Abstract
ABSTRACT: Supplemental irrigation during dry spells could reduce maize yield losses in tropical semi-arid regions, notably in small farms. However, good quality water reserves are not sufficient to meet the demands of farming communities. Consequently, our objective was to evaluate the productivity and profitability of maize under different simulated rainfall scenarios, with and without supplemental irrigation (SI) with brackish water. The field experiments were carried out during the cropping seasons of 2018 and 2019 on Ultisol. The experiment followed a randomized block design in the split-plot scheme with four replicates. The plots were formed by simulating the water supply in the soil corresponding to four water scenarios (rainy, normal, drought and severe drought), and the sub-plots with or without SI with brackish water (Electrical conductivity of 4.5 dS m−1). Mean yields of green maize ears were 13,083, 11,532, 10,358 and 9,609 kg ha−1 for rainy, normal, drought and severe drought scenarios, as supplemented with brackish water. For the same treatments without SI the values were 11,394, 7,896, 3,913 and 1,374 kg ha−1, respectively. Data on farmer's income showed that under normal, drought and severe drought supplementation with brackish water becomes economically advantageous from 0.9, 1.0 and 2.4 ha, respectively, while maize cultivation without SI is not advantageous under the last two scenarios. For severe drought conditions, however, SI using brackish water reduced commercial yield by 27 % with negative effects on the farmers’ profitability. In this case, it is necessary to use water with either lower salinity or select salt tolerant crops.
Highlights
Rainfed farming predominates in most of the world, and represents approximately 80 % of the entire cultivated area (FAO, 2017)
This is hampered by the scarcity of low-salinity water reserves, which have been insufficient to meet the demands of farming communities
The plots were formed by the simulation of soil water application corresponding to four water scenarios – rainy, normal, drought and severe drought, and the subplots with or without supplemental irrigation with brackish water
Summary
Rainfed farming predominates in most of the world, and represents approximately 80 % of the entire cultivated area (FAO, 2017). In the semi-arid region of Brazil there is a predominance of rainfed agriculture, but the contribution to the gross value of production is much lower. A number of studies show that supplemental irrigation could reduce crop yield losses in dryland areas, in semi-arid regions (Chauhan et al, 2008; Oster and Grattan, 2002). This is hampered by the scarcity of low-salinity water reserves, which have been insufficient to meet the demands of farming communities. The use of marginal-quality waters, including brackish and wastewater, may be an alternative for certain production activities of biosaline agriculture in semi-arid regions (Hamdy et al, 2005; Terceiro Neto et al, 2013)
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