Dynamic Of Salt Ions In Soil-maize System By Drip Irrigation With Saline-alkali Land

The problems of soil salinization and secondary salinization are widespread in the world,and this problem has become a resource constraint factor for sustainable development of the world's agriculture.Most of the previous studies have focused on the relationship between water movement and salt accumulation and desalination,and there are few studies on the composition and concentration dynamics of salt ions in soil solutions during the movement of water and salt,but the single salt ions are really harmful to crops.Based on the above questions,in this paper,maize was used as the test crop,and drip irrigation was adopted for farmland irrigation,two kinds of irrigation treatments are set?LI10:10mm;LI20: 20 mm?.In 2017-2018,studies on salt cation in saline soil and maize under drip irrigation were carried out in Gegu town,Jinnan district,Tianjin.This paper analyzes the dynamics of total salt and salt cation concentration in soil,the dynamics of salt cation concentration in maize,the correlation between soil and salt ions in maize,and the absorption and transport selectivity of salt ions in soil by maize.The paper discusses the dynamic response of salt ions in the soil-maize system of saline-alkali soil.The main conclusions are as follows:?1?The variation rules of soil total salt concentration under different irrigation treatments are similar in 2017 and 2018.There is a shallow aggregation of soil salinity from May to July,from the whole section,the salt concentration decreases with the increase of soil depth.The 20-60 cm soil layer forms salt desalination,and the soil salt content of LI10 treatment is higher than that of LI20 treatment,and the intensity of the episodes of LI10 treatment is large,and the soil salinity decreases with the increase of irrigation amount.In August,the salt dilution layer is moved to 0-20 cm soil layer,and the phenomenon of soil salt bottoming is obvious.?2?The changes of salt cation concentration are similar under different irrigation treatments in 2017 and 2018.0-20 cm soil layers are the most significant areas of Na⁺ accumulation from May to July,and in August,the soil water-soluble Na⁺ aggregation area moves down.From May to August,K+ always shows shallow clustering phenomenon.The differences of Ca²⁺ and Mg²⁺ concentrations in different depths of soil are not obvious,however,there are some phenomena of superposition of Ca²⁺ and the phenomenon of bottoming of Mg²⁺.Among them,Na⁺ is most similar to total salt distribution.The concentration of salt cations in LI10 treatment is higher than that in LI20 treatment after the water,and the concentration of salt cations decreases with the increase of irrigation amount.The water-soluble cation concentration of soil shows Na⁺>K+>Ca²⁺>Mg²⁺.?3?The salt cation concentrations in roots,stems and leaves under different irrigation amounts treatment show different degrees of difference.The salt cation concentration LI10 treatment in roots,stems and leaves of maize is higher than LI20 treatment after the water,and the concentration of Na⁺ is more significantly affected by irrigation and rainfall,and Na⁺ concentration in different organs of maize decreases with the increase of irrigation amount.The concentrations of Na⁺,K+,Ca²⁺ and Mg²⁺ in different organs of maize are different.Na⁺ absorbed by maize under different irrigation amounts treatment mainly accumulats in the roots,and the transportation to stems and leaves is less,while K+ is more concentrated in the stems and leaves of young tissues of maize,and Ca²⁺ and Mg²⁺ concentrations in the maize are root>leaf>stem.The salt cation concentration in maize shows K+>Ca²⁺>Mg²⁺>Na⁺.?4?Soil soluble Na⁺,Ca²⁺ and Mg²⁺ concentrations are positively correlated with the Na⁺,Ca²⁺ and Mg²⁺ concentrations in maize roots under different irrigation amounts treatment,and the correlation is the closest.The Na⁺ in roots has the highest correlation with the Na⁺ in soil layers of 40-60 cm,and the Ca²⁺ and Mg²⁺ in roots has the highest correlation with the Ca²⁺ and Mg²⁺ in soil layers of 20-40 cm.There is a positive correlation between soil soluble K+ and K+ in leaves under different irrigation amounts treatment,and the correlation is the closest.The concentration of K+ in leaves increases with the increase of soil K+ concentration.?6?The absorption and transport selectivity of salt ions in soil by maize under different irrigation amounts treatment are similar.RSK,Na and RSMg,Na of the maize are higher,and the roots has strong absorption selectivity for K+ and Mg²⁺,and K+ and Mg²⁺ inhibit Na⁺ more than Ca²⁺ inhibits Na⁺.The transport selectivity coefficients of maize from root to stem are TSK,Na>TSMg,Na>TSCa,Na,and maize mainly restricts excessive Na⁺ transportation through K+,and accumulates more Na⁺ in root.The transport selectivity coefficients of maize from stem to leaf are TSCa,Na>TSMg,Na>TSK,Na,and during the transport from stem to leaf,Ca²⁺ is the main ion that inhibits Na⁺.