GM soya to the rescue?
The phenomenal rise of Roundup Ready (RR) soya beans has its roots in the problems farmers in the US and Argentina were facing in conventional chemical weed management in the early 1990s. Some weed species had become resistant to several herbicides in common use, while the newer generation of herbicide products, active at very low dose, required very precise timing and skill to be used effectively. Farmers needed to tread a very narrow line between an insufficient dose and an over-generous one that could also damage the crop. These problems led to rising weed management costs, less predictable weed control and periodic yield loss from herbicide damage. When genetically-modified soya, resistant to the broad-spectrum herbicide glyphosate, made its debut in 1995, it promised a simple, flexible and cost-effective solution.
In both countries, RR soya slotted easily into large-scale operations and the growing adoption of zero-tillage systems. RR soya growers could apply glyphosate at a much wider range of doses than the trickier low-dose products. At the same time zero-tillage made land preparation, sowing and agrochemical application much easier, reducing the number of machinery passes through the field to between two and four, compared with between five and eight under conventional systems. Zero-tillage growers can also use smaller or fewer tractors than conventional ones. This combination of RR soya and zero-tillage made for greater flexibility, simplified many of the logistical and labour hurdles faced by large-scale farmers and required a narrower set of skills among workers and those making the decisions.
It is not surprising that Argentine growers therefore responded enthusiastically when RR soya seed was introduced to the market in the 1996-97 season. Within two years, 51% of the national soya acreage was sown with RR soya, increasing to 99% by 2002. In the US, herbicide-tolerant varieties account for about three quarters of the soya crop. Another potent attraction was that, unlike in the US, RR soya seed was not sold with the high technology fee or the contractual agreement that prohibits farmers from saving seed for the following season. Replanting remains widespread as are illegal sales of RR seed by farmers, so that in 2003, it was estimated that only 20% of RR soya seed sown in Argentina was actually sold by the seed companies.
Changing the face of the land
The dramatic take-over of RR soya in Argentina has been accompanied by a huge expansion in soya cultivation, from six million ha in 1995-96 to 14.2 million ha by 2003-04. Expansion on such a scale is bringing about major changes in land use, biodiversity, food production and rural livelihoods. In the fertile Pampas region, soya now covers up to 80% of cultivated farmland. Acreage of many major food crops has fallen by 15-52%, with the exception of wheat, which is often rotated with soya. Over 40% of the new soya acreage has been carved out of uncultivated forest and savannah land, with a further 27% from pasture and hayfields. The Agriculture Ministry estimates that for each 500 ha cultivated under intensive soya, one new job is created on farm, yet the same land under medium-scale family farming would support several families and at least six jobs. The government now recognises the social upheaval generated by ‘farming without farmers’ under the intensive soya system.
While soy production has more than doubled since 1996, this expansion has left the country less food secure. The share of the population facing hunger has risen sharply, while meat, dairy and egg production has dropped significantly, as well as staple foods.
The herbicide treadmill
Cultivation of RR soya is linked to a massive increase in herbicide sales and use in Argentina. Sales data from CropLife’s national affiliate, CASAFE, are analysed along with government crop acreage data and expert information on application dose and frequency to build up a picture of the current level of reliance on herbicides, especially glyphosate. Herbicides account for around two thirds of all pesticides used in the country. According to the industry’s figures, glyphosate products made up 40.8% of total pesticides sold in 2000, increasing to 44% in 2003. Almost all the growth in pesticide volumes applied since 1995 is due to glyphosate usage. Of the top ten herbicide products sold in Argentina, four contain glyphosate, taking 87% share of sales in 2003. Table 1 details the steady rise in dose, application frequency, and volume of glyphosate under RR cultivation and increasing use of other herbicides.
By 2000, Argentine soya growers applied an average of 2.3 glyphosate applications a year, compared with only 1.3 applications on soya in the US. The difference reflects the higher levels of zero-tillage of soya in Argentina. Farmers here generally burn off early weeds with a glyphosate application just before or at planting, followed by one or two applications when the crop is growing. Their dosage also exceeds that of their American counterparts: an average of 1.20 kg per ha, compared with 0.76 in the US, across conventional and zero-tillage systems. Chemical fallowing, the use of herbicide after harvest to clear unwanted vegetation over winter, is also widespread and accounts for significant glyphosate use.
