Isolation And Screening Of Potassium-releasing Bacteria And Study On The Release Of Potassium From Paddy Soil

The main soil types in Heilongjiang Province are black soil,meadow soil,chernozem,white clay soil,dark brown soil and aeolian sand soil.Due to different soil types,clay minerals and chemical composition,the form,fixation and release rules of soil potassium are also different,and the supply capacity of soil potassium is different.Potassium solubilizing bacteria can decompose aluminosilicate minerals and convert mineral potassium in soil into soluble potassium to promote the growth and development of crops.Understand the interaction between minerals and microorganisms,and seek new potassium solubilizing bacteria resources with good potassium solubilizing effect and strong potassium solubilizing ability to release the unusable potassium in the soil,so as to improve the agricultural productivity on the original basis.In this paper,the different forms and mineral compositions of soil fertility elements and potassium elements in paddy fields of Heilongjiang Province were analyzed;An improved plate method for rapid screening of potassium solubilizing bacteria was used to screen out the potassium solubilizing bacteria with high potassium-releasing ability from rice rhizosphere soil,and physiological and biochemical identification and 16S r DNA identification were carried out;In order to reveal the biogeochemical mechanism of potassium release by potassium solubilizing bacteria,the effects of potassium solubilizing bacteria on different minerals and paddy soil were studied.The results of soil geochemical analysis of paddy fields in Heilongjiang Province showed that the contents of organic carbon（4.35%）,total nitrogen(877 mg·kg^-1)and total phosphorus(1550.2 mg·kg^-1)in Qitaihe soil samples were the highest,while those in Daqing and Qiqihar soil samples were relatively low;The highest content of water-soluble potassium in Qiqihar soil sample is 69.92 mg·kg^-1,the highest content of available potassium in Qitaihe soil sample is 375.2 mg·kg^-1,the highest content of slowly available potassium in Shangzhi soil sample is 1041.6 mg·kg^-1,and the highest content of total potassium in Daqing soil sample is 241.6 g·kg^-1,which belongs to high standard from the aspect of abundance and deficiency.X-ray diffraction analysis of the whole rock:the soil samples are mainly composed of clay minerals,quartz,K-feldspar and plagioclase,and some of them contain calcite,iron dolomite,siderite,pyrite and other minerals,among which the content of K-feldspar in Qiqihar soil is 16%.X-ray diffraction analysis of clay minerals:there are illite,kaolinite,chlorite and illite/Montmorillonite Mixed Layer in the soil samples,and the illite content of Huanan soil sample is the highest,accounting for 36%.Five strains of potassium solubilizing bacteria were isolated from rice rhizosphere soil in Dongning and Qiqihar city by bromothymol blue plate screening.Among them,strain S1 had the best potassium solubilizing effect,which was 3.852 mg·L^-1,and had the strongest acid producing ability in the potassium solubilizing process,with the lowest p H value of 3.82;The correlation coefficient between the size of halo measured by the modified plate and the dissolved potassium in the culture medium reached 0.992,which was a very significant correlation level.The results of Gram staining showed that strain S1 was gram negative,and strain S1 was Burkholderia by morphological observation,physiological and biochemical identification and 16S r DNA identification.Strain S1 can effectively release potassium from potash feldspar,muscovite and biotite,and gradually increase with the increase of days.The potassium content in the solution of strain S1 was the highest after treatment with biotite.After 30 days,the potassium content was 90.48 mg·L^-1.Muscovite was the second,49.96 mg·L^-1.Potassium feldspar is relatively small,7.79 mg·L^-1.However,strain S1 had the highest potassium content in Dongning and Qiqihar soil samples,which were 5.8 mg·L^-1and 5.3 mg·L^-1,respectively.The p H value of the solution decreased after the interaction with mineral and soil,indicating that the action of acid was an important mechanism of potassium release in the potassium release process of strain S1.The SEM observation of K-feldspar,muscovite and biotite before and after the action of strain S1 showed that the dissolution trace of mineral surface was obvious,and a distinct bacterial mineral complex was formed on the surface.The energy spectrum analysis showed that there was a large amount of potassium on the surface of the complex,which was judged to be an organic-inorganic complex.The content of slow available potassium in the soil before and after strain S1 treatment was compared.After strain S1 treatment,the content of slow available potassium in all the nine soil samples was increased,which was 1.4-33.5%higher than that of the control.The Daqing soil sample increased the most,and Qiqihar soil sample increased the least.Strain S1 transformed insoluble mineral potassium into slow-working potassium and solution potassium,which improved the potential of potassium supply in soil.X-ray diffraction analysis of the whole rock after the action of strain S1 showed that the mineral content of the whole rock of Dongning soil samples decreased from 7.1%to zero,all of them were decomposed,and new minerals were observed,including amphibole,siderite,dolomite and anhydrite,with less content.X-ray diffraction analysis of clay minerals after the action of strain S1 showed that the content of clay minerals in the two soil samples increased significantly.The content of clay in the Dongning soil sample increased from 17.6%to50.5%,which was 2.8 times higher than that of the control.The clay content of Qiqihar soil samples increased from 4.7%to 14.7%,which was 3.1 times higher than that of the control.However,the types of clay minerals remain the same,which are illite,kaolinite,chlorite and illite/smectite mixture.The effect of strain S1 destroyed the structure of potassium minerals in the soil samples,changed the mineral composition,and accelerated the soil weathering ability.In the process of weathering,the primary minerals will gradually decrease and be transformed into secondary minerals,increasing the content of secondary minerals.