Study On Drip Irrigation Model And Irrigation System Of Sugar Beet In Soda Saline-alkali Soil

The lack of surface water resources,low rainfall and increasing agricultural water consumption in the West Liaohe Plain lead to the continuous rise of groundwater exploitation and lead to the imbalance of mining and replenishment.Unreasonable irrigation methods and irrigation systems also lead to continuous accumulation of surface salt,soil alkalinity degree is serious,the emergence of a large area of soda saline-alkali land.In recent years,the integrated technology of drip irrigation has been widely applied in the irrigated area of West Liaohe Plain,alleviating the pressure of water resources demand.Advanced water-saving irrigation techniques need to be combined with efficient water management methods in order to maintain a positive cycle of soil and water environment and yield considerable crop benefits.Therefore,this study carried out drip irrigation mode optimization and irrigation system optimization experiments in the mild soda saline-alkali land of the West Liaohe Plain to explore the effects of different drip irrigation methods and irrigation quota on soil solute transport,sugar beet growth and water consumption rule.The AquaCrop model was used to optimize the sugar beet irrigation system,and the appropriate drip irrigation system under film for different hydrological years was proposed.The results can provide theoretical basis and technical support for rational water-saving irrigation of beet in mild soda saline-alkali land.The research results are as follows:（1）The total salt content under shallow drip irrigation was 5.92%higher than that under film drip irrigation,and the contents of total nitrogen,organic matter and available phosphorus were 5.41%,5.34%and 22.99%lower than that under film drip irrigation.Drip irrigation had little effect on p H,alkalinity and available potassium.The salinity and alkalinity of soil decreased in different degrees during the whole growth period when the irrigation amount was 261～273mm.Under drip irrigation under membrane,total nitrogen increased by 10.98%,organic matter,available phosphorus and available potassium decreased by 17.37%,21.91%and 27.53%,and the soil nutrient content of beetroot layer was higher than that of other irrigation treatments.（2）The irrigation amount between 216～241mm under membrane drip irrigation could promote the plant height and leaf growth of beet,increase the net photosynthetic rate and intercellular CO₂concentration of the plant,and keep the total dry matter quality at a high level.The yield of beet under 216～241mm irrigation was 17.66%higher than that under the local irrigation system,and the sugar content was higher under216～223mm irrigation.The yield under film drip irrigation was 10.32%higher than that under shallow drip irrigation.Comprehensive factors of water saving and high yield showed that the irrigation amount between 216～223mm under drip irrigation under film was more suitable for local beet growth.（3）During the growth period of beet,the water consumption of shallow buried and under film drip irrigation was 488.52～611.06mm and 435.81～569.15mm,respectively.Compared with shallow buried drip irrigation,the total water consumption under film drip irrigation was 9.97%lower,the water consumption intensity was 3.04%～18.28%lower,and the water use efficiency was 22.78%higher.The water use efficiency of216～223mm irrigation was higher than that of other irrigation treatments and 38.37%higher than that of local irrigation systems.Under the condition of drip irrigation under film,the irrigation amount is 216～223mm,and the water required for crop growth can be guaranteed under the premise of water saving.（4）Based on the AquaCrop model,the optimal drip irrigation system in typical years of mild soda saline-alkali land in West Liaohe Plain was as follows:irrigation quota was200mm in a wet year,irrigation quota was 40mm,and irrigation was performed 5 times during growth period;Irrigation quota was 230mm in a normal year,irrigation quota was33mm,irrigation was 7 times in growth period;The irrigation quota in the dry year was290mm,and the irrigation quota was 32mm,and the irrigation was 9 times during the growth period.