臺灣地區高溫多雨,土壤中的有機質分解快速,為提高作物產量,導致肥料或堆肥施用量有增加的趨勢。近年來運用農業廢棄物製作的生物炭改良土壤性質已逐漸被關注。生物炭添加至土壤中,可顯著改良土壤物理化學性質。然而,不同的生物質原料及熱裂解條件會影響生物炭本身的基本性質,進而影響生物炭添加至土壤後對土壤性質的改善能力。本研究利用農業廢棄物銀合歡木材與稻殼以700℃熱裂解製成的生物炭,同時添加堆肥(牛糞堆肥),進行168天之室內孵育試驗及42天之小白菜盆栽試驗。孵育過程中觀察添加生物炭後土壤氮礦化潛勢之變化,並藉由種植小白菜評估共同添加生物炭與堆肥後小白菜產量與養分吸收之影響。結果顯示,本研究供試土壤(下水埔系)之pH屬微酸性,添加生物炭後顯著提升土壤pH值,尤其以木質炭之效果較佳。孵育初期(21天內),各處理氮礦化皆達最旺盛,尤其以稻殼炭處理最高。本試驗所有處理於21天後皆以生物性的氮固定為主,且添加木質炭及稻殼炭皆具有促進氮的固定化作用之效果。此外,本試驗結果指出,倘若土壤單獨添加生物炭並不會提升小白菜產量;然而,若共同添加4%木質炭與60 ton ha-1堆肥可明顯增加小白菜對氮的吸收效率與產量。
Decomposition of soil organic matter (SOM) was rapid in Taiwan due to high annul temperature and heavy rainfall. Excessive application of fertilizer and/or compost is prevail in order to increase crop production. In recent, biochar application in soils has been already noticed because it could obviously improve soil properties, particularly in physical aspects. However, original feedstocks of biochar largely influence their improved efficiency in soils. Therefore, this study aims to apply biochars of rice hull and woods made of whitelead trees into the compost-amended soil (sandy loam soil) to evaluate the changes of nitrogen minerlization potential in the soil during 168 days incubation. The results indicated that soil pH increased after biochars incorporation due to biochars’ liming effect, particularly for the wood biochar. During 21 days of incubation, N mineralization was obviously, especially in the treatment of rice hull biochar incorporation. After 21 days of incubation, biological immobilization of nitrogen was dominant in all treatments, and biochar-amended ones facilitated the N fixation process. In addition, the study further indicated that incorporation of 4% wood biochar in the compost (60 t/ha)-amended soil could obviously increase N usage efficiency for Chinese cabbage (Brassica rapachinensis) in the soil, and increased their production.