Many a times, we come across the word "Yield Plateau", showing no further improvement in yield per hectare for a crop. If so, what are the major reasons? If one wishes to explain yield plateau in a macro perspective (instead of agronomic variables like plotwise inputs, irrigation etc.), what could be the factors that one should account for?
Thanx.
Good Question. From the macro perspective, both institutions and policies are important to explain yield plateau. Yet they are not physical constraints or limits, these or operational and implementation constraints to get the right input and advice to the farmer and the farmer applying them. Little research has been done on delineating these factors form the production economics perspective. Some of the frontier function analysis attempt to explain this but not fully. good area to work on. Hope this is useful.
About one half the increase of major crop species can be attributed to genetic improvement and the other to environmental cause in the improvement of agronomic practices.
As genetic improvements occur the increases may show a diminishing return as the improvements are implemented. When water and nutrition for crops is not optimized all these practices have big effects as the irrigation and nutrition is added the ability to continue shows the same diminishing return phenomenon.
While modern agriculture has done a lot to concentrate on varietal improvements and inputs they have not concentrated on soil improvement and in fact many of the worlds soils have deteriorated under modern agriculture practice. The New Deal soil conservation efforts are long gone as they do not jibe with the vested interests of input practices.
The ability to go back to the future by concentrating on soil conservation and improvement is the better way to raising the bar for our agricultural systems and also can work to counteract the environmental and greenhouse gas problems we are experiencing in human society.
The original Green Revolution was Green in word but certainly not in deed. We need to have True Green Revolution which would point to the health of our soil resources as a bottom line and this would be measured in Carbon and Nitrogen sequestration in our soil resources.
In virgin soils the soil organic matters were superior of 5% and in most cultivated soils these are around 1% the optimizing of our soil resource is a program which address global change issues, the sorry state of our environment, and the issues related transitioning to warmer drier climates.
Yield plateau is mainly due to almost complete adoption of existent technology and no new technology coming up for the near future. Sometimes resource constraints viz lack of fertilizer, pesticides available at proper time, limitations by natural factors such as water, fertility exhaustion, market limitations also restrict the yield levels.
Check the paper on Stochastic plateau by Tembo et al. (2008): Am. J. of Ag Econ. Maybe you could build more from there.
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