Problems of crop production in drylands
3.1 Problems or constraints for crop production in dry farming regions
Most of the cropping in the arid and semi arid regions continues to be under
rainfed conditions. A majority of the farmers are small farmers with meagre
resources. The poor resource base permits only low input subsistence farming with
low and unstable crop yields. The low productivity of agriculture in dry farming
regions is due to the cumulative effect of many constraints for crop production. The
constraints can be broadly grouped in to
a) Climatic constraints,
b) Soil related constraints,
c) Traditional cultivation practices
d) Heavy weed problem
e) Lack of suitable varieties and
f) Socio economic constraints.
3.1.1 Climatic constraints
A) Rainfall characteristics: Among the different climatic parameters rainfall is an
important factor influencing the crop production in dry regions
(i)Variable rainfall: Rain fall varies both in time and space dimension. Annual
rainfall varies greatly from year to year and naturally its coefficient of variation is
very high. Generally, higher the rainfall less is the coefficient of variation. In other
words, crop failures due to uncertain rains are more frequent in regions with lesser
rainfall. The average annual rainfall of India is 1192 mm where as in Andhra Pradesh
it is 890 mm. Based on the average annual rainfall, the India can be divided into four
zones. More than one third of total geographical area in India receive rainfall less
than 750 mm ( Table.3.1)
Table 3.1 Classification of India into different zones based on rainfall
Zone Average annual rainfall
(mm)
Per cent of geographical
area
Zone I
(very low rainfall area)
< 350 13
Zone II
(low rainfall area)
350 to 750 22
Zone III
(Medium rainfall area)
750 to 1125 36
Zone IV
(High rainfall area)
> 1125 29
(ii) Intensity and distribution: In general, more than 50 per cent of total rainfall is
usually received in 3 to 5 rainy days. Such intensive rainfall results in substantial loss
of water due to surface runoff. This process also accelerates soil erosion. Distribution
of rainfall during the crop growing season is more important than total rainfall in
dryland agriculture.
iii) Aberrations or variations in monsoon behaviour
(a) Late onset of monsoon: If the onset of monsoon is delayed, crops/varieties
recommended to the region cannot be sown in time. Delayed sowing lead to
uneconomical crop yields.
(b)Early withdrawal of monsoon: This situation is equally or more dangerous than
late onset of monsoon. Rainy season crops will be subjected to terminal stress
leading to poor yields. Similarly, post-rainy season crops fail due to inadequate
available soil moisture, especially during reproductive and maturity phases.
(c) Prolonged dry spells: Breaks of monsoon for 7-10 days may not be a serious
concern. Breaks of more than 15 days duration especially at critical stages for soil
moisture stress leads to reduction in yield. Drought due to break in monsoon may
adversely affect the crops in shallow soils than in deep soils.
B) High atmospheric temperature: Because of high atmospheric temperature the
atmospheric demand for moisture increases causing high evapotranspiration losses
resulting in moisture stress.
C) Low relative humidity: Low relative humidity results in high ET losses causing
moisture stress whenever moisture is limiting.
D) Hot dry winds: Hot dry winds causes decicassion of leaves resulting in moisture
stress. High turbulent winds especially during summer months cause soil erosion
resulting in dust storms and loss of fertile soil.
E) High atmospheric water demand: Due to high atmospheric water demand the
potential evapotranspiration (PET) exceed the precipitation during most part of the
year.
3.1.2 Soil Constraints
The different soil groups encountered in dryland areas are black soils, red
soils and alluvial soils. The constraints for crop production are different in different
soil groups. The predominant soil group is alluvial where the problems for crop
production are not so acute as in red and black soils .The different soil constraints for
crop production are
a) Inadequate soil moisture availability: The moisture holding capacity of soils in
dry regions is low due to shallow depth especially in alfisols (red soils), low rainfall
and low organic matter content.
b) Poor organic matter content: The organic matter content in most of the soils
under dryland conditions is very low (< 1 %) due to high temperature and low
addition of organic manures. Poor organic matter content adversely affects soil
physical properties related to moisture storage.
c) Poor soil fertility: Due to low accumulation of organic matter and loss of fertile
top soil by soil erosion the dry land soils are poor in fertility status. Most of the dry
land soils are deficient in nitrogen and zinc.
d) Soil deterioration due to erosion (wind, water): In India nearly 175 m.ha of
land is subjected to different land degradations, among them the soil erosion is very
predominant. The erosion causes loss of top fertile soil leaving poor sub soil for crop
cultivation.
e) Soil crust problem: In case of red soils, the formation of hard surface soil layers
hinders the emergence of seedlings which ultimately affect the plant population.
Crusting of soil surface after rainfall reduces infiltration and storage of rainfall, due to
high run off.
f) Presence of hard layers and deep cracks: Presence of hard layers (pans) in soil
and deep cracks affect the crop production especially in case of black soils.
3.1.3 Cultivation practices
The existing management practices adopted by the farmers are evolved based
on long term experience by the farmers.
The traditional management practices are
Ploughing along the slope
Broadcasting seeds/ sowing behind the country plough leading to poor as
well as uneven plant stand
Monsoon sowing
Choice of crops based on rainfall
Application FYM in limited quantity
Hand weeding
Mixed cropping
Use of conventional system of harvesting
Traditional storage system
3.1.4 Heavy weed infestation: This is the most serious problem in dryland areas.
Unfortunately the environment congenial for crop growth is also congenial for weed
growth. Weed seeds germinate earlier than crop seeds and try to suppress the crop
growth. The weed problem is high in rainfed areas because of continuous rains and
acute shortage of labour. The weed suppression in the early stage of crop growth is
required to reduce the decrease in crop yields.
3.1.5 Lack of suitable varieties: Most of the crop varieties available for cultivation
in dry lands are meant for irrigated agriculture. There are no any special varieties
exclusively meant for dryland areas. Hence still more efforts are required to develop
varieties in different crops exclusively meant for dryland agriculture.
3.1.6 Socio-economic constraints: The economic condition of the dryland farmers
is very poor because
a) Less access to inputs
b) Non availability of credit in time
c) The risk bearing capacity of dryland farmer is very low
Hence the dryland farmers resort to low input agriculture which results in
poor yields.
3.2 Management of Natural Resources
The national resources that are to be managed on sustainable basis are soil,
water, vegetation and climate .India is blessed with vast natural resources of land,
water, vegetation and climate but with poor quality of life. They can be managed by
a) Characterization and development of sustainable land use plans for each
agro ecological region in the country
b) Soil and moisture conservation
c) Integrated soil fertility management
d) Interbasin transfer of surface flow which is otherwise going as waste for
seas and oceans
e) Creation of live storage of water by constructing reservoirs
f) Integrated water management of surface and ground water sources
g) On farm irrigation water management to enhance water use efficiency