Introduction
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A leading concern facing the future of agricultural production is the availability of water. It is expected that climate change will cause more extreme climate events including droughts and floods and shifts in plant growing zones. As populations grow, more efficient use of water in growing food will be of key importance.
Today, some 2.8 billion people live in water-scarce areas, but by 2030, it is expected that about half of the world’s population will live in water stressed areas.
Past overuse of fossil water from aquifers will make it necessary to improve the efficiency of irrigation and rainfed agriculture methods to grow tomorrow’s food. The increasing competition for water in urban areas and for energy uses will lessen what is now available for agriculture, estimated to be 70 to 80 percent of global fresh water use. As other interests gain a share of the fresh water supply, the production of food will need to increase at the same time that the water used to grow it decreases.
Agriculture is done using both rainfed and irrigation farming. About 80 percent of globally cultivated land is done with rainfed farming, accounting for 60 percent of world food production. Using smart methods to enhance efficient and creative water use in rainfed agriculture has the potential to increase production. The majority of the world’s poor and hungry live on rainfed farms in South Asia and sub-Saharan Africa, so techniques which can improve water use in these regions are very valuable. While irrigation levels have declined since the 1970s for various reasons, irrigation has the potential to expand in the future in parts of Africa.
Productivity of irrigated land is more than three times that of unirrigated land. Around 40 percent of the world’s food is produced on the 20 percent of land which is irrigated. The monetary value of the yield of irrigated crops is more than six times that of unirrigated crops because crops with higher market values tend to be grown on irrigated land.
Many of the methods known to conserve water and use it efficiently have been practiced for thousands of years in some very arid regions of the world with great success. The best systems require little maintenance while yielding maximum results. The ability to add water during crucial growth periods can greatly increase crop yields.
To follow, is a list of water saving techniques which will be helpful in growing more food with less water. Because every parcel of land requires its own best unique solution, I hope readers find this post both useful and inspirational. Please feel welcome to add other methods not included on this list, in the comments below.---Kay McDonald
1. Drip, or Micro-Irrigation
Drip irrigation delivers water (and fertilizer) either on the soil surface or directly to the roots of plants through systems of plastic tubing with small holes and other restrictive outlets. By distributing these inputs slowly and regularly, drip irrigation conserves 50 to 70 percent more water than traditional methods while increasing crop production by 20 to 90 percent. The water and fertilizer are also more easily absorbed by the soil and plants, reducing the risks of erosion and nutrient depletion.
Usually operated by gravity, drip irrigation saves both the time and labor that would otherwise be needed to water crops, leading to larger harvest yields. Small systems on timers can easily be set up by the home gardener, too.
This technology must be innovated and tailored to the crop and conditions. For example, some systems are now solar powered and tubing materials have changed. There are many styles of drip inserts which can be incorporated into the hoses and soaker hose segments can also be used. Instead of using plastic tubing, ceramic can be used as it is more porous.
Small stream diversions, water collection tanks, or holding ponds can be used to provide a gravity water supply for drip irrigation systems. Hand or peddle powered pumps or elevated buckets can also be used.
These micro-irrigation systems, while affordable, are less suitable for major rice growing areas or for staple grain growing. They are more suitable for high value vegetable gardens. Care should be taken to avoid the build-up of salts in drip-system soils.
Within the last two decades, the area irrigated using drip and other micro-irrigation methods has increased more than six-fold, to over 10 million hectares. The adoption of drip irrigation in more areas holds much hope for growing more food with less water.
2. Bottle Irrigation and Pitcher (Olla) Irrigation
Buried clay pot (olla) irrigation is an ancient technology that uses a logical idea. By burying a porous clay pot up to its neck, and filling it with water, a gardener has a 70 percent efficient watering system. Water weeps slowly out of the pot and moistens an area about one-half the diameter of the olla. Since soil is not saturated, the environment created is very healthy for the plant roots, which form a mat around the olla. (Many modern gardeners kill plants by overwatering.)
A perfect olla has a thick wall, is fired at a high temperature, has rough surfaces, and holds one quart to two gallons of water. After burying the pot and filling it with water, the top can be covered with a rock to keep it clean and prevent evaporation.
Depending upon the crop and the rainfall, filling the pots two to three times a week may be adequate.
To use an olla, place it in the middle of several plants so that the plants draw moisture from the center and grow outward onto dry land. This uses the space and the water very efficiently. Smaller ollas may be used to water containers or patio pots.
