三至五年之水旱輪作及不同施肥處理對一些表土物化性質之影響

• Main Authors: Yang Chi Hsiang, 楊智翔
• Other Authors: M. C. Wang
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/63501036711158464833

碩士 === 國立中興大學 === 土壤環境科學系 === 89 === Abstract The transformations of organic materials in soil environment greatly affect physical, chemical, and biological of soils. The aim of this study was to investigate the changes of some selected physical and chemical properties of the soils of a field plots after 3 to 5years of paddy-upland crop rotations with various fertilizations. The applications of the organic materials were easily decomposable green manure, compost of decomposable agriculture waste, and peat of resistant decomposition. Other than the applications of various organic materials to the plots of experimental field, the amounts of 1/3 and 2/3 of chemical fertilizer N were complemented. Spring rice and autumn corn were rotated to plant in the field. After the harvests of rice in July 1998, of corn in January of 1999 and 2000, and of rice in July 2000, the surface soils were collected from the four replicated plots of the field. The soil samples were subjected to the measurements of pH and electrical conductivity (EC) values, and the determinations of water content at 1/30 MPa, bulk density, and contents of organic C and water-stable aggregate of soils with particle-size of 2-1 and 1-0.5 mm. The results showed that the applications of organic materials to the plot soils prevented soils from the decrease of pH value, and increased the amounts of soluble salts to provide plant nutrients. The applications of organic materials increased organic C contents of plot soils. The organic C content of soil with particle-size of 2-1 mm amended with peat was highest (0.93%) and 1.86 times of that of the check. The organic C content of the soil amended with compost was the next and then that of the soil amended with green manure. The organic C content of soil with particle-size of 1-0.5 mm had the similar trend. After the harvest of spring rice, the water contents of the plot soils at 1/30 MPa tension, amended with organic materials were higher then that of the plot soils amended with chemical fertilizer and the check. This is probably due to the increase of soil organic C content. After the planting of corn, the organic C content of the plot soils followed the same trend except for that of the plot soils amended with green manure . There was no significant difference between the organic content of the soil amended with green manure and the check. This may be attributed to faster decomposition rate of green manure during the growth of upland corn. After the planting of rice, the contents of water-stable aggregate of the plot soils with particle-size of 2-1 mm, amended with peat and compost were significantly higher then that of the plot soils amended with chemical fertilizer and the check. The content of water-stable aggregate of the plot soils amended with peat was the highest (93.3%) and 1.05 times of that of the check. That of the plot soil amended with compost was the next and that of the check was the least. Similarly, the contents of water-stable aggregate of the plot soils with particle-size of 1-0.5 mm followed the same trend. After the planting of upland-corn, other then the plot soil amended with green manure, the content of water-stable aggregate of the plot soil had the same trend as that after the planting of paddy-rice. There was no significant difference between the content of water-stable aggregate of the plot soil amended with green manure and that of the plot soils amended with chemical fertilizer and the check. This is attributed to highly oxidized state of the plot soil of upland-corn, changing from highly reduced state of that of paddy-rice. Further, green manure is easily decomposable in soil environment. After the planting of rice, the bulk density of the surface soils of field plots amended with the organic materials significantly higher then that of the check. This is probably because of the increase of soil organic C by the amendment of organic materials to the field plots. However, after the planting of corn, the differences of the bulk density of the surface soils among the 7 treatments became insignificant. It is due to highly oxidized state of upland-corn changing from highly reduced state of paddy-rice, resulting in greater decomposition rate of organic matter. The impact influence of the applications of organic materials to soils in improving soil physical properties is the increase of soil organic C content, resulting in the formation of soil aggregates, which in turn results in potential water-holding capacity and lowering soil bulk density. Chemically, the applications of organic materials prevent soil from decreasing pH and increase the amounts of soluble salts. Therefore, the applications of organic materials to soils improve physicochemical properties of soils, leading to suitable environment for plant growth. For the maintenance of crop production as well as quality and soil physicochemical properties, fertilization and cultivation strategies merit more close attention.