Facts and Myths of Feeding the World with Organic Farming Methods - Principles of Sustainable Soil Management in Agroecosystems - page 99

were from meat. Today, China is a rapidly developing economic power, and in 2007,
the number of calories per capita was 2981, and 420 were from meat (FAOSTAT
2012). Therefore, it is most likely that if the world population becomes more prosper-
ous, the demand for grain and other feeds to produce more meat and animal products
will increase that will require more nitrogen. Unless synthesized ammonia is used,
the only other feasible method to add additional N to the crop production system
is by growing leguminous crops and incorporating them into the soil so the N can
be used for growing nonleguminous crops such as cereals. This would, however,
require enormous amounts of added cropland. Most leguminous crops, even when
grown in favorable areas, will generally not supply more than 100 to 150 kg N ha -1 ,
so this would almost double the land requirement for cereal production, which is not
a feasible alternative.
4.4 NEED FOR BETTER MANAGEMENT OF N FERTILIZERS
It is apparent to most that crop production in the future will continue to depend
largely on the application of N fertilizer that is produced by the Haber-Bosch pro-
cess. At the same time, there is increasing awareness that along with the benefits of
this amazing and important process that has played such an important role in food
production, there is a real potential that the environment can be seriously affected.
A few, including Nielsen (2005), have expressed great concern over the large use of
N fertilizer and went so far as to state that the Haber-Bosch process was a “fantastic
invention—or was it?” Townsend et al. (2003) also expressed great concern about
human health effects of a changing global nitrogen cycle. They stated that changes to
the global nitrogen cycle affect human health well beyond the associated benefits of
increased food production, and that many intensively fertilized crops become animal
feed, helping to create disparities in world food distribution and leading to unbal-
anced diets, even in wealthy nations. Townsend et al. (2003) suggested that the net
public health consequences of a changing N cycle are largely positive at lower lev-
els, but they eventually peak and then become increasingly negative as our creation
and use of fixed N continues to climb ( Figure 4.3 ). Based on the conceptual model
shown in Figure 4.3, Townsend et al. (2003) postulate that low to moderate increases
in fertilizer use in developing countries will improve food availability and overall
nutrition with only minor elevated losses of reactive N to the environment. Ladha et
al. (2005) stated that about 60% of the global N fertilizer is used for producing the
world's three major cereals: maize, wheat, and rice. These three cereals account for
almost 90% of all cereals (FAOSTAT 2012). Figure 4.2 shows the world production
of cereals increased almost three times between 1961 and 2009 (FAOSTAT 2012),
but the amount of atmospheric N 2 fixed as ammonia that was almost entirely used
for the production and use of N fertilizer increased about 10 times during the same
time period (Smil 2011). Assuming the average N content of cereals to be 1.6%, the
amount of N removed with all cereals in 1961 was approximately 14 Mt compared
to about 40 Mt in 2009. In contrast, about 10 Mt of N was fixed in 1961 compared
to about 100 Mt in 2009. This clearly indicates that much of the N added as fertil-
izer is not utilized directly by the plants. Although this fact has been recognized for
many years, it is still not entirely clear where the N that is not used by the plants ends