Lecture 7: Water Management Flashcards

1
Q

WATER MANAGEMENT

A
  1. time application of needed water
  2. removal of excess water
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2
Q

EFFECTS OF LACK OF WATER

A
  1. poor crop stand
  2. stunted growth
  3. yield reduction
  4. pest/diseases
  5. nutrient deficiency
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3
Q

TOMATO BLOSSOM END ROT

A
  1. calcium deficiency (lack of water)
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4
Q

EFFECTS OF EXCESS WATER

A
  1. nutrients leaching from soil
  2. high acidity of soil
  3. water-logged condition
  4. lack of oxygen causing root death
  5. root-rotting pathogens
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5
Q

EXAMPLES OF ROOT-ROTTING PATHOGENS

A
  1. Phytophthroa
  2. Pythium
  3. Rhizoctonia
  4. Fusarium
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6
Q

EFFECTS OF FLUCTUATION IN WATER SUPPLY

A
  1. fruit cracking (tomato, mango, banana, carrots)
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7
Q

PURPOSE OF IRRIGATION

A
  1. timing and frequency of irrigation
  2. adequate supply of water
  3. efficient method
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8
Q

FACTORS AFFECTING IRRIGATION PROGRAMS

A
  1. soil factors
  2. climate factors
  3. plant factors
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9
Q

IRRIGATION: SOIL FACTORS

A
  1. soil texture, structure, depth
  2. affects WHC, water percolation
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10
Q

IRRIGATION: CLIMATIC FACTORS

A
  1. temperature, length and intensity of sunlight, relative humidity, wind movement
  2. affects rate of water loss (evaporation and transpiration)
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11
Q

IRRIGATION: PLANT FACTORS

A
  1. rooting characteristics, drought tolerance, growth stages
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12
Q

DROUGHT RESISTANCE

A
  1. dictated by genetics
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13
Q

DROUGHT TOLERANT CROPS

A
  1. siniguelas
  2. cashew
  3. mango
  4. tamarind
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14
Q

DROUGHT-SUSCEPTIBLE CROPS

A
  1. banana
  2. lanzones
  3. durian
  4. papaya
  5. cacao
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15
Q

STAGES AFFECTED BY WATER STRESS

A
  1. early vegetative growth
  2. flowering
  3. fruit setting
  4. fruit development
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16
Q

FLOWER INDUCTION

A
  1. triggered by application of irrigation after brief drought
  2. durian, rambutan, citrus, lanzones, coffee
17
Q

METHODS TO DETERMINE IRRIGATION SCHEDULES

A
  1. available soil moisture
  2. evapotranspiration rate
  3. visual symptoms of plants
  4. feel of soil
  5. soil-cum-sand mini plot technique
18
Q

IRRIGATION SCHEDULE DETERMINATION: SOIL MOISTURE

A
  1. gravimetry: oven drying and computing for soil moisture content
  2. tensiometer: measure water potential; inversely proportional to amount of available water
19
Q

THRESHOLD LEVEL IN ESTIMATING AVAILABLE SOIL MOISTURE

A
  1. 50% of available water
20
Q

IRRIGATION SCHEDULE DETERMINATION: EVAPOTRANSPIRATION

A
  1. use of evaporative pan
  2. applied over short time intervals
21
Q

IRRIGATION SCHEDULE DETERMINATION: VISUAL SYMPTOM

A
  1. temporary wilting
  2. color of foliage
22
Q

IRRIGATION SCHEDULE DETERMINATION: SOIL FEEL

A
  1. sandy: dry; doesn’t form ball
  2. loam: crumbly; particles hold together
  3. clay: pliable; forms ball; doesn’t form ribbon
23
Q

IRRIGATION SCHEDULE DETERMINATION: SOIL-CUM-SAND TECHNIQUE

A
  1. choose 2-3 hills from representative section
  2. dig pits of 1 cubic meter
  3. add 5% sand to soil and return mixture to pit
  4. plant seedlings
  5. limiting soil moisture: wilting of seedlings 2-3 days ahead
24
Q

METHODS OF IRRIGATION

A
  1. surface irrigation system
  2. sprinkler irrigation
  3. drip system
  4. sub-surface irrigation system
25
Q

SURFACE IRRIGATION SYSTEM

A
  1. furrow method
  2. flooding method
  3. basin method
26
Q

SURFACE IRRIGATION: FURROW METHOD

A
  1. row crops (corn, peanut, banana)
  2. uniform gentle slopes (0.25-2.5%)
  3. windy areas
  4. abundant water
27
Q

SURFACE IRRIGATION: FLOODING METHOD

A
  1. lowland rice
  2. closely planted upland crops
  3. flat areas
  4. windy areas
  5. abundant water
28
Q

DISADVANTAGE OF FURROW AND FLOODING METHOD

A
  1. inefficient
  2. weed growth
  3. limited application
29
Q

SURFACE IRRIGATION: BASIN METHOD

A
  1. crops planted far apart (tree)
  2. more efficient
  3. flat to steep slope areas
30
Q

SPRINKLER IRRIGATION

A
  1. highly pressurized water
  2. use of network of pipes
  3. fine droplets of water
31
Q

ADVANTAGE OF SPRINKLER IRRIGATION

A
  1. sandy soil
  2. flat to steep slope areas
  3. more efficient
  4. temperate reduction
32
Q

DISADVANTAGE OF SPRINKLER IRRIGATION

A
  1. high initial investment
  2. high operating cost
  3. water distribution affected by wind
  4. diseases and wind growth
  5. high evaporation losses
33
Q

DRIP SYSTEM

A
  1. use of network of pipes
  2. drips as water output
  3. water applied directly to root zone
  4. continuous supply of small amount of water
34
Q

ADVANTAGE OF DRIP SYSTEM

A
  1. wide application
  2. highly efficient
  3. combines irrigation and fertilization
35
Q

DISADVANTAGES OF DRIP SYSTEM

A
  1. high initial investment
  2. clogging of nozzles
36
Q

SUB-SURFACE IRRIGATION SYSTEM

A
  1. applied below soil surface
  2. reacher plant root system by capillary movement
  3. potted indoor plants; greenhouse plants
37
Q

SOURCES OF IRRIGATION

A
  1. river, stream, lake (dam; pumping)
  2. farm reservoir
  3. water impounding system
  4. ground water (open well; tube well)