Issues Magazine

GM and Biodiversity: Partners in Conservation and Productivity?

By T.J. Higgins

Over the next 40 years there will be marked increases in agricultural inputs, and an additional one billion hectares of wild land will be appropriated for crops and pastures.

The editorial in Nature on 29 July 2010 was very upbeat about feeding the projected nine billion people in 2050 on the one hand but raised a very sobering question on the other. Even the sobering question raised the prospect that the “cost to the planet” could be saved by technology, both low and high forms.

Not too many people are as sanguine as the Editor of Nature. Many people would subscribe to a more complex set of conditions to be met if we are to feed and clothe the future billions of human bodies. At the very least we will need:

  • policy and social changes;
  • new regulatory regimes controlling food production; as well as
  • the major scientific and technological advances envisaged by Nature.

Luckily, the next 50 years is likely to be the last period of rapid agricultural expansion. Thereafter, the planet should be in a “steady state” – and let’s hope it is indeed steady.

To guide us through the next 50 years, let’s first examine what happened over the past 50 years. World population more than doubled but crop production kept pace – in fact, it almost tripled. This was achieved by a modest increase in cropped area (to 1.5 billion hectares) combined with a better than doubling of yield per hectare. This doubling of yield was achieved by a combination of factors including better plant varieties, more pesticides, more fertiliser, more irrigation and more mechanisation.

We can conclude, therefore, that there had been increased agricultural intensification that had undoubted benefits and, also equally undoubted, costs. The benefits included sparing of wild lands for biodiversity. There was less malnutrition of the human race. The costs, however, included much more water use and abuse, more chemical run-off (closely related to water abuse), more soil erosion and increased greenhouse gas emissions.

The ecosystem is divided into the managed part and the wild part, with the managed part comprising nearly 40% of the total. About one-third of the managed ecosystem is cultivated (9% of this is under genetically modified [GM] crops) and about two-thirds is under pastures. Almost one-fifth of the cultivated land is irrigated. To obtain the massive increase in yield/ha, more than 120 million tonnes (MT) of nitrogen and phosphorus fertiliser were applied, as well as nearly four million tonnes of pesticides. These inputs are not just increasing yields – they are having negative impacts on both the managed and wild ecosystems.

Over the next 40 years there will be marked increases in agricultural inputs and an additional billion hectares of wild land will be appropriated for crops and pastures. That means there will be less wild land, and what is still left is likely to be negatively affected by what will then be 10 million tonnes of pesticides and more than 200 million tonnes of fertilisers – remembering that we reach peak oil (which means nitrogen fertiliser) in 2014 and peak phosphorus in 2035.

50 Critical Years

The next 50 years are critical both in terms of meeting human needs through the managed ecosystem and minimising damage to the wild ecosystem. It is now recognised that crop yield increases are falling behind projected demand, and unless this is corrected (largely by more investment in R&D) then the area under cultivation will increase even further.

It is clear that we should not just be talking about food security but food and ecological security, since they are so interlinked. Yield must increase or the area under cultivation must be greatly expanded. A partial win/win could emerge in which intensive production makes use of better practices in managing crops, soils, water, fertilisers and pesticides while at the same time more diverse cropping and forestry systems could provide better livelihood options that support biodiversity and environmental services.

Such “sustainable intensification” is emerging as a strategy to increase yields (and thus spare as much land as possible for wild land) and to manage the soil and water quality by using inputs such as pesticides and fertilisers with even greater efficiency and sensitivity than over the past 50 years.

Will GM play a role in this sustainable intensification strategy? Bear in mind that GM crops are still only 9% of the world’s cropped area, are grown by 3% of the world’s farmers and have only been on the scene since 1996. Nevertheless, that 15-year period is long enough to evaluate whether GM crops can help steady a trend line going towards the target of food and ecological security by 2050.

Studies of GM crop yields in developed and developing countries have shown that the majority reported increases – but nearly one-quarter found no increases and some even found yield reductions. Fortunately it was in developing countries where most of the yield increases were found. Studies of economic impacts of GM crops reported mostly positive outcomes, but one-quarter were neutral or negative. Again, there was a greater proportion of positives in developing economics.

The average yield of cotton in India increased by 70% between 2001 and 2008. Half of the gain was attributed to GM cotton – which serves to emphasise the very substantial gain being made in conventional agriculture as well. There was more than a 50% decrease in cotton bollworm insecticides used in India between 1998 and 2006. In China in 2009, seven million farmers grew GM cotton – yield increased by more than 9% while insecticide use decreased by 60%.

In Brazil between 1997 and 2008, herbicide sprays were reduced, which meant that less diesel and water inputs were needed and there were reduced CO2 emissions. Further dramatic gains are expected in the next 10 years.

So far we have concentrated on developing countries since that is where most of the people are – as well as much of the remaining biodiversity – but what about GM crops in developed countries?

The US has rapidly adopted GM corn, soybeans, cotton, canola and sugarbeet. Over the past 40 years there has been a steady increase in corn yield from about 5 tonnes/ha in 1965 to more than 9 tonnes/ha in 2005. These gains are attributed to hybrids, irrigation, nitrogen fertiliser, conservation tillage, integrated pest management and, notably, the recent gains are attributed to Bt corn – a genetically modified organism (GMO). Thus the big gains were first made by conventional methods of intensification but GM has made a contribution as well.

The future will be interesting as there will have to be reductions in nitrogen fertiliser and irrigation.

Precision Agriculture

Global fertiliser input is expected to soar to more than 320 MT from the current 120 MT. Nitrogen and phosphorus will both be critical and their conservation will be a matter of great concern.

Nitrogen, for instance, is poorly utilised, resulting in eutrophication and greenhouse gas emissions. There is intense research on how to use nitrogen more efficiently, including advances in precision agriculture. One way in which GM may help is in the more efficient use of nitrogen by plants, as has been shown for a GM variety of canola that has an extra gene for amino acid metabolism. This is still in the experimental phase but field trial results indicate that it may be possible to obtain the same yield with much less nitrogen.

What has been our experience in Australia, a developed country with GM crops? There was no increase in the yield of cotton, as expected, but there were reductions in the level of active ingredients applied – 44% with first-generation Bt cotton and an 85% reduction with the second-generation Bollgard Bt cotton.

In terms of sprays per season, spraying of Ingard cotton for Helicoverpa (a genus of moth that is a major agricultural pest) was reduced from more than nine sprays to less than four sprays, while sprays for other pests remained unchanged at a little more than two per season. When Bollgard II cotton came on the scene, sprays were reduced from more than eight to less than one for Helicoverpa, although spraying for other pests increased from one to more than two. Cumulatively, the total insecticide sprays were reduced from more than nine to less than three.

This has led to better survival of beneficial insects, which in turn helps to control secondary pests. Bt cotton fields are now considered to be “living crops”, not “biological deserts”, and they could be the foundation for a long-term integrated system of pest control.

GM crops can and should be part of our global managed ecosystem. They can increase yield and spare land for the natural ecosystem, increase income and therefore help reduce poverty, and reduce inputs for the protection of soils and water.

To do their part in long-term intensification of food, feed and fibre production to satisfy human needs and wants, we will need enlightened leadership to drive new regulatory regimes as well as political and social changes.

First published in ATSE Focus, October 2010 .