy consumption 4. Environmental impact 5. Inefficient water use Sustaining Water 1. Efficient water inputs/ irrigation system 2. Rain harvesting 3. Waste water recycling 4. Drought-resistant crop variety 5. Precision agriculture techniques Advantages of irrigation - Increase cropping efficiency - Increase crop productivity and yield - Increase cropping intensity (1, 2^nd^ & 3^rd^ cropping season) - Output/input = efficiency rate Benefits of irrigation - Availability of water in the field especially during the time of land preparation and critical growth period of the crops - Controlled irrigation tends to regulate the activity of some microbial soil organisms and activate chemical processes in the soil - Irrigation provides the necessary conditions for efficient utilization of fertilizers by plants, and control of pests and diseases. - Irrigation increases farm profits, thereby lowering the cost of production. - Irrigated lands command higher assessed values than those unirrigated - Irrigation leads to more stable and permanently settled community FW 3% other 0.9 Rivers 2% Hydrosphere -- water's surface - Water depletion - Mismanagement - Excessive use - Population - Agricultural intensification Factors affecting water use - Population - Agricultural use - Household size Water conservation -- includes all the activity to sustain fresh water and to protect hydrosphere for the current future human need Sources of water - Precipitation -- rain harvesting - Surface water -- lake ponds, water reservoirs, low-lying areas. - Irrigation water - Atmospheric water - Deep well Drainage -- removal of excess water Agricultural drainage -- removal of excess water where there is an economic crop. Purpose of drainage To provide a root environment that is suitable for the maximum growth of plants. Objective Increase production and sustain yields over a long period of time. Benefits of drainage - Mosquito control - Better root environment - Longer growing season - Fewer plant disease - Salinity control - Better soil condition Effect of poor drainage - Decreased oxygen content in the soil - Decreased rate of organic matter decomposition - Toxic compound development (ferrous & sulfideious) - Decrease nutrient uptake - Increased carbon dioxide concentration - Decrease oxygen Parameters in calculating the quantity of water - The environment - The subsurface geo-hydrological condition - The type of crop - The stage of its growth Health -- ensuring household food security and improving health - Providing with a reliable source of water for drinking and hygiene socio-economic- more land under crops timing and semi-and region to an agricultural area - More crops per ha per year - More crop production per ha per year Negative impact - Water quality degradation - Agricultural intensification Major causes of pollution in groundwater - Inappropriate use of inputs - Poor management of irrigation and Drainage techniques Negative impact on water quality - Human health - 4 million child deaths due to diarrhea - High level of nitrate - Potash for added sweetness in crops can cause cyanosis syndrome and carcinogenic - Surface water pollution, especially that polluted due to high nitrate and phosphate is a serious ecological risk. Definition of system - interrelated, interdependent, interconnectedness What is pace factor - Rough estimate of determining the distance from one point to another usually used by steps - Importance, easy way of measuring distance AGROMETEROLOGY - Study of the interaction between the weather and climate with agriculture Meteorology - Study of atmosphere and phenomena - Weather and climate - Vital since this helps farmers understand and predict how weather conditions will affect their crops - This can inform farmers, of decisions about planting, harvesting, and managing their crops to maximise fields and minimize losses. - Weather - short term - Climate - long term Weather- day-to-day atmospheric conditions in a particular Climate - the average weather conditions over a long period typically 30 years or more. Microclimate -the localized climate conditions within a specific area such as a field or orchard Phenology -the study of the timing of plant life cycle events, such as germination flowering, and fruiting - Orchard means it only has one crop in a large area The difference of weather and climate is the measure of time Temperature -affects plant growth development and flowering Precipitation -influence crop water availability and soil moisture Sunlight -essential for photosynthesis and plant growth Wind -can