If the pots lose flow after many years of use, they can be soaked in vinegar to reopen pores. Always use clean or settled water and don’t add fertilizer so as not to clog the clay’s pores.
Here is a source from which to order ollas in the U.S.: http://growingawarenessurbanfarm.com/ollas
USING RECYCLED BOTTLES FOR BOTTLE-MICRO IRRIGATION
As shown in these two pictures, there are various designs to aid in using a recycled bottle as a slow release pot or plant waterer. Wine bottles, plastic bottles, and almost any bottle will work. Holes can be tapped into plastic sides or lids, or commercial plastic spikes can be purchased which the bottle can be inserted into. Or, a bottle can simply be filled with water and inverted next to a plant into moist soil. The online store, Gardener's Supply Company offers some of these apparatuses as do home supply, hardware, and gardening stores.
3. Zai Pits
Zai planting pits are hand dug holes about ten inches wide, ten inches deep, and three feet apart (25cm x 25cm holes one meter apart). They are used to trap water and increase soil fertility, especially in arid regions with degraded, crusty soils. The pits are planted with a mixture of crop residues, manure, and seeds, and covered with a mulch of grass or leaves.
When digging the pits, the excavated soil is used to make a small ridge around the pit to help capture rainfall. The pits can be reused if silt and sand are removed annually.
This simple technique can increase the amount of crops that smallholder farmers produce by 50 percent after just three years.
4. Drought Tolerant Crops and Seeds
Grow the right crop for the growing region. Regions which suffer water shortages are wise to plant crops which are more tolerant to drought. These include finger millet, pearl millet, Guinea millet, cowpea, teff, lentils, amaranth, fonio, emmer, various sorghums, African rice, Ethiopian oats, irregular barley, mung beans and many grasses. Ideally, researchers would be working with all of the crops on this list to improve the seeds for our crop requirements of tomorrow.
For example, researchers have improved cassava varieties over the past four decades which can increase yields two to four-fold over traditional varieties. Traditional millets require little water and can grow in poor soils without any synthetic fertilizers. Millet is a heat resistant crop which has high calcium and fiber content as well as essential amino acids.
In addition, drought tolerant crop seeds are available both through biotechnology and from native seed varieties. Examples of drought tolerant seeds available today include corn, rice, and cotton. Just as importantly, there are flood resistant rice seeds available. Having the right, reliable, and quality seeds in hand for a new planting season is of utmost importance.
5. System of Rice Intensification (SRI) or System of Crop Intensification (SCI) or System of Root Intensification (SRI)
Millions of smallholder farmers have found that by using SRI and SCI methods of farming, they can get higher yields with fewer inputs through setting up an environment with optimal conditions for the plant. The effect is to get crop plants to grow larger, healthier, longer-lived root systems, accompanied by increases in the abundance, diversity and activity of soil organisms. These organisms constitute a beneficial microbiome for plants that enhances their growth and health.
These principles, applied to growing rice in systems for 30-some years, are being successfully applied to growing vegetables, legumes, wheat, corn, finger millet, and sugarcane. The methods use 25 to 40 percent less water, and make crops more resilient to temperature and precipitation stresses. Crops can be productive with less irrigation water or rainfall because SRI or SCI conditions enhance the capacity of soil systems to absorb and provide water.
SRI methodology is based on four main principles that interact in synergistic ways:
● Establish healthy plants early and carefully, nurturing their root potential.
● Reduce plant populations, giving each plant more room to grow above and below ground and room to capture sunlight and obtain nutrients.
● Enrich the soil with organic matter, keeping it well-aerated to support better growth of roots and more aerobic soil biota.
● Apply water purposefully in ways that favor plant-root and soil-microbial growth, avoiding flooded (anaerobic) soil conditions.
6. Ripper-Furrower Planting System
In northern Namibia, farmers are using a ripper-furrower to rip 60 cm (2 feet) deep and form furrows which function to harvest rainfall. The crop seeds are planted into the rip lines with fertilizer and manure. When it rains, the water is funneled by the furrows to the crop roots.
Tractors are used the first year to start the ripped furrow system. After the first year, farmers plant crops directly into the rip lines using an animal drawn direct seeder.
This practice is being used to plant drought tolerant millet, sorghum, and maize. Farmers using the system are encouraged to practice crop rotation with legumes.
