Why we need to change from intensive to environmentally friendly sgriculture

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Torstai 12.11.2020 klo 19:23 - Mikko Nikinmaa

Intensive agriculture has relied heavily on ploughing and harrowing, fertilization and the use of pesticides. As a result, it has been possible to increase yields so much that whereas in 1960’s one was considering 5 billion humans to be maximum for feeding, there are now about 7.8 billion of us. Further, the absolute number of starving people has decreased, as the world population has increased beyond 5 billion. A success story? I am afraid not, only a temporary solution, which is currently being reversed: all the aspects of intensive agriculture are beginning to show their downsides. All of them indicate that intensive agriculture as carried out today is not sustainable.

First, soil fertility throughout the world is decreasing. The decrease happens fastest in tropical soils, but also the temperate, long-cultivated soils have recently started to show signs of becoming exhausted. The major reason for the loss of fertility is the fact that present agricultural practises are based on having fields without plant cover for a long period of time. Land without plant cover loses the most fertile topsoil as a result of leaching: if the land were covered with plants, much less soil would be lost when it rains or winds blow. Also, native land is a carbon dioxide sink, but ploughing and harrowing makes it a carbon dioxide source. It would certainly be possible to change agricultural practises to plant-cover requiring ones. To stop the decrease of soil fertility, that should be done. It should also be done, as the soil lost from fields ends up in rivers, lakes and the sea, causing their eutrophication.

To maintain soil fertility, artificial fertilizers have increasingly been used. Mineral phosphate deposits are overused, and much of the fertilization ends up in the aquatic environment contributing to eutrophication of water. To decrease flow of fertilizers into rivers and lakes, protective zones with plant cover are required. However, a much better alternative would be agriculture, which does not involve ploughing and harrowing.

Finally, the use of pesticides, especially insecticides, in copious amounts has been the landmark of intensive agriculture. Unfortunately, pests have begun to tolerate pesticides better and better, which results in increasing pesticide need to maintain efficacy. And this is not all; three quarters of all food crops require insect pollination, and it has clearly been shown that insect populations throughout the world are decreasing. Although definitive cause-and-effect relationships between insecticide use and decreasing population sizes have not yet been obtained, it is quite reasonable to suppose that it is the case. Instead of increasing use of chemical insecticides and other pesticides, biological control of pests has been advocated for the past fifty years. However, even though it would be much more environmentally friendly than the present chemical-dependent pest control, biological pest control has not become the most important way for controlling pests.

Thus, the very points that have been the cornerstones of increasing yields in intensive agriculture are now causing all sorts of problems ultimately leading reduced yields. There are alternatives to the present-day practises, but they require a complete change of cultivation methodology.

Avainsanat: soil fertility, insecticide, eutrophication, pesticide

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