Crucially, the new study takes into account two important factors whose potential impact on crop yields has been neglected so far. First, the new work considers the potential impact of increased cropping intensity, i.e. production of more than one harvest annually. Secondly, in collaboration with economists in Professor Gernot Klepper’s group based at the Kiel Institute for the World Economy (IfW) in Kiel, the LMU team estimated the degree to which yields could be enhanced if profit-maximizing management practices, focusing on commercial production of crops for national and international markets, were adopted on a global scale.
Eightfold increase possible
Multiple harvests could increase yields by 39% without expanding the land area devoted to agriculture. However, the new study estimates that adoption of a commercially oriented approach to land usage, in which crops are cultivated on current cropland at locations where they yield the highest profits, could boost this result by a further 30%. The regions projected to have the greatest potential to benefit from such a step are Sub-Saharan Africa, Latin America, India and China. If, in addition, one assumes that optimal agricultural practices appropriate for each major commercial crop are implemented on a global scale, a further increase of 80% is feasible, according to the authors. This last estimate agrees with an earlier estimate by the UN Food and Agricultural Organization (FAO). Putting all of these factors together, the new study concludes that global crop yields could be enhanced relative to current figures by close to 150%.
The authors themselves were surprised by the projected magnitude of the potential increase in crop yields. Thus, their study suggests that yields in Sub-Saharan Africa could be increased by up to eightfold. Moreover, significant increases are also attainable in Asia. “This latter result was unexpected, because agricultural land in India, for example, is already subject to highly intensive use. But, obviously, great potential lies in improving crop and farm management practices,” says Wolfram Mauser.
In Europe, on the other hand, the prospects for improvements in yield are less rosy. “In few other regions around the world is agriculture so intensively practiced and so profit-oriented – on top the climate will not support more than one harvest per year,” Mauser points out. “In Sub-Saharan Africa, in contrast, many farmers practice subsistence agriculture, but our data show that it would be perfectly possible to grow high-value crops for the world market there,” he adds. “Previous studies have failed to take into account the fact that market-oriented, commercial agriculture is capable of achieving much higher yields than farmers in many countries do today, where styles of agriculture are determined much more by local tradition than by economic considerations. For this reason, these investigations have seriously underestimated the global yield potentials of food crops,” says Gernot Klepper.
More emphasis on sustainability
The new study is based on data for the 18 plant species that contribute most to global food production, including rice, maize, soybeans and wheat, and considers their potential yields when grown optimally on today’s cropland under current climatic conditions. “In subsequent studies we will investigate the possible effects of climate change. The indications are that the negative and positive effects of climate change on agricultural productivity will more or less cancel each other out,” says Mauser. “However, climate change will very probably lead to substantial shifts in world trade, because it will increase yields in northerly regions, and is more likely to reduce them in the tropics,” Klepper adds.
The collaborative study produced by the geographers at LMU and the economists at the IfW could stimulate regionally targeted efforts to enhance the efficiency and sustainability of agricultural practices around the world. As the LMU group demonstrated in an earlier publication, an expansion of cropland could most probably be achieved only at the expense of ecosystems, such as forests, that provide valuable ecosystem services to society. “Our latest results indicate that the rising demand for food does not necessarily imply that cropland must be increased. Moreover, this demand can be met by more efficient exploitation of our major crop plants, and does not provide a justification for the development and widespread cultivation of genetically modified plants,” says Mauser.
Wolfram Mauser, Gernot Klepper, Florian Zabel, Ruth Delzeit, Tobias Hank, Birgitta Putzenlechner and Alvaro Calzadilla: Global biomass production potentials exceed expected future demand without the need for cropland expansion
In: Nature Communications 2015 (DOI: 10.1038/ncomms9946)