Saturday, December 09, 2006

Soil and Bioavailability of P in Food


Researchers find that soil phosphorus levels may affect plant phytate levels as much as plant breeding. Phytate is the principal storage form of phosphorus in many plant tissues, especially bran and seeds.

Phytate is generally not bioavailable to humans and non-ruminant animals. Accordingly, there has been a push to develop low-phytate crop varieties. Not only is the phosphorus in low-phytate grain crops more digestible by people, low-phytate grains free up minerals essential to human nutrition: zinc, manganese and iron. This new research shows that grain raised with higher levels of soil phosphorus can have higher levels of phytate. I have not read ($) the journal article, but my thoughts are that the discovery of this soil connection was not anticipated: normally nutritional availability does not decrease with increased soil nutrient levels. If this relationship can be validated, it is an important breakthrough that affects human nutrition, efficient use of phosphorus (a non-renewable resource), farm costs, and environmental quality.

Swine and poultry operations benefit. Low-phytate feed results in lower manure phosphorus for these non-ruminants, a welcome prospect for waste management and addressing water quality concerns. Swine rations often need phosphorus added to ensure bone and muscle development for rapid growth, driving the market development for new, low-phytate crop varieties. The alternative to low-phytate feed is to use a feed additive, phytase. Currently, neither approach is particularly cheap.

Appreciation and attribution:
Sugar Creek Farm for a great photo.
GMO Pundit aka David Tribe for posting on this.

($) According to my read of HighWire Publishers Free Online Full-text Articles list, the journal article will be made available at no cost April 2, 2008 (18 months after publication).

1 comment:

Philip Small said...

ARS Press Release: Adjusting Fertilizer to Create Low-Phytate Crops

Adjusting Fertilizer to Create Low-Phytate Crops

November 29, 2006

Giving too much phosphorus to wheat and barley plants has been shown to raise the amount stored as phytate, rather than as more digestible forms of phosphorus. This finding is important for two reasons: Livestock that are fed high-phytate grains excrete more phosphorus in their manure, which can pollute water. Also, phosphorus is a finite resource that could be irreplaceable once it has been thoroughly mined, which could happen in the next 25 years.

Agricultural Research Service (ARS) geneticist Edward J. Souza and colleagues at the University of Idaho Research and Extension Center in Aberdeen — David Bowen, Mary J. Guttieri and Karen M. Peterson — made the discovery. Souza, formerly at the
University of Idaho, is now research leader of the ARS Soft Wheat Quality Research Unit in Wooster, Ohio. Guttieri is now with the Ohio Agricultural Research and Development Center in Wooster, and Bowen is now with Pioneer Hi-Bred International, Inc., Johnston, Iowa.

The researchers found that soil phosphorus levels may affect grain phytate levels as much as plant breeding can, offering two complementary solutions to the nutritional and environmental problems caused by high phytate levels in grains. Besides being more environmentally sound, getting the application rate for phosphorus fertilizers just right might improve the nutrients delivered by grain crops such as wheat and barley.

Not only is the phosphorus in low-phytate grain crops more digestible by people, but low-phytate grains free up minerals essential to human nutrition: zinc, manganese and iron. ARS plant geneticist Victor Raboy, in Aberdeen, is a co-author of a paper on phosphorus development in barley seeds—one of four papers by Souza, Guttieri and Peterson in the November-December 2006 issue of Crop Science Journal. Raboy pioneered development of low-phytate corn, rice and barley. His patented work also led to low-phytate soybeans.

A summary paper is available online.

ARS is the U.S. Department of Agriculture's chief scientific research agency.