Water and Irrigation The water cycle Water and

Water and Irrigation

The water cycle

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

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

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

Water and irrigation • Water and plant growth – Leaves ≈ 65% water – Roots ≈ 70% water – Fruits ≈ 85% water • Melons ≈ 95% water ! • Water 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 water • Wilted = lack of turgidity!

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

Water and irrigation • Excess soil moisture – Lack of aeration, root cells can’t function well – Result is wilted foliage! – Diseases • Fungal and bacterial • Damping-off (a fungal disease)

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

Respiration C 6 H 12 O 6 + 6 O 2 6 CO 2 + 6 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 humidity – Fungal spores germinate on foliage and fruit Botrytis

Water and irrigation - problems • Excess humidity – Guttation

Water and irrigation - problems • Excess 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 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 200 x their weight Potassium co-polymer Break down over 3 -5 years

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

Water Quality • Hard 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 isn’t pure! – Contains nitrogen and sulfur from the atmosphere – Is acidic! – Where do aerial pollutants come from on the East Coast?

Irrigation - subsurface • Capillary mats

Irrigation - subsurface • Wicks

Irrigation - subsurface • Water wick and reservoir

Irrigation - subsurface

Irrigation - surface • Soaker hose

Irrigation - surface

Irrigation - surface Gatorbag

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

Irrigation - overhead

Irrigation - overhead • Breakers

Irrigation - overhead

Keeping moisture in! Anti-dessicants - reduce transpiration

Keeping moisture in! Burlap shading on evergreens reduces transpiration