Study On Effect Of Modified Lignin And Organic Acids On Soil Phosphates

In this paper, incubation experiments were conducted to study the effects and mechanisms of humic acid(HA), modified lignin and low-molecular-weight organic acids on increasing availability of phosphorus(P) in selected soils. In the first part, incubation experiments under 25~30 were carried out to study the effects and mechanisms of modified lignin H1 and H2 on improving available phosphorus(available-P) content in the soils, at the same time, ammonium citrate(CA) and Ethylene Diamine Tetraacetic Acid (EDTA) which were served as control treatments in order to select more desirable materials. Whereafter, based on the findings of the above mentioned experiments, another thorough set of incubation experiments under different culture temperatures were conducted to study the effects and mechanisms of HA, CA, and H2 on increasing soil available-P. Experiments to study the effects of two different mixtures of organic acids on soil availability of phosphorus were also conducted. The main findings were summarized as following:1. Addition of H1, H2, CA and EDTA to the tested soils increased available-P in soil at different extents, and treatment H2 had the best effect. Compared with treatment of check (CK), on average, treatments of H1, H2, CA and EDTA improved tested soils Olsen-P by 6.9%, 13.2%, 6.6%, and 5.2% respectively. All phosphorus activated materials (P-activated materials) increased the content of Ca-P and Fe-P and decreased content of O-P at different extents. Soil Ca-P content in treatments H1, H2, CA and EDTA increased by 24.0% 31.9% 20.0% and 17.8% respectively. The effect of each P-activated material was related to the change of inorganic-P component with the different P-activated material treatments. In the Black soil, Ca-P was an important quick and direct phosphorus resource to available-P, which showed direct and notable influence on soil available-P. Treatment H2 got the best effect by improving Ca-P content to increase soil available-P.2. Effects of the different P-activated materials on improving soil available-P with temperature changing were different. Treatments of HA, CA, and H2 got the best effects under 10 . Compared with treatment CKp, treatment HA, CA, and H2 improved soil available-P by 43.2%, 53.5%, and 30.3%, respectively under 10 condition, 44.5%, 34.3%, and 23.0%, respectively under 20 , and 1.8%, -1.7%, and -4.8%, respectively under 30 . The effect of HA on soil available P was affected very little by temperature change under 10 and 20 , and the effects of improving available-P were almost the same under these two temperature conditions.Soil available-P in treatments HA, CA, and H2 decreased with temperature rising, hereinto, available-P of HA and CA were decreased significantly with temperature rising. Compared with 10 , soil available-P under 20 and 30 with treatment of HA decreased by 17.9% and 35.3%, respectively, and that with treatment CA decreased by 28.8% and 41.7%, respectively. Soil available-P in treatment with H2 decreased significantly when temperature rose from 10 to 20 and 30 . Compared with 10 treatment, soil available-P decreased by 23.3% and 33.5% , respectively under 20 and 30 . And when temperature rose from 20 to 30 , available-P was decreased, but the difference was not significant. Inorganic-P components in soils with different P-activated materials changed differently with temperature changing. Contents of Ca2-P, Ca8-P, and Fe-P in soils with treatments of HA, CA, and H2, declined differently with temperature rising. Compared with treatment CKp, Contents of Ca2-P, Ca8-P, and Fe-P in the soil were influenced greatly by temperature rising. And temperature changing had the biggest influence on Ca2-P. Ca2-P content in soils with treatments HA, CA, and H2 increased by 47.6%, 31.7%, and 32.5%, respectively under 10 , and decreased by 28.4%, 28.0%, and 29.8%, respectively under 30 . Content of Al-P in soils with the P-activated material treatments, had relatively small change. With CA treatment, contents of Al-P in soil were almost equal under 20 and 30 conditions, but significantly decreased compared with 10 condition. With H2 treatment, soil Al-P contents were almost equal under 10 and 20 , but significantly declined compared with that under 30 condition.Available-P was affected by inorganic-P components and their proportions, which were influenced by P-activated materials. Different temperature and different P-activated materials had different effect on contents of different inorganic-P components. P-activated materials improved available-P through influencing content of Al-P and Ca2-P. Under 10 , 20 , and 30 , soil Al-P had the biggest influence on available-P in treatments with CA. With treatment H2, the most important inorganic-P components contributing to soil available-P under 10 , 20 , and 30 were Al-P, Ca2-P, and Al-P, respectively, while with HA treatment, the most important inorganic-P components contributing to soil available-P under 10 , 20 , and 30 were Ca2-P, Al-P, and Al-P, respectively. Al-P also had significant contribution on available-P under 10 .3. Experiments on effect of low-molecular-weight organic acids on soil available P in a black and a red soil indicated that the black soil had better available-P supply than the red soil tested. Different levels of low-molecular-weight organic acids (LA) and low-molecular-weight organic acids which was mixed with selected amino acids (LAA) improved Olsen-P level significantly in Jiangxi red soil and Jilin black soils, and Olsen-P contents in soils with LA, or LAA treatments were significantly improved, compared with their corresponding control treatment (CKp). Treatments of 0.5g LA/1.0g DAP(diammonium phosphate) (0.5LA) and 0.6g LAA/1.0g DAP (0.5LAA) were more effective than treatments with normal rate of LA and LAA in Jiangxi red soil. Treatment with 1.2g LAA/ 1.0g DAP was more effective than treatment with 1.0g LA/ 1.0g DAP, and treatment with 1.2g LAA/ 1.0g DAP was the most effective treatment in Jilin black soil. On average, compared with the treatment of CKp1.0g LA/ 1.0g DAP LA , 0.5g LA/1.0g DAP 0.5LA 1.2g LAA/ 1.0g DAP LAA , and 0.6g LAA/1.0g DAP 0.5LAA decreased P fixation rates by 10.5%, 22.3%,11.3% and 19.4%, respectively in Jiangxi red soil, and by 8.6%, 10.6%, 14.1% and 11.8%, respectively in Jilin black soil. In other word, LA and LAA could reduce P fixation rates significantly in red soil and Jilin black soil. Treatments with 0.5g LA/1.0g DAP or 0.6g LAA/1.0g DAP (0.5LA and 0.5LAA) were more effective than full normal rate treatments in red soil, while 1.2g LAA/ 1.0g DAP LAA showed better than other treatments in Jilin black soil.