There is increasing hope that trickle irrigation can help solve the water shortage problem. Instead of watering a large area, the water trickles drop by drop down to the roots.
The problem is worldwide and is becoming more serious every day, according to USDA Agricultural Research specialists. The need for water for an increasing population grows while availability of good-quality water decreases.
Pollution takes its toll of good water, including that from toilets, bathtubs and sinks, also that with industrial acids, chemicals, oils and greases discharged by factories, sometimes into sewer systems and sometimes directly into waterways.
Even the water in some swimming pools may be hazardous, according to Dr. J. Alan Beech, Florida International University toxicologist. Beech says he has detected small amounts of chloroform, a suspected cancer agent, and nitrate, a chemical linked to the "blue baby" syndrome, in the water of 145 municipal and commercial swimming pools in the Miami area.
The chloroform appears to be the result of a reaction between the chlorine used to kill bacteria in the water and organic matter that drifts into the pool, he says.
A team of Michigan State University researchers has found that a grassy basin can filter runoff from croplands fertilized with manure to reduce pollution of rural waterways. The researchers constructed a half-acre buffer basin on a cooperating farmer's swine farm. "We've found that 25 percent reductions in pollutants because of it," their research report says.
Lew Morgan of the Toftrees Country Club in State College, Pa., used treated sewage effluent to water the golf course during a period of drought and it worked.
"It would be just a matter of days before I could no longer irrigate," he says. "I had to get more water and fast. The Department of Land and Water Resources was doing experimental irrigation of treated sewage effluent on corn and wheat fields adjacent to Toftrees. We got the go-ahead from the university to tap into their irrigation line. Toftrees, thus, has joined a small minority of golf courses in the United States to make use of recycled water for its irrigation."
USDA Science and Education Administration scientists are doing research to determine whether brackish (salty) water can be used to grow cotton and sorghum.
The primary objective is to determine the yield of cotton under controlled realistic field conditions when irrigated with saline agricultural drainage waste water, their report says.
Other objectives will be to evaluate the extent of salt buildup in the soil that could limit crop yield, and to determine whether the soil can be returned to normal by irrigating with water of low salinity.
Rainwater enters the soil profile by infiltration. When the infiltration rate is less than the rainfall rate, a portion of the rainfall becomes surface runoff, which causes stream flooding and is the primary cause of soil erosion. If the infiltration rate is to occur efficiently and rapidly soil air must be vented to the atmosphere.
When vents do not exist, the air becomes compressed, which slows the infiltration rate and thus causes increased surface runoff. Agricultural engineers at Penn State University and the Northeast Watershed Research Center are investigating methods for venting soil air and reducing excess soil water.
One method is to place shallow subsurface drainage lines in fields where air entrapment may be a problem. The farmer can look forward to reduced runoff and less soil erosion since the entrapped soil air can escape through the subsurface rain lines, thus permitting maximum infiltration and additional water storage capacity.
In much of the west the water supply is being used far faster than the surface water can replace it, according to Dr. Robert W. Deimel, USDA SEA. Within the last 10 years, he says, 30,000 acres of irrigated Arizona farmland has changed to barren land as the water beneath it receded so far down that the cost was prohibitive to pump it up. This is happening now in much of the west, he added.
"For the foreseeable future, this will continue. But the fact remains that this country has an ample supply of water. It has 33 rivers that each flow with more than 7-1/2 million gallons of water per minute. It has an average rainfall of nearly 30 inches.What America does not have is one central clearinghouse responsible for gathering information that now is available from widely diverse sources.
"One possibility is to better manage the existing supplies and to develop more crops which will do well with saline, or little water. Cotton, for example, can be grown with relatively poor quality water; sorghum requires less water than many other crops. Another possibility is to construct water projects such as the Salt River project in Arizona."