Soil degradation caused by irrational land utilization has greatly threatened sustainable development of the world agriculture. In degraded soil aggregates are readily crushable or breakable and the increasing amount of small-sized aggregates affects stability of the soil structure. In recent years, soil erosion led by soil degradation affects the lives of thousands of millions of people around the world. Biomass ash, a combustion product of agricultural wastes, is low in pH, porous in structure and rich in phosphorus, potassium and other nutrients. Its use as soil amendment can not only improve soil physical and chemical properties and yield of crops but also reduce incidence of crop diseases. Therefore, biomass ash is a new type of green and potentially valuable material that can be used to improve soil quality. In this study, saw-dust ash prepared in an incinerator at 800 ~ 900 ℃ was selected as biomass ash (H). Besides this, other soil amendments including lime (S), lime with zeolite (SF), biological fertilizer (W), plant ash (C), were used, separately, in addition to chemical fertilizer (NPK) in a pot experiment using degraded yellow soil from the Wulong Fairy Hill area in Chongqing for comparison. A lettuce - spinach - lettuce rotation system was adopted to determine effects of the soil amendments on yield and quality of the vegetable and soil fertility as well as on nutrient contents in soil leachate. The aim of this study is to provide scientific basis for comprehensive evaluation of effects of the soil amendments ameliorating degraded yellow soil. Results showed as follows: (1) The effects of the soil amendments varied significantly from one another. Treatments NPKH and NPKW were higher than all the others in lettuce yield. The use of soil amendments in addition to chemical fertilizer helped reduceNO₃^?-N content in lettuce as compared with the use of Chemical fertilizer alone, the content of amino acids in lettuce was the highest in Treatment NPKH; (2) The effects on the degredated soil also differed with type of amendment. The use of soil amendments increased soil organic matter and pH. The content of soil organic matter decreased with the planting going on, but the decrease was the least in Treatment NPKH, which was followed by Treatment NPKC. The effects of the amendments on alkalytic N did not differ much, but the effect of raising soil available P and available K was the highest in Treatment NPKH, with the effect on soil available P in particular, being 190.0% ~ 242.9% higher than that in Treatment NPK. (3) The use of chemical fertilizer alone in degraded soil may easily lead to N loss, which may amount to 22.08 ~ 39.06 mg L^-1 in total N (TN). The leachates from Treatments NPKH, NPKW and NPKC were lower than those from the others in TN concentration. NO₃^?-N was the main form of soil nitrogen lost with leachate, and similar in trend and very closely related to TN (P<0.01, r=0.869). During the pot experiment, Total phosphorus (TP) and disissoluble phosphorus (DP) concentrations in the leachates displayed significant correlationship (P<0.01, r=0.892). DP accounted for more than 60% of TP in concentration. In Treatment NPKH, as ash per se contained a large volume of P, besides the portion absorbed by the crops, a portion was lost with leachate. The concentration of TP and DP in the leachate from Treatment NPKH reached 0.70 ~ 1.35 mg L^-1 and 0.67 ~ 1.27 mg L^-1, respectively, significantly higher than those in the leachates from the other treatments’, thus posing a risk of eutrophying the nearby waterbody.