Increasing Ag Water Productivity

By Farooq Baloch

"By 2050, there will be about 9.2 billion people," according to Kenneth G. Cassman, University of Nebraska-Lincoln professor of agronomy, "this is going to require massive increases in demand for food, energy and water."

He said the world is short on land and water to feed those people so the answer has to be producing more food with less water.

The professor said industries will not be able to grow further unless they find ways to conserve water. "When current supplies are stretched to the limit and you want to expand," he said, "the only way to do that is through conservation."Cassman's research group at UNL works on trying to understand how to increase water productivity of agriculture, including water use, efficiency and conservation. His research concerns how to quantify water and what can be done to improve its efficiency.

"Water in Nebraska is connected with agriculture," he said.

"The easiest way of saving water is not to irrigate," Cassman said, "but that's not the answer because irrigated agriculture contributes 40 percent of the human food supply."

He said pricing water consumption could also help conserve water.

The UNL agronomist said there is a massive need to increase agricultural yields using less water per unit of food produced. "If this isn't done there is both economic and environmental disaster on the road ahead," he said.

The Big Picture
Cassman said dropping water tables across major production areas of the world are a real concern because it's a key measure of the energy required to lift the water from the aquifer to the surface for irrigation, industrial or domestic uses.

The former director of UNL's Center for Energy Sciences Research said in the U.S., one of the major production areas is the Great Plains - a vast prairie region extending from south Canada into Texas through west central U.S. - where irrigation helps grow crops such as corn, wheat, sugar beets, alfalfa and dry beans.

"There isn't enough rainfall for highly productive agriculture, therefore water levels are also dropping in this region," he said.

Cassman said there is concern about the long-term viability of the Ogallala aquifer - a vast yet shallow underground water table aquifer located beneath the Great Plains.

He said water levels are also lowering in Nebraska, which is a water-limited state.

Some areas in the U.S., including Nebraska, are under water stress, according to the United Nations Environment Program's report: An Overview of the State of the World's Fresh and Marine Waters, 2nd Edition, 2008.

Cassman said "water levels are lowering in Pakistan, Northern India, Southern China and Bangladesh - a major breadbasket of the world - because they are over-drawing." He further said the water level is dropping in the North China, which is a major producer of corn and wheat. "There's a concern that it's going to be able to continue in irrigated agriculture," he added.

The Challenge
Cassman said the challenge is to double the food supply in about 40 years with existing irrigated area and using less water per unit of area.

"In 2050, there will 2.2 billion more people than today and they will be much wealthier on average because of economic development, particularly in world's most populous countries," he said. "They will need more food, which will require more land and more water," he added.

Research and Technology Can Help
"Right now some people are working on enhancing productivity; others on enhancing water efficiency," he said. The answer, according to Cassman, is going to be bringing those two efforts together.

The forefront here, he suggested, is to bring groups together within universities to have a tandem effort that seeks to increase both yields and water efficiency at the same time.

Cassman said science and technology in general comes up with new ways of growing food and producing goods and services.

Giving the example of Tri-Basin, one of the natural resource districts in south central Nebraska, he said, "they have challenges with water supply for irrigated agriculture." Kansas sued Nebraska in 1998 for drawing more water from the Republican River than was allowed under a 65-year-old compact with Kansas and Colorado.

He said the NRD board, whose members are elected by the residents of that NRD, required all the farmers to install flow meters on irrigation wells. It also required farmers to report the amount of irrigation water applied to each irrigated field from each flow metered-well, he said.

"We used that data from nearly 800 individual fields to evaluate how well they are doing with regard to water productivity and nitrogen efficiency," he said, "and found some amazing results statistically."

Over three years - by using crop simulation models and a geographic information system, data baseson soils and weather, Cassman and his team were able to re-create the entire water productivity of the system: the average, the ranges and the best farmers.

"We did statistical analysis to identify what management practices, if they were changed, could increase the productivity with which the water is used and at the same time increase yields," he said.

The researchers found that they could actually put together a package of technologies, along with existing technologies, that would increase yields and reduce water use by about one-third in that NRD.

Cassman also suggested farmers can install sensors on their sprinklers so they don't apply irrigation water if the soil is too wet because of the rain.

Role of Education
"Every one of us is concerned with every drop of water and making sure that it is used wisely and properly," Cassman said, "however, the biggest responsibility will be on the shoulders of people under 30 that are going to be the most effective."

Cassman said this is a competitive world with limited resources and every country in the world wants to obtain the resources to maintain a standard of living and their economic growth rate.

"The only way to compete is to have an educated workforce, in science in particular, because it's a world that's becoming more complex," he said.

Cassman said education is important even for understanding questions about what's the best policy to ensure Nebraska uses its water wisely in the future for sustainable economic development and better quality of life.

He said it is important to have a society in which young people are interested in science and want to understand how things work and said it's also important for the U.S. to keep up with other countries in educating its people. "If other countries are educating their kids, allocating resources and understanding how to solve these problems better than us, they will be taking showers and we won't, they will be driving cars in the future and we will be walking."

Nebraska's Position
"Since Nebraska is such a large producer of agricultural products, both livestock and crops," he said, "we are now in a favorable position (compared with) other states in the country in terms of being able to maintain our economy and our standards of living."

Cassman said Nebraskans can be proud that they have developed a political system called the NRD System. "The citizens in that district vote to elect a board, which has the authority to tax the residents of the NRD to initiate programs complying with over drafting of aquifers," he said, adding that managing that resource is in the hands of every Nebraskan because they are the ones who use the water supply.

He said that the University of Nebraska's Robert B. Daugherty Water for Food Institute is going to be one of the world's leading centers in using all kinds of science and knowledge to help find solutions to some difficult questions. Also, he said, the research conducted at UNL can be applied in other parts of the world. "So the spin-off to the world is incredible."