Highlights
- The distribution of crop and fodder production in organic and conventional farms is established for eight regions of Sweden.
- Regional yield per ha (mass and metabolic energy) of grain and fodder crop production is calculated for both farm types.
- Milk production is calculated for herds fed diets to maximize yield per ha of total energy of grain plus milk or of milk.
- Total regional yield of human food per ha from milk and remaining grain is estimated for both herd-feeding strategies.
- Organic Agriculture (OA)/Conventional Agriculture (CA) yield ratios of human food production range 0.43 to 0.74 across regions and are inversely related to CA yield.
Context
Most information on relative yield of organic (OA) and conventional agriculture (CA) is from plot experiments of individual crops grown with organic or inorganic fertilizers, respectively. Commonly reported values are 0.75–0.91, a relatively small difference. But organic manures are produced through biological nitrogen fixation(BNF) by legumes. How much and what else does that land in legumes contribute to overall yield?
Objective
Establishment of OA/CA yield ratios for crop-dairy production at regional scale accounting for proportions of land in crop and fodder production and their contributions to overall food yield using human metabolizable energy (HME) as a unifying parameter of yield of grain and milk.
Significance
This analysis establishes smaller relative yields of OA than are commonly reported. Smaller yields per crop area in OA are further reduced at farm (system) level relative to CA by the larger proportion of land required in legume-based crops and pastures. Ruminant animals provide some compensation for that land by converting human-inedible fodder to human food. Consequently, transformation of CA farmland to OA would require additional land, up to 130% in productive southern and central regions, to maintain equal overall yield. More such comprehensive data are required for calculation of OA/CA yield ratios at the system level.