Improving 'crop per drop' key

Improving 'crop per drop' key

With a growing global population, food producers must discover ways to produce more food using the same volume of water.

WATER plays an increasingly important role in solving the planet's food security challenges, with researchers at the University of Minnesota projecting that simply increasing crop water productivity could feed an additional 110 million people while meeting the domestic water demands of more than a billion.

Improving crop water productivity — quantified as the amount of food produced per unit of water consumed — has the potential to improve both food security and water sustainability in many regions of the world.

A study conducted by researchers at Minnesota's Institute on the Environment (IonE) and the Institute of Crop Science & Resource Conservation at the University of Bonn, Germany, analyzed crop production and water use by climatic zone for 16 staple food crops. Results of the study were published May 29 in the online journal Environmental Research Letters.

The crops studied, including wheat, maize, rice, sugarcane, etc., account for 56% of global crop production by tonnage, 65% of crop water consumption and 68% of all cropland by area. IonE said the study is the first of its kind to analyze water productivity for so many crops on a global scale.

Among its findings, the study concluded that in the drier regions of the planet, bringing up the poorest-performing crops to the 20th percentile of crop water productivity could increase annual production on rain-fed cropland to provide enough food for an estimated 110 million people without increasing water use or planting additional acreage.

Looking at irrigated land, on the other hand, a similar improvement could reduce water consumption enough to meet the annual domestic water needs of nearly 1.4 billion people while maintaining current levels of production.

"Since crop production consumes more fresh water than any other human activity on the planet, the study has significant implications for addressing the twin challenges of water stress and food insecurity," said Kate Brauman, an IonE postdoctoral research scholar and lead author of the report.

Brauman used Africa as one example, noting that if low crop water productivity in rain-challenged parts of the continent achieved the 20th percentile of productivity, total rain-fed food production in Africa could be increased by more than 10% without additional crop acreage. Similar improvements on irrigated cropland could reduce total water consumption by 8-15% in traditionally parched regions of Africa, Asia, Europe and South America.

According to the study, water consumption by crop varies substantially across the globe, reflecting differences in cropping density, crop choice, soil characteristics, irrigation availability and agricultural management, as well as climatic drivers of evapotranspiration.

For the 16 food crops studied, 83% of the water used originated as rainfall on cropland; however, 52% of rainwater consumption and 82% of irrigation water consumption occurred in regions where lack of precipitation is a potentially production-limiting factor.

Some factors that inhibit crop water productivity are beyond the scope of farmers' management, including climate-related issues. The IonE authors identified several non-climate drivers, however, including a focus on improving yield, or achieving "more crop per drop."

Nonetheless, specific management strategies will need to be tailored to local circumstances and resources. Studies in Nigeria, Sudan and Niger, for example, show that nitrogen and phosphorus limitations restrict millet and sorghum yields; improving soil nutrient conditions by reducing wind-driven erosion could boost yields in those countries, producing more bushels with roughly the same volume of water.


Making every drop count

Farmers in the U.S., meanwhile, are focused on doing their part to produce more food without using additional water.

The National Corn Growers Assn. (NCGA) launched an interactive educational module last month designed to help corn farmers understand water issues and ways to enhance water quality on their farms.

"NCGA is dedicated to continuous improvement, education and supporting water conservation and input management," Dean Taylor, chair of NCGA's Production & Stewardship Action Team, said. "Our goal in producing these tools is to communicate the actual production-related practices farmers are successfully implementing related to water quality."

The 30-minute interactive learning module was developed to share best management practices related to water quality while also imparting an understanding of key regulatory requirements and elements of the Clean Water Act.

Farmers have increasingly been called to focus on improving water quality by employing practices that limit nutrient runoff from farm fields. In Ohio, for example, an alliance of farm organizations, environmental advocates, academia, agribusinesses and other interested parties have begun a multi-step initiative to positively affect water quality both short term and over an extended time frame (Feedstuffs, April 8).

According to the alliance, led by agricultural groups such as the Ohio Agribusiness Assn. and Ohio Farm Bureau Federation, a recent farmer survey showed 82% compliance with Ohio State University-approved soil testing practices, and a pollution reduction project in the Lake Erie Basin reduced phosphorus applications by more than 180,000 lb. across 8,653 acres.

Furthermore, farmer-to-farmer outreach in Ohio's Grand Lake watershed helped achieve 100% compliance with the state's water quality mandates, and 4,421 farmers attended 163 nutrient and water quality training sessions hosted by Ohio State University Extension.

A statement from the alliance noted that 290 farmers in Ohio are part of a test project that has expanded the use of cover crops, variable-rate applications, nutrient incorporation, controlled drainage structures and best management practices as ways of mitigating nutrient runoff. Recent water quality studies have suggested that such efforts can reduce phosphorus escapes by nearly one-third.

Water is one of the most vital nutrients in agricultural production, and by any measure, food production is a major user of the world's water resources. With a global population projected to reach 9 billion people by 2050, producing more food with the same — or, perhaps, even fewer — resources is also likely to be a necessity.

Figuring out ways to produce more crop per drop while also protecting water quality and preventing runoff-related issues is an essential component of that global food challenge.

Volume:85 Issue:28

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