Agriculture Reference
In-Depth Information
ecological (supporting biomass, forests, buffering action) and the economic (food,
fodder, and fiber production) functions of these soils are important as the crop and
livestock production systems in India are highly integrated in a farming systems
mode.
16.3 CONSTRAINTS IN RAINFED PRODUCTION SYSTEMS
Unlike irrigated agriculture, the productivity of rainfed crops has remained low
with some exceptions. Low yields under rainfed conditions are attributed to several
constraints ranging from cultivation to marketing. Such constraints lead to lower
biomass production, lesser root biomass, and less or no residue recycling with the
attendant low levels of soil organic C (SOC) concentration in rainfed soils. Principal
constraints to achieving higher productivity of rainfed crops are briefly discussed
below.
16.3.1 U
nceRtain
R
ainfall
Due to uncertainty in rainfall, agriculture in rainfed regions depends on the amount
and distribution of monsoons. Increased frequency of droughts is a major challenge
to rainfed agriculture (
Figure 16.1
). Prolonged moisture stress at critical growth
stages results in lower productivity.
16.3.2 d
egRaded
S
oilS
Degraded soils with high risks of accelerated erosion resulting in loss of fertile
surface soil and SOC are major factors. The magnitude of soil loss ranges from
5 to 150 Mg ha
-1
year
-1
depending upon soil type, vegetation, and slope of the land.
There have been several estimates of degraded lands/wastelands reported by differ-
ent organizations. These estimates have been harmonized by adopting spatial data
integration in a geographical information system (GIS) environment (Maji 2007)
(
Figures 16.2
and 16.3). The total degraded area is estimated at 120.72 M ha, of
which 104.19 M ha (86.3%) is arable land and 16.53 M ha (13.7%) is open forestland.
Of the total degraded land area, 73.27 M ha (60.7%) is affected by water erosion,
12.40 M ha (10.3%) by wind erosion, 5.44 M ha (4.5%) by salinity, and 5.09 M
ha (4.2%) by soil acidity. Some areas are affected by more than one degradation
process (Maji 2007).
16.3.3 l
ow
-i
npUt
a
pplication
Use of production inputs like fertilizers, supplemental irrigation, good-quality seeds,
pesticides, and herbicides is lower in rainfed than irrigated crops. Thus, productivity has
remained low. Though it has been amply demonstrated that soils in rainfed regions are
multinutrient deficient, balanced use of these inputs in rainfed crops is rarely achieved.
There are wide disparities of inputs between irrigated and rainfed regions due to numer-
ous uncertainties in the crop production. Statewise consumption of fertilizers under
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