Effects Of Combined Application Of Biochar And Organic Fertilizer On Farmland Soil And The Growth And Development Of Broomcorn Millet

The ecological environment of the Loess Plateau is special,the land is barren,the soil erosion is serious,the rainfall is less and the distribution is uneven,the drought and thin are closely linked.The Loess Plateau is also one of the main production areas of millet in China.In recent years,with the promotion of the national policy of chemical fertilizer reduction,we studied how to reduce the amount of chemical fertilizer and improve the yield of millet to a certain extent,and explored the effect of organic-inorganic combined application on reducing chemical fertilizer,improving the agricultural ecological environment and realizing the sustainable development of agriculture Development plays a very important role and significance.Split block design was used in the experiment.The main treatment was different fertilizer ratio,and the secondary treatment was different millet varieties.A total of 6fertilizer combinations and 2 varieties of millet were set up,Conventional fertilization for local farmers（urea application only）(N 150 kg·hm^-2,N150)、On the basis of farmers’habit of applying fertilizer,10%of chemical fertilizer nitrogen was reduced and organic fertilizer was increased(120 kg·hm^-2+organic fertilizer,NO10)、On the basis of farmers’habit of fertilization,20%of chemical fertilizer nitrogen was reduced and organic fertilizer was increased(nitrogen application rate 120 kg·hm^-2+organic fertilizer,NO20)、Reducing 10%chemical fertilizer N,increasing 5%organic fertilizer+5%biochar(nitrogen application rate kg·hm^-2+organic fertilizer+biochar,NO5B5)and reducing 20%chemical fertilizer N,increasing 15%organic fertilizer+5%biochar(nitrogen application rate 90 kg·hm^-2+organic fertilizer+biochar,NO15B5),There are six treatments.The design was a completely randomized block design.In order to find out a more effective proportion of nitrogen fertilizer,improve nitrogen use efficiency,and provide a theoretical basis for reducing nitrogen and increasing efficiency in agriculture in China.The main conclusions are as follows:（1）Reasonable fertilization is helpful to increase the content of protein,crude fat and amylose,and increase the yield of millet.Compared with no fertilization treatment,all fertilization treatments increased the yield of broomcorn millet to a certain extent.For glutinous broomcorn millet varieties,NO5B5 treatment had the best yield increasing effect,with the increase rates of 34.09%and 21.72%respectively in two years.Compared with conventional fertilization treatment,the increase rates of 21.53%and 12.58%respectively in two years,followed by NO15B5;For Japonica millet varieties,N150 had the best yield increasing effect,with the yield increasing ranges of 22.60%and 16.81%respectively in two years,followed by NO15B5.No5b5 treatment significantly increased protein content of glutinous millet varieties,and crude fat content of glutinous millet varieties increased significantly under NO20 and NO5B5 treatments,while protein and crude fat content of Japonica millet varieties decreased slightly under different fertilization treatments.The amylose content of glutinous millet varieties was more sensitive to fertilizer treatment.No15b5 treatment significantly increased the amylose content,while NO10 and NO5B5treatments significantly decreased the amylose content.Japonica millet varieties were not sensitive to fertilizer treatment.（2）The results showed that the combination of organic fertilizer,biochar and nitrogen fertilizer could significantly improve the agronomic traits of Japonica glutinous millet.N150and NO10 treatments were beneficial to increase the tiller number and panicle number of Japonica glutinous millet at maturity stage.No5b5 treatment had the most significant effect on the increase of main stem diameter.In japonica glutinous millet varieties,NO15B5treatment had the best effect on the increase of plant height,with the increase range of 7.21%and 9.37%respectively in two years,Among glutinous millet varieties,NO5B5 treatment had the best effect on plant height,with the increase rates of 6.56%and 2.94%respectively in two years.（3）With the development of growth period,the photosynthetic characteristics,relative chlorophyll content and biomass of broomcorn millet increased at first and then decreased.The net photosynthetic rate of two broomcorn millet varieties at grain filling stage was NO10>NO5B5>N150>NO15B5>NO20>CK,and the maximum photochemical efficiency Fv/FM was N150>NO15B5>CK>NO20>NO10>NO5B5,The relative chlorophyll content in leaves of NO5B5 treatment was the best in all growth stages,and the increase range was 5.35%-30.88%.（4）The effects of different fertilizer treatments on soil fertility of broomcorn millet were different.NO10,NO20 and NO15B5 treatments could significantly improve the p H value of rhizosphere soil of broomcorn millet.Compared with no fertilizer treatment,the average increase of two broomcorn millet varieties was 0.84%-3.07%,and compared with conventional fertilizer treatment,the average increase was 0.99%-3.65%.Except NO20treatment,all fertilization treatments significantly increased soil total nitrogen content by2.54%-10.76%compared with no fertilization treatment,and significantly decreased soil total nitrogen content by 1.29%-8.97%compared with conventional fertilization treatment.Except for N150,all fertilization treatments significantly reduced soil total phosphorus content by 5.15%-17.20%.N150 and NO10 treatments significantly reduced soil total potassium content by 1.81%-4.84%.NO20 and NO5B5 treatments significantly increased soil organic carbon content by 2.27%-3.66%.（5）Compared with the control treatment,all fertilization treatments significantly increased soil enzyme activities.N150（nitrogen fertilizer application alone）treatment could increase the activities of urease and protease to the greatest extent,with the increase range of147.59%-621.49%.NO10 and NO20（nitrogen fertilizer+organic fertilizer）treatments could greatly increase the activities of soil catalase and protease The activity of acid phosphatase increased by 108.87%-1213.94%.The activities of sucrase and protease increased by 107.54%-364.90%under NO5B5 and NO15B5（nitrogen fertilizer+organic fertilizer+biochar）.The results showed that the combination of biochar,organic fertilizer and nitrogen fertilizer could effectively improve the agronomic traits,physiological characteristics,soil fertility and soil enzyme activity of Japonica glutinous millet varieties,and ultimately affect the grain yield and quality.