World losing 2,000 hectares of farm soil daily to salt-induced degradation

A press release from United Nations University: Salt-spoiled soils worldwide: 20% of all irrigated lands — an area equal to size of France; Extensive costs include $27 billion+ in lost crop value / year. UNU study identifies ways to reverse damage, says every hectare needed to feed world’s fast-growing population.

Every day for more than 20 years, an average of 2,000 hectares of irrigated land in arid and semi-ari
d areas across 75 countries have been degraded by salt, according to a new study — Economics of Salt-induced Land Degradation and Restoration — published today by the UNU Institute for Water, Environment and Health (UNU-INWEH).

Currently an area the size of France is affected — about 62 million hectares (20 percent) of the world’s irrigated lands, up from 45 million hectares in the early 1990s. Salt-induced land degradation occurs in arid and semi-arid regions where rainfall is too low to maintain regular percolation of rainwater through the soil and where irrigation is practiced without a natural or artificial drainage system.

Irrigation practices without drainage management trigger the accumulation of salts in the root zone, affecting several soil properties and reducing productivity. “To feed the world’s anticipated nine billion people by 2050, and with little new productive land available, it’s a case of all lands needed on deck,” says principal author Manzoor Qadir, Assistant Director of the Water and Human Development programme at UNU-INWEH. ”We can’t afford not to restore the productivity of salt-affected lands.”

Zafar Adeel, Director of UNU-INWEH, notes that the UN Food and Agriculture Organization projects a need to produce 70 percent more food by 2050, including a 50 percent rise in annual cereal production to about 3 billion tonnes....

Campbell's River in the Murray-Darling Basin, shot by Rangasyd, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license 

Effects of growing rice in low water, high salt conditions

Research Asia News: Rice is a staple food across Asia, with both people and economies reliant on its successful harvest. One paper finds that low water input does not affect rice growth as much as the levels of nutrients in soil can, and the second suggests that, although rice is seriously stressed by high salt levels in soil, this can be countered by the application of locally produced compost.

Approximately 576 million tonnes of rice are produced globally each year, with about 90% produced and consumed in Asia. 75% of the world's rice is grown in irrigated lowlands, and with water for agriculture becoming increasingly scarce, the question of the effect of low water levels on rice growth is becoming more critical. Jahan, M. S. and colleagues at the Faculty of Agriculture at Universiti Putra Malaysia, set out to determine the effect, on both rice production and the chemical properties of the soil in which rice grows. They found that iron content in soil slowly increases as rice is growing, but even more so after water is drained off. Manganese, on the other hand, increased sharply after flooding, but decreased after that. They found that water levels did not affect the growth of rice as much as expected. Their results provide recommendations for water management as saturation throughout the cultivation process does not seem to be as important as is believed. Low water input rice production could be implemented and fresh water saved for other sectors.

In a second paper in the same issue, Muhammad Ibrahim and colleagues from Pakistan’s University College of Agriculture and Government College University as well as the South Korea’s National Academy of Agricultural Science, looked at salt levels in soil and the effect on rice growth. They took twenty day old rice plants and transplanted them into clay pots filled with either normal or saline soil. They found that the saline soil had a significant effect on the growth of the rice, but when they applied compost the results improved. Further work is needed to optimise the compost mixture and resulting growth but their work provides hope for many poor rice farmers as compost can be locally made and produced from a variety of waste materials.

A rice terrace in Yangshuo, China, shot by McKay Savage, Wikimedia Commons via Flickr,  under the Creative Commons Attribution 2.0 Generic license

New NASA Salt mapper to sharpen climate forecasts

NASA: Salt is essential to human life. Most people don't know, however, that salt -- in a form nearly the same as the simple table variety -- is just as essential to Earth's ocean, serving as a critical driver of key ocean processes. While ancient Greek soothsayers believed they could foretell the future by reading the patterns in sprinkled salt, today's scientists have learned that they can indeed harness this invaluable mineral to foresee the future -- of Earth's climate.

The oracles of modern climate science are the computer models used to forecast climate change. These models, which rely on a myriad of data from many sources, are effective in predicting many climate variables, such as global temperatures. Yet data for some pieces of the climate puzzle have been scarce, including the concentration of dissolved sea salt at the surface of the world's ocean, commonly called ocean surface salinity, subjecting the models to varying margins of error. This salinity is a key indicator of how Earth's freshwater moves between the ocean, land and atmosphere.

Enter Aquarius, a new NASA salinity-measurement instrument slated for launch in June 2011 aboard the Satélite de Aplicaciones Científicas (SAC)-D spacecraft built by Argentina's Comisión Nacional de Actividades Espaciales (CONAE). Aquarius' high-tech, salt-seeking sensors will make comprehensive measurements of ocean surface salinity with the precision needed to help researchers better determine how Earth's ocean interacts with the atmosphere to influence climate. It's a mission that promises to be, to quote the old saying, "worth its salt."

"We ultimately want to predict climate change and have greater confidence in our predictions. Climate models are the only effective means we have to do so," said Aquarius Principal Investigator Gary Lagerloef, a scientist at the Seattle-based independent laboratory Earth & Space Research. "But, a climate model's forecast skill is only as good as its ability to accurately represent modern-day observations."

Density-driven ocean circulation, according to Lagerloef, is controlled as much by salinity as by ocean temperature. Sea salt makes up only 3.5 percent of the world's ocean, but its relatively small presence reaps huge consequences….

Global differences, on average, between evaporation and precipitation, the main elements of the global water cycle. Eighty-six percent of global evaporation is from the ocean surface, and 78 percent of global precipitation falls back over the ocean. Changes in these patterns affect the salinity of the ocean surface. Scientists will incorporate Aquarius salinity data into computer models used to improve predictions of future climate. Image credit: Committee on Earth Observation Satellites