Water and Irrigation

The water cycle

Water and irrigation Soil infiltrationSoil infiltration –Clay = slow –Sand = fast

Water and irrigation Soil water retentionSoil water retention –OM and clay = high –Sand = low Gravitational water = ground water (well water)Gravitational water = ground water (well water)

Water and irrigation Field capacity = maximum amount of water that a soil can hold against the force of gravityField capacity = maximum amount of water that a soil can hold against the force of gravity Capillary water = available to the plantCapillary water = available to the plant Wilting point = point at which a plant is unable to take up additional water from the soilWilting point = point at which a plant is unable to take up additional water from the soil Hygroscopic water = water not available to the plantHygroscopic water = water not available to the plant

Water and irrigation Water and plant growthWater and plant growth –Leaves 65% water –Roots 70% water –Fruits 85% water Melons 95% water !Melons 95% water ! Water is a solvent in plants that helps to dissolve mineral nutrients and sugars and to transport themWater is a solvent in plants that helps to dissolve mineral nutrients and sugars and to transport them

Water and irrigation Turgid = plant parts filled with waterTurgid = plant parts filled with water Wilted = lack of turgidity!Wilted = lack of turgidity!

Rule of Thumb 1 of water is needed per week during the growing season

Water and irrigation Excess soil moistureExcess soil moisture –Lack of aeration, root cells cant function well –Result is wilted foliage! –Diseases Fungal and bacterialFungal and bacterial Damping-off (a fungal disease)Damping-off (a fungal disease)

Anaerobic respiration After a flood alcohol builds-up = fermentation and death of roots!

Respiration C 6 H 12 O O 2 6 CO H 2 O Aerobic = Oxygen is available, produces high energy Anaerobic = Oxygen is not available, produces low energy

Anaerobic respiration In animals causes lactic acid to build-up

Anaerobic respiration In plants causes alcohol to build-up = fermentation

Containers - SIZE matters! Which will drain best ?? Assuming the same: -volume -potting mix -drainage holes

Containers - SIZE matters!

Water and irrigation - problems Excess humidityExcess humidity –Fungal spores germinate on foliage and fruit Botrytis

Water and irrigation - problems Excess humidityExcess humidity –Guttation

Water and irrigation - problems Excess rainfallExcess rainfall –Cracking of sugar-rich crops like cherries and tomatoes –You should not overhead irrigate these fruits when they are close to harvest! –Erosion –Leaching of mineral nutrients –Anaerobic respiration produces alcohol in water-logged roots

Water and irrigation - problems Water deficiencyWater deficiency –First symptom is gray foliage (esp. ferns) –Leaves and stems wilt –Leaves curl and drop off –Fruits wither and drop –Plants often experience temporary wilting in summer (leaves transpire more than roots take up!). Esp. on vine crops with large leaves

Primrose

Blossom end rot on tomato Caused by water stress and insufficient calcium

Blossom end rot on pepper Caused by water stress and insufficient calcium

Leaf scorch on maple

Water retention crystals Hold 200x their weight Potassium co-polymer Break down over 3-5 years

Water Quality PollutantsPollutants –Algae blooms from excess phosphorus in surface water –Depletes oxygen from the water at night and kills fish!

Water Quality Hard waterHard water –High concentration of dissolved minerals (often found in well water) –Water softeners replace calcium and iron with sodium chloride (table salt) which is damaging to houseplants!

Water Quality Even rainwater isnt pure!Even rainwater isnt pure! –Contains nitrogen and sulfur from the atmosphere –Is acidic! –Where do aerial pollutants come from on the East Coast?

Irrigation - subsurface Capillary matsCapillary mats

Irrigation - subsurface WicksWicks

Irrigation - subsurface Water wick and reservoirWater wick and reservoir

Irrigation - subsurface

Irrigation - surface Soaker hoseSoaker hose

Irrigation - surface

Irrigation - surface Gatorbag

Irrigation - overhead Sprinkler-soaker hose (can have significant water loss)Sprinkler-soaker hose (can have significant water loss)

Irrigation - overhead

BreakersBreakers

Irrigation - overhead

Keeping moisture in! Anti-dessicants - reduce transpiration

Keeping moisture in! Burlap shading on evergreens reduces transpiration