TITLE:
Optimizing Tillage and Irrigation Requirements of Sorghum in Sorghum-Pigeonpea Intercrop in Hamelmalo Region of Eritrea
AUTHORS:
Tesfalem Weldeslassie, Ramesh Prasad Tripathi, Woldeselassie Ogbazghi
KEYWORDS:
Residual Soil Moisture, Sorghum-Pigeonpea Intercrop, Supplementary Irrigation, Water Use Efficiency
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.4 No.4,
April
26,
2016
ABSTRACT: Sorghum (Sorghum
bicolor L. Moench) is cultivated as monocrop in Eritrea. Efforts were made
to grow sorghum-pigeonpea (Cajanus
cajan L. Millspp.) intercrop on the tillage, fertilizers and
supplementary irrigations necessary for sorghum. Experiments were conducted in
terraced fields at Hamelmalo during 2013-15 to evaluate growth and yield of
sorghum-pigeonpea intercrop in split plot design with conventional tillage
(CT), reduced tillage (RT) and zero tillage (ZT) in main plots and rainfed (I0),
50% of full irrigation (I1), 75% of full irrigation (I2)
and 100% of full irrigation (I3) in subplots. All irrigations were
stopped 15 days before sorghum maturity. Full irrigation was 60 mm applied at
50% depletion of available soil water in 1 m profile. Sorghum growth was
faster than pigeonpea until 85 days from planting and pigeonpea growth
accelerated only after sorghum harvesting. About 80% of sorghum roots were within 0.6 m
profile but more than 75% of pigeonpea roots were below 0.60 m depth. This
showed a weaker competition between the two crops for nutrients, water and
light. Both grain and
stover yields of sorghum were optimum in RT + I2 during the 2 years.
Highest grain yield was 6900 kg·ha-1 in RT + I3 in 2013,
which was at par with that in RT + I2. Mean residual soil moisture
at sorghum harvesting was 74 mm·m-1, which decreased to 8 mm·m-1 by pigeonpea harvesting. Residual moisture was more in the irrigated than
non-irrigated plots. Pigeonpea yields were optimum (1363 kg·ha-1)
in RT + I3 and lowest (297 kg·ha-1) in ZT + I0.
Average water use by sorghum-pigeonpea was 374 mm by sorghum harvesting and 438
mm by pigeonpea harvesting, producing total sorghum equivalent yield of 7475 kg·ha-1.
This raised average water use efficiency from 12.6 kg·ha-1·mm-1 at sorghum harvesting to 17.1 kg·ha-1·mm-1 at pigeonpea
harvesting. Benefit was doubled at 50% of full irrigation and >4 times at
75% of full irrigation.