土壤與堆肥摻合比對綠屋頂植物之影響

Abstract

利用堆肥化過程 (composting) 將有機廢棄物中不穩定之有機物轉化為安定的腐植質成分，不但可有效減少生活中有機廢棄物，亦可用以改善土壤性質，增進作物收益。本研究係添加不同比例之堆肥 (compost) 於土壤，作為綠屋頂 (green roof) 植物之生長介質，透過植物的生長情形評估堆肥與土壤的最適化摻合比例，以達到最佳的堆肥利用率。 本研究以堆肥和土壤混合比例 0%、5%、10%、15%、20%、40%、60%、80% 及100% (w/w) 進行摻合，實驗始末分別進行土壤性質分析，其項目包括 pH 值、電導度 (EC)、有機質、水溶性氮、水溶性磷、全鉀、全鈣及全鎂含量，並比較不同摻合比之植物生長情形，為維持研究之穩定度與比較性，本研究選用綠屋頂中常見之景天科 (sedum) 植物作為測試標的，植物之生長指標 (growth index) 以植物之重量記錄。 由研究結果顯示，堆肥比 20% 時，僅少數植物之生長不受抑制；且堆肥比大於 20% 時，植物之生長皆受抑制；而堆肥比在 15% 以下時，植物之生長無受抑制情形。由土壤性質分析結果，推論植物生長抑制主要受電導度的影響；因此，本研究建議堆肥與土壤摻合比以不超過 15% 為佳。

The application of compost could be an effective method in reducing the organic waste by the process of composting, unstable organics convert to stable humus components and that can help to improve the soil properties and, thereby, increase the yield of crops. This research was an application of the compost utilization in green roof. Compost was used as an organic input to the growing medium, and the optimal correct ratio of compost was determined by the performance of plant growth.

In this research, the ratio of compost was controlled to 0%, 5%, 10%, 15%, 20%, 40%, 60%, 80% and 100% (w/w). Factors including pH, EC, organic matter, dissolved N, P, total K, Ca, and Mg contents in the medium were determined in the beginning and at the end of experiment, and the results were compared with the plant growth. Sedum plant, which is normally used in green roof, was used in the experiment, and plant growth index was recorded by plant weight to compare the plant growth.

The results showed that only a small amount of plant in 20% of compost had no inhibition in plant growth; plant growth in all the experiment was inhibited when the compost ratio was more than 20%. On the other hand, there was no inhibition response when the compost ratio was less than 20%. From the result of growth medium property analysis, it is inferred that the plant growth inhibition was mainly effected by EC value. Therefore, this study suggests that the amendment of soil by compost should not be more than 15%.