When it comes to potassium fertilizer, as a child in the countryside, Marin naturally thought of phosphate fertilizer. Fertilization of crops generally requires three types of fertilizers: nitrogen, phosphorus, and potassium.
The ancient Chinese people applied manure, which was actually nitrogen fertilizer. Because, manure contains nitrogen. However, nitrogen fertilizer alone is not enough. Europeans don't fertilize, so the yield of wheat per mu is only a few hundred catties. The Chinese people apply manure, and the yield per mu can reach more than two hundred catties.
Later, in addition to applying manure, the Chinese also sprinkled plant ash on the ground. Plant ash contains potassium, which is barely a weakened potassium fertilizer. With the application of these two kinds of natural fertilizers, the wheat yield of Huaxia people can reach about 300 catties per mu.
As for the paddy fields in the south of the Yangtze River, there are many fish and shrimps in them because of the vertical and horizontal ditches. These fish and shrimp are rich in phosphorus. Phosphorus seeps into the ground after the fish and shrimp die. Its effect is equivalent to the phosphate fertilizer of later generations.
Therefore, some paddy fields in the south of the Yangtze River that have been applied with manure, plant ash, and rich in phosphorus can have a high yield of five or six hundred catties per mu. Because, in this kind of field, the three elements of nitrogen, phosphorus and potassium are complete...
Of course, the ancients did not understand the principle of fertilizers, and they did not know that dead fish and shrimps can also fertilize the fields. Therefore, it has been said that the land in the south of the Yangtze River is fertile and the land in the north is barren. Actually, that's not the case at all.
The actual situation of later generations has proved that as long as the three types of fertilizers are applied, the fields in the north and the south will have the same high yield.
On the island of Texel, Marin promoted manure and plant ash. It's just that the vegetation resources on Texel Island are not as abundant as those in the interior. The potassium content of plant ash is very limited, so Marin sent people to the Harz Mountains to buy bitter salt mines (potassium salt mines) and directly add potassium salts as potash fertilizers.
However, it is very difficult to obtain this phosphate fertilizer. Because Morocco, which is rich in phosphate fertilizers, cannot be provoked by Marin. Even Western Sahara, another place rich in phosphate fertilizers, is also within the control of the Moroccans.
Marin had read time travel novels before, and knew that near Laayoune in Western Sahara, there was a super-large phosphate mine with reserves of up to 2 billion tons, not far from the sea.
However, it is now Moroccan territory. Morocco is not too strong, but definitely not weak. It is no problem for people to pull out 10,000 to 20,000 Arab cavalry. Therefore, if you want to seize the phosphate rock in Western Sahara, you have to ask the Moroccan machete first.
As for trading with the Moroccans, buying phosphate rock can be done more than a hundred years later, but absolutely not now...
Because, after the 17th century, the Holy See declined and its authority was no longer there. Everyone could trade with heretics without any problem. But now it is the end of the 15th century, and the authority of the Holy See is still strong.
If it is a big country like Spain and Portugal, it may be possible not to give face to the Holy See. As for Marin's Texel Island, he dared not give face to the Holy See. Trading with heretics, and the Green Cultists, the deadly enemies of Christians, can easily be declared a heresy by the Holy See.
The Holy See itself may have mediocre fighting power, but now the Holy See has a strong appeal. If he is on the blacklist of the Holy See, Marin will be waiting to be beaten by a group...
Therefore, before the European Reformation and religious wars, Marin absolutely did not dare to confront the Holy See. And defeating Morocco is currently unlikely. Therefore, regarding the phosphate fertilizer issue, Marin must think of another way...
I remember that when I was studying chemistry in middle school, Marin heard from his junior high school chemistry teacher that the bones and scales of fish were rich in phosphorus. Even in fish meat and fish viscera, the phosphorus content is good.
"In other words, fish bones, fish scales, and fish viscera can also be used as low-level phosphate fertilizers?" Marin sat at the table and thought.
Thinking of this, Marin took a few attendants and rode to the two fishing ports of Thorenche and Odesshild to conduct field research.
Sure enough, whenever the fishing boats returned to the port, after a large number of sea fish were unloaded, the fishermen began to kill the fish one after another...
A large number of fish scales were hung down and randomly thrown on the ground. Huge amounts of fish guts are discarded and even thrown into the sea…
And every time after eating, many fishermen's homes also have a lot of leftover fish bones, which are treated as garbage and thrown out at will...
"Damn it! It's such a waste!" Marin, who was on the inspection, couldn't help feeling distressed.
"Master, what's the matter?" asked Ban Shaoer.
"These... are all high-quality phosphate fertilizers! Just throw them away for nothing!"
"Phosphate fertilizer? What the hell?" Saul asked with question marks all over his head.
"You don't even know..." Marin shook his head.
The next day, Marin issued an order, ordering all the fishermen in the two major fishing ports to collect all the leftovers from killing fish (except for fish galls containing highly toxic cyanide), and the remaining fish bones after eating fish. pay. Anyone who litters without permission will be fined...
These collected fish scales, fish viscera, fish bones and other fish scraps, Marin intends to organize people, dry them, and then smash them into natural green fertilizers similar to plant ash. Or, throw it directly into the cesspit, and ferment the manure together with the manure and plant ash.
Although, the phosphorus content of this kind of fish killing waste is far less than that of phosphorus fertilizer. However, it can also provide a plant ash-like effect.
Moreover, because of Marin's strong support, there are now more than 20 large fishing boats with a displacement of 100 tons in the two fishing ports of Thorenche and Odesshild. Every day, the two fishing ports handle dozens of tons of fish scraps alone.
The phosphorus content of these leftovers is about 1%. Although it can't keep up with the special phosphate fertilizer, it can still be used as a phosphate fertilizer if the amount is large.
Manure (nitrogen fertilizer), potassium fertilizer (potassium salt) and phosphate fertilizer (fish-killing leftovers) are fully applied. Not to mention reaching the level of a thousand catties per mu in later generations, at least it is about the same as the yield per mu of the upper-class paddy fields in the south of the Yangtze River in the Ming Dynasty. Six hundred catties per mu...
In other words, Marin intends to use the leftovers of fish killing that were discarded as garbage by fishermen as the most primitive and natural phosphate fertilizer...