affect crop transpiration, pollination, and soil erosion Weather station -collect data on temperature, precipitation, humidity, wind speed, and other meteorological parameters Remote sensing -uses satellites to monitor crop conditions and weather patterns over a large area Weather models -predict future weather conditions based on current data and atmospheric dynamics APPLICATION OF AGROMETEOROLOGY - Rain gauges/snow gauges - used to collect rain and snow - Crop selection- identifying suitable crops for specific regions based on climate conditions - Planting and harvesting -- determining optimal planting and harvesting dates to maximize yields - Irrigation management -scheduling irrigation to meet crop water needs efficiently - Pest and disease control -predicting outbreaks of pests and diseases on weather conditions - Risk management -assesting Challenges and future directions - Climate change -adapting to changing climate conditions and developing resilient agricultural practices - Data availability -- ensuring that the data, especially in remote areas - Technological advancements -integrating new technologies such as artificial intelligence and machine learning into agrometeorological applications Agrometeorology plays a crucial role in sustainable agriculture by providing farmers with the knowledge and tools to make informed decisions - Improve productivity - Reduce environmental impact - Ensure food security - Smart farming - Precision agriculture Atmosphere -a gaseous layer that summons our planet and is essential for life Envelop of gases - Composition of atmosphere - nitrogen, oxygen, and CO2 Layers of the atmosphere - TROPOSPHERE -lowest layer/75% greatest - STRATOSPHERE -50km from troposphere/the ozone layer calm air/cloudless/greater visibility - MESOSPHERE -middle layer/coldest layer -90 oC/creating shooting star/fewer oxygen - THERMOSPHERE -hottest layer/thousand degrees/500km - EXOSPHERE -outermost layer/thin atmosphere/satellites orbit the earth. - Hydrology -is the study of the movement, distribution and quality of water on earth Gases and particles in the atmosphere Nitrogen N2 Oxygen o2 Argon Ar Neon Ne Permanent Gases Hydrogen H Helium He Xenon xe Water vapor H2O Carbon dioxide CO2 Methane CH4 Nitrous oxide N2O Variable gases Ozone Aerocol's O3 CFC's Primary Gases Greenhouse Gases - Nitrogen - CO2 - O3 -H2O - Oxygen - CH4 - CFC's KEY HYDROLOGIC PROCESSES - Precipitation -snow, rain, sleet, hail Factors influencing -temperature, atmosphere pressure wind patterns, topography Measurements -rain gauges, snow gauges - Evaporation -liquid to water vapor Factors affecting -- Temperature, humidity, windspeed, surface area Measurement -- evapometer - Transpiration- lost of water through leaves Factors affecting -- temp, humidity, windspeed, and soil moisture Measurement -- lysimeter - Infiltration -- movement of water in the soil Factors- soil texture, soil structure, soil moisture, soil cover Measurement -- infilmometer - Surface runoff -- flow of water in land surface Factors -- precipitation, intensity, soil infiltration capacity, slope, land cover Measurement -- stream gauges - Groundwater flow -- movement of water in the subsurface Factors -- hydraulic gradient, aquifer, properties, well pumping Measurement -- groundwater well, piezometer - Interception -- captures precipitation by vegetation, building and other objects Factors -- vegetation density, leaf area index, precipitation intensity Measurement -- interception gauges IMPORTANCE OF HYDROLOGIC PROCESS TYPES OF HUMIDITY - Absolute humidity -the mass of water vapor per unit vol of air - Relative humidity -ratio of the actual amount of water vapor in the air to the maximum amount of water vapor the air can hold FACTORS AFFECTING HUMIDITY 1. Temperature 2. Evaporation 3. Condensation 4. Advection -refers to the movement of air masses Dew point -the temperature at which air becomes saturated with water vapor and condensation begin to over of - Good indicator, how the air is to reaching its maximum vapor capacity Atmospheric pressure AP - The force exerted per unit area Factors affecting AP 1.altitude 2.temperature 3.wind 4.weather systems Pressure Gradient - The rate at which AP changes over a distance - Responsible for the moist of air formation of winds Condensation - Process by which water vapor in the atmosphere cools and changes its state from gas to liquid or solid Factors affecting condensation - Cooling - Adiabatic cooling -- air can cool as it rise due to decrease in pressure - Contact of cold surfaces TYPES OF CONDENSATION 