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戀上養耕共生

戀上養耕共生
Hooked on aquaponics

Brattleboro couple spreads the word about a more sustainable way of raising plants and fish
By Alexandra Ossola/The Commons
BRATTLEBORO—For visitors to the home of Mark and Susie Crowther, the blue plastic barrels can be the elephant in the room.
What are those barrels doing in a room of their own, people wonder, and why do they keep emitting sounds of rushing water?
They’re aquaponics systems — closed, symbiotic systems in which the Crowthers can efficiently raise plants for their consumption and fish, using recycled materials and water.
Aquaponics is gaining traction on a larger scale as an alternative to traditional methods of produce and fish farming. In developing countries with a limited water supply, people like aquaponics guru Travis Hughey are introducing the concept as a way for individuals to grow their own food while making the most of their limited resources.
Thanks to some research, seeds, water, fish, and a bit of creativity, Mark Crowther has become an avid aquaponics hobbyist, and he is working with the Bonnyvale Environmental Education Center (BEEC) in West Brattleboro to host two workshops in May.
Aquaponics has been used for centuries, as far back as the Aztec empire, when engineers from Tenochtitlan created floating islands of reeds on which they planted seeds for fruits and vegetables.
These days, though, the systems can be as large as lakes or portable and small enough to fit on a tabletop indoors.
To Crowther, the key to creating these systems is to tailor them to the space available; each one of his systems is built from several 55-gallon blue plastic barrels, one sitting cylindrically on the floor as a tank for the fish, the other half-barrel placed perpendicular on top of the other, as a larger plant bed.
There’s a large hole in the bottom barrel above the waterline so that he can access the fish (in Crowther’s system these are golden shiner minnows, “because they were available at the local bait shop,” he said).
The top half-barrel is full of expanded shale, which is Crowther’s “grow bed media” into which the seeds were planted.
This grow bed media is essential in any aquaponic system because it houses those bacteria that enable the plants to absorb the nitrogen. He chose the shale because it’s lightweight, porous, and local.
“But the grow bed media can even be free,” Crowther said. “You can just go down to a brook or river and pull out a bunch of pebbles.”
The final key component to this system is a small electric pump that brings the water from the fish’s bottom barrel to water the plants on the top barrel. A simple bell siphon then flushes the water back down to the fish tank once it fills to a certain level.
The nitrogen cycleThe concept behind aquaponics is based in the nitrogen cycle, which many of us learned in middle-school science class.
Nitrogen in the soil that was deposited by precipitation takes the form of nitrates, which plants need to grow. (Fertilizers incorporate nitrates for this reason.) All fish excrete ammonia, a nitrogen compound, which can kill them if it accumulates to too high a concentration in the water.
Plants are able to absorb that ammonia in the water with the help of the bacteria nitrosomona and nitrobacter. Because the water is recycled, a closed aquaponics system uses approximately 90 percent less water than traditional farming methods, and the system allows both the fish and the plants to exchange nitrogen to their mutual benefit.
Crowther’s interest in aquaponics came about as a synthesis of many other lifelong interests, primarily with aquariums, gardening, and science.
“[I saw aquaponics as] a way of getting back into traditional gardening and incorporating my passion for being an aquarium hobbyist in the past,” he said.
“We love to farm, but the drawback of traditional farming in Vermont is that once you harvest your food, you don’t get to start up until the following spring,” he added.
“With aquaponics you can grow a wide variety of crops year round,” Crowther said. “I thought maybe it would be interesting to get the fish into the system and farm in a way where I didn’t have to pull a weed.”
Crowther primarily grows cool-season vegetables — lettuce and a few spice plants (including mustard and cilantro) — in his system.
While his system is too small to raise fish that could be “table-ready” (that is, suitable for human consumption), larger systems could incorporate harvestable fish (trout, tilapia, perch, etc.).
Crowther preferred his first system to incorporate local species, which meant that they had to be cold-water fish.

With issues of overfishing from the world’s oceans and the myriad problems associated with fish farming (including larger environmental impact and escapement), aquaponics can seem like a panacea for those who raise fish.

However, the question rapidly arises if the artificial lights, pumps, and materials used in an aquaponics system are more cost effective than the fish and produce grown by more conventional methods used to raise the food that now appears in grocery stores.

Crowther believes that the best way to make these systems economically viable is to suit the systems to their climate; he intends to move his systems outside during the summer, replacing the artificial (and costly) heat and lighting with sunlight.

