Deficit Irrigation and Source of Water: Possible Mitigation Option of Arsenic Load in Fodder Maize and Cowpea in Lower Gangetic Plain Zone of West Bengal, India

Abstract

The objective of this experiment is to reduce arsenic uptake in fodder crops by managing through frequency of irrigation water and sources. Farmers of West Bengal grow fodder crops like maize, cowpea, lucerne, etc. in arsenic (As) contaminated areas during the winter season (November to March) under irrigated conditions. The experiment was executed in the arsenic-contaminated village (Ghentugachhi) with a Latitude of N 23º1'19.9" and Longitude of E 88º34'31.8", West Bengal, India during winter seasons 2017-18, 2018-19 and 2019-20. The total arsenic (As) found in the shallow tube well water was 0.120 mg L-1 (mean value) and the total arsenic content in pond water was 0.040 mg L-1 (mean value). The experiment was planned in a factorial experiment in a split-split plot design. The number of crops was two (fodder maize and cowpea), the source of irrigation was two and the frequency of irrigation was three. The crops were, therefore, tested against two sources of irrigation viz.: (i) Pond water and (ii) shallow tube well water; and frequency of irrigation water viz.: (i) Irrigation at 20 Days After Sowing (DAS), (ii) Irrigation at 20 and 35 DAS and (iii) Irrigation at 20, 35 and 50 DAS. The cowpea fodder crop received comparatively less arsenic uptake than maize fodder. Pond water irrigated fodder crops show significantly less arsenic concentration in plant parts compared to shallow tube well water irrigated fodder crops. The frequency of irrigation considerably showed the variation of arsenic concentration in fodder crops. The crops irrigated with single irrigation showed less arsenic uptake in plant parts than the two or three irrigation. Among the edible parts leaf arsenic uptake is less than the shoots.