Yield

One study found a 20% smaller yield from organic farms using 50% less fertilizer and 97% less pesticide.^[15] Studies comparing yields have had mixed results.^[16] Supporters claim that organically managed soil has a higher quality^[17] and higher water retention. This may help increase yields for organic farms in drought years.
One study from the Danish Environmental Protection Agency found that, area-for-area, organic farms of potatoes, sugar beet and seed grass produce as little as half the output of conventional farming.^[18] Michael Pollan, author of The Omnivore's Dilemma, responds to this by pointing out that the average yield of world agriculture is substantially lower than modern sustainable farming yields. Bringing average world yields up to modern organic levels could increase the world's food supply by 50%.^[19]
A 2007 study^[20] compiling research from 293 different comparisons into a single study to assess the overall efficiency of the two agricultural systems has concluded that

...organic methods could produce enough food on a global per capita basis to sustain the current human population, and potentially an even larger population, without increasing the agricultural land base. (from the abstract)

The researchers also found that while in developed countries, organic systems on average produce 92% of the yield produced by conventional agriculture, organic systems produce 80% more than conventional farms in developing countries, because the materials needed for organic farming are more accessible than synthetic farming materials to farmers in some poor countries. On the other hand, communities that lack sufficient manure to replenish soils would struggle with organic farming, and the soil would degrade rapidly.^[21]

Energy efficiency

A study of the sustainability of apple production systems showed that in comparing a conventional farming system to an organic method of farming, the organic system is more energy efficient.^[22] A more comprehensive study compared efficiency of agriculture for products such as grain, roughage crops, and animal husbandry. While the study did not investigate specific additional requirements of arable land or numbers of farm laborers to produce total yields for organic farming vs. conventional farming, leaving open the question of overall capacity of organic farming to meet current and future agricultural needs, it concluded that organic farming had a higher yield per unit of energy over multiple crops and for livestock. However, conventional farming had higher total yield.^[23] Conversely, another study noted that organic wheat and corn production was more energy efficient than conventional methods while organic apple and potato production was less energy efficient than conventional methods.^[24] A long-term study, spanning two decades, noted that crop yields were 20% lower in organic systems while fertilizer plus energy input was 34% to 53% lower. However, pesticide input was reduced by 97% in organic farm system