RA 00015.pdf - OAR@ICRISAT

wide range of agroclimatic and economic
environments.
By investigating all facets of resource inventory,
development, management, and utilization
and all factors involved in crop production
in a systems approach, ICRISAT scientists
expect to develop alternative viable systems
for farmers in the SAT. Although the research is
focused on the small farmers of limited means
who comprise the majority of the farm population
of the SAT, the large farmers who occupy
much of the land and employ most of the labor
are also expected to benefit.
Watershed Operations and
Development
Research Watersheds on Vertisols and
Alfisols
The locations and layout of present and proposed
research watersheds were presented in
ICRISAT's Annual Report for 1975-1976.
Some important characteristics for each watershed
unit studied during the 1976—1977 seasons
have been summarized in Table 64. On the basis
of previous results, a broad-bed system of 150 cm
width was applied to several watersheds (Fig 80).
On the deep Vertisols, crops were again planted
in dry soil during the first half of June.
Experience over the past 4 years shows that this
practice appears quite suitable for establishing
crops early, thereby gaining in effective length of
growing season and in attaining greater rainfalluse
efficiency. H owever, the success of this
technique depends upon: (i) the feasibility of
planting relatively deep ( > 6 cm) to protect the
seed from germination after early, small showers
and also upon seedling tolerance to potential
drought stress (e.g. sorghum, pigeonpea, and
maize), (ii) sufficient reliability that after the
selected sowing date, rains-once they beginwill
continue [the probability of a rainy week
( > 20 mm) followed by another rainy week must
exceed 45%], and (iii) absence or control of
rodents or other factors which might damage the
seed in dry soil.
Figure 80. One row of pigeonpea and two rows of
a cereal crop on a 150-cm bed on a
Vertisol at 1CR1SA T Center.
Watershed Development and Feasibility
Studies
Lined, elevated inlets for runoff storage units
(tanks) were used previously to create aboveground
storage and thereby increase storage-toexcavation
ratios in BW7. Satisfactory experience
with unlined inlet channels justified the
removal of the cement and stone slab lining from
the BW7 B tank which decreased costs from Rs
2.22/m 3 of storage to about Rs 1.75/m 3 . Previous
tank construction in BW7 was executed using
exclusively human labor and draft animals. A
new tank was constructed below BW8 using 40
hr of bulldozer time to build the elevated inlet
channel and the bund up to the elevation where
the bund width was adequate for efficient dozer
use; labor was then used to finish further bund
construction and shaping. This circular tank
(capacity 4800 m 3 , storage/excavation ratio =
2.6) was completed at a cost of Rs 1.10/m 3 of
storage (Fig 81); these results compare favorably
with earlier tank development costs in BW7
which ranged from Rs 2.00 to 2.50/m 3 of storage.
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