Peak Yield? Climate and Crop Productivity
by Moses Seenarine, 12/19/17
Since the 1960s, feed crops' yield growth have jumped remarkably, but this rise is part of an ongoing process over the past 10,000 years. In pre-historic times, it took 3,000 acres (12 sq km) of land to feed one human forager, but now it takes 1/3 of an acre (1,300 sq m) to feed one person. So the amount of food grown per acre (43,500 sq ft) has multiplied by a factor of 10,000 in 10,000 years.
Global grain yields now average about 3.5 tons per hectare (2.5 acre). In the US, yields are double at seven tons per hectare. That difference in yield primarily reflects more access to capital and energy by US farmers and TFCs who can afford vast quantities of fertilizer, mechanized farm equipment, irrigation systems, pesticides, and other tools that dramatically boost agricultural yields, at least in the short-term.
An analysis of the effects of 2,800 weather disasters in 177 countries on 16 cereals from 1964 to 2007 show that climate change may have already begun to take a toll on agriculture. Drought and extreme heat in the last 50 years have reduced cereal production by up to 10%. And, the impact of these weather disasters was greatest in the developed nations of North America, Europe, Asia and Australia. Production levels in the global North dropped by 20% because of droughts, double the global average.
Crops and methods of farming are uniform across immense areas, so if a drought occurs in a way that is damaging to those crops, they all suffer. In agriculture, crop yield or agricultural output, refers to both the measure of the yield of a crop per unit area of land cultivation, and the seed generation of the plant itself. For instance, if three grains are harvested for each grain seeded, the resulting yield is 1:3. The figure, 1:3 is considered by agronomists as the minimum required to sustain human life.
Ominously, grain yields are already stagnant and have stopped rising in many parts of the world. On a global scale, stagnating yield is affecting four major grain types that produce two-thirds of the world's calories - maize, rice, wheat and soybeans. Yields of these four crops are growing by only 0.9 to 1.6% a year. Yields in 25% to 33% of the crop producing areas are stagnating, like those in Australia, Argentina, Guatemala, Morocco, Kenya, and the US states of Arkansas and Texas. In parts of the UK, in areas that produced the highest outputs 20 years ago, yields have actually dropped.
Just nine or 10 plants species principally feed the world. An international research team ascertained that 16 of the 21 foods they inspected reached peak production between 1988 and 2008. Menacingly, this synchronization of peak years in upwards of three-quarters of edible plants suggests the whole food system is becoming overwhelmed. Maize reached its peak rate in 1985, followed by rice three years later, in 1988. Vegetables reached their peak rate in 2000, while wheat reached its peak rate in 2004, followed by sugarcane in 2007. Soybean reached its peak rate in 2009. As an outcome of peak food, larger production means greater amounts of land under cultivation.
Since GM crops were planted, the US staple crop system has performed worse than non-GM crops in Europe - in yields, pesticide use, genetic diversity and resilience. For the US system, there is a dangerous downward yield trend in recent years. Stagnating yields may be due to the soil damage caused by the use of heavy machinery and a long-term decline in organic matter content in soils. The upshot is additional fertilizers have to be used to boost yields.
Excerpt from "Meat Climate Change: The 2nd Leading Cause of Global Warming," by Dr. Moses Seenarine.