Seeing that Huang Bai had a name that was relatively unfamiliar to ordinary people called cork, and the cork layer was extremely developed, and it could be peeled off and used as cork, Xu Yi suddenly remembered their school library.

The reading room of the library is covered with cork floors, and after so many years, Xu Yi feels that every time he enters the library, it is a wonderful trip. Although the yellow-brown floor is mottled with spots, and the floor that does not look smooth at all looks unusually monotonous, it has a solid and heavy feeling. It's just that I really stepped on it, but I found that under this rough style, there is another kind of inclusive delicacy.

The completely tasteless cork is soft and elastic, stepping on it is like walking on the clouds, the footsteps fall, the ground is stepped on, and the feet are quickly restored to their original state, giving people a very comfortable feeling, and unlike the ordinary hardwood floor, which jingles when stepped on, and the cork floor does not make any footsteps at all.

Even better, even if something accidentally falls to the ground, it won't break, and it won't even make too much noise. Xu Yi remembered that he once accidentally dropped a book on the ground, and the floor was smashed into a small hole by the book, thinking that the floor had been broken, and went to the administrator with a worried mood, but the administrator smiled and shook his head at him and said that it was okay, and sure enough, when he came back, he was surprised to find that the floor was magically restored to its original state.

After staying in the library for several years, Xu Yi didn't see any damage to the floor, it seems that behind this softness, there is actually another kind of strength hidden.

Thinking of this, Xu Yi also had higher expectations for the barberry, but when he looked up the information, he found that the common cork was not obtained from the barberry tree at all. Instead, the cork that is stripped from the cork oak and is widely used all over the world is mainly produced from three tree species: cork oak, yellow barberry, and cork oak, but relatively speaking. The latter two are not well-known at all.

The world's largest producer of cork is in Portugal on the Mediterranean coast, and hundreds of thousands of hectares of oak trees grow in the province of Alentejo in south-central Portugal. It is also the largest oak forest in the world.

The Alentejo is located at the southern tip of Europe, located in the southeast of the Tagus River, with a vast undulating plain, the Strait of Gibraltar connected to Africa from the Mediterranean Sea and the Atlantic Ocean, the climate is affected by North Africa, drought and little rain in summer, such special natural climatic conditions, long-term natural selection has created a thick cork bark here to protect the water from evaporation, this is the cork tree. The Latin name for the cork oak is Spanish oak. It is a deciduous tree that grows up to 25 meters tall and more than a meter thick, with dark gray bark covered with deep and shallow longitudinal cracks.

Every summer is the busiest season for cork harvesting in the Alentejo, when local farmers take tractors over several hills to the oak trees where they are supposed to harvest their bark, cut the bark into pieces more than a meter long with a sharp axe with a two-foot-long handle, and pry the other end with the handle of the axe, and a large piece of the tree is peeled off.

After the farmer peels off the bark. The last number of the year is written on the trunk of the tree, and after nine or ten years, when the new cork has grown to a sufficient thickness, the skin can be taken again.

The peeled bark is naturally dried for half a year before it is transported to the processing plant and placed in a cauldron. Cook in boiling water for more than an hour to remove salt, tannins, gums from the cork, and to get rid of pests. and bacteria, which can also make the cooked cork thicker. Resilient, boiled cork needs to be flattened. After about 20 days, the cork becomes straight, soft and elastic, which is easy to process and produce wine bottle stoppers, cork soles, floor tiles, etc.

The cork produced by the Alentejo oak tree is an important export resource for Portugal, with almost 60% of the world's cork produced here.

From planting, it takes twenty or thirty years to peel the bark for the first time, and it takes nine to ten years to peel the bark for the next time. The first peeling is about 10 centimeters from the ground to the height of the chest, and the next peeling, it is about a foot high. The bark peeled for the first and second time has no economic value. The cork veneer is peeled for the third time before it can be used. It takes almost fifty years to wait from planting a tree to generating economic value, so long that there is a local Alentejo proverb: "Eucalyptus for us, pine for our children, cork oak for our grandchildren." ”

Thick cork has about 40 million cells per cubic centimeter, like containing 40 million small air sacs, which makes the cork very soft, very elastic, a rough appearance wraps a soft and strong heart, which is undoubtedly the best portrayal of cork oak.

Relatively speaking, as a plant of the same species, cork oak is a unique tree species for the production of cork in China, but because of the natural environment and species differences, the growth rate of cork oak is relatively slow, and it takes more than 15 years to peel it again.

Xu Yi vaguely remembered that the village chief had told him that there was a history of planting Mongolian oaks and cork oaks to feed silkworms before the joint production contract in his hometown.

