Agriculture Reference
In-Depth Information
population is vulnerable to food insecurity (Bationo et al. 2007). Rice import into
SSA increased from 0.5 Tg of milled rice in 1961 to 6.0 Tg in 2003 (Balasubramanian
et al. 2007). In Bangladesh, and elsewhere in SA, water management in rice is linked
with accumulation of arsenic (As) in both soil and rice under wetland conditions,
with severe health hazard (Khan et al. 2010). Productivity of the rice-wheat sys-
tem, the basis of the Green Revolution of the 1970s in SA, is stagnating because of
soil degradation and excessive withdrawal of groundwater. The tube well irrigation
in the Indo-Gangetic Plains is closely linked with the energy security. Therefore,
production of biofuels (both the first and second generation) can increase competi-
tion for grains, biomass, land area, water, and nutrients. The payback period for the
so-called carbon debt created by conversion of primary forest (or drainage of
peatland) may range from 100 to 1000 years depending on the specific ecosystem
involved in the land use change event (Kim et al. 2009; Fargione et al. 2008). Energy
consumption in farmland operations also involves the use of fertilizers (especially
of N), herbicides, and pesticides (Lal 2004a). About 300 Tg of CO 2 is released annu-
ally from the manufacture of 100 Tg of fertilizer N by the Haber-Bosch processes
(Jensen et al. 2012). Therefore, integration of fertilizer trees within cropland can
supply as much as 60 kg N/ha/year (Akinnifesi et al. 2010), and use of legumes is
considered crucial to mitigation of human-induced climate change (Jensen et al.
2012). Thus, enhancing use efficiency of fertilizer, water, pesticides, and other fos-
sil fuel-based farm operations is critical to sustainability of agroecosystems. For
example, use of legumes in the rotation cycle can reduce the use of nitrogenous
fertilizer and decrease emission of N 2 O. Jensen et al. (2012) estimated that globally,
between 350 and 500 Tg CO 2 emission is avoided as a result of 33 to 46 Tg N that is
biographically fixed each year. With increased energy conservation and improved
use efficiency, the US economy could save an estimated 33% of its energy consump-
tion (Pimentel et al. 2004).
19.5 TECHNOLOGICAL OPTIONS
The strategy is to adopt innovative technology, enhance SQ, and support diverse ESs
and functions (e.g., food security, water security, and energy security). Thus, there is
a range of best management practices (BMPs) of soil, crop, water, and nutrient man-
agement, and for adaptation to changing and uncertain climate. Some generic BMPs
listed in Figure 19.3 must be adapted, fine-tuned, and validated under site-specific
situations.
19.5.1 M anageMent of C ropland S oilS
Arable land use and its intensification can have strong ecological impacts (Stoate
et al. 2001), including changes in the SOC pool and its dynamics. With regards to
management and restoration of degraded/desertified cropland soils, therefore, the
SOC pool is a key parameter that must be enhanced/maintained above the threshold
level (Powlson et al. 2011). In this context, measurement and modeling of the SOC
pool on arable lands is a priority (Tang et al. 2006). In general, conversion of natural
ecosystems to agroecosystems on land use changes can lead to reduction in the SOC
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