Effects of drip irrigation parameters with brackish water on soil water-salt distribution and watermelon yield in gravel-sand mulched field

TAN Junli; SHANG Qian; YANG Zongkai; HAN Gengzhe; XUE Xu; TIAN Haimei; WANG Yuemei; WANG Xina

doi:10.13522/j.cnki.ggps.2025228

Abstract：[Objective]Optimal drip irrigation parameters using brackish water is important for crops grown in gravel-sand mulched fields but is currently lacking,limiting the rational use of brackish water resources.This paper presents the results of a field experiment that investigated the effects of emitting rate and irrigation amount on soil water-salt distribution,as well as growth,fruit yield and quality of watermelon in such soils.[Method]The experiment was conducted in a watermelon field.It involves three emitting rates:2.0,3.0 and 4.0 L/h,and three irrigation amounts:112,224 and 336 m3/hm2.During the experiment,we measured the spatiotemporal distribution of soil water and salt,growth indexes,yield and fruit quality of the watermelon.[Result]①Soil water content in the 0-100 cm soil profile increased with irrigation amount.When the irrigation amount was the same,soil water content in the 0-40 cm soil profile decreased as emitting rate increased.②Within 0-30 cm horizontally from the emitter and 0-100 cm soil depth,soil electrical conductivity increased with increasing emitting rate,while decreasing with increasing irrigation amount.③At the end of first growing season,most treatments resulted in soil desalination in the 0-100 cm soil layer,except the combinations of 336 m3/hm2+3.0 L/h emitting rate and 336 m3/hm2+4.0 L/h emitting rate,which that led to a salt accumulation in the 0-100 cm soil.④Combinations of 224 m3/hm2 irrigation amount+3.0 L/h emitting rate and 336 m3/hm2+3.0 L/h emitting rate improved growth and fruit yield of the watermelon by 74.7%and 72.1%,respectively,compared to that in the 112 m3/hm2+2.0 L/h treatment;it also improved fruit quality and irrigation water use efficiency.⑤Structural equation analysis showed that the drip irrigation parameters indirectly affected growth,yield and fruit quality of watermelon,through directly regulating soil water and salt redistribution in the soil profile.[Conclusion]Considering soil water-salt distribution,soil salt balance,growth,yield and fruit quality of the watermelon,the optimal parameters for drip irrigation using brackish water in gravel-sand mulched fields are an irrigation amount of 224 m3/hm2 combined with an emitting rate of 3.0 L/h.