Improvements Of Biochar On Soda Saline-alkali Soil In Songnen Plain

Songnen Plain is an important agricultural and animal husbandry base in northern China,which is one of the three soda saline soil distribution areas in the world.The soil was affected by high salt concentration,high pH value,ion toxicity and high alkalinity.The physical and chemical properties of the soil were bad,which seriously inhibited the growth of crops,and the improvement of soda saline alkali soil in Songnen plain can relieve the pressure of grain production in Northeast China.Our study will through the experiment of applying biochar in soda saline alkali soil of Songnen Plain,exploring the changes of soil nitrogen,phosphorus and potassium in saline alkali soil ecosystem under different biochar treatments(0?5?10?15?20?25?30 t/hm2)were applied.We analyzed the effects of biochar on soil organic matter,cation exchange capacity,Na+,Ca2+and Mg2+concentration,and from the perspective of biochar soil crop system,a comprehensive and in-depth study on the mechanism of nutrient change in soda alkali soil and maize was carried out.It provides a scientific basis for the scientific and rational use of biochar in production practice,and provides a scientific reference for the improvement of saline alkali land.The main results are as follows:(1)In 0-20cm and 20-40cm soil layers,biochar application significantly reduced soil pH,salt content and Na+concentration at seedling stage and harvest period,and T20 treatment decreased the most.T20 treatment Soil pH value decreased from 8.48 to 7.71,soil salt content decreased from 8.2 to 2.3 g/kg,and soil Na+ concentration decreased from 117.33 to 52.17 mg/kg.(2)In the soil layer of 0-20 cm and 20-40 cm,the application of biochar at seedling stage and harvest period significantly increased the NPK content of soil.The content of soil available potassium increased by 2.29%-97.14%,the content of soil available phosphorus increased by 8.06%-93.29%,the content of soil alkali hydrolyzed nitrogen increased by 7.06%-47.32%,the content of soil total nitrogen increased by 7.06%-47.30%,the content of soil total phosphorus increased by 10.77%-76.18%,and the content of soil total potassium increased by 8.19%-87.41%.Soil available potassium,available phosphorus,alkali hydrolyzable nitrogen,total nitrogen,total phosphorus and total potassium had extremely significant positive correlation.(3)After biochar application,the contents of organic matter,CEC,Ca2+ and Mg2+ in 0-20 cm and 20-40 cm soil layers were significantly increased.Soil organic matter content increased by 67.80%,CEC increased by 9.78%-59.39%,soil Ca2+ concentration increased from 2.46 mg/kg to 4.76 mg/kg,and soil Mg2+concentration increased from 5.43 mg/kg to 12.54 mg/kg.(4)The addition of biochar increased the nutrient content of the aboveground and underground parts of maize,and decreased the Na+ concentration.The total nitrogen content,total phosphorus content,total potassium content,Ca2+content,Mg2+ content,Na+content,Na+content and Na+content were increased by 22.06%-160.93%,6.44%-90.19%,15.88%-230.61%,4.68%-59.22%,1.06%-74.24%and 11.36%-50.77%respectively.Total nitrogen,total phosphorus,total potassium,calcium and magnesium ions in maize were significantly negatively correlated with soil pH,Na+concentration and salt content.(5)The application of biochar can promote the growth and production of maize and increase the yield of maize.The grain weight per spike of biochar treatment was T20>T25>T15>T30>T10>T5.The 100 grain weight of maize plants increased from 23.34 g to 28.89 g,and the yield of corn increased by 18.14%-50%.(6)Through principal component analysis,CEC,pH,salinity explained 90.5%of the changes of soil physical and chemical properties,and their effects on physical and chemical properties were as follows:cation exchange capacity>pH value>salt content,which were the main environmental factors that changed the physical and chemical properties of soil,and could be used as the key indicators to evaluate the effect of soil improvement in soda saline alkali soil.(7)The 20 t/hm2 biochar treatment had the best improvements on soil physical and chemical properties,soil ion concentration and plant nutrient content,20 t/hm2 was the best application amount of biochar.