Impacts of Climate Change on Agriculture - Climate Resilient Agriculture for Ensuring Food Security - page 59

Fig. 4.7 Potential impact of climate change on wheat production in India

this would be small in the early part of the
growing season, but after mid-July the soil mois-
ture defi cit would be considerably larger than at
present, and, for some crops, this implies substan-
tially increased demand for irrigation (Rowntree
et al. 1989 ). Of course, the amount of water avail-
able for plant growth is affected by a combination
of climatic and non-climatic variables such as
precipitation, temperature, sunshine, wind speed
as well as soil porosity, slope, etc.
The effects of high temperature and soil
moisture on major fi eld crops in the USA are
presented in Table 4.9 .
The increased temperature would result in
more water shortages, and the demand for irriga-
tion water would rise. Increase in air temperature
will lead to more potential evapotranspiration in
the areas south of 40°N. Likewise, water shortage
due to climate change would result in about 20 %
net decline in the rice yields in India.

Table 4.8 Effect of high temperature on yield of wheat
and chickpea crops
Temp. gradient
(°C)

Biological yield
(g m −2 )

Grain/seed yield
(g m −2 )

Wheat
0 1,216 368

+1.0 1,060 320

+2.1 1,000 295

+2.5 914 280

+2.9 798 251

Chickpea
0

773 228

+0.9 722 197

+2.3 695 195

+2.6 638 192

+3.1 606 190

4.3.6 Effects on Moisture

Availability

Changes of temperature would also have an effect
on moisture availability for crop growth, whether
or not levels of rainfall remained unchanged.
In general, at mid-latitudes, evaporation increases
by about 5 % for each 1 °C of mean annual
temperature. Thus, if mean temperature were to
increase in the east of England by 2 °C, potential
evaporation would increase by about 9 %
(assuming no change in rainfall). The effect of

4.3.7 Effects on Livestock

A rise in temperature could also have a signifi cant
effect on the performance of farm animals, in addi-
tion to the effects that might fl ow from altered yields
of grassland and forage crops. Young animals tend
to be less tolerant of a wide range of temperature