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Figure 10. Dhone’s geomorphic units
As a result of erosion, clays are transported to
valleys where they form calcareous clayey soils
which are at times saline. Red soils suffer from the
physical limitations of crusting and compact sub
soils, while black soils suffer from crusting and
low infiltration rates due to high exchangeable
sodium percentage (>7.0). Soil salinity is a serious
problem in the case of black soils and in red soils
when irrigated with saline waters.
Soil depths vary as a result of differential
erosion. High levels of erosion continue to occur
on many of the steeper slopes with soil losses
ranging from 4 to 10 t ha -1 y -1 . Wind erosion is
also common in the mandals particularly from
river bed areas and groundnut fields. Both the
soils are universally deficient in nitrogen.
Red and black soils are poor in phosphorus,
while potassium may become a limiting factor
in light soils dominated by the clay mineral
kaolonite. Deficiency of zinc, sulphur and
calcium is widespread in the case of red soils that
are under continuous groundnut cropping.
Similarly in black soils, zinc deficiency is a major
limitation for crop production under intensive
farming. Boron toxicity is also reported to inhibit
crop growth in these mandals.
Table 3. Length of crop growing period for main soil types in the
five APRLP districts (Source: ICRISAT)
District Soil Type First moist Humid Second Length of
period period moist period growing
(days) (days) (days) period
(days)
Anantapur Sandy Alfisol 49 7 56 112
Kurnool Sandy Alfisol 77 35 42 154
Vertic Soil 77 35 42 154
Mahabubnagar Vertisols 27 141 21 203
Vertic Soils 27 141 14 189
Sandy Alfisol 27 141 14 182
Nalgonda Sandy Alfisol 42 112 28 196
Prakasam Vertic Soils 71 91 18 180
Orthids 70 96 18 186
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