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  • 學位論文

都市農園之蔬菜栽培與應用

Vegetable Cultivation and Application in Urban Farm

指導教授 : 林淑怡
共同指導教授 : 張育森(Yu-Sen Chang)

摘要


近年,都市化使都市農園逐漸受到重視。但於都市中種植可食作物其安全性需要小心評估,且栽培型式和一般田間栽培環境不同,其栽培型式對都市農園實施成效亦為另一個重要環節。故本研究隨機挑選臺北地區六處都市農園進行調查,了解目前都市農園應用現況,並調查於臺北地區進行可食作物栽培之食用安全性,探討採收後經過充分清洗對降低危害風險的效果,搭配適當地點、作物種類、介質配方及容器型式之選擇,作為未來都市農園推廣之參考。 目前臺北地區都市農園多於硬舖面空間以容器進行栽培。育材模型股份有限公司生產栽植箱和興農股份有限公司生產之我家菜園栽植箱是最普遍用以栽培植物的容器。依據容器對栽培介質特性之影響,我家菜園栽植箱可能較育材栽植箱之保水性佳。受蔬菜季節性和容器栽培空間之限制,民眾偏好於春夏季種植果菜類,秋冬季則主要種植葉菜類和辛香類蔬菜。介質的使用上大多以田土和無土介質混合而成。依調查結果,在維護管理良好狀況下,介質之總體密度在0.4-0.7 g.cm-3、總孔隙度在75%-80%、容器容水量在57%-64%和通氣孔隙度在15%-20%條件下,所有蔬菜種類生長效果佳。上述介質理化性狀亦在前人研究建議範圍內。 食用安全性上,重金屬銅(Cu)和鋅(Zn)明顯有葉菜類較果菜類和根莖菜類易累積的趨勢。葉菜類中又以落葵(Basella alba L.)具有較高重金屬濃度,可能和其葉片構造粗糙具絨毛易吸附空氣污染物有關;而地瓜葉(Ipomoea batatas(L.) Lam.桃園2號)則為相對低累積重金屬的蔬菜種類。鉛(Pb)則顯示以根莖菜類較其他蔬菜種類易累積,可能和植株吸收鉛後大多存在根部有關。交通流量影響上,大部分蔬菜種類植體重金屬濃度不受交通流量影響,少部分受影響種類,多以交通流量相對較多的基隆路邊種植所含濃度有偏高的趨勢。而不同種植區的蔬菜產量無顯著性差異,因此和所含重金屬的稀釋和濃縮效應較無關,落塵量則受交通流量影響,因此,初步推測試驗中少數受交通流量影響的蔬菜重金屬濃度偏高可能和交通流量造成的落塵量有關。