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把園林廢物運到堆填區 根本毫無理由

2016/2/15 — 16:20

Kelvin Kwok攝

Kelvin Kwok攝

根據環保署的資料顯示,香港2013年棄置到堆填區的園林廢物達到56,210噸,即是每日丟棄約154噸的園林廢物,這些園林廢物中包括很多在市區被砍下來的樹木、枯葉及雜草等,它們都是能夠自然分解到泥土的有機物,根本毫無理由運到堆填區。

在澳洲的堆填區中會設有一個場地專門處理各種園林廢物。零碎的有機物如枯葉、雜草等會經過堆肥後成為肥料從新販賣給園藝公司,堆肥所需時間由3個月至5個月不等,視乎天氣而定。而大件的有機物如樹木等則會利用碎木機切碎成為木碎,作為覆蓋物 (Mulch)之用。不過,由於將樹木運送到堆填區的成本太高,私人的園藝公司往往會自行碎木,然後賣或免費送給附近居民以減低成本。

根據我在澳洲的經驗,約半斗地的菜園每3個月就能消化1卡車約2噸的園林廢物。如以我們所租的農地計算,4.8斗地每3個月就能消化9.6噸園林廢物,即每年能夠消化38.4噸園林廢物;全港常耕農地面積約有729公頃,即每年能夠消化約10,808噸園林廢物;全港整體農地面積約4,523公頃,亦即每年能夠消化約67,057噸園林廢物,完全能夠將香港所有的園林廢物消化掉!

廣告

那麼,這些覆蓋物又有甚麼用呢?首先,這些覆蓋物能夠阻隔陽光直射地表,一方面減少水份的蒸發,節省很多灌溉用的水資源,另一方面阻止下面的雜草生長。第二,當這些覆蓋物逐漸腐爛,它們會成為營養重新回到泥土。第三,這些覆蓋物能夠減低雨水對泥土的衝擊,並減少大量的水土流失。第四,美觀,香港的花槽中的泥質惡劣,觀賞價值極低,這些覆蓋物除有實際功用外,也能在觀感上有所提升。

由於覆蓋物非常有用,我回港前已不停打探香港在哪裏能找到木碎,可惜卻找不到答案,原因是堆填區沒有任何收費。堆填區不收費意味著將一切園林廢物棄置是最低成本的方法,各個樹藝公司在砍樹後只要付運輸的費用即可乾手淨腳,毫無負擔。但如果想將樹木碎掉成為木碎的話,那麼就另外租一架車載著碎木機到砍樹現場即時碎木,然後再找一架車載著碎木到指定的需求地點。可是,香港地小路窄,樹藝公司通常不能夠在砍樹現場久留,於是另一方法是將樹木運回倉庫,在倉庫碎木,然後再找一架車載著碎木送到指定的需求地點。所增加的成本可想而知有多麼的貴,即使不計車費油錢,碎木的人工也不可小覷。因此,即使你願意付錢買木碎也不一定買得到。

廣告

好吧,找不到就是找不到,我唯有借鑑朋友的方式,用斧頭、樹剪等將樹枝弄碎,鋪了一條通往農田入口的道路。事實上,木碎覆蓋物還有另一用處,就是將路和田清晰分割開,讓遊人知道哪兒是路能夠踐踏,哪兒是田壢不該踐踏。

According to the Environmental Protection Department, the amount of green waste being sent to the landfill during 2013 was 56,210 tons, which means around 154 tons of green waste are being sent to the landfill everyday. These green waste includes trees, leaves and some weeds which all of them can be decomposed and none of them should be sent to the landfill.

In Australia, there are special sites to treat green waste within the landfill. Loose stuff like leaves and weeds can be composted and sold to the gardening companies as fertilizers. It takes around 3-5 months for the green waste to decompose and the speed depends on the weather. Large and bulky stuff like trees shall be shredded into wood mulch. However, since the cost to send the wood stuff to the landfill is too expensive, the private arboricultural company rather shred them by themselves and sell or give away the wood mulch to the nearby residents.

According to my experience in Australia, a 340-square-meter garden can make use of about 1 truck load of green waste(8 tons) in 3 months. Our land is around 3237.6 square meter and hence can digest around 9.6 tons of green waste in 3 months, that is 38.4 tons in a year. The total size of active farmland in Hong Kong is around 729 hectares, that means 10,808 tons of green waste can be digested in a year. The total size of farmland in Hong Kong is around 4,523 hectares, that means 67,057 tons of green waste can be digested and hence all the green waste in Hong Kong can be digested potentially!

But what is the function of mulching? Firstly, they prevent the sunlight reaching the soil surface, not only it can retain soil moisture, it also control the growth of weeds. Secondly, when these mulch decompose, they will turn into nutrients and back to the soil. Thirdly, they can protect soil from rain for erosion control. Lastly, they look great. The soil in the flower beds along the road in Hong Kong are always poor and look awful. The mulch can also provide ornamental function apart from the actual benefits to the environment.

As the mulch are so useful, I have been looking for wood mulch source in Hong Kong when I was still in Australia. However, I failed to find any since and the reason is: There is no charge for the landfill. Dumping all the materials to the landfill is the cheapest and easiest way to treat all the green waste. If the arboricultural company really wants to do it in a more environmentally friendly way, they will need an extra truck to move the wood shredder to where the trees shall be cut and shred the wood on site. After that, they will need another extra truck to move the wood chips to the destination. There is another constraint for this since the roads are too narrow in Hong Kong. They might not have the time and space to shred the wood on site. In that case, they will have to move all the materials back to the warehouse and shred the wood in the warehouse and send the wood chips to the destination. You can imagine how much extra costs shall incurred: the transportation, the labour, etc. So, it is not even possible if you don’t mind to pay for the wood chips.

Alright, I can’t find suppliers of wood chips. So, I shall make my own my axes and loppers as suggested by my friends. We paved a road to the entrance of the farm with wood chips, of course not as fine as the one shredded by machines. Oh, I forgot to mention another function of wood mulch, which is to define where is the garden bed and where is the road, so people won’t step on our garden beds.

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