Tilapia has become popular with fish farmers because they “grow so quickly and reproduce like crazy,” Crowther said, but this type of warm-water fish would require too much heat to be viable here in Vermont.

Cold-water fish like perch and rainbow trout are better suited to the climate, and they still grow large and fast enough to be sold commercially.

To Crowther, aquaponics is ripe for taking hold in the region because “we are already invested in education, sustainability, and organic food and are confined to a short outdoor growing season.”

“Unfortunately, aquaponics has never gained ground on a commercial level in our area because of the brief exposure Brattleboro had to Carbon Harvest,” he said, referring to the currently stalled aquaponics endeavor on Brattleboro’s Old Ferry Road.

Carbon Harvest planned to grow tilapia and various types of produce, but has not gotten off the ground due to financial difficulties.




One of Carbon Harvest’s planning errors, Crowther said, might have been attempting to grow a warm-water fish, which meant that the entire building had to be heated to a tropical level that is simply cost-prohibitive.

“That was too bad for Brattleboro, but smaller systems could work for the community from more of a grassroots level, if not on a commercial level,” he said. “The idea is still worth spreading so people can see the value in farming this way.”

Crowther sees those who would be most interested in aquaponics as people who are interested in sustainable agriculture, who are curious about where their food comes from, who respect nature, and who want to bring some of it into their homes.

With some plans pulled from the Internet, some creativity and a do-it-yourself attitude, anyone can construct an aquaponics system.

“One advantage of this is that it’s not an elitist undertaking,” he said. “You don’t need much money to get started.”

Crowther is working with BEEC and Transition Putney to host workshops at the Putney Public Library on Wednesday, May 15, at 7 p.m., and Sunday, May 19, at 1 p.m., on aquaponics. Participants will learn how to construct their own portable aquaponics systems, and all ages are welcome.

“Once kids figure out that you can very easily adapt an aquarium to grow lettuce with a simple 10-gallon tank and a 5-gallon bucket, they’ll realize that it’s fun to watch things grow and will be interactive with this whole process,” he said.

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蔬菜對溫度日照條件的要求

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全日照  8個小時日照 瓜類、茄果類、豆類、山藥、豆薯(地瓜)。番茄、黃瓜、茄子、辣椒等喜溫中、強光性
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其次是根莖類,如:馬鈴薯、甜菜、胡蘿蔔、白蘿蔔、甘藷、山藥等等。至少需半日照,才能生長,芋頭雖喜歡全日照,但比其他蔬菜耐蔭。 
需要中等光照大白菜、甘藍、芥菜、蒜、洋蔥。 

長日性蔬菜白菜、甘藍、芥菜、蘿蔔、胡蘿蔔、芹菜、菠菜、萵苣、蠶豆、豌豆、大蔥、洋蔥。

短日性蔬菜豇豆、扁豆、莧菜、空心菜。         

中光性蔬菜黃瓜、番茄、茄子、辣椒、菜豆

菜豆

菜豆喜溫暖,不耐高溫和霜凍。菜豆種子發芽的適溫為20-30℃;在40℃以上的高溫和10℃以下的低溫,種子不易發芽。幼苗生長適宜氣溫為18-25℃。花芽分化的適宜氣溫為20-25℃,過高或過低溫度易出現發育不完全的花蕾、落花。

菜豆對光照強度的要求較高。在適宜溫度條件下,光照充足則植株生長健壯,莖的節間短而分枝多,開花結莢比較多,而且有利於根部對磷肥的吸收。當光照強度減弱時,植株易徒長,莖的節間長,分枝少,葉質薄,而且開花結莢數少,易落花落莢。

菜豆根系強大,能耐一定程度乾旱,但喜中度濕潤土壤條件,要求水分供應適中,不耐澇。生長期適宜土壤濕度為田間最大持水量的60%-70%,空氣相對濕度以80%為宜。開花結莢期對水分最敏感,此期土壤乾旱對開花結莢有不良影響,開花數、結莢數及莢內種子數減少。土壤水分過大時,下部葉片黃化,早脫落。空氣濕度過大會引起徒長、結莢不良。

菜豆具有深根性和根瘤菌,對土壤的要求不甚嚴格,但仍以土層深厚肥沃、排水良好的輕砂壤土或粘質壤土為好。土壤過於粘重、低溫、排水和通氣不良則生長不良,炭疽病重。菜豆喜中性至微酸性土壤,適宜的土壤pH為5-7.0,其中以州6.2-6.8最適宜。菜豆最忌連作,生產中應實行2-3年輪作。

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黑檸檬

黑檸檬
Dried lemons are actually limes and are used heavily in Persian Gulf and also Iranian cuisine where they add a strong bitter flavor in addition to sourness. They are made by boiling ripe limes in salt water, and then sun drying until the insides turn black. The outside color varies from tan to black. They are sold whole or ground.