於採收後經過清洗僅有鎳(Ni)和鉻(Cr)在此試驗中經過清洗於部分種植地區及蔬菜種類上有顯著降低重金屬濃度的現象,其中以鉻最顯著,其他重金屬元素則於清洗後無顯著降低的效果,但經過清洗後部分重金屬濃度於部分種植地區及蔬菜種類上仍有降低的趨勢。 栽培介質篩選上,泥炭土(PM):蛭石(V):真珠石(P)在介質比例3:1:1之蕹菜(Ipomoea aquatica Forsk.)和莧菜(Amaranthus mangostanus L.)表現普遍優於或近似1:1:1之植株,其介質EC值和容器容水量高於介質比例1:1:1者。蔬菜作物相對其他作物為需水性高種類,因此,介質理化性狀若在合理範圍內,保水性及EC值相對較高之介質配方PM:V#2:P#2 = 3:1:1和PM:V#3:P#3 = 3:1:1可能較適合生長快速且需水性高的葉菜類,加上比例3:1:1介質成本較低,因此適合作為推廣都市農園建議使用之介質配方。 在容器大小和型式上,以民眾偏好使用的育材網孔式栽植箱和我家菜園非網孔式栽植箱分別於春夏季種植蕹菜,秋冬季種植葉萵苣(Lactuca sativa L.)。兩種容器型式在介質含水量上雖無顯著性差異,但以我家菜園非網孔式栽植箱於春夏季和秋冬季下皆有偏高的趨勢,且其介質EC值顯著高於育材網孔式栽植箱,可能因育材網孔式栽植箱之養份隨多餘的水分從孔壁排出,而造成EC值偏低。春夏季作物蕹菜種植於我家菜園非網孔式栽植箱下生長表現較佳,可能因台灣夏季高溫炎熱、蒸發散快,對於需水性較高的蕹菜種植於保水保肥性較高的我家菜園非網孔式栽植箱中生長表現較佳。秋冬季作物葉萵苣則種植於育材網孔式栽植箱下生長表現較好,其可能因台灣北部冬季多綿綿細雨,相對雨量多,對於需水性相對較低作物,在通氣性較好的育材網孔式栽植箱中生長,根系有較充足的氧氣供應,有助於根系生長和植物發育。 總結來說,於臺灣臺北地區進行都市農園,選擇種植適合蔬菜種類可改善食用安全性,建議可挑選低累積性的果菜類、根莖菜類(如地瓜)或地瓜葉,避免挑選可食部位粗糙具絨毛的蔬菜種類(如落葵)。種植區則建議遠離交通流量高的地區或是選擇頂樓等落塵較不易直接飄落的地區種植,於採收後經充分清洗,有助於提高都市農園之可食作物安全性。為了有較佳的生長表現,建議可使用介質配方PM:V#2:P#2 = 3:1:1和PM:V#3:P#3 = 3:1:1,於乾旱季節或需水性較高的蔬菜以非網孔式栽植箱種植,於潮濕環境適合以網孔式栽植箱種植,對於蔬菜作物生長表現上有較佳的趨勢。除上述建議事項外,良好的維護管理方式,是使都市農園持續實施,發揮對環境、社會和教育等功能的另一個關鍵點。

