An Approach to the Determinants of the Agricultural Output Dynamics in the USA - The Agricultural Economics of the 21st Century - page 4

Department in the USA to help in the economic, social, and cultural changes of
rural areas (Jewett 2013 ).
Sometimes, the policies designed for agriculture can have indirect effects within
the sector and within society. For example, the agricultural policies in the USA
have influenced caloric ingestion, but that effect has decreased over the last few
years (Rickard et al. 2013 ). Another example is the fact that subsidies for agricul-
tural production and export, in the USA and in the European Union, create some
distortions in the international trade of agricultural products (Bruno et al. 2012 ).
Taking into account the influence of the US economy on the emergent world, it
seems important to present this original study in order to raise understanding about
the USA's agricultural dynamics and about the interrelationship between agricul-
tural output and other sustainable, social and economic variables. For that, the
World Bank database ( 2014 ) was considered and we used time series econometric
instruments, through the Stata ( 2014 ) software and taking into account as a base
model the Cobb and Douglas ( 1928 ) function of production.
2 Data Description
The percentage of land for agriculture in the USA decreased continuously from
49 % in 1961 to about 45 % (Fig. 2.1 ). This is a phenomena verified in many
developed countries where the agricultural sector reduced the percentage of area,
due to the increase of the weight of other sectors and because of improvements
made to the efficiency of the sector.
On the other hand, the area used for forest increased its weight slightly in the last
two decades, from about 32 % in 1990 to around 33 % in 2011 (Fig. 2.2 ).
Figure 2.3 confirms what was referred to previously in Fig. 2.1 . Indeed, the
agricultural productivity, at 2005 constant prices, increased from about US$10,000
in 1980 to US$60,000 per worker in 2009 and 2010. This is a significant improve-
ment in the performance in the dynamics of the USA's agricultural economics.
The fossil fuel energy consumption weighed against the total of energy con-
sumed (Fig. 2.4 ) decreased by about 12 % from 1961 to 2012, from around 96 % to
84 %.
The CO 2 emissions increased slightly in the 1970s and decreased slightly
towards the end of the last decade (Fig. 2.5 ), but, in general, more or less about
20 metric tons per capita.
The percentage of methane emissions (Fig. 2.6 ) and nitrous oxide emissions
(Fig. 2.7 ) from agriculture increased by about 10 % in both cases, from 1990 to
2010. This again, seems to be in unison with the reduction in land for agriculture
and with the rise in agricultural productivity at constant prices.
The rise in the percentage of population in urban clusters, from 1961 to 2012,
was of about 10 %, from 40 % to 50 % (Fig. 2.8 ). The increase in population in large
urban centers can help the economic dynamics in some cases, through the number
of producers (New Economic Geography) and improvements to the scales of firms
(Keynesian theory), but can also be the origin of problems such as urban congestion
and regional asymmetries. So, this is a question that requires more careful analysis.