These practices together lengthen the growing season and improve the soil’s structure, fertility, and moisture retention. They improve crop growing in both droughts and floods. Average maize yields have increased from 300 kg/hectare to 1.5 tonnes/hectare, or five-fold in Namibia since using this system.
This method of rainwater harvesting especially aids in regions where soil is dry, solid, and crusty. Whereas the rain previously ran off, now it soaks into the ground right where it is needed to grow the crop.
7. Acequias
The above photo is a wooden aqueduct near Las Trampas, New Mexico on the High Road to Taos. The aqueduct spans a deep gorge at an approximate elevation of 8,000 feet above sea level.
This is an example of an acequia, which is a historical engineered canal that carries snow runoff or river water to a distant field. Acequias are commonly ditches, and need to be planned, maintained, and overseen by groups of cooperative farmers. Acequia water law requires that all persons with irrigation rights participate in the annual maintenance of the community ditch including the annual spring time ditch cleanup.
Acequias originated in Spain and were built later in the Spanish-American colonies.
8. Subsurface Irrigation Systems
Below is a graphic from the Netafilm subsurface irrigation system.
Advantages of subsurface irrigation systems include:
• water savings
• improved crop yields
• no surface evaporation
• no soil and nutrient run-off
• nutrients can be applied at the root
• there is less disease and fewer weeds
• it requires less labor
• produces uniform moisture at the root zone
• reduced amount of energy is required for pumping
Subsurface irrigation is especially suitable for hot, windy regions.
Disadvantages include the high initial cost requirement, clogging and leaking problems, and potential rodent damage. Problems can’t be seen since they are below the ground. Maintenance requirements are chemical injections, an annual clean-up flush, and draining the pipes before it freezes each fall.
A 2009 Colorado State University study estimated that a subsurface drip irrigation system costs $1,000 to $2,000 per acre and lasts 12 to 15 years, or up to 20 years with good maintenance. CSU adds that “if center pivots last 20 to 25 years, these must last 10 to 15 years to be economically competitive.”
9. Water Storage
In the photo above, an excavated water holding reservoir was dug to collect water during heavy rains. It was built lower than the remaining field where some terracing work was also done, so that gravity could do the collecting. A drip irrigation system with some type of pump might be added, and the small pond can also be lined with plastic.
Holding ponds or small storage tanks on small farms can also be fed through canal irrigation. They can collect the water when it is available to be used by the farmer — when needed or when it is a convenient time to irrigate.
There are many kinds of tanks: steel rimmed tanks, plastered concrete tanks, cisterns which are covered storage tanks either above or below ground, and birkahs which are open reservoirs. For both the cisterns and birkahs, channels, dykes, or (stone) walls constructed as wings can be used to aid in collecting water for the reservoir.
Holding ponds fed by canal systems are useful for center pivot irrigation, too.
10. Black Plastic Mulch, and Organic Mulches Can Save 25 Percent in Water Requirements
Organic vegetable producers in drier, cooler climates such as ours on the front range of Colorado like to use black polyethylene plastic film as mulch on vegetable row crops for multiple reasons.
When drip irrigation is laid underneath the plastic film, it delivers water and fertilizer to the plants and evaporation is reduced. But, because there is no surface evaporation of water, it is easy to over-irrigate crops. For this reason, a moisture probe should be used to check root zone moisture levels.
In addition to providing water conservation, this synthetic mulch controls weeds and warms the soil, making for an earlier crop. The black plastic mulch can be covered with hay or straw to protect crops from excessive heat later in the summer.
Other than black plastic film, which can only be used one season, black woven landscape cloth is often used, which can be reused up to seven years.
Organic mulches such as straw, hay, grass clippings, pine needles, and leaves also conserve moisture. These organic mulches add organic matter to the soil after they decompose. One needs to pay attention how different organic mulches can change the soil chemistry, however.
Cover Crops, too...
Finally, green living mulches, or cover crops, can help to conserve moisture -if the right cover crop is used for the right agricultural crop- given its soil and climate conditions.
11. Sand Dams
Sand dams were developed by the Romans in 400 BC.
Experts agree that Africa is especially well-suited to benefit from this fairly simple concept. One sand dam can provide clean drinking water and enough water for gardening and farming for a thousand people, lasting several months after the rains have fallen.
As a rain water collection system, they create a life generating spring where there was none before, by storing wet season water in sand, which filters the water and keeps it from evaporating.
A hand pump can be installed in sand dams to access the deeper, stored, clean water.