並列摘要


In recent years, the result of urbanization has attracted more attention to urban horticulture. Furthermpre, the cultivation methods of urban farms is different from that of general field cultivation, and its cultivation type is also an important link to the successful implementation of the urban farm. Therefore, this research investigated six randomly selected urban farms in the Taipei region to understand the current applications in urban farming, as well as examined the safety of edible crops grown in the Taipei region. The effects of thorough cleaning after harvesting in reducing the risk of harm in vegetables were also studied. Selections of appropriate locations, crop types, media formulations and container types will also be suggested to build a model for best-practice of urban farming in the future. Currently urban farming in the Taipei city mostly uses containers for cultivation on hard pavements. “Yù cái” planting box by “yù cái” Co., Ltd. and “Wo jia càiyuán” by SINON Co., Ltd are the most commonly used containers for growing plants. In terms of how the planting box affects media characteristics, “Wo jia càiyuán” planting box exhibits better water retention ability relative to yu-cai. Due to the seasonality of vegetables and limited space of container, people tend to grow fruit vegetables in the spring and summer, and leafy vegetables and spice vegetables in fall and winter. Field soil mixed with soilless media is the preferred type of media. According to the survey results, under good maintenance, all types of vegetables grew better when the total density of the media was 0.4-0.7 g.cm-3, total porosity 75% -80%, container capacity 57% -64% and air porosity 15% -20%. Above physical and chemical properties of media were also within the suggested ranges from previous studies. On the safety of edible crops, heavy metal Cu and Zn accumulated significantly more in leafy vegetables than in fruit vegetables and stem and root vegetables. Among the leafy vegetables, ceylon spinach (Basella alba L.) had high concentration of heavy metal which may be related to the rough and hairy leaf texture making it more easily to absorb air pollutants. Sweet potato (Ipomoea batatas (L.) Lam. Taoyuan #2) leaf had relatively low heavy metal accumulation. The stem and root vegetables accumulate Pb more easily than other vegetable species since Pb may mostly stored in the root after being absorbed by the plant. On the influence of traffic flow, the concentrations of heavy metals in most vegetable species were not affected by traffic flow. The few species which were affected by traffic flow with higher heavy metal concentration were planted on the busy roadsides of Keelung Road. Since there was no significant difference in the yields of vegetables planted in different areas, imply that it was not related to the dilution or concentration effect of heavy metal. Instead, the amount of dust was affected by the traffic flow. Therefore, it is suggested that the high concentration of heavy metals in affected vegetables may be related to the amount of dust caused by traffic flow. When cleaning thoroughly after harvesting of vegetables, only accumulations of Ni and Cr have been significantly reduced in some planting locations and vegetable type, especially for the Cr. After cleaning, other heavy metals were also display reduction trend in a portion of the heavy metal concentration in some planting locations and vegetable types, but not statistically significant. On the media selections, water spinach (Ipomoea aquatica Forsk.) and edible amaranth (Amaranthus mangostanus L.) had better or similar performance when grown in the media with peat moss(PM): vermiculite(V): Perlite(P) in the ratio of 3:1:1 than the ratio of 1:1:1. The EC value of the medium and the container capacity were also higher with 3:1:1 ratio than the medium ratio of 1: 1: 1. Vegetable crops often need more water than other types of crop. When the physical and chemical properties of medium in the ranges suggested by previous studies, media formula PM: V # 2: P # 2 = 3: 1: 1 and PM: V # 3: P # 3 = 3: 1: 1 may be more suitable for leafy vegetables which grow fast and demand more water. Furthermore, the lower cost of media formula with 3:1:1 ratio makes it ideal for use in urban farming. In terms of container size and type, we used people generally prefered “yù cái” and “Wo jia càiyuán” planting boxes to grow water spinach in the spring and summer, and leaf lettuce (Lactuca sativa L.) in fall and winter. The effect of these two types of container on media water content showed no significant difference. Nonetheless, “Wo jia càiyuán” non-mesh planting box exhibited a tendency in higher water retention with the EC value of the media significantly higher than that from the “yu cai” mesh planting box. The lower EC value from the “yucai” container may be attributed to the loss of nutrient along with excess water discharged through the mesh openings in the planting box. Warm-season vegetable- water spinach grown in “Wo jia càiyuán” non-mesh planting box had better growth performance. Under the conditions of high temperatures and fast evaporation during summer in northern Taiwan, wo jia caiyuan non-mesh planting box was able to retain better water and fertilizers may leading to the better growth performance of water spinach with high water demand. As a cool-season vegetable, leaf lettuce grown in “yù cái” mesh planting box had better growth performance. Because of the frequent drizzling during winter in northern Taiwan, “yu-cai” mesh planting box provides better ventilation that allows crops with lower water demand to access sufficient oxygen supply to develop a strong and healthy root system and plant growth. In conclusion, selecting the right types of vegetables to grow may improve food safety when practicing urban farming in the Taipei region. Fruit vegetables, stem and root vegetables(such as sweet potao) and sweet potato leaves, that have low metal accumulation are recommended while vegetables such as Ceylon spinach which contain rough and hairy edible parts should be avoided. The planting location is recommended to be as far away from areas of high traffic flow as possible. Rooftops where dust from the traffic does not fall directly are anthor choice of planting location. Thorough washing after harvesting further improves the food safety of plants of urban farming. To promote good growth performance, media formulas PM: V # 2: P # 2 = 3: 1: 1 and PM: V # 3: P # 3 = 3: 1: 1 are suggested to use with non-mesh type of box during the dry season or when planting vegetables of high water demand, and mesh type of box may be used when the environment is wet. In addition to the above recommendations, regular and proper maintenance is another key point to the continued operation of the urban farm and expanding its environmental, social and educational functions.

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