Desktop version

Home arrow Engineering arrow The dark side of technology

Source

How successful is a monoculture with pesticides?

Large tracts of land devoted to a single crop may well be ideal for massive-scale farming and harvesting, but they are still going to be vulnerable to pests and degradation of the soil with repeated usage, so we are back to the problems associated with herbicides, pesticides, and fertilizers. The real question for world food production will not be, ‘Are they economic in the short term?’ (clearly they are, or the approach would not be used), but ‘Are they also a long-term solution?’ In parallel with this, we need to ask what are the environmental drawbacks and dangers from new diseases, and what are the risks of genetic abnormalities (either of the crops or the animals and humans who eat them, or merely come in contact with them).

Monoculture approaches may initially offer high-yielding crops, but it is very short-sighted to assume that we can discard all the other varieties that have evolved over many millennia. Just as with computer documentation, there is a danger that rushing into new technology will lose many valuable alternatives. For agriculture, if climate or disease patterns change, the apparently less effective versions may be preferable to the current high-yielding ones. To avoid this disaster scenario, it is essential to have globally organized seed banks that carefully preserve the many different varieties. Several countries (including the UK) have made some attempts at storage sites, and there is a seed vault in Spitsbergen which has some 1.5 million types of seed samples. The location is in the Arctic Circle, so it will continue as a low-temperature store even without artificial refrigeration. Such stores include wild varieties (currently viewed as weeds), as this increases the genetic diversity of the store.

In terms of the economics, the monoculture large field is never going to be near the consumer, so real costs and efficiency must include transport costs, and perhaps refrigeration, as the products are moved to market. This is critical for perishable goods. Further, continued growth of the same crop will depend on the addition of fertilizers. Their usage can be reduced if skilfully applied at the correct point in the growth process, and also if they are targeted at the crop, not by some aeroplane spraying randomly over a field, with material blowing in unwanted directions.

However, added fertilizers become less effective over time—a 60 per cent drop in yield over ten years is not atypical. To an impartial observer, the arithmetic looks very different than it does to the farmer, who initially saw a big boost in productivity (profit). Because a 60 per cent drop in yield may be below even the original productivity, and certainly it will if the treatment costs are high, there may be a net fall in profit. This will be hidden for most people, as the change in prices with inflation over a ten-year period (typically a doubling) will disguise the fact that the real value has dropped. So overall there is a hidden economic factor that, just because the yield increases with fertilizers, there is no guarantee that the process is more economic. Once locked into the fertilizer and herbicide system, the cost of the chemicals may increase the production price far more than the yield. In agriculture, profit margins can be very small, and driven by supermarkets, rather than the public, and there is often a very fine line between profit and failure.

A major weakness of the fertilizers is that they do not stay on the original field, but instead are washed into the surrounding waterways where they are equally effective in promoting growth and new plants. This is a global problem, and various numbers are quoted from all the major countries implying that typically at least half of all water systems are contaminated by run-off from agriculture. This includes not only fertilizers but also insecticides, etc.

As I have emphasized, for large acreage of a single crop, there will not be natural predators to deal with pests, so there must either be a reliance on having a crop that in some way has been modified to resist a particular pest, or there must be spraying with insecticides. Historically, modified crops may have developed via natural selection, or more recently by an induced genetic modification. The latter is a highly emotive route, and it tends to polarize opinions of the various protagonists, but a rational assessment will probably find both positive and negative arguments with evidence from both viewpoints.

 
Source
Found a mistake? Please highlight the word and press Shift + Enter  
< Prev   CONTENTS   Next >

Related topics