RA 00015.pdf - OAR@ICRISAT

Table 74. Rainfall-use efficiencies obtained in
alternative fanning systems on Vertisols
and Alfisols at ICRISAT Center,
1976-1977.
Watershed
Cropping Systems Value of Gross
No. and water use a,b produce RUE C
Deep Vertisols:
(Rs/ha) (Rs/cm)
BW2 Maize/Pigeonpea 4960 69
Maize/Chickpea 3410 47
BW3 A Maize/Pigeonpea 4930 68
Maize/Chickpea NS 3800 53
Maize/Chickpea S 4511 63
BW4 A Sorghum/Pigeonpea 4130 57
Sorghum/Ratoon 3080 43
BW4C Sorghum Local 660 9
Sorghum Improved 1330 18
BW6B Sorghum Local 1240 17
Sorghum Improved 1330 18
Medium Deep Vertisols:
BW7B Maize/Pigeonpea 3470 48
Maize/Chickpea NS 3250 45
Maize/Chickpea S 3850 53
BW8 A Sorghum/Pigeonpea 2210 30
Sorghum 1010 14
Alfisols:
RW2 B Setaria/Pigeonpea 2640 40
Sorghum and Ratoon
NS 3160 49
Sorghum and Ratoon
S 3520 54
Groundnut/Safflower 3180 49
a Total rainfall during the growing season (Jun to Feb) was
720 and 650 mm on BW1-8 and RW2, respectively.
b The symbol NS when added to a cropping system indicates
that crops were grown rainfed and on residual soil moisture;
the symbol S stands for the application of supplemental
water.
c Gross RUE is the rainfall-use efficiency calculated on the
basis of the total vaiue of the products grown in a cropping
system.
Vertisols, the RUE values obtained on watersheds
in broad beds were two to three times those
obtained with traditional rainy season fallow
with local and improved varieties. RUE's on
medium deep Vertisols and Alfisols were substantially
lower than those obtained in deep
Vertisols. On both deep and medium deep Vertisols
(at the 0.6 % slope) the RUE's obtained for
intercrops and for the combined sequential crops
were higher on broad beds than on flat-planted
soils. There are clear indications that in years of
early rainy season termination, the use of supplemental
water to irrigate a second crop at
planting time may be critical to substantially
increase RUE on at least part of the land and to
make it feasible to grow a sequential crop. On
Alfisols, the RUE's on watersheds in broad beds
generally exceeded those on flat-planted areas.
The range of RUE values clearly shows the
potentials of improved resource use in a year of
relatively low rainfall in the late rainy season. It is
of course realized that RUE values derived from
gross returns, although reflecting the actual
quantity of production, only partially reflect the
differences between alternative systems of farming
because of differentials between the costs
incurred in different systems. However, some
tentative calculations show that when input costs
are taken into account, the differences in RUE
values between improved and traditional systems
become even greater.
Implications and Future Plans
Experience in watershed-based research over the
past few years and agroclimatic analyses show
that in many years sufficient moisture is available
on deep Vertisols for intercropping or sequential
cropping consisting of a short-duration rainy
season crop followed by a dry season crop; the
early termination of the rains the past year has
been an exception. However, harvesting, drying,
and threshing of crops during the latter part of
the rainy season and the susceptibility of most
present sorghum and millet genotypes to grain
mold and weathering pose a serious problem (as
a temporary solution, maize is grown on many
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