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養耕的現狀

How Aquaponics Works
They say one person's trash is another's treasure. The day-old bagels a franchise views as too stale for customers taste perfectly delicious to the hungry when they're distributed at a homeless shelter. The annoying, hyperactive puppy one family abandons at the dog pound because it chews shoes becomes another family's rambunctious little delight. What one group sheds as waste, another takes in as nourishment. It's a lovely circle.
With aquaponics, this same circle is turning -- only it doesn't have anything to do with bagels or puppies. Aquaponics is a method of cultivating both crops and fish in a controlled environment. The fish are kept in tanks, and the plants are grown hydroponically -- meaning without soil. They sit in beds, but their roots hang down into a tub of water. When fish live in tanks, their waste builds up in the water, and it eventually becomes poisonous to them. But what is toxic for fish is nourishing for plants -- they love nothing more than to suck down some fish waste. So with aquaponics, the fish waste-laden water from the fish tanks is funneled to the tubs where the plants dangle their roots. When the plants absorb the nutrients they need from that water, they basically cleanse it of toxins for the fish. Then that same cleansed water can be funneled back into the fish tanks.

This method of farming fish and crops is a good thing on several different levels. First of all, it removes fertilizer and chemicals from the agricultural process. The fish waste acts as a natural fertilizer for the crops, instead. Second of all, it saves water because the water is recycled within the tanks rather than sprayed across a field of crops with abandon. Thirdly, an aquaponics environment can be set up anywhere, so it reduces the need for local communities to import fish and crops from other countries. That saves fuel -- also a positive.
­Aquaponics, with its fancy name, may sound like a trendy new concept developed by environmentalists. But it's actually as old as the hills. The origins of aquaponics can be traced to ancient Egyptian and Aztec cultures. The ancient Aztecs developed chinampas, man-made floating islands, which consisted of rectangular areas of fertile land on lake beds. Aztecs cultivated maize, squas­h and other plants on the chinampas and fish in the canals surrounding them. The fish waste settled on the bottom of the canals, and the Aztecs collected the waste to use as fertilizer [source: Growfish]. Additionally, countries in the Far East like Thailand and China have long used aquaponic techniques in rice paddies.

Let's learn how this ancient farming method is applied today.
Aquaponics Basics
Cultivating plants and fish through aquaponics is both easy on the environment and easy on finances. Aquaponic systems don't use any chemicals, and they require about 10 percent of the water used in regular farming. The systems are closed -- that is, once they've been filled with water, only a small amount is introduced into the system thereafter to replace evaporated water. But how can a water-based system use less water than conventional farming?

The answer is the continual reuse and recycling of water through naturally occurring biological processes. Basically, the waste from fish produces natural bacteria that converts waste like ammonia into nitrate. This nitrate is then absorbed by plants as a source of nutrients. The basic principle of aquaponics is to put waste to use.

Let's take a look at the step-by-step process:

Fish living in aquaponic tanks excrete waste and respirate ammonia into water. Ammonia is toxic to fish in high concentrations, so it has to be removed from the fish tanks for fish to remain healthy.
Ammonia-laden water is processed to harvest helpful types of bacteria such as Nitrosomonas and Nitrobacter. Nitrosomonas turns ammonia into nitrate, while nitrobacter converts into nitrate. Both of these nitrates can be used as plant fertilizer.
Nitrate-rich water is introduced to the hydroponically grown plants (plants grown without soil). These plants are placed in beds that sit on tubs filled with water, and the water is enhanced by the nitrate harvested from the fish waste. The plants' bare roots hang through holes in the beds and dangle in the nutrient-laden water.
The roots of the plants absorb nitrates, which act as nutrient-rich plant food. These nitrates, which come from fish manure, algae and decomposing fish feed, would otherwise build up to toxic levels in the fish tanks and kill the fish. But instead, they serve as fertilizer for the plants.
The hydroponic plants' roots function as a biofilter -- they strip ammonia, nitrates, nitrites and phosphorus from the water. Then, that clean water is circulated back into the fish tanks.
Because fish waste is used as fertilizer, there's no need for chemical fertilizers. The money and energy it would take to put those chemicals to work is saved. In fact, the only conventional farming method that's used to operate an aquaponics system is feeding the fish.

Now you know how aquaponics works on a biochemical level. But which kinds of fish are best for these systems? And which plants thrive in them? Let's find out.

Aquaponics System Requirements
Many warm-water and cold-water fish species have been adapted to aquaponics systems. The most commonly cultivated fish in aquaponics systems are tilapia, cod, trout, perch, Arctic char and bass. But out of all of these, tilapia thrives best. Tilapia are very tolerant of fluctuating water conditions, such as changes in pH, temperature, oxygen and dissolved solids. They also are in high demand -- this white-fleshed fish is frequently sold in markets and restaurants.

Which plants thrive well in aquaponics systems? That depends on the density of the fish tanks and the nutrient content of the fish waste. In general, the best plants to cultivate in an aquaponics system are leafy greens and herbs. The high-nitrogen fertilizer generated through fish waste allows plants to grow lush foliage. So, leafy plants tend to flourish in aquaponics systems. Lettuce, herbs and greens like spinach, chives, bok choy, basil, and watercress have low to medium nutritional requirements and usually do well in aquaponics systems.

Plants yielding fruit have higher nutritional requirements, and although they grow well in aquaponics systems, they need to be placed in systems that are heavily stocked and well established. Vegetables like bell peppers, cucumbers and tomatoes can be cultivated in these types of aquaponics systems. The only plants that don't seem to respond as well are root crops like potatoes and carrots. Without soil, these crops wind up misshapen, and they're hard to harvest properly.




Aside from plants and fish, the other major component of aquaponics is the water itself. That said, carefully monitoring the water's pH, which determines acidity, is of the upmost importance to ensure safe levels for the fish. Water quality testing equipment is very important to ensure that both fish and plants remain healthy. It's also important to keep an eye on dissolved oxygen, carbon dioxide, ammonia, nitrate, nitrite and chlorine. The density of the fish in the tanks, the growth rate of the fish and the amount of feed they're given can produce rapid changes in water quality, so careful monitoring is important. Although the ratio of fish tank water to hydroponic product depends on fish species, fish density, plant species and other factors, a general rule of thumb is a ratio of 1:4 tank contents to bed contents. Basically, for every one part of water and fish, you'll want to have four parts plant and bed material.

Some aquaponics systems are outfitted with biofilters, living materials that naturally filter pollutants out of water and that facilitate the conversion of ammonia and other waste products. Other systems feed fish waste directly into the hydroponic vegetable beds. Gravel in the vegetable bed acts has a bioreactor, a material that helps carry out the chemical processes of living organisms. The gravel does this by both removing dissolved solids and providing a place for the nitrifying bacteria to convert into plant nutrients.

Want to bring food production into your backyard? Read on to learn how to set up your own aquaponics system.

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蔬菜對溫度日照條件的要求

蔬菜對溫度日照條件的要求
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。

菜豆生育過程中,主要吸收鉀和氮較多,還要吸收一定量的磷和鈣,才能良好發育。結莢期吸收磷鉀量較大。磷鉀肥對菜豆植株的生長發育、根瘤菌的發育、花芽分化、開花結莢和種子的發育等均有影響。缺乏磷肥,菜豆嫩莢和種子的品質和產量就會降低。缺鈣,幼葉葉片捲曲,葉緣失綠和生長點死亡。缺硼,則根係不發達,影響根瘤菌固氮,使花和豆莢發育不良。 耐陰半陰(大概3-4小時日照) 應選擇耐陰的蔬菜種植,如萵…

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…