Study On Soil Secondary Salinization Under Facility Agriculture In Fujian Province And Washing Desalinization

As the rapid development of facility agriculture in recent years,the facility vegetable planting area has increased year by year.The particular cultivation mode of facility vegetables has caused secondary salinization of the soils,which resulted in a series of problems,such as the reduction of the yield and quality of vegetables,and even the death of vegetables.The soil and environmental conditions in the southeastern China is quite different from those in the traditional facility vegetable production areas.There are not enough studies on the soil secondary salinization in the southeastern areas.Therefore,a survey on the soil salinazation was carried out over some typical facility vegetable production bases in Fujian Province.The effects of washing with water for removing soluble salts in the soils of the facility vegetable base was also studied.The main results were as follows.(1)The secondary salinization in the facility vegetable bases in Sanming City was the most serious among the soils in the three cities.Most investigated soils in Sanming cities have been highly salinized or extremely salinized.The soils of the facility vegetable bases in Longyan City were less salinized.Most of the facility vegetable soils in Longyan City were slightly salinized.The secondary salinization of the soils in the facility vegetable bases in Zhangzhou City was the weakest among the three cities because most soils were only slightly or non-salinized.(2)Water-soluble anions were the major components in the water-soluble salts in the facility vegetable soils in the three cities.In the osils from Sanming City,water-soluble anions occupied 53.82%-58.64%of the water-soluble salts while the proportion was 48.17%-75.70%for the soils from Longyan City.In Zhangzhou City,53.82%-58.64%of water-soluble salts was anions.Water-soluble Ca2+and K+were the main components in the water-soluble cations while water-soluble SO42-was the main component in the water-soluble anions.the secondary salinization of soil in the investigated soil.In Sanming City,the proportion of water-soluble salts in water-soluble salts that account for the most serious secondary salinization in soil accounts for 65%-79%of the total water-soluble salts.The secondary salinization was the weakest in the soil surveyed by the city of Zhangzhou.The water-soluble salt anions accounted for only 53.82%-58.64%of the total water-soluble salts in the soil.The water-soluble anions accounted for the proportion of water-soluble salts in the three cities in sequence:Sanming City>Longyan City>Zhangzhou City.The total amount of water-soluble salts in the three places was Sanming City>Longyan City>Zhangzhou City.(3)Washing with water effectively reduced the secondary salinization.After five times sequential washing with water,the EC,water-soluble NO3-,water-soluble SO42-and water-sloble Ca2+ in surface soils(0-10 cm,10-20 cm)reduced by 51.9%,80.73%,61.44%,and 36.93%,respectively.(4)After five times of washing with water,the alkali-hydrolysable N and rapidly available P in the soils did not change apparently whereas DTPA-extractable Ni,Zn,Cu,and Mn increased in the soil layer of 0-10 cm.In the soil layer of 10-20 cm,washing led to increase in DTPA-extractable Fe and Mn while led to decrease in alkali-hydrolysable N,rapidly available P,DTPA-extractable Ni,Cu,and Zn.As a whole,washing with water did not bring obvious negative effects to soil nutrition.