The basic concepts of organic and conventional agriculture have been already explored, but how can we compare these two systems? A simple way to answer this question is to make a direct comparison of the productivity of these systems. However, the problem is that we can’t assume a standard productivity for both systems because conventional agriculture uses a lot of external inputs in order to increase their productivity. For example, the Figure 7 shows that the global trends in cereal production have increased approximately 100 kg per capita in the last 40 years; however, the demands of nitrogen, phosphorus, water and pesticides have experienced a highly increase (Tilman et al. 2002). In contrast, as I discussed above, the philosophy of organic agriculture is to minimize the use of external inputs. For these reasons, the best way to compare these systems is to use the efficiency of each system. With this proposal, efficiency will be equal to total production less the internal and external inputs (e.g. fertilizers, insecticides, gas, etc).         

Figure 7. Global trends in cereal and meat production; total use of nitrogen and phosphorus fertilizers; increased use of irrigation; total global pesticides production (from Tilman et al. 2002 & UNEP/GRID-Arendal 2008)

The efficiency of one system is directly associated with the relationship of productivity (e.g. kg of corn/ha) versus inputs (e.g. fertilizers, labor, machinery). For example, Pimentel (1993) compared the energy balance of corn and potato crops under conventional and organic systems (Table 2). The results of Pimentel’s work showed the efficiency of these systems in terms of output/input ratio, where the organic systems have the highest efficiency for corn and potato crops (Table 2). In a different work, Lansink and coworkers (2002) came with similar conclusions to the Pimentel’s work. Lansink’s work showed that organic crop farms and organic livestock farms in Finland were 24% more efficient than conventional crop farms and conventional livestock farms (Table 3). But what is the biggest difference between the efficiency of conventional and organic farms in the Tables 2 and 3? The big distinction for the low efficiency of conventional crops is the excessive energy used on chemical fertilizers. Tilman and coworkers (2002) argue that one of the problems of conventional agriculture is associated with the low efficiency of the crops to capture and use the fertilizers. For example, Figure 8 shows that in the last 40 years there has been a huge decrease in efficiency of N in cereal crops (Tilman et al. 2002). In contrast, organic agriculture is more efficient with the use of N because instead of using external sources of N (e.g. urea), organic agriculture recycles nutrients through the use of alternatives like crop rotation with legumes, green covers, compost, etc (see Table 1, Figures 1 &2). In conclusion, all of this information shows that organic agriculture is on average more efficient than conventional agriculture.

Table 2. Energy inputs per hectare for conventional and organic corn and potato production systems (Pimentel 1993).

Table 3. Efficiency and productivity of organic and conventional crop farms and livestock farms (Lansink et al. 2002)

Figure 8. Nitrogen efficiency of cereal production (from Tilman et al 2002)