1.Dew 2.Frost 3.Fog 4.Cloud Precipitation -any form of water that falls from the sky Factors affecting precipitation 1.temperature 2.humidity 3.AP 4.hopography STREAM FLOW/RIVERFLOW -natural channel of discharging water FACTORS AFFECTING STREAMFLOW - PRECIPITATION - INFILITRATION - TOPOGRAPHY - INTERCEPTION - LAND USE PRACTICES Measurement -- stream gauge -it needs the velocity of water and the depth of water (hydrographs use in measurement) Factors affecting measurements is the depth of water Importance of streamflow - Hydro power - Water resources - Ecosystem - Navigation Subsurface flow -movement of water in the underground FACTORS AFFECTING SUBSURFACE FLOW - Land use - Porosity - Permeability - Aquifers -- capacity to stores and transmit water - Hydraulic gradient -slope of the water table IMPORTANCE - Water resources - Ecosystem/environmental flows - Contaminant transport Challenges of future - Groundwater depletion - Climate change - Sustainable groundwater mgt. - Groundwater contamination **Soil Water in relation to plant growth** - soil and water are critical components of the resource base upon which agriculture depends. Importance of soil determines nutrient availability affects irrigation & drainage management practices important in run-off and erosion processes affects tillage and farm management practices Five Essential Functions 1\. Medium of plant growth Physical support Provides water and air Provides essential elements 2\. Regulating Water - The soil helps control the fate of water in hydrologic system. - Soil affects: - Water loss - Utilization - Contamination - Purification 3\. Habitat of soil organisms - The minerals and microbes in soil are responsible for: - Filtering, buffering, degrading, immobilizing, and detoxifying organic and inorganic materials, including industrial and minucipal by-products and atmospheric deposits. 4\. Recycler of raw materials - Carbon, nitrogen, phosphorus and many other nutrients are stored, transformed and cycled through soil. - This is a good thing for it keeps them out of our water systems. 5\. Engineering medium - Buildings need stable soil for support, the bearing capacity determines the ease of stable construction. Four Major Components of Soil - Air - Water - Organic matter - Mineral matter- Inorganic component of the soil; makes more than 90% of the soil solids Composition of Soil by Volume - Mineral -- 45% - Organic Matter -- 5% - Pore space -- 50% Ideal soil: - Air -- 25% - Water -- 25% Weathering and soil formation - Physical weathering- disintegration of rocks and minerals into smaller particles. - Chemical weathering- chemical decomposition of primary minerals and synthesis of new or secondary minerals. Factors of soil formation 1. Parent material- is the bedrock that has been either slowly broken up at a site or transported there by water or other natural agents. 2. Climate- rainwater makes the \'\'softening\'\' of rock and soil possible by the process of weathering. \- soils have slowly changed color and density as the result of wetting and drying, warming and cooling, and freezing and thawing. 3. Living organism- plants (both aboveground and below ground parts), bacteria, fungi, ants, and many other living organisms shape each small part of the soil. 4. Topography- hilly areas commonly have more different kinds of soil than very flat areas. 5. Time- soil develops to maturity and generally becomes a better medium for plant growth, but over time, it becomes more weathered and infertile. Soil physical properties 1\. Texture- relative proportion of soil inorganic particles as determined by the size of each particle \- done by separating into 3 size ranges: SAND 0.05 to 2mm SILT 0.002 to 0.05 mm CLAY \< 0.002 mm 2\. Structure- shape & arrangement of soil particles into aggregates- used to classify soils; can influence crop productivity \- used to identify class of soil \- used to identify grade of soil \- affected by climate, biological activity & soil mgt practices - Platy in pale subsurface soil - Prismatic in subsoil, particularly in grassland regions - Columnar in sodium-affected subsoil of grassland regions - Block in clay-enriched subsoil, particularly in forested regions - Granular in dark surface soil GRADE -- (Distinctness and durability of Peds) - Structureless-- no aggregation or orderly arrangement - Weak- poorly formed nondurable, indistinct peds that break - into mixture of a few entire and many broken peds and - unaggregated materials. - Moderate-- well formed, moderately durable peds, indistinct in - undistributed soil