Abstract
Drip irrigation (DI) has been widely utilized for crops and its water-saving effect has been confirmed by numerous studies. However, whether this technology can save so much water under the field scale during practical application is still uncertain. In order to answer this question, evapotranspiration (ET), soil water content, transpiration and evaporation over the DI and border irrigation (BI) in an arid area of NW China were continuously measured by two eddy covariance systems, micro-lysimeters, the packaged stem sap flow gauges and CS616 sensors during 2014–2018 growing seasons. The results showed that the DI averagely increased crop water use efficiency (CWUE) by 11% per year against BI. The deep drainage under DI treatment was lower than BI by 8% averagely for the five-year period. While for the ET, the DI averagely decreased ET by 7% and 40mm per year against the traditional BI. The decrease in ET was mainly due to the significant reduction in soil evaporation instead of transpiration. Oppositely, we found that DI may increase maize (Zea mays L.) transpiration in some year for the better preponderant growth of crop. Thus, the accelerating effect on transpiration of DI and its reducing effect on soil evaporation should be considered simultaneously. In our experiment, DI only improved CWUE and WUE (water use efficiency) by 11% and 15% on average in a large farmland scale, unable to always be more than a 20% improvement, as concluded by many other field experiments. Consequently, the water-saving effect of DI should not be overestimated in water resource evaluation.
Highlights
Water scarcity is becoming more and more serious globally as a result of climate change and population increase [1]
Our results showed that the change of irrigation methods from border irrigation (BI) to drip irrigation (DI) could improve the maize crop water use efficiency (CWUE), WUE and
Our study showed the annual transpiration under two treatments was similar and concluded that more water-saving DI would not reduce transpiration of crops, but even enhance transpiration to promote the growth of crops due to the warming effect of DI
Summary
Water scarcity is becoming more and more serious globally as a result of climate change and population increase [1]. Film-mulched drip irrigation technology is a kind of new surface irrigation technology to meet the water-saving agriculture development and has been widely considered as a reliable irrigation way in terms of water saving and production increasing, and widely promoted and used in arid and semi-arid regions. In this irrigation method, the drip irrigation lines are laid on the soil surface and under the plastic film, and the water enters the soil surface through the drip irrigation line’s emitters and gradually wets the soil. Verma (2007) [8] conducted experiments on a peach field, finding out film mulching drip irrigation saved irrigation water by 59.1%, and promoted fruit yield by
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