Effect of deficit irrigation and mulch on water use and yield of drip irrigated onions

Abstract

A field experiment was conducted at Melkassa Agricultural Research Centre in the Central Rift Valley of Ethiopia (located at latitude 8° 24'N, longitude 39° 21'E and altitude 1,550 m above sea level) during the 2008/2009 dry season to study the 'Effect of deficit irrigation and different mulch covers on water use and yield of drip irrigated onion (Allium Cepa L., cultivar: Bombay Red)'. A drip irrigation system with 144 laterals was used for the experiment. Two factors, namely deficit irrigation at four levels (0, 25, 50 and 75% of Total Available Water, TAW) and mulch covers of four different types (no mulch or bare soil, straw mulch, clear plastic and black plastic) were combined in a randomized complete block design and laid out as treatments in plots 0.4 m x 5 m. Three replications were used. Results showed that onion bulb yield decreased with increase in levels of water deficit. In contrast, both crop water use and irrigation water use efficiencies increased with increase in water deficit level. Use of mulch significantly increased bulb yield. Plots with mulch covers yielded higher than 30 t.ha -1 compared to the bare soil yield of 28.3 t.ha -1 (straw>clear plastic>black plastic>bare soil). Water use was similarly reduced by the presence of mulch covers. A hydraulic performance evaluation of the drip system showed there was an average emitter flow rate variation of 13.7%, a coefficient of uniformity of 85% and an overall irrigation application efficiency of 94.4%.

Water Productivity Indices of Onion (Allium cepa) under Drip Irrigation and Mulching in a Semi-Arid Tropical Region of Colombia

“…In this study, the irrigation water productivity (IWP) values for onion crops ranged from 2.18 to 3.42 kg m −3 , which were found to be considerably lower than those reported by Ramalan et al [61] in Ethiopia (9.16-15.94 kg m −3 ) and Igbadun et al [29] in Nigeria (3.8-5.2 kg m −3 ). However, the findings of this study also indicated that the water productivity of onion crops is comparable to that reported by Nyath et al [62] for traditional vegetables (1.29 kg m −3 ) and alien vegetables (1.37 kg m −3 ).…”

Marketable yield of onion under different irrigation depths, with and without mulch

“…Bandeira et al (2013) also obtained highest marketable yield of onion bulbs applying water depth corresponding to 100% ETc, compared with 75% ETc, performing irrigation management with Class A pan and without using mulch. Similar effect of different irrigation depths on onion bulb yield have also been observed by Olalla et al (2004), Enciso et al (2009), Ramalan et al (2010) and Igbadun et al (2012). Kumar et al (2007) demonstrated that a greater water comfort to the onion crop is obtained when the soil is maintained close to field capacity (100% ETc), promoting …”

<b>Organic cultivation of onion under castor cake fertilization and irrigation depths

“…Igbadun and Oiganji (2012), Ramalan, Nega, and Oyebode (2010) and Ribeiro et al (2016) observed that irrigation depths had similar effects on the yield of onion bulbs. The reduction in irrigation depth of 36% (321 to 204 mm) in 2014 and of 37% (444 to 278 mm) in 2015 resulted in losses of 29, 30, 33, and 11% and 38, 38, 34, and 17% in TY, MBFW, MBDW and MBD, respectively, in each year.…”