In fact, because it is too far north, the agricultural conditions in St. Petersburg were very poor. In later generations, the agriculture in Leningrad Prefecture was mainly based on aquaculture, producing dairy products, meat, eggs, etc. As for the planting industry, it mainly planted potatoes and vegetables.

Among them, vegetables are definitely mainly greenhouse vegetables. Although potatoes are very suitable for cold temperate areas, Marin definitely doesn't want to take out this nuclear weapon.

What happens when potatoes are available? The Irish people have potatoes, from 1.9 million in 1700 to 8 million before the Great Famine in 1845!

In the 18th century, Prussia was also poor, and it was also relied on Frederick the Great to promote potatoes, which made Prussia, as poor as a ghost, survive wars. Later, this trick was widely learned by Europeans, and Tsarist Russia also used this trick, and the population continued to grow until it exceeded 100 million. Therefore, during World War I, Tsarist Russia mobilized 15 million troops.

For this reason, Marin was not willing to introduce potatoes to Europe anyway. But the St. Petersburg area is really not suitable for growing grains. Rye and oats can grow there normally. However, it is currently at the forefront of the Little Ice Age. St. Petersburg has such a high latitude that it is almost close to the Arctic Circle, which is really not suitable for growing grains.

But it is impossible to completely transform Liangzan into a livestock country, right? Liangzan’s Grand Duke is happy, but Liangzan’s farmers are not happy. After all, it is difficult to adapt to the lives of livestock farmers when they are used to eating grains.

"What should they plant?"

Marin spread out the map and looked at the location of St. Petersburg carefully. This guy, the latitude of St. Petersburg is as high as 60 degrees north latitude, which is much northerly than the 53 degrees and 27 minutes in Mohe.

In addition, St. Petersburg has another disadvantage - because due to the influence of the North Atlantic warm current, it is certainly warmer than Moscow in winter (but this is useless because it is all sub-zero and has no use for agriculture), but it is also cooler than Moscow in summer. Moscow can even have high temperatures of more than 30 degrees in summer, while St. Petersburg has a maximum temperature of less than 30 degrees in summer due to the influence of the ocean.

If we look at human comfort, the summer in St. Petersburg is definitely very comfortable. However, from an agricultural perspective, this is not good. Because crops like wheat require higher temperatures during the grouting and fruiting period. Because the latitude is low, winter wheat in St. Petersburg also needs to freeze to death in winter, and spring plowing will not be frozen in May. However, because the temperature has been low, when the summer is approaching 30 degrees, the wheat has not yet grown, and it is not time to bear fruit. When the grouting is fruiting, well, it has entered the low temperature period again, and it will soon snow... Therefore, it is not suitable for growing wheat here.

Moreover, there are no wheat varieties that are fast-ripening in this era, and wheat is generally late-ripening. In addition, there are no fertilizers that promote early-ripening such as phosphorus fertilizer and potassium fertilizer, so they cannot grow at all.

Rye is also the problem, and it is difficult to spend the winter at such a high latitude. Although rye is cold-resistant, it is resistant to the small cold in northern Germany, rather than the super cold winter in St. Petersburg. Moreover, the total accumulated temperature of rye is quite high, reaching more than 2100 degrees. After all, only oats with a relatively short growth cycle and a small accumulated temperature (1350-1600 degrees) are suitable.

However, oat yield per mu is low. Even in later generations, new varieties and expenses were used, the yield per mu was only 200 kilograms, which is 400 kilograms. The varieties of this era used in Beihai China, even if nitrogen, phosphorus and potassium are complete, the yield per mu will not exceed 300 pounds, and generally more than 200 pounds. Unlike rye, fertilizer can exceed 500 pounds.

If you don’t use fertilizer, you will be even worse. The yield per mu is only about 100 pounds (fertile land like black soil), or even less than 100 pounds. And even if you don’t use fertilizer, as long as the land itself is fertile, it can produce more than 100 pounds per mu.

Of course, the St. Petersburg area is not the black soil of Ukraine, it is not natural fertile soil, and the agricultural conditions are not very good. If the Ryazans were asked to plant oats without providing fertilizer, it would be difficult to exceed a 100-pound per mu yield.

And Marin could not provide fertilizer for Ryazan, because there is still some supply in the Beihai area, so how can Ryazan be supplied?

However, Malin thought of a good idea for them - the Erpu system! Of course, it is an improved Erpu system!

Europe had a system of two-bedrooms that took turns to fallow, but it was not too scientific. The ancient Europeans' two-bedrooms were just to let the land be cultivated one year and abandoned one year. When abandoning the land, weeds were left to grow and ignored.

This can certainly use the weed corpses to restore some ground strength, but it is very limited. Why? Because weeds are not fertile enough!

