Die Agrarspezialisten Holger Kirchmann und Megan H. Ryan schreiben über das Platzproblem des Ökolandbaus:
A number of long-term field trials in Europe reveal that crop yields are on average 20% lower in organic systems that combine crops with animals and 33-45% lower in organic systems with crops alone compared to their conventional counterparts (Table 1). The impact of the addition of animals reflects a greater degree of on-farm recycling of nutrients through animal manure and lower removals of nutrients from the system.
The low yields on organic farms mean that to produce the same amount of food as conventional farms, more land is needed. For instance, to sustain food production in Europe, widespread adoption of organic farming without animals would require an increase in land area of 64%, assuming crop production is reduced by 39%, and adoption of organic systems with animals would require an increase in land area of 25%. Indeed, for Danish dairy farming, Halberg and Kristensen (1997) concluded the area farmed would need to be extended by 47% to sustain yields with conversion to organic production. As Borlaug and Dowswell (1994) and Avery (1995) pointed out “growing less food per acre leaves less land for nature”. If conventional farming is widely replaced by organic farming, clearing of wildlife habitats and conversion of natural and semi-natural ecosystems into agricultural land is unavoidable in systems that did not originally produce a food surplus. This would increase the proportion of man-made ecosystems in the world with a corresponding negative impact on conservation of biodiversity. From a global perspective, biodiversity cannot be conserved through more organic farming.
Wer mehr über diese und andere Probleme des derzeitig Kults um Ökolandbau und Biolebensmittel erfahren möchte, dem sei das neue Buch „Biokost & Ökokult. Welches Essen ist wirklich gut für uns und unsere Umwelt“ von Dirk Maxeiner und Michael Miersch empfohlen.