Effects Of Cultivation Rice Years On Soil Salinity And Soil Nutrients In Saline-sodic Paddy Field

Saline-alkali soil is widely distributed in the western part of the Songnen Plain in Northeast China.Planting rice is an effective and feasible way to improve saline-alkali soil and increase grain yield.Assessing the effectiveness and sustainability of this approach requires monitoring changes in soil salinity and nutrient content.This paper relies on the long-term localization experiment of improved rice in saline-alkali soil in the field test station,and systematically studied the soda-alkaline soil-cultivated rice for 1 year and 7 years(same plot),3 years and 9 years(same plot),6 years and Soil salinity(pH,conductivity,sodium adsorption ratio),main nutrients(organic matter,total nitrogen,total phosphorus,total potassium and alkali nitrogen)in 12 years(same plot),9 years and 15 years(same plot),rapid-acting phosphorus,available potassium)content changes.The soils of four species of cultivating rice in 2011 and 2017 were collected successively.The soil collection depth is 100 cm,divided into 5 layers(0-20 cm,20-40 cm,40-60 cm,60-80 cm and 80-100 cm).The collected soil samples were naturally air-dried and the pH and conductivity and nutrient content were determined.The results showed that the soil pH value and conductivity decreased with the increase of rice age.Under the same opening year,the pH value and conductivity generally increased with the increase of soil depth.With the increase of the rice age,the salt factor(pH value)in the same soil layer tends to decrease year by year,while most of the nutrients show a trend of increasing year by year,indicating that the increase of planting years will increase the soil nutrient and decrease the salinity.Soil organic matter,total nitrogen,alkaline nitrogen,total phosphorus,available phosphorus content in the soil layer showed that with the increase of the number of reclamation years have been increased in different degrees,such as the basic performance of organic matter is the surface 0-20 cm soil organic matter content with the increase in the number of reclamation years increased,the increase reached 3%-14.3%;The increase of alkaline nitrogen content reached 6.7%-89.3%.The content of soil total nitrogen increased with the increase of reclamation years,and the depth content of each soil layer increased in different degrees,among which the increase of soil total nitrogen content was the most obvious in the rice field 40-60 cm,which was reclaimed for more than 1 years,and increased by 134%,while the total nitrogen content of other deep soil layers in four paddy fields was also significantly increased.The soil available phosphorus is also basically showing an upward trend.Among them,the increase of available phosphorus content in paddy field was the most obvious in 15 years after opening,and the increase of available phosphorus in 0-20 cm reached 156.1%,and the increase of 20-40 cm and 40-60 cm increased by 119% and 139% respectively.The growth of various soil layers in rice fields reached 3%-76.8%.Compared with other depths,the increase of total phosphorus content in soil at 0-20 cm is the most obvious.The increase of paddy field is the most obvious in the 7 years of reclamation,and the total phosphorus content in other depths of other paddy fields also increases slightly.The available potassium is At 0-20 cm,the soil layer content decreased greatly,the reduction ranged from 19% to 42%,while the soil content in the depth of 20-100 cm increased slightly,the soil in 0-100 cm increased the available potassium content with the opening years.It tends to be close.There was no special law in the total potassium content of the soil at all levels,and there was no significant change(P<0.05).Among them,there was almost no change in the 7 years of cultivation and 1 year of cultivation.The total potassium content of the 60-80 cm soil layer increased by 14% compared with the 9 years of cultivation,and the 60-80 cm soil layer of the 12 years of cultivation was more than the 60-80 cm soil layer of the 6 years of cultivation.The potassium content increased by 17.96%,and the organic matter content in the 80-100 cm soil layer also increased slightly,with an increase of 7%.We made some new discoveries on these four rice fields with different rice planting years by analyzing the salt and nutrients of each soil sample,and the linear correlation analysis was carried out for each factor.The pH value of soil and total nitrogen,total phosphorus,alkali nitrogen and available phosphorus were found.There was a negative correlation between organic matter and organic matter.There was no significant correlation between total potassium content and pH value.The available potassium content was significantly negatively correlated with soil pH in the early stage of reclamation,but it was quick-acting with the increase of the opening years.There was no significant correlation between potassium content and pH.Among the four rice fields with the same rice age,soil conductivity was negatively correlated with total nitrogen,total phosphorus,alkali nitrogen,available phosphorus and organic matter,and it was significant;however,there was no significant correlation between total potassium content and conductivity.In the early stage of reclamation,there was a significant negative correlation between available potassium content and soil conductivity.There was no significant correlation between available potassium content and conductivity as the number of years of reclamation increased.Therefore,comprehensive agricultural measures should be taken to improve and grow rice in saline-alkali rice fields.