## 1 Introduction  
Soil salinization is a global widespread problem, which would limit agricultural production and threaten food security dramatically in arid and semi-arid regions [1, 2]. According to statistics, salt-affected soils account for approximately 25% of the total land area, widely distributing in over 100 countries around the world [3].  
Salt accumulation has detrimental influence on soil physicochemical properties and crop growth as well. This upward movement of salt is caused by the combined influence of groundwater transport, soil evapotranspiration and other water input. The groundwater which contains soluble salt tends to transport via capillary rise to upper soil layer due to continuous evapotranspiration [4]. Simultaneously, liquid water also moves up to compensate for the water loss, and thereby, salt accumulates and precipitates in topsoil. The solid salt may also occupy the pore between soil particles and thereby weaken soil porosity. More importantly, the vast majority of crops' roots concentrate in the top 0 to 30 cm soil layer [5], so it is of great importance to ensure an acceptable salt conditions in the toposil for realizing regional agro-ecological value.  
Macropores are continuous pores with over 0.05 mm diameter, which naturally exist in the form of root channels, wormholes, or soil aggregate gaps. The irregular structure makes it complicated and difficult to conduct accurate infiltration simulation [6]. However, macropores have been considered as a key element to support water flow because they usually work as a water pathway that preferentially delivers solutions into deeper layer [7, 8].  
More importantly, preferential flow under saturated condition tends to be dominated via macropores due to gravity [9]. This provides an important evidence of macropores for promoting soil infiltration. Therefore, artificial macropores were introduced into degraded lands for improving solute transport and bioremediation [10; 11]. Aeration, another type of macropore, was tested to promote root penetration and soil environment in grass land [12; 13]. Despite the positive paradigm in soil remediation, artificial macropores are merely a suboptimal option for exploiting ill-drained fields, as the empty macropore structure is difficult to maintain due to the collapse and clogging. [PERSON] et al. [10] protected the macroporous structure by filling glass fibers, and doubled plant biomass was surveyed one year later. However, the enhanced infiltration may result from the capillary force which was produced by fibrous material.  
In China, more than 36 million ha degraded lands are suffering from salt toxicity, among which coastal saline soils occupy significant proportion. Generally, coastal saline soils are vulnerable to climatic changes because of the intrusion from marine water and poor drainage capacity [14; 15]. In this study, a novel solution was proposed to alleviate salt accumulation of coastal saline farmland. Specifically, we designed artificial macropores with sandy fillings (AMSF) method to determine how they contribute to water migration in saline soils, based on our hypothesis that if coastal lands with poor drainage capacity could be improved, it would be helpful in stimulating water downward transport, reducing salt accumulation, as well as thereby achieving an acceptable farmland. Therefore, column experiments were carried out to compare the drainage capacity of artificial macropore under different salinized levels; irrigation experiments with freshwater were conducted to monitor the water and salt movement, and alfalfa (_Medicago sativa_ L.) was sown to observe plant growth.  
Accordingly, the objective of this study was to create artificial macropores which filled with sandy material, to evaluate its potential benefits for salt-affected soils, and to thereby enhance soil infiltration, improve leach of toposoil with salt accumulation, and increase plant biomass.