that break into many entire and some broken peds but little unaggregated material - Strong-- Well-formed, durable, distinct peds, weakly attached to - each other that break almost completely into entire peds. 3\. Porosity Ratio of volume of openings (voids) to total volume of material More packed = lower porosity Affected by shape and size of particle \% pore space = \[ 1 - ( bulk density ÷ particle density) \] x 100 Soil water -- water which fills all or parts of pores Size of pores Macropores - Allow ready movement of air and drainage of water Biopores -- macropores created by roots, earthworms, and other organisms micropores -Too small to permit air movement Slow water movement Aeration may be inadequate for satisfactory root development. 4\. Water holding capacity - Amount of water a soil can hold - Affected by soil texture - Small particles (silt & clay) = higher water holding capacity - Higher organic matter = higher WHC (due to affinity of OM to water) 5\. Soil solidity a\. Density- weight of soil contained in a specific volume BULK density (pb) PARTICLE density (pS) b\. Void ratio (n) c\. Specific gravity - Real specific gravity (Rs)-- ratio of the weight of soil solids to the weight of water having the same volume as the solids - Apparent specific gravity (As)-- ratio of the dry weight of a given volume of soil as it exists in place to the unit weight of an equivalent volume of water. Rs =As only if porosity, P = 0 Rs =pS ,while As = pb 6. Infiltration rate - ability of soil to absorb water; the rate of which refers to how fast water enters the soil surface - It depends on the type of soil, porosity, and the - degree of adhesion or bonding of the soil particles - Since the consistence varies with moisture content, the consistence can be described as dry, moist, and wet. - Consistence includes rupture resistance, stickiness and plasticity. - The rupture resistance is a field measure of the ability of the soil to withstand an applied stress or pressure using the thumb and forefinger. - Rupture Resistance - measure of the strength of the soil to withstand an applied stress - Stickiness - capacity of soil to adhere to other objects - Plasticity - Degree a soil can be molded or reworked causing permanent deformation without rupturing. 9.Color - reflective of the amount of organic material, conditions of drainage and the level of oxidation and weathering of the soil. - Light-colored soil- low organic matter- courser soil and heavy leaching - Darker colors - higher organic content-high water tables and poor drainage, or from the color of the parent material. - Red and yellow shades - can mean finely-textured soil. Indicates good drainage - Red and brown subsoil - show that there is free movement of air and water through the soil. - Reddish soils -generally very old soils which are acidic and low in basic cations. - Dark blueish or Grayish coloration (mottling) - indicates poor drainage. - Red, yellow and gray hues of subsoils - reflect the oxidation and hydration states or iron oxides Some properties of water 1. Hydrogen bonds 2. Specific heat - - is the heat energy required to raise the temperature of a substance by a specific amount, the high specific heat of water stabilizes temperatures and results in the relatively uniform temperature of land near large bodies of water. this is important for the growth of crops and natural vegetation. 3. heat of Vaporization.- the amount of heat needed to turn one gram of a liquid into a vapor, without a rise in the temperature of the liquid, because of the high heat of vaporization, evaporation of water has a pronounced cooling effect 4. Heat Conduction or Thermal conductivity.- water is a good conductor of heat. survival of crops in the spring can depend on thermal conductivity. 5. Surface Tension.- the high surface tension of water provides the tensile strength required for the ascent of water in the xylem. - Surface soil moisture- the water that is in the upper 10 cm of soil - Root zone soil moisture- the water that is available to plants, which is generally considered to be in the upper 200 cm of soil. - Hygroscopic water - Water at permanent wilting point - Water at field capacity - Gravitational or drainage water - **Field capacity** is the point at which the gravitational or easily drained water has drained from the soil. Traditionally, it has been considered as 1/3 bar tension. - **Permanent wilting point** is the soil moisture content where most plants can no longer remove water and would experience permanent wilting and is considered to occur at 