If it's Moday it must be Monsanto time

Last April The Independent in the UK published an article on yield declines in Roundup Ready resistant soya bean crops.

The main premise appeared to be supported by entries such as this at Potash Corp in 2007:

Manganese Response of Conventional and Glyphosate-Resistant Soybean

Project Leader: Dr. Nathan Nelson, Kansas State University, Agonomy, 2708 Throckmorton Plant Sciences Center, Manhattan, KS 66506-5501.
Telephone: (785) 532-5115. Fax: (785) 532-6094.

Weed control benefits of glyphosate resistant (GR) soybeans have resulted in nearly complete adoption of GR soybean varieties by U.S. producers, despite an apparent yield decrease that accompanies this decision. Although the reasons for the yield decrease are not known, there is some evidence that GR soybeans have reduced manganese (Mn) uptake compared to conventional soybeans. Therefore, Mn additions may help overcome the apparent yield disadvantage of GR soybeans. The objectives of this study are to: i) evaluate nutrient uptake, distribution, and biomass accumulation in a GR soybean cultivar compared to a non-GR sister line, and ii) determine the response of a GR and non-GR soybean cultivar to soil and foliar Mn applications. Field plots were established at five locations (Scandia, Manhattan, Ashland Bottoms, Rossville, and Ottawa) in North Central and Eastern Kansas in 2006 and 2007 to compare conventional and GR soybean response to three rates of soil applied and two rates of foliar Mn. Response variables include yield, biomass, plant height, Mn uptake, and leaf, and grain Mn concentrations.

Application of Mn increased GR soybean yields between 6 and 14 bu/A at the Scandia site, but results were inconsistent at the other sites. Conventional soybeans were not responsive to Mn at any of the locations in 2006, but were responsive at the Scandia site in 2007. Over all, soybean yields were greater at the Scandia location compared to the other locations for both years, suggesting that the yield increase from Mn application to GR soybeans may only occur in high yielding environments (>60 bu/A). Trends indicated a yield response to both soil-applied and foliar-applied Mn, but the results were inconsistent across locations. Preliminary plant analyses show that there was no significant difference in Mn uptake between the GR and non-GR varieties. There were some differences in nutrient partitioning, where the non-GR soybeans had more K remaining in the leaves at R6 growth stage. Further analysis of 2007 data will be conducted to confirm these observations.

The premise appeared to also be supported by one of the other studies cited in The Independent article which concluded:

This research provides evidence that the GR soybean variety used in this study did not accumulate Mn in the same manner as the conventional variety, and did respond to application of Mn in this high-yield environment.

However, its author Dr. W.B. Barney Gordon objected to The Independent's summary of his findings and backed away from any statement that GMO soya bean may lead to lower crop yields (scroll through to Page 3).

According to Elmore et al in the Agronomy Journal:

Yields were suppressed with GR soybean cultivars. Our other work showed that there was no effect of glyphosate on GR cultivars (Elmore et al., 2001). The work reported here demonstrates that a 5% yield suppression was related to the gene or its insertion process and another 5% suppression was due to cultivar genetic differential. Producers should consider the potential for 5 to 10% yield differentials between GR and non-GR cultivars as they evaluate the overall profitability of producing soybean. Cultivar choices are best based on (i) previous weed pressure and success of control measures in specific fields, (ii) the availability and cost of herbicides, (iii) availability and cost of herbicide-resistant cultivars, and (iv) yield, and not solely on whether cultivars are herbicide resistant. Based on our results from this study and those of Elmore et al., 2001, the yield suppression appears associated with the GR gene or its insertion process rather than glyphosate itself.

What is becoming obvious in all this, is the fact that Australian farmers who plant GMO soya bean may initially save on pesticide application rates, but will inevitably face extra targeted fertiliser costs and the possibility exists that the genetic modification process itself may be responsible for some percentage of lower yield results anyway.

Not exactly the win-win situation that Monsanto and friends are presenting as the 'truth' and something NSW North Coast cane farmers should be aware of as they frequently alternate cane with soya bean.

Extra reading if you are interested in global agriculture here.

U.K. Soil Association 2008 press release here.

* This post is part of the North Coast Voices' effort to keep Monsanto's blog monitor (affectionately known as Mr. Monsanto) in long-term employment.