Effects of Different Fertilizers on Nitrification Activities and the Compositions of Nitrifying Bacterial Polulations of Tropical Soils

• Main Author: 涂惠珠
• Other Authors: 趙維良
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/66969943901854233361

碩士 === 東吳大學 === 微生物學研究所 === 82 === Nitrification is the process of converting ammonium to nitrate by way of nitrite. This process will not only reduce the toxic effect of high concentration of ammonium against plant growth but also increase the fertilitiy of soils. However, this process can also cause soil acidification. Nitrate carrying negative charge is easily been repelled by the clay particles, so it can move rapidly through the soil profile. Therefore, it can move into groundwater by simple leaching process and cause great harm to our health if ingested, in order to estimate the nitrifying activity of soil samples, one can obtain the information by multiplying the numbers of the nitrifying bacteria to the measured nitrifying potential of that soil. In this study, the methed of most probable number (MPN) was used to estimate the numbers of ammonium-oxidizing bacteria and nitrite-oxidizing bacteria in soils receiving chemical or organic fertilizer. At the same time, we had also measured the effects of different fertilizers on the short-term nitrifying activities of Taiwan clay and sandstone shale and slate alluvial soil. The results indicate that in soils samples without the addition of ammonium sulfate, we had detected little or no accumulation of both nitrite and nitrate. On the other hand, when ammonium sulfate was added, we observed an increase in the concentration of nitrate while no nitrite accumulation was been detected. Generally speaking, in all the treatments the amount of nitrate been accumulated was the lowest in sandstone shale and slate alluvial soil amended with chemical fertilizer. The results also indicated that in both Taiwan clay and sandstone shale and slate alluvial soil, the rates of nitrification varies with seasons. However it is clear that the above rate is faster in soils receiving organic fertilizer. Besides soils' physical and chemical properties, the compositions of nitrifying bacterial population may also play an important role. When NaClO3 was used to inhibt the conversion of nitrite to nitrate, we observed that the inhibitory results varied with soils and with seasons. However, in soils receiving organic fertilizer usually has high NO2--N accumulation than soils receiving chemical fertilizers. Although the numbers of ammonium-oxidizing bacteria is generally higher than the numbers of nitrite-oxidizing bacteria, no direct relationship could be established between the numbers of nitrifying bacteria and soils' nitrifying activities. Nevertheless, from the results obtained from those experiments involving the usage of nitrification inhibitors, it is clear that the compositions of nitrifying bacterial population varied not only with soils but also with seasons. Antiserum against Nitrosomonas europaea was also prepared in this study which was to be used for the identification purpose in future experiment.