15 bars tension. - **Available water** is defined as the water held in the soil between field capacity and wilting point. Methods of Measuring Soil Moisture - Soil moisture can be measured or estimated in a variety of ways - low cost feel method - Use of expensive neutron probe units - Use of different resistance-block types - Use of tensiometers **Electrical Resistance Blocks**--- A meter is used to read the electrical resistance of moisture blocks installed in the ground. The blocks come in a variety of configurations but generally incorporate two electrodes imbedded in a gypsum material. **Tensiometers**---This is a sealed, water-filled tube with a vacuum gauge on the upper end and a porous ceramic tip on the lower end. **Feel Method**---A soil probe is used to sample the soil profile. Soil moisture is evaluated by feeling the soil. **Gravimetric method** - A direct measurement of soil water content and is the standard method by which all indirect methods are calibrated. **The neutron probe** - An electronic instrument with a radioactive source that is lowered into the soil in an access tube installed in the soil. Importance of measuring soil moisture - Soil moisture information is valuable to a wide range of government agencies and private companies concerned with weather and climate, runoff potential and flood control, soil erosion and slope failure, geotechnical engineering, and water quality. - Simulations with numerical weather prediction models have shown that improved characterization of surface soil moisture, vegetation, and temperature can lead to significant **forecast improvements.** - Soil moisture information can be used for early warning of droughts, irrigation scheduling, and crop yield forecasting. Soil water movement thru the soil profile - Infiltration - Percolation Classification of plants according to water requirement: - xerophytes- xero means little or none and \"phytes\" comes from the word phyto, meaning plant- low water requirements - hydrophytes- high water requirements - mesophytes- plants with moderate water needs **Irrigation Methods/Systems** The selection of an irrigation system is based on: 1\. soil, 2\. crop, 3\. economics, 4\. water quality, and 5\. management considerations. **Four Major Irrigation Methods** 1\. Surface irrigation systems 2\. Sprinkler irrigation systems 3\. Micro irrigation systems 4\. Sub irrigation systems Crops Categories **Category 1. Row or bedded crops**: sugar beets, sugarcane, potatoes, pineapple, cotton, soybeans, corn, sorghum, milo, vegetables, vegetable and flower seed, melons, tomatoes, and strawberries. **Category 2. Close-growing crops** (sown, drilled, or sodded): small grain, alfalfa, pasture, and turf. **Category 3. Water flooded crops**: rice and taro. **Category 4. Permanent crops**: orchards of fruit and nuts, citrus groves, grapes, cane berries, blueberries, cranberries, bananas and papaya plantations, hops, and trees and shrubs for windbreaks, wildlife, landscape, and ornamentals. Methods of Irrigation a. **overhead irrigation**, wherein the soil is moistened in much the same way as rain - **watering can**. It is the simplest piece of overhead irrigation equipment and is commonly used in small-scale upland farming. - **hose pipe.** This method can be used if there is a piped water-distribution system where a hose pipe can be connected to a tap or outlet and there is enough pressure in the water as it emerges from the hose pipe. - **sprinkler Irrigation.** This method is the application of water to the surface of the soil in the form of spray, simulating that of rain. b. **Furrows irrigation**, which wets only a part of the ground surface - **furrow irrigation**. It is accomplished by running water through small channels or furrows while it moves down or across the slope of the field. - **corrugation irrigation**. It is a variation of the furrow method and it uses small rills or corrugations for irrigating closely spaced crops, such as small grains and pastures. c. **flooding**, which wets the entire land surface - **ordinary flooding.** Water is applied from field ditches to guide its flow and it is difficult to attain high irrigation efficiency using this method. - **border-strip flooding.** A field is divided into a series of strips by borders or ridges running down the predominant slope or on the contour. - **level-border or basin irrigation.** Water is supplied to level plots surrounded by dikes or levees. - **Contour-ditch irrigation.