Irrigation depth far exceeds water uptake depth in an oasis cropland in the middle reaches of Heihe River Basin.

Bin Yang,Xiaomin Sun,Xuefa Wen

doi:10.1038/srep15206

Abstract

Agricultural irrigation in the middle reaches of the Heihe River Basin consumes approximately 80% of the total river water. Whether the irrigation depth matches the water uptake depth of crops is one of the most important factors affecting the efficiency of irrigation water use. Our results indicated that the influence of plastic film on soil water δ18O was restricted to 0–30 cm soil depth. Based on a Bayesian model (MixSIR), we found that irrigated maize acquired water preferentially from 0–10 cm soil layer, with a median uptake proportion of 87 ± 15%. Additionally, maize utilised a mixture of irrigation and shallow soil water instead of absorbing the irrigation water directly. However, only 24.7 ± 5.5% of irrigation water remained in 0–10 cm soil layer, whereas 29.5 ± 2.8% and 38.4 ± 3.3% of the irrigation water infiltrated into 10–40 cm and 40–80 cm layers. During the 4 irrigation events, approximately 39% of the irrigation and rainwater infiltrated into soil layers below 80 cm. Reducing irrigation amount and developing water-saving irrigation methods will be important strategies for improving the efficiency of irrigation water use in this area.

Highlights

In an irrigation event or over longer time scales, the deep percolation of irrigation water is mainly quantified based on soil water balance equations, enabling the water use efficiency and proper scheduling of irrigation to be assessed[6,7,30]
The objectives of this study were to (1) investigate the seasonal water uptake depth of maize based on δ18 O, (2) attempt to utilise δ18O to quantify the proportion of irrigation water infiltrating to different soil strata after irrigation, and (3) evaluate the deep percolation during the periods of 4 irrigation events based on the soil water balance equation
This could be confirmed by the results that soil water content (SWC) and soil temperature of the mulched soil in the 0–5 cm depth increased by 1.7 ± 3.1% and 0.7 ± 1.1 °C (p < 0.05), respectively

Summary

Introduction

In an irrigation event or over longer time scales, the deep percolation of irrigation water is mainly quantified based on soil water balance equations, enabling the water use efficiency and proper scheduling of irrigation to be assessed[6,7,30]. These oases are patchily distributed and surrounded with fixed or semi-fixed sand dunes, in which agricultural production is maintained by irrigation. The objectives of this study were to (1) investigate the seasonal water uptake depth of maize based on δ18 O, (2) attempt to utilise δ18O to quantify the proportion of irrigation water infiltrating to different soil strata after irrigation, and (3) evaluate the deep percolation during the periods of 4 irrigation events based on the soil water balance equation

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Conclusion