Optimizing Tillage and Irrigation Requirements of Sorghum in Sorghum-Pigeonpea Intercrop in Hamelmalo Region of Eritrea

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 (I 0), 50% of full irrigation (I 1), 75% of full irrigation (I 2) and 100% of full irrigation (I 3) 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 + I 3 in 2013, which was at par with that in RT + I 2. 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 + I 3 and lowest (297 kg•ha −1) in ZT + I 0. 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.

Field edge rainwater harvesting and inorganic fertilizers for improved sorghum (Sorghum bicolor L.) yields in semi-arid farming regions of Marange, Zimbabwe

“…Drought is a primary sorghum production constraint and is the leading cause of yield decrease (Gruber, 2017). Sorghum cultivation in Zimbabwe's marginal agro-ecological regions IV and V is entirely dependent on rain (Mukarumbwa and Mushunje, 2010) and vulnerable to moisture stress at key stages of crop development (Weldeslassie et al, 2016). Small-scale farmers in semi-arid agro-ecologies obtain meager yields (0.5 t/ha) which are below subsistence level (Musara et al, 2019) resulting in high yield gaps compared to output at commercial farms (3 t/ha) (Macauley and Ramadjita, 2015).…”

Assessment of measured and estimated meteorological data in terms of sorghum production on the example of Hamelmalo, Eritrea

“…Rainfed sorghum is endangered by the risks of water stress during critical growth stages and droughts. Sorghum yields of about 4 t ha −1 can be assured only by irrigating once in terraced plots with high amount of residual soil moisture (Tripathi & Ogbazghi, 2010;Weldeslassie et al, 2016).…”