Agriculture Reference
In-Depth Information
return of residues and organic matter has been, therefore, leading to deterioration in
soil quality and hence land productivity (Schreier et al. 2001; Sherchan and Karki
2006; Paltridge et al. 2011).
Numerous studies have indicated that cropping intensification, with greater reli-
ance on agrochemicals and decreasing soil organic matter, in the hill regions of
Nepal, is unsustainable and leads to land degradation due to soil erosion and nutri-
ent losses during the high rainfall monsoon season (Pilbeam et al. 2002; Gardner
and Gerrard 2003; Acharya et al. 2007; Dahal et al. 2009). Moreover, preferential
application of nitrogenous and phosphorous fertilizers by farmers has apparently
led to micronutrient imbalances in the cultivated soils (Andersen 2001; Paltridge
et al. 2011). Recent studies conducted by Raut et al. (2012) revealed that intensive
rice crop production in Nepal leads to soil acidification, which increases the rate of
denitrification and release of the potent greenhouse gas N
2
O into the atmosphere,
hence enhancing global climate change (Table 6.1). Soil acidification due to exces-
sive nitrogen fertilization and the consequent enrichment of soil, water, and atmo-
spheric nitrogen through ammonia volatilization and nitrate leaching have also been
reported in eastern China and the North China Plain (Ju et al. 2009; Guo et al. 2010).
In India, intensified agriculture using extensive irrigation was found to increase the
regional moisture flux, which modified the convective available potential energy of
the region, leading to a reduction in the surface temperature and modified circulation
patterns causing meso-scale changes in monsoon precipitation (Douglas et al. 2009).
Lal (2004, 2007, 2011) points out that forest and soil degradation has major implica-
tions for environmental quality, climate change, and food security in the South Asia
region. Thus, clearly, intensive farming can have local-, regional-, as well as global-
scale impacts on the environment and climate.
TABLE 6.1
Effects of Intensified Agriculture on Soil pH and N
2
O/(N
2
+ N
2
O) Product
Ratios in Lowland and Upland Farming of the Nepal Mid-Hills
Soil pH (Mean ± SD)
N
2
O/(N
2
+ N
2
O)
Land Use Type
Traditional Farm
Intensive Farm
Traditional Farm
Intensive Farm
Lowland C1
5.42 ± 0.11
4.93 ± 0.11
0.59
0.91
Lowland C2
5.38 ± 0.11
4.60 ± 0.11
0.48
0.66
Lowland C3
4.94 ± 0.05
4.27 ± 0.05
0.81
0.99
Upland C1
5.64 ± 0.06
4.78 ± 0.06
0.74
0.90
Upland C2
5.27 ± 0.04
4.62 ± 0.04
0.62
0.62
Upland C3
4.48 ± 0.06
4.02 ± 0.06
0.82
0.75
Upland C4
5.05 ± 0.05
4.21 ± 0.05
0.50
0.63
Means
5.17
4.49
0.65
0.78
Source:
Adapted from Raut, N., P. Dorsch, B.K. Sitaula, and L.R. Bakken,
Soil Biology and
Biochemistry
55, 104, 2012.