** It involves controlled flooding from field ditches along the contour of the land, which allows the water to flood down the slope between field ditches without employing dikes or other means that guide or restrict its movement. d. **drip or trickle irrigation** wherein the water is directed to the base of the plant. Water is applied to the soil through small orifices. The small orifices, often called emitters, are designed to discharge water at rates of 1 to 8 liters per hour. e. **sub-irrigation**, wherein the surface is rarely wet since the water is supplied from the soil underneath. This requires complete control of the water table so that the root zone is kept relatively free of excess water **Sprinkler Irrigation Systems** Water is applied at the point of use by a system of nozzles (impact and gear driven sprinkler or spray heads) with water delivered to the sprinkler heads by surface and buried pipelines, or by both. Basic Components There are many types of sprinkler systems, but all have the following basic components: 1\. The **pump** draws water from the source, such as a reservoir, borehole, canal, or stream, and delivers it to the irrigation system at the required pressure. It is driven by an internal combustion engine or electric motor. If the water supply is pressurized, the pump may not be needed. 2\. The **mainline** is a pipe that delivers water from the pump to the laterals. In some cases the mainline is placed below ground and is permanent 3\. The **lateral** pipeline delivers water from the mainline to the sprinklers. It can be portable or permanent and may be made of materials similar to those of the mainline, but is usually smaller. In continuous-move systems, the lateral moves while irrigating. 4\. **Sprinklers** spray the water across the soil surface with the objective of uniform coverage. Sprinkler irrigation systems have two major advantages and disadvantage over surface irrigation systems. 1\) First, the field does not need to be LEVELED or GRADED. In fact, steep slopes can increase uniformity if pipe sizes are selected such that pipe friction loss equals elevation gain (pressure remains constant). 2\) Second, if there is NO RUNOFF or PONDING, then variation in soil properties does not influence sprinkler application uniformity. 3\) One of the disadvantages of sprinkler irrigation, especially in arid regions, is evaporation and wind drift before the droplet reaches the soil. Five Types of Sprinkler Systems 1. Center pivot Sprinkler System is a movable pipe structure that rotates around a central pivot point connected to a water supply. Center pivot irrigation systems are the most popular sprinkler irrigation systems in the world because of their 1\. high efficiency, 2\. high uniformity, 3\. ability to irrigate uneven terrain, and 4\. low capital, maintenance, and management costs. 2. Turf Sprinkler System - generally have a decreasing application rate vs. distance from the sprinkler. Ideally, the overlapped patterns from two adjacent sprinklers results in a uniform application. Application rate (mm/hr) is calculated as a function of 1\) flow rate, 2\) angle of coverage, and 3\) sprinkler spacing. 3. Wheel-line and hand-line Sprinkler System - (also known as wheel move, side roll, or lateral roll) are generally used to irrigate pastures or hay in regions where farms are not large enough for center pivot irrigation systems. Wheel lines are often used on 40-acre fields (¼ mile by ¼ mile, 1,300 m x 1,300 m), but they are also used on smaller fields. 4. Orchard Sprinkler System - Most orchards are irrigated with undertree impacts, rotors, or microsprinklers. Overtree sprinklers on tall risers have fallen out of favor because wetted canopies tend to have disease problems. The fact that trees have large rooted areas reduces the importance of uniform application, as long as each tree receives an equal volume of water. 5. Micro-Irrigation System - Water is applied to the point of use through low pressure, low volume discharge devices (i.e., drip emitters, line source emitters, micro spray and sprinkler heads, gravity and low pressure bubblers) supplied by small diameter surface or buried pipelines. **Sub Irrigation Systems** Water is made available to the crop root system by upward capillary flow through the soil profile from a controlled water table. Each irrigation method and irrigation system has specific site applicability, capability, and limitations. Subsurface drip irrigation is the most widely used drip irrigation method. In order to protect the drip tubing from cultivation practices, laterals are buried approximately 15 cm below the ground surface.