Black Lime is a spice used in Middle Eastern dishes. It is made by boiling fresh lime in salt water and sun drying until the insides turn black. The outside color varies from tan to black. It is sold whole or ground.

黑檸檬實際上是使用萊姆,並且在波斯灣和伊朗料理中被大量使用,除了酸味外,它們還添加了強烈的苦味。它們是利用鹽水煮成熟萊姆,然後曬乾,直到內部變黑。外部顏色從棕褐色變化到黑色。他們可以整顆或切片販售。
黑檸檬是用於中東菜餚的香料。它是通過在鹽水中煮沸新鮮的檸檬並經天然乾燥,直到內部變黑。外觀從棕褐色變成黑色。
USE Black limes are usually used in legume, seafood or meat dishes. They are pierced, peeled or crushed before adding them to the dish. After cooking they become softer and edible. They can also be powdered and added to rice dishes. Powdered black lime is also used as an ingredient in Gulf-…

為何冰箱冷凍室非得是零下18度?

為何冰箱冷凍室非得是零下18度? 不少家庭的冰箱有led面板,可顯示冷藏室和冷凍室溫度。每次看到那個零下18℃,不少人,包括筆者在內就會禁不住提出一個小疑問:為什麼冷凍室溫度非得是零下18℃?最多零下1℃不就結冰了嗎?搞這麼低溫度實在是浪費電呢。

聰明如很多人是這樣推測的

百思不得其解,於是很多人,包括筆者在內就開始推測後面的機制了。冷凍室的零下18℃其實不費電,相反,它是節約電力的一個好措施。為何?

冰箱隔一段時間,內部溫度升高後,它就要啟動壓縮機,嗡嗡嗡的。頻繁啟動壓縮機不僅耗電,冰箱的壽命也會降低,還有就是很吵人。怎麼辦?簡單,先把冷凍室的溫度搞得低低的,比如零下18℃左右。


然後,冷凍室的冷氣往上走,來到冷藏室,如此,就能長時間保持冷藏室的溫度處於0到8℃以內了。

待冷凍室的冷氣散失過多,溫度升高到零下幾度時,再啟動冰箱的壓縮機把溫度再次降到零下18℃,如此,冰箱的啟動次數就變少了。

實際是這樣嗎?很遺憾,不是。

原因之一:不一樣的水

水到零度以下就結冰了,這是絕大多數人的認識。然而仔細一想,這不適用於冰箱的冷凍室。因為冷凍室存放的不是上百升礦泉水,而是各種各樣的食物。

食物中含有大量水這沒錯,但這些水同時含有大量的鹽、糖等物質。就像每1升海水中大約含有35克鹽,所以平均起來,要到零下1.33℃時海水才會結冰。

因此,要想把食物凍結,並不是溫度只要達到水的冰點就可以,得保證足夠低的溫度,食物中的水才能凍結,這很重要,因為食物中只要有液態水存在,這就等於是為各種細菌的繁殖提供了必備條件。

圖為牛肉薄片在不同溫度和不同時間內測得的牛肉中凍結水量的曲線。

當牛肉薄片的溫度為零下4℃時,只有70%的水分被凍結;溫度下降到零下9℃左右時,也還有3%的水分未凍結;即使牛肉薄片的溫度降低到零下18℃時,也不是100%的水分都被凍結住。

原因之二:嗜冷微生物

根據微生物對不同溫度的適應範圍,可將微生物分為三大類,嗜熱菌、嗜溫菌和嗜冷菌。在食物的冷藏和冷凍過程中,我們面對的「敵人」是嗜溫菌和嗜冷菌。

一般來說,能引起食物腐敗和食物致毒的嗜溫菌,在低於3 ℃情況下不產生毒素,當然,個別菌種例外。

而對於嗜冷菌,一般得在零下10 ℃到零下12 ℃時才會停止生長。

有的黴菌甚至要到零下15~零下18 ℃時才會停止生長。

瞧,我們以為,零下幾攝氏度後微生物就被殺死或停止繁殖了,但…