The popularity of glyphosate is also related to its low and decreasing price during the soya boom, and large supplies imported from China at very low cost. Its patent expired in 2000 in the US and in 2001 in other countries. The price of the 48% formulation in Argentina more than halved during 2000-01, for example, from US$5.63 to US$2.67 per litre. Price of glyphosate in the US continues to fall too, as the number of generic manufacturers grows.
| Table 1. Changes in herbicide use triggered by expansion of zero-tillage and Round-up Ready soya beans | ||||
| 1996/97 | 1999/2000 | 2002/03 | 2003/04 | |
| Area under RR soya (million ha) | 0.400 | 6.769 | 12.481 | 14.112 |
| Glyphosate applications | ||||
| Average rate glyphosate application (kg/ha) | 1.14 | 1.2 | 1.26 | 1.30 |
| Average number applications | 1.8 | 2.3 | 2.36 | 2.5 |
| Volume applied (million kg) | 0.82 | 18.68 | 37.11 | 45.86 |
| % total glyphosate use on soya | 13.5% | 63.8% | 78.9% | 69.9% |
| Other herbicide applications on RR soya | ||||
| % soya area treated | 2% | 10% | 35% | 45% |
| Average rate application (kg/ha) | 0.30 | 0.40 | 0.60 | 0.65 |
| Volume applied (million kg) | 0.002 | 0.27 | 2.62 | 4.13 |
| Total herbicide applications on RR soya | ||||
| Volume applied (million kg) | 0.8 | 19.0 | 39.7 | 50.0 |
Storing up trouble
As glyphosate use has intensified, so has the selection pressure on vegetation for developing resistance to the chemical, as tolerant individual plants within a population survive and multiply. Tolerance to glyphosate has now been recorded for at least 11 weed species in Argentina. Farmers’ use of other herbicides has started to increase in the last few years, now accounting for 8% of herbicide application on RR soya, possibly reflecting a decline in the effectiveness of glyphosate. Dicamba use, for instance, has increased by 157% since 2001.
Recent soya diseases and yield depression in the US point to associations between reliance on RR soya and glyphosate and changes in soil microbial communities. Glyphosate applications can trigger an increase in levels of the important fungal disease agent
Fusarium and adversely affect the nitrogen-fixing ability of the bacterium found in the root nodules of soya. The consequences for Argentine soya could be severe if similar microbial impacts are revealed. The common practice of wheat-soya double-cropping and maize rotation under zero-tillage is especially vulnerable to
Fusarium infection as untilled soils favour its growth. Glyphosate impact on nitrogen fixation is worse under drought stress and in unfertile soils, and much of the soya acreage in Argentina is on nutrient depleted soil. Heavy glyphosate usage could end up yielding unhealthy plants, reduced yields and higher fertilisation costs.
South American soya has already been suffering serious damage from a fungal rust disease since 2001, which appeared in Argentina the following year and has grown worse. There are no varieties resistant to the Asian form of this disease and current attempts to control it focus on early detection and fungicide application. While the agrochemical companies are busy promoting fungicides, there is no attention to possible ecological impacts, or to tackling the problem more holistically by reducing soya acreage and diversifying rotations.
The country’s economic reliance on RR soya for export revenue, based on cheap seed and cheap glyphosate, is now vulnerable, as Monsanto is pushing to introduce technology fees and contracts and the large-scale imports of Chinese glyphosate have fallen. Argentine soya may lose its competitiveness after findings that protein content and quality is inferior to soya from other countries. A radical re-think of production policy and practice is needed, reducing reliance on glyphosate and diversifying cropping and tillage patterns for a more sustainable farming future.
Rust, resistance, run down soils, and rising costs- problems facing soybean producers in Argentina. Charles M. Benbrook, Technical Paper no. 8, Ag BioTech Info Net, 2005, http://www.biotech-info.net/highlights.html#technical_papers
[This article first appeared in Pesticides News No. 67, March 2005, pages 10-11]