|Mineral Fertilizer Use and the Environment (IFA - UNEP, 1998, 52 p.)|
Mineral fertilizers and land are substitutable in the sense that an increase in the use of fertilizers permits a reduction in the area of land cultivated, and vice-versa. The use of mineral fertilizers has environmental costs but all farming, as most of man's activities, has an environmental impact. Overwhelmingly the evidence is that mineral fertilizers are necessary for the welfare of mankind. There are environmental risks but they are minor in relation to the benefits.
N.E. Borlaug (1997) stated:
Take the cases of the United States, India and China as examples. In 1940, when relatively little inorganic fertilizer was used, the production of the 17 most important food, feed and fiber crops in the USA totaled 252 million tons from 129 million hectares. Compare these statistics with 1990, when American farmers harvested approximately 600 million tons from only 119 Mha - 10 Mha less than 50 years before. If the United States attempted to produce the 1990 harvest with the technology that prevailed in 1940, it would have required cultivating an additional 188 million hectares of land of similar quality. This theoretically could have been achieved either by ploughing up 73% of the nations permanent pastures and rangelands, or by converting 61% of the forest and woodland area to cropland. In actuality, since many of these lands are of much lower productive potential than the land now in crops, it really would have been necessary to convert a much larger percentage of the pasture and rangelands or forests and woodlands to cropland. Had this been done, imagine the additional havoc from wind and water erosion, the obliteration of forests and extinction of wildlife species through destruction of their natural habitats, and the enormous reduction of outdoor recreation opportunities. Impressive savings in land use have also accrued to China and India through the application of modern technology to raise yields. Had the cereal yields of 1961 still prevailed in 1992, China would have needed to increase its cultivated cereal area by more than three fold and India by about two fold, to equal their 1992 harvests. Obviously, such a surplus of agricultural land was not available.
Land that Indian, Chinese and U.S. farmers spared as a result of rising cereal yields. Area used is the land actually harvested; area spared is additional land that would have been needed if 1961 yields had not increased.
Source: Norman E. Borlaug (1997).