Fruit and other trees can be planted near the dams and grass can be added for erosion control.
To construct the dams, villagers line up to dig a deep trench which is filled with concrete and the rainy season backfills the new wall with sand over several rainy seasons. These walls might be 90 meters long and 2-4 meters high. Located across small rivers which stop flowing in the dry season, the sand becomes about 40% saturated with water and can hold 2 to 10 million liters.
This technique has been used in India, Africa, and South America for the past fifty years, but remains underutilized.
To learn more, watch this video.
12. Plastic Buckets for Starting Young Trees
A great time-saver for irrigating newly planted trees is to use recycled 5-gallon plastic buckets. These are often discarded at construction sites. You first need to drill one or two 1/32 inch or smaller holes towards one side of the bottom of the bucket. Set it next to your small tree and fill with water every 1 to 2 weeks. You may move it to the opposite side of the tree each time you refill it.
Or, you can connect a small tube from the bucket into the soil to slowly irrigate, as in the photo above.
Gravity does the remainder of the work for you. If you have a row of seedling trees for a new windbreak, you can refill your water buckets from a tractor water tank if you have one. The idea may be adapted to irrigate berry shrubs and tomatoes, too.
13. Efficiency through Center Pivot Irrigation
As compared to the old days when center pivot irrigation lost an enormous amount of water through evaporation by spraying the water high into the air during hot weather, today’s systems are much more efficient. This efficiency comes from putting sprinkler heads, or nozzles on hose drops, as pictured above, to minimize water drift and evaporation. (Often the hose drops are lower than in this photo.) The systems can be customized with many available options. These newer Low Energy Precision Application (LEPA) center-pivot systems also use less electricity.
The above diagram is the schematic for an organic vegetable farmer’s field here in Boulder County, Colorado. This scheme is used in the center pivot’s electronic control box to set the time, and thus, the amount of irrigation applied to each specific vegetable crop. By planting the field of vegetables in a pie shape, each vegetable’s irrigation requirement can be customized for maximum water use efficiency.
This is the holding pond which supplies the water for the center pivot irrigation. It is fed from snow melt that is distributed through nearby surface ditch irrigation. In this semi-arid region, these water holding ponds are extremely valuable to local farmers.
Soil sensors can be employed to monitor soil moisture levels for center pivot irrigation which can report results directly to the owner’s computer. This helps to prevent over-irrigating.
14. Rotational Grazing Systems
The above USDA photo is an example of a shared water tank for cattle in a four-paddock rotational grazing system in Iowa. Although livestock can get the majority of their water from lush forage which is 70 to 90 percent water, they still need to have a supply of drinking water. (Cattle can require 15-20 gallons of water per day, yearlings 10-15 gallons, and sheep 2-3 gallons per day.)
With good grazing management, decreased water run off and increased soil organic matter keeps pastures more resistant to droughts. During hard rains, pastures can absorb water better due to organic matter in the soils and better forage cover as compared to industrial farm fields. Reduced erosion rates preserve these fertile soils with higher water holding capacity for future crop production. The key is not to overgraze the land.
Pastures have reduced soil and fertilizer run off compared to cropped fields and barnyard herds. The animals hooves help break up the soil surface allowing better water penetration and their manure fertilizes the plants and makes healthy microbial life in the pasture soils. The input costs for the farmer are low and he or she sells “grass” in the form of meat on the hoof.
15. Gravity Drip Bucket Irrigation Systems for Vegetable Gardens
Bucket gardens are a simple technology that is gaining a foothold for subsistence farmers in Africa, India, and at least 150 other nations. Utilizing plastic buckets or larger containers, and drip irrigation tape, these systems enhance food security.
Buckets need to be elevated on stands that are at least three feet above the ground — on the high end of the garden, if it is not flat. Beds should be prepared with compost or organic material and manure and then leveled. The drip tape can then be set up, and with care, the system should last 5-7 years.
Next, see one method of attaching drip lines to the bottom of a plastic bucket.
Below is a diagram of a system which is sold by Chaplin living waters.
This next photo shows an elaborate bucket drip irrigation set-up in Kenya.
Chaplin Living Waters website is found here where you may order bucket kits.
END OF PART 1. To go to PART 2, click HERE.
END OF PART 1. To go to PART 2, click HERE.
Readers, note that this originally appeared on my former site, Big Picture Agriculture, February 2013.
Copyright Notice: Please do not republish from this post in part or in full without permission.