If you want to restore the fertility, the best way to restore the soil without fertilizer is actually to plant legume crops. Legume crops can absorb nitrogen in the air and convert them into organic nitrogen (that is, nitrogen fertilizer). This function is called nitrogen fixation.

If the land was abandoned, it would be difficult to restore the ground force without fertilization or the ground force was limited. However, if the legume crops grew, the ground force would recover faster. If the grains were planted in the second year, the harvest would be much better.

In addition, in the 18th and 19th centuries, the British developed a very powerful secondary garden system - planting alfalfa on fallow land, and then grazing sheep...

Alfalfa is a legume crop, which has a nitrogen fixing effect and can fertilize the land. After the sheep eat alfalfa, they pull down sheep manure and eggs on this land, which is also fertilizer. Under the dual action, the ground force recovers very quickly.

Of course, the British at that time did not understand this principle, but they just found that the effect was good. After all, the British were traditionally engaged in raising sheep. And the good effect of raising sheep in alfalfa was unintentional.

Because of the fallow planting of alfalfa and raising sheep, the British's wheat yield per mu could exceed 200 pounds, reaching about 230 to 40 pounds. This effect is basically the same as the effect of using manure in ancient China.

This chapter is not finished yet, please click on the next page to continue reading the exciting content later! But only nitrogen fertilizer is useless. Nitrogen fertilizer can only ensure that the plant grows vigorously, but its impact on the results is not as good as phosphorus fertilizer.

Phosphorus fertilizer has the effect of urinating premature ripening on grains, which can shorten the growth period, and increase the fruiting rate and promote fullness of grains. This is the largest fertilizer variety for the increase in grain yield.

Of course, if the nitrogen fertilizer is sufficient and the plant grows well, it will have a significant impact on the grain yield. So, the yield per mu is only about 100 kilograms or even less than that. If the manure is used, it can reach more than 200, which is doubled.

Of course, this is for ordinary wheat, and the upper limit of rye and wheat is quite high. The upper limit of oats is low, and the yield per mu of varieties in later generations was only 200 kilograms. In this era, even if the advanced second-bed system of the British in later generations was used, the yield per mu was estimated to increase from dozens of pounds to more than one hundred pounds.

However, it is enough for people of this era. Moreover, there is no shortage of land in the St. Petersburg area. The yield per mu is not enough, so the land area can be collected.

Moreover, this "English two-bed system" of growing alfalfa and sheep can also allow the Ryazan people to produce a large amount of wool and mutton while producing a large amount of oats, which can be said to be a killing of multiple goals.

Of course, because it is a cold area, it must be a cold-resistant and coarse-resistant sheep. The fine-wool sheep may be difficult to withstand the cold. But this is not a problem. After all, Marin is not Lei Feng, not to help Ryazan be powerful. He just hopes that Ryazan will become an obstacle to the expansion of the Grand Principal of Moscow after moving to the St. Petersburg area. Even Marin hopes that Ryazan will occupy the coast of the Arctic Ocean, causing the Grand Principal of Moscow to lose the sea outlet of the Arctic Ocean.

The "English Two-Peacher System" of the Ryazans of the Marin Church is worthy of them. After all, this new Two-Peacher System can not only increase the production of oats, but also obtain a lot of wool, mutton, and sheepskin products, which is definitely profitable.

According to the news of his cousin Peter, the St. Petersburg area is currently sparsely populated and belongs to the border area. In the past, the Ryazan people had some land that could be reclaimed. You should know that the Ryazan Grand Duchy of Ryazan was once very large, but after being annexed by the Moscow Grand Duchy, only the area of ​​Ryazan Prefecture in later generations was left, not even 40,000 square kilometers. When we came to the St. Petersburg area, there were at least 70,000 to 80,000 square kilometers, which was enough for them to use.

In addition, it occupied the St. Petersburg region and could also annex the Karelian Republic region to the north. Although this land is not suitable for agriculture, it is fine to use it for animal husbandry. Even if sheep cannot be raised, can we still raise reindeer?

As for the Murmansk region further north, it seems that Marin had already let the Rap people occupy it. I almost forgot that Marin was still the chief of the Rap people. Marin suddenly felt that it was time to send people to manage the Rap people along the Arctic Ocean...

...

In fact, Marin also knows a kind of grain that is very suitable for the St. Petersburg region, that is, the main grain on the Qinghai-Tibet Plateau - barley. Barley requires lower temperatures, and the accumulated temperature is only 1,300 degrees, which is lower than oats. Moreover, it can also blossom and bear fruit at low temperatures, and the growth period is only 100 to 130 days, which is very suitable for the St. Petersburg region. Moreover, the yield per mu is much higher than that of oats.

But Marin was unwilling to do this for the Liangzan people because it was a killer weapon like potatoes. If the Moscow people also got barley seeds and planted them on their vast land, it would be no problem to rise rapidly.
Chapter completed!