4.2 Effect of agricultural land use on soil nutrient
use
Land use managements may produce considerable influence
on soil nutrient absorption and nutrient use efficiency.
As shown in Table 5, the NAR and NEER
changed significantly among the three agricultural land
use types. Good soil quality must produce good crop
yield and maintains better environmental quality
(Sharma et al., 2005). Intensive agriculture such as orchard
and vegetable productions has become popular
due to better economic outputs for the local farmers.
However, intensive agriculture is known to emit more
nutrients, particularly N and P to the environment,
which may result in serious water quality impairment
(Gillingham and Thorrold, 2000; Monaghan and Smith,
2004; Ma et al., 2009).
This dual effect of intensive agriculture is better explained
by the two parameters, NEER and NAR, used in
this study. If the economic benefit (NEER) is considered
only, orchard and vegetable production has much more
benefit than the cropland does. However, a different
conclusion may be derived if the higher NAR is the
primary concern. Obviously, it is hard to determine the
best management practices and regulation for sustainable
agriculture if both economic and environmental
effects are taken into account. The results of this study
suggest that the orchard and vegetable field as the most
popular land use shift from cropland may provide higher
economic benefit, but at the same time this land use
shift may pose higher risk of nutrient loss to potentially
environmental impairment. For the long-term sustainability
of both agriculture and the environment, systematic
best management practices and balanced land use
policies must be developed to provide an optimal solution
aimed at both improving the soil nutrient use efficiency
and reducing the adverse environmental effect.