| In order to solve the problems of high degree of salinization of salty saline soil in the Yellow River Delta,difficulty in salt leaching,low soil fertility and poor crop growth,the experiment and theoretical study on the improvement of coastal clay soil by humic acid were carried out.The study uses the combination of indoor simulation test,theoretical analysis and field test,based on the soil column adsorption leaching simulation test to explore the effect of humic acid on the water and salt adsorption performance of the coastal clay soil,and to determine the different humic acid addition.The changes of soil salinity and salt discharge efficiency were analyzed.The effects of humic acid improvement on soil water and salt content change and wheat yield in field profile were analyzed under strong evaporation conditions in spring.The mechanism of humic acid improvement on coastal clay soil improvement was explored.With the measures,the main results are as follows:(1)Adding humic acid can effectively improve the water holding capacity of the soil and increase the amount of salt adsorbed by the soil.The soil water content of T1-T5 treatment increased by 0.7%,0.9%,0.8%,0.9%and 0.7%,respectively,and the difference was significant(P<0.05).The soil moisture content of T2 treatment reached the highest,which was 37.75%.With the increase of humic acid addition,the soil salinity increased gradually between CK-T2treatment and decreased between T2-T6 treatments.Compared with CK treatment,T1 and T2treatments were significantly different(P<0.05).(2)Humic acid can significantly increase the amount of soil salinity and effectively promote the leaching of soil salinity.And under the rinsing of FW1 and FW2,the salt leaching amount of T2 treatment reached the maximum,which was 2.26g/kg and 2.23g/kg,respectively,and the difference was significant compared with CK treatment(P<0.05).The leaching rate of soil salinity in CK-T2 treatment increased,and the total leaching amount of soil salinity decreased with the increase of humic acid content in T2-T8 treatment.(3)Humic acid can significantly improve the salt discharge efficiency of soil,and with the increase of humic acid addition,the soil salt discharge efficiency of CK-T2 treatment showed an increasing trend,and T2-T8 treatment showed a downward trend..Among them,the F2 and FW2 were washed,and the T2 treatment had the highest salt discharge efficiency,which were6.88g/L and 8.19g/L,respectively.(4)While increasing the soil water content,humic acid can significantly inhibit the accumulation of soil salinity in 0-20cm and 0-60cm soil layers.T1,T2,T3,T4,and treatment Compared with CK treatment,the salt content of each soil layer was significantly reduced.T2treatment in 0-20cm and 0-60cm soil layer,soil salinity and CK treatment decreased by 8%,32%,respectively,the difference is significant,water content increased by 7%,1%compared with CK treatment,the difference Significant.(5)Humic acid can significantly increase wheat yield compared to CK treatment.In 2017and 2018,with the increase of humic acid addition,the yield of CK-T2 treatment increased,T2-T4 showed a downward trend,and the yield of wheat reached the highest at T2 treatment,which was 6760.24kg/hm~2 and 9134.93kg/hm~2.Based on the results of indoor and field analysis,it is recommended that the optimum application amount of humic acid in the field is 0.12kg/m~2. |
