Wednesday, 28 September 2011

Increasing water use efficiency in potato production

Planting potatoes in flat, rather than ridged beds can increase irrigation water use efficiency in some production systems, according to U.S. Department of Agriculture (USDA) researchers.

Historically, US potato growers seeded their crops in ridged rows (as British growers tend to do) and watered their plants by channelling surface irrigation to flow through the furrows between the rows. Even though most commercial potato producers in the Pacific Northwest now irrigate their crops with sprinklers, they still typically use ridged-row planting systems.

But this planting configuration allows irrigation runoff to collect in the furrow and percolate below the crop root zone. This means that the water is unavailable to the crops, and can also lead to increased nitrate leaching from the soil.

The researchers found that using a flat bed system increased yields by an average of 6 percent, even though 5 percent less water was used for irrigation. This meant that using flat beds instead of ridged rows for potato production led to an overall 12 percent increase in irrigation water use efficiency. The gains were attributed to several factors, especially the probability that planting potatoes in flat beds improves water and nitrogen use efficiency because more water reaches the potato roots.

Read the report in full here.

Wednesday, 21 September 2011

Increased tropical forest growth could release carbon from the soil

Research by the UK Centre for Ecology & Hydrology and the University of Cambridge shows that as climate change enhances tree growth in tropical forests, the resulting increase in litterfall could stimulate soil micro-organisms leading to a release of stored soil carbon.

The study, published in the scientific journal Nature Climate Change, looked at rainforest at the Smithsonian Tropical Research Institute in Panama, Central America, to study how increases in litterfall - dead plant material such as leaves, bark and twigs which fall to the ground - might affect carbon storage in the soil.

Results show that extra litterfall triggers an effect called 'priming' where fresh carbon from plant litter provides much-needed energy to micro-organisms, which then stimulates the decomposition of carbon stored in the soil.

Read more here.

Monday, 19 September 2011

Radical overhaul of farming could be 'game-changer' for global food security

New practices could enhance rather than degrade the world's ecosystems, double agricultural production and protect natural systems.

According to the authors of new research released recently at the World Water Week in Stockholm, a radical transformation in the way farming and natural systems interact could simultaneously boost food production and protect the environment — two goals that often have been at odds.  The authors warn, however, that the world must act quickly if the goal is to save the Earth's main breadbasket areas — where resources are so depleted the situation threatens to decimate global supplies of fresh water and cripple agricultural systems worldwide.

A new analysis resulting from the joined forces of the International Water Management Institute (IWMI) and the United Nations Environment Programme (UNEP) outlines the urgent need to rethink current strategies for intensifying agriculture, given that food production already accounts for 70 to 90 percent of withdrawals from available water resources in some areas.   The report, An Ecosystem Services Approach to Water and Food Security, finds that in many breadbaskets, including the plains of northern China, India's Punjab and the Western United States, water limits are close to being "reached or breached."  Meanwhile, 1.6 billion people already live under conditions of water scarcity, and the report warns that number could soon grow to 2 billion.   The current situation in the Horn of Africa is a timely reminder of just how vulnerable to famine some regions are.

Read more here.

Tuesday, 13 September 2011

Crops with deeper roots capture more carbon, fight drought

Creating crops with deeper roots could soak up much more carbon dioxide from the air, help mankind fight global warming and lead to more drought-tolerant varieties, a British scientist says in a study. Douglas Kell of the University of Manchester says crops can play a crucial role in tackling climate change by absorbing more of mankind's rising greenhouse gas emissions from burning fossil fuels.

Doubling root depth to two metres would also make crops more drought resistant, improve soil structure and moisture, store more nutrients and reduce erosion, Kell says in the study published online in the Annals of Botany journal. Plants use carbon dioxide (CO2) and sunlight to grow and carbon is stored in the roots and leaves. Deeper and more bushy roots would store more carbon underground.

Many crop varieties have root systems that don't extend beyond one metre, limiting their access to water during drought but ensuring rapid growth above ground and bumper yields when the weather is good.

"Doubling root biomass to a nominal two metres is really the key issue, together with the longevity of the carbon they secrete and sequester below-ground," Kell says in the study.

He said previous studies have doubted the benefits of deep roots locking away large amounts of carbon. But this was because the studies did not take soil measurements much below a metre.

"What matters is not so much what is happening now as what might be achieved with suitable breeding of plants with deep and reasonably long-lived roots. Many such plants exist, but have not been bred for agriculture," he says.

Read more from Reuters here.

Tuesday, 6 September 2011

USDA Scientists Study Effects of Rising Carbon Dioxide on Rangelands

Rising carbon dioxide (CO2) levels can reverse the drying effects of predicted higher temperatures on semi-arid rangelands, according to a study published in the scientific journal Nature by a team of U.S. Department of Agriculture (USDA) and university scientists.

Warmer temperatures increase water loss to the atmosphere, leading to drier soils. In contrast, higher CO2 levels cause leaf stomatal pores to partly close, lessening the amount of water vapour that escapes and the amount of water plants draw from soil. This new study finds that CO2 does more to counterbalance warming-induced water loss than previously expected. In fact, simulations of levels of warming and CO2 predicted for later this century demonstrated no net change in soil water, and actually increased levels of plant growth for warm-season grasses.

"By combining higher temperatures with elevated CO2 levels in an experiment on actual rangeland, these researchers are developing the scientific knowledge base to help prepare managers of the world's rangelands for what is likely to happen as climate changes in the future," said Edward B. Knipling, administrator of the Agricultural Research Service (ARS), USDA's principal intramural scientific research agency.

Read more from the USDA here.

Friday, 2 September 2011

Intercropping perennials with maize brings substantial benefits

Growing perennial cover crops under annual maize crops can bring substantial benefits to the soil and environment without compromising maize yields, according to Iowa State University research. The study shows that soil and water quality, and possibly even farm profits could all stand to benefit from this technique.

The researchers used standard agronomic practices to manage a cover crop of perennial Kentucky bluegrass – the most suitable crop found – between rows of maize which was established annually using strip tillage. The system they used kept soil, carbon and nutrients in the fields, rather than it being lost to erosion, runoff and the atmosphere, and still allowed 200 bushels of corn to be yielded per acre (12.6 tonnes/hectare). This compares very favourably with these 10-year average yields for the state of IOWA.

One of the drivers for the research was the potential future demand for stover – corn residues – for use in producing biofuels. Currently this usually remains on the ground after the crop is harvested and helps reduce soil erosion and replenishes nutrients and organic matter. But the prospect of this being removed led many to fear that soil erosion and nutrient loss would increase as biofuel technologies developed.

Read the full report here.