Agriculture Reference
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of several agriculturally beneficial microbes. According to researchers, a
small increase in temperature in low carbon soil results in higher carbon
dioxide emissions as compared with medium and high carbon soil 12 . This
phenomenon makes low carbon soil more vulnerable to warming. It has
been shown that soil nitrogen availability is reduced in drier soil condi-
tions. This is because dry soil adversely affects root growth and decom-
position of organic matter that adversely affect the activity of biological
nitrogen fixing bacteria. Reduced nitrogen fixation in turn reduces soil
fertility. Supplementing higher dose of chemical fertilizers to compen-
sate soil degradation induced fertility depletion, with intention to harvest
sustained and higher crop productivity, is a common thought. Excessive
use of chemical fertilizers damage living processes of the soil and makes
it more vulnerable to edapho-climatic variability. At the same time, they
contribute to emission of nitrous oxide, a potent greenhouse gas. Climate
change accelerates soil erosion and land degradation processes which ulti-
mately induce desertification of fertile soil and contributes in expansion of
arid zones. The impact of climate change has already resulted as contrac-
tion of several million hectares of fertile cultivated land.
19.2.5 CROP DIVERSITY
The fourth IPCC Report (Lakshmanan et al., 2007) states that by the
end of this century climate change will be the main cause of depletion in
biodiversity. If there is an increase of the average global temperature by
1.5-2.5°C, then approximately 20-30 percent of known plants and animal
species will be under threat of extinction. Climate change will increase the
pressure of land degradation and habitat loss, as well as genetic erosion
which is already intensifying by growing uniform agricultural systems
across the India as well as the world. According to the Food and Agricul-
tural Organization (FAO), three-quarters of the global crop diversity is al-
ready lost. This is particularly problematic as the loss of genetic diversity,
both in natural ecosystems and cultivated crops, is facing problem of the
impact of climatic change. Changes in the climate pattern also favor the
diffusion of invasive alien species which are considered to be second most
destructive threat to global biodiversity and agro ecosystems. Invasive
alien species are able to conquer new territories when changed ecoclimatic
zones become favorable for their breeding. Since these species constitute
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