 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Influence of Soil Moisture Content on Time Courses of Nitrogen Mineralization and Immobilization Caused by Applications of Different Plant Residue to Soils with Different Te ผู้เขียน: Tesfaye Ertebo,  ดร.อำนาจ สุวรรณฤทธิ์, ศาสตราจารย์เกียรติคุณ , นายวิสุทธิ์ วีรสาร, ผู้ช่วยศาสตราจารย์ , ดร.จงรักษ์ จันทร์เจริญสุข, รองศาสตราจารย์ สื่อสิ่งพิมพ์:pdf AbstractA laboratory aerobic incubation experiment was conducted at room temperature to determine the influence of soil moisture contents on time courses of N mineralization and immobilization caused by application of different plant residues. The experiment was carried out in a completely randomized design with a 4 ? 3 ? 3 ? 6 treatments and three replications. The experimental treatments were factorial combinations of four factors: (1) four plant residue types (control, leucaena, sesbania, stubble of faba bean and stubble of maize; (2) three soil textures (loamy sand, loam and clay soil); (3) three moisture levels [50, 75 and 100 % field capacity (FC)]; and (4) six incubation periods (0, 15, 30, 60, 90 and 120 days). The treated samples were analyzed for mineral N (NH4 + + NO- 3) to determine mineralization and immobilization of N. Incorporation of sesbania residue in soils resulted in N mineralization with the rates decreasing with increase in time of incubation. Throughout 120 days of incubation (DI), N mineralization increased with the increase in soil moisture content up to 100 % FC in case of the loamy sand soil but up to 75 % FC in case of the clay soil. In case of the loam soil, N mineralization was not affected by soil moisture content during 30 DI but increased with increase in soil moisture content up to 100 % FC after 30 DI. Incorporation of leucaena residue in soils resulted in either no or slight change in mineral N in the soil during 30 DI regardless of kind of soil. The mineralization and immobilization if occurred either ended after 90 DI or continued to more than 120 DI depending on kind of soil. Incorporation of faba bean stubble or maize stubble in soils mostly resulted in immobilization of N in the soils during the early stages of incubation time and thereafter it either continued up to 120 DI or stopped depending on kind of soil. Both in case of immobilization and mineralization, they mostly increased with soil moisture content up to 100 % FC. For sesbania residue, most suitable soil moisture levels for maximizing N mineralization were 100 % FC in the loamy sand and loam soils and 75 % FC in the clay soil whereas those for leucaena residue were 75 % FC in the loamy sand and clay soils and 100 % FC in the loam soil. In case of incorporation with faba bean or maize stubble, N immobilization could be limited by limiting soil moisture content regardless of soil texture. However, after some specific times of incubation, increases in soil moisture content enhanced N mineralization in the loamy sand and loam soils. |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Influence of Rates of Application of Different Plant Residues on Time Courses of N Mineralization and Immobilization in Soils with Different Textures) ผู้เขียน:Tesfaye Ertebo, ดร.อำนาจ สุวรรณฤทธิ์, ศาสตราจารย์เกียรติคุณ, นายวิสุทธิ์ วีรสาร, ผู้ช่วยศาสตราจารย์, ดร.จงรักษ์ จันทร์เจริญสุข, รองศาสตราจารย์ สื่อสิ่งพิมพ์:pdf AbstractAn aerobic incubation experiment was conducted at room temperature (19 to 23 ?C) to determine the influence of rates of application of different plant residues on time courses of N mineralization and immobilization in soils with different textures. The experiment was carried out in a completely randomized design with three replications. The experimental treatments were factorial combinations of four factors: (1) three rates of plant residue applications (0, 1.25, 2.50 and 5.00 mg of plant residue g-1 soil); (2) three soil textures (loamy sand, loam and clay soils); (3) four plant residue types (leucaena, sesbania, faba bean stubble and maize stubble); and (4) six incubation periods (0, 15, 30, 60, 90 and 120 days). The treated samples were analyzed for extractable mineral N (NH4 + + NO- 3) to determine mineralization and immobilization of N. From the results, the following conclusions and recommendations were drawn. (1) Application of sesbania residue into soils resulted in N mineralization with the rate that increased with fineness of soil texture but decreased with increasing time of incubation. In the cases of the loam and clay soils, N mineralization increased with increasing rate of residue up to 5.00 mg g-1 soil throughout the incubation period but, in the case of the loamy sand soil, N mineralization increased up to the highest rate after 30 days of incubation (DI). (2) Application of leucaena residue into soils resulted in N immobilization that increased with fineness of soil texture during 0-15 DI. N mineralization, increased with fineness of soil texture and rates of application up to 5.00 mg g-1 soil after 15-30 DI onwards, but decreased with time of incubation. (3) Application of faba bean stubble or maize stubble resulted in N immobilization at the rate that increased with fineness of soil texture. In the loamy sand soil N immobilization was mostly observed throughout 120 DI. In the loam and clay soils, N immobilization that increased with fineness of soil texture occurred during 0-15 DI. After 15-30 DI, N mineralization, at the rate that was independent of the rate of residue application in the case of the loam soil but decrease with increase in the application rate in the case of the clay soil, took place. |