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Irrigation Systems
Rainwater
Most farmers in the world depend solely on seasonal rains to water their crops
Rainwater
Advantages: No labor required Free No technology or equipment required
Disadvantages: Not suitable for all crops in all climates A dry year can severely lessen yields or loose
an entire crop Bad droughts and lead to little or no income
and/or famine
Hand Watering
Watering individual plants by hand
Usually involved hauling buckets, watering cans or a hose
Hand Watering
Advantages: Minimal and low-tech equipment needed Very cheap Water applied directly to plants
Disadvantages: Labor intensive Inefficient for watering a large amount of
land Slow
Surface or Flood Irrigation
Water moves over and across the land by simple gravity flow
This has been the most common method of irrigating agricultural land
Surface or Flood Irrigation
Advantages: Relatively small investment on low-tech
equipment Simple to understand
Disadvantages: Labor intensive High maintenance Can lead to water-logging and soil salinity if
there is not adequate drainage Won’t work well on uneven surfaces
Sprinkler
Water is piped in and distributed by overhead high-pressure sprinklers or guns from a central location in the field or from sprinklers on moving platforms
Sprinkler
Advantages: Even distribution of water Unaffected by uneven land surfaces Ability to apply fertilizers and herbicides through
the system Less labor required
Disadvantages: Can cause crusting of soil surface Strongly affected by windy conditions High maintenance requirements Initial investments can be high Wet foliage is susceptible to disease Up t0 50% of water can be lost to evaporation
before plants absorb it
Center Pivot
Water is distributed by a system of sprinklers that move on wheeled towers in a circular pattern
This system is common in flat areas of the United States
Center Pivot
Advantages: Even distribution of water Ability to apply fertilizers and herbicides through the
system Covers a large area with less sprinkler heads Low labor
Disadvantages: Can cause crusting of soil surface and soil erosion Strongly affected by windy conditions High maintenance requirements Expensive to setup and fix Technical knowledge of system required
Lateral Move Irrigation
Water is distributed from a main hose through a series of pipes, each with a wheel and a set of sprinklers
After an area has been sufficiently watered the system is moved across the field either by hand mechanically
Lateral Move Irrigation
Advantages:Similar to center pivot irrigationLower input costs than center pivot
Disadvantages:Also similar to center pivot
irrigationHigher labor requirements than
center pivot
Drip Irrigation
also known as trickle irrigation
Water is delivered near the plants roots, drop by drop
Drip Irrigation
Advantages:Ability to irrigate irregularly shaped
fieldsMinimal soil erosionHighly efficient and conserves waterReduced risk of disease from wet
foliage Waters only root zone of plants Less soil crusting and weedsLess water lost to evaporation
Drip Irrigation
Disadvantages:Very expensive investmentInitial setup is labor and time intensivePost-season cleanup requiredUses lots of plasticCan result in seed germination
problemsRequires sediment-free water
Drip Irrigation
Used since ancient times when buried clay pots were filled with water, which would gradually seep into the grass
Modern drip irrigation began its development in Afghanistan in 1886 with clay pipes
The advent of modern plastic allowed for vast improvements in tubing
Plastic emitters and modern drip irrigation was developed in Israel by Simcha Blass
Drip Irrigation
Drip irrigation is a sustainable solution in many, BUT not all agricultural applications.
Ideal for watering landscapes, vegetable crops, orchards and vineyards.
Not ideal for large field crop production such as alfalfa or soybeans.
Greatly reduces the overall amount of water used by supplying water only where the plants can use it
What is the Best?
Irrigation method used depends on :Crop being grownTopographyRegionClimateWater availabilityAvailable money and labor
Sustainable Water
Practices
Don’t Lose to Evaporation
When crops are irrigated by overhead sprinklers nearly 50% of the water is lost to evaporation before it is absorbed by the plants.
Even when watered with drip irrigation water evaporates faster than it is absorbed.
Evaporation is caused by the sun hitting and heating water molecules.
Watering plants in the early mornings or late afternoon/evening when the sun is not shining will greatly reduce water lost to evaporation
Mulch Magic
Mulch is a protective cover placed over soil to help retain moisture…as well as reduce erosion and suppress weeds.
Mulching provides a more natural environment for plants by mimicking leaves that pile up on the forest floor.
Materials: Organic mulches include yard clippings,
leaves, straw, shredded tree bark, sawdust and compost
Synthetic mulches such as rubber from recycled tires and plastic sheeting
Mulch Magic
Swales
A Swale is a ditch on the contour of a hillside.
It does not direct water, but rather holds it and allows it to gradually infiltrate the soil down-slope of it. Soil and water run-off are caught in the swale, which becomes a fertile area. Gradual infiltration of water and nutrients in the swale slowly improve soil structure down-slope.
Swales
How a swale works: Swale Plume
Example of what can be accomplished with swales: Greening the Desert