When it was still a production team, these two kinds of trees were planted on several hills in the village, and the silkworms would be stocked in turn every spring, and after the cocoons were formed, they would be sent to the county's local product company by car, and then sent by the local product company to the city's silk reeling factory for processing.

It's just that later, the city's silk reeling factory was not profitable, and the factory was closed down, so the task of breeding silkworms was not assigned to the village, and the silkworms were naturally not raised, and the oak trees on several hills were naturally placed there as charcoal forests, and then distributed to each family, they were also cut down and planted with fruit trees or planted with bamboo.

It takes so many years for cork oak to collect cork, and Xu Yi knows why there used to be a cork oak tree in the village, but he never knew that this tree could be peeled and collected cork. It took thousands of years for the Portuguese to discover the best use of cork, and the history of planting this in their village is only a few decades before and after, and they don't know that this thing has such a great use value, so naturally there is nothing to regret, and the cause of this is inseparable from the cultivation method of cork oak for silkworm breeding and cork oak for processing cork.

Other trees are planted in the hope that they will grow into mature trees in the future, but the exception is the quercus tree, which raises silkworms.

Even for the purpose of accumulating timber, other trees cut off the tips when they grow tall enough, but after the small oak tree for silkworm cultivation is planted, it has to be cut off from the roots for five or six years at most, leaving only a short stump for it to send out new branches, waiting for it to grow for another five or six years, and then cutting off the branches, and so on and so on and so on and so on and so on and so on and so on and so on and so on and so on and so on and so

So there are the following reasons for this: oak trees have a characteristic that the older the leaves of the tree are thicker and harder, the leaves of the tree that grow to a certain age can not be bitten by the silkworms, and they cannot absorb nutrients, which will naturally delay the growth of the silkworms, on the other hand, if the tree is too big, the silkworms and cocoons on the tree can not be found when standing on the ground, how to manage this?

At the beginning, the village went up the mountain to cut stakes in winter, and when the spring dawned, the oak tree would send out purple-red sprouts from the roots, of course, the first year of germination of the tree was too tender, there was not much nutrition, and the branches were too few, so they could not be used to raise silkworms, otherwise it would not only delay the growth of the oak tree, but also affect the yield of silkworms.

Silkworm raising is generally carried after cutting the stump three years and four years old oak trees, three-year-old oak trees grow to the height of an adult's chest, and the leaves that grow are tender green, just suitable for raising silkworms.

Silkworms hatch from the eggs and have to shed their skin a total of four times before they can form cocoons and pupate.

After the silkworms were raised on such small trees for three years, the villagers moved them from the trees and raised them to the oak trees, which were about the height of adults and had grown for four years. The leaves grown by such trees are harder than the leaves of three-year-old oak trees, but the protein and other nutrients in the leaves are also higher, so that the leaves can meet the needs of the silkworms to grow up and accumulate silk protein.

When the baby silkworms grow into big silkworms, their abdomen even feels a little transparent, and they don't like to eat leaves, the villagers move them for the last time.

In the past, every time they were moved, they were moved around on small trees so that they could collect more young leaves to eat, but when they were cocooned, they needed to be moved to the large trees that remained on the silkworm farm.

Silkworms are cultivated outdoors, when the spring silkworms make cocoons, it is also the season of bird activities in the mountains, long-term choices make the silkworms develop the habit of cocooning on the big trees, as long as they are put on the big trees, they will find a safe place by themselves, roll up one or two leaves, and form a yellow-brown cocoon in the middle, the thickness of fingers.

The south is breeding mulberry silkworms, the whole body of the silkworm is snow-white, but the thickness of the chopsticks, more than an inch long, the size of the silkworm is much larger than the silkworm, the whole body is green or yellow-brown, almost can grow to seven or eight centimeters long, and the cocoon is much larger than the silkworm cocoon of the mulberry silkworm, but the silkworm silk is thicker than the silkworm, and it is not easy to dye, and it is easy to turn yellow, so the selling price is always inferior to the mulberry silk. This silkworm is almost two inches long.

When raising silkworms, it is often necessary to move the silkworms from one tree to another, on the one hand, so that the silkworms can eat more and fresher young leaves, and on the other hand, it is also to let the oak trees that have raised the silkworms grow well in the remaining days, so as not to delay the growth and affect the silkworms in the next year.

I didn't understand before, because the accumulated temperature was enough, the village often stocked the silkworms twice a year on the same woodland, and the spring silkworm production in the coming year was never up, or the agricultural technology station went to the countryside to guide, and the village knew that the tree also needed to rest, so after that, the village did not raise autumn silkworms in the woodland where spring silkworms were raised.

Xu Yi thought that if he planted cork oaks in his own space, he would probably grow well, even if he didn't water and plant for a year, he would probably be able to try to peel the skin, and could he also raise some silkworms in this space......?