Agriculture Reference
In-Depth Information
different paces in different countries, many of which are as yet suboptimal (Pagiola
1995; Brown and Shrestha 2000; Murgai et al. 2001; Fan et al. 2012). Numerous fac-
tors determine farmers' decisions to intensify production, including market access,
infrastructure, input availability (Brookfield 2001; Dahal et al. 2009), caste or eth-
nicity, farm labor availability, extension services, education level, land management
training (Paudel and Thapa 2004), as well as inducing factors such as extreme land
shortage, land holding size, environmental and technological constraints (Turner
and Shajaat Ali 1996), and poverty, leading to degradation of common property
resources (Pinstrup-Andersen and Pandya-Lorch 1994; Lopez 1998).
One of the main ways in which intensification of agriculture influences the envi-
ronment is through its effects on biodiversity. Most intensified production systems
lead to a reduction in crop diversity, as well as the diversity of soil organisms and
reduced soil organic matter, thus leading to imbalance and degradation of the soil
(Matson et al. 1997; Lal 2007, 2011). This is in part due to large areas cropped in
monoculture systems and in part to reduced livestock rearing as farmers become
specialized; hence, less farmyard manure (FYM) is applied to the soil (Ali 1996;
Thorne and Tanner 2002; Lal 2011). Fragoso et al. (1997) observed from studies
in India, Mexico, and Peru that earthworm communities exhibited lower species
richness, reduced numbers of ecological groups, and predominance of endogenic
groups under intensive farming compared with undisturbed ecosystems. Likewise,
Black and Okwakol (1997) noted that land clearing, preparation for cropping, and
other agricultural management practices significantly affected termite diversity
and activity. Although they are regarded by most farmers as pests, termites likely
play a major beneficial role as ecosystem engineers as well as promote essen-
tial ecosystem processes, such as decomposition of lignin, in semiarid regions.
Kahindi et al. (1997) on the other hand, found that because of a high degree of
host specificity, loss of a single rhizobial species from an agroecosystem could
result in loss of nitrogen fixation by a particular legume. However, because of the
inoculants industry enabling compatible rhizobial genotypes to establish effective
nitrogen fixation, a high biodiversity of N-fixing bacteria may not be required to
ensure function in intensively cropped soils. In the mid-hills of Nepal, Begum
et al. (2011) observed that the diversity and population densities of some soil meso-
fauna, such as collembola and mites, were significantly higher in forested areas
than in agricultural fields.
In Nepalese hill farming, tillage and various land preparation practices have been
integral to subsistence farming systems on often marginal and steep sloping lands
(Bajracharya 2001). However, past farming practices were typically of low inten-
sity (one or two crops per cropping cycle) and integrated crop-livestock systems
where farmers exclusively used FYM and compost. With the increasing availability
of modern agrochemicals, changes in food habits, irrigation facilities, and growing
demands, farmers have progressively intensified production with multiple and high-
value crops now being grown in peri-urban areas (Brown and Shrestha 2000; Dahal
et al. 2009). This has been accompanied by the expansion of cultivated land areas
and a reduction in organic inputs and manure due to decreasing numbers of livestock
reared per farm household (Bajracharya 2001; Karki 2006; Acharya et al. 2007). The
disruption in the balance among extraction of nutrients from the soil by crops and
