Preface. Pesticides are the main cause of the insect apocalypse, which reverberates up the food chain, leading to loss of biodiversity and extinction. And pesticides are made out of oil, which probably peaked globally in 2018, and pesticides only last 5 years on average before pests develop resistance. So we have to get rid of them — it’s past time we looked for alternatives, especially since they will inevitably stop working or being manufactured as petroleum grows scarce. And yet Rachel Carson warned us in 1962 in her book Silent Spring about this, and six decades later we’ve done little to solve it.
About 400 different pesticides are being used in the U.S., and 150 of them are considered hazardous to human health according to the World Health Organization. The U.S. Geological Survey data showed estimated that at least one billion pounds of agricultural pesticides were used in 2017. Of that, about 60%—or more than 645 million pounds—of the pesticides were hazardous to human health, according to the WHO’s data (Acharya 2020).
Another method of reducing pesticides, fertilizer, and water is intercropping — the simultaneous cultivation of multiple crops on a single plot of land, which can significantly increase the yield. Farmers have applied intercropping for as long as we can remember. Intercropping appears to give a 16-29% larger yield per unit area than monocultures in intensive agriculture under the same circumstances, while using 19-36% less fertilizer (Li et al 2020).
Alice Friedemann www.energyskeptic.com Author of Life After Fossil Fuels: A Reality Check on Alternative Energy; When Trucks Stop Running: Energy and the Future of Transportation”, Barriers to Making Algal Biofuels, & “Crunch! Whole Grain Artisan Chips and Crackers”. Women in ecology Podcasts: WGBH, Crazy Town, Collapse Chronicles, Derrick Jensen, Practical Prepping, Kunstler 253 &278, Peak Prosperity, Index of best energyskeptic posts
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Larsen AE et al (2020) Impact of local and landscape complexity on the stability of field-level pest control. Nature Sustainability.
Larsen and Noack scoured Kern county records from 2005 through 2017 focusing on factors such as field size, as well as the amount and diversity of croplands. What they found was that increasing cropland with larger fields generally increases the amount and variety of pesticides applied, while crop diversity has the opposite effect.
As field size increases, the area gets larger more quickly than the perimeter, while smaller fields have proportionally larger perimeters. And a larger perimeter may mean more spillover from nearby predators like birds, spiders and ladybugs that eat agricultural pests.
Smaller fields also create more peripheral habitat for predators and competitors that can keep pest populations under control. And since the center of a smaller field is closer to the edge, the benefits of peripheral land in reducing pests extends proportionally farther into the small fields.
Landscapes with diverse crops and land covers also correlated with reduced pesticide variability and overall use. Different crops in close proximity foster a variety of different pests. Though this may sound bad, it actually means that no single species will be able to multiply unimpeded.
When crops are grown over a wide area, it’s hard to stop a large outbreak of a pest in an area of almost unlimited food resources.
References
Acharya P (2020) The United States still uses many pesticides banned in other countries. The Counter
Larsen AE et al (2017) Identifying the landscape drivers of agricultural insecticide use leveraging evidence from 100,000 fields. PNAS. www.pnas.org/cgi/doi/10.1073/pnas.1620674114
Li C et al (2020) Syndromes of production in intercropping impact yield gains. Nature Plants. Simpler explanation in phys.org here