As a kind of crop with high and stable yield, sweet potato has the characteristics of wide adaptability, strong stress resistance, drought tolerance and barrenness, less pests and diseases, etc., planted in places with better water and fertilizer conditions, and the general yield per mu can reach 2000-3000 kg of spring potatoes.

Zhang Nan, as a person who has never been hungry, naturally does not understand the ancients' dedication to food, although Zhang Nan was a poor dick before the crossing, but after living so big, he really didn't starve Zhang Nan.

But the ancients were different, for them, food represented life and survival. The ancients compared food to "heaven" and believed that food was "the life of the people".

As early as the Spring and Autumn Period, the ancients had begun to realize the importance of accumulating grain.

At the beginning of "Guanzi Herdsman", it is said: "Whoever has landed herdsmen should stay in the warehouse at four o'clock." If the country has more wealth, those who are far away will come, and if the land is opened, the people will stay. Cangqiao actually knows etiquette, and if you have enough food and clothing, you know honor and disgrace. ”

And Guan Zhong also has a point of view, "Su is the ability of the king, and the great business of the master." The way of man is the way of governing the country". He stressed that grain production is an important task of the state and that grain is of great significance to the governance of the country and the country.

Therefore, the importance of food, whether for the people or for Li Er as a ruler, is self-evident.

"Qingquan, have you really seen this thing that yields thirty stones per mu?" Li Er asked tremblingly.

"I've seen it, and it's delicious, but I'll get tired of eating too much." Zhang Nan said.

"Tired." The corners of Li Er's mouth twitched, originally Li Er wanted to let Zhang Nan be hungry for a few days, so that he could see if he would get tired of it, but then gave up this idea.

"So, where did you eat this grain? It will definitely not be the territory of my Tang Dynasty, let's say, which country has such a divine object, I want to send troops to take it. With a wave of his hand, Li Er decided that as long as whoever was holding this magical food, Li Er would chop off his hand.

Zhang Nan was asked at once, and he didn't know where sweet potatoes came from to China, so Zhang Nan immediately checked them in the system, and finally learned that sweet potatoes were introduced by Western missionaries in the last years of the Ming Dynasty, and from Luzon Island in the Philippines to the Jiangnan area, and then gradually spread to all parts of the country.

Zhang Nan, who got the answer, said to Li Er: "Your Majesty, do you have a map, I'll point it to you." ”

After Li Er heard this, he hurriedly ordered someone to get the map, Zhang Nan looked at this poorly marked map, and he had no desire to look at it.

"Your Majesty, are you sure this thing can be called a map?" Zhang Nan asked speechlessly.

"Why isn't this a map, I can hear it clearly when I look at my map." Li Erdao.

Zhang Nan looked at Li Er's map, which was not much more detailed than a child's diaper, and began to admire the generals of the Tang Dynasty, it is really embarrassing for you to be able to use such a map and win battles.

"Forget it, the minister will give the emperor a real map today." After speaking, Zhang Nan swapped out a map of the territory of the Tang Dynasty from the system. However, this map has been intimately marked by the system to the territory of the Eastern Turks.

Li Er was also very happy with this map with fine labels and clear territorial divisions, after all, this map looked much more intuitive than the globe given by Zhang Nan, and even the small islands in the waters around Datang were clearly marked.

Not only was Li Er comfortable looking at such a detailed map, but Li Er's generals also stretched their necks one by one to look at Zhang Nan's map, and Cheng Yanjin almost put his eyes on the map to see.

Li Er also noticed the funny appearance of the generals, coughed twice and said: "Okay, don't worry, Aiqing, I will send someone to draw a new map at that time, and give one to you who lead troops to fight, okay." ”

"Thank you, Your Majesty." As soon as the generals heard that everyone had a share, they immediately thanked Li Er.

"Alright, Qingquan, quickly mark this place with such a treasure for me." Li Er asked impatiently.

Zhang Nan looked at the map and pointed out the territory of the Philippines to Li Er, but Zhang Nan didn't know if the current Philippines was a country, or if they were all monkeys in the trees.

"Is there such a treasure in such a small place?" Li Er obviously didn't believe that there could be such a treasure in the Philippines, a place where birds don't seem to.

According to Li Er's understanding, such a treasure should be in the hands of a powerful country like the Tang Dynasty, and then he will send troops to fight against that country directly, so as to conform to the identity of the treasure. But Zhang Nan pointed out such a big point to himself, which made Li Er really incomprehensible.

"Your Majesty, don't underestimate such a place, this place really grows sweet potatoes." Zhang Nan nodded and said.

"It turns out that such a treasure is called sweet potato." Li Er nodded, acknowledging the name of sweet potato.

In fact, sweet potato seedlings can also be exchanged in the system, but like this kind of food that can change the pattern of Datang, the price of the system will be very expensive, so Zhang Nan also dispelled the idea of exchanging it from the system.

"Prepare now, send someone to find sweet potatoes overseas." Li Er gave the order.

At this time, Niu Jinda stood up and said: "Your Majesty, the old minister is willing to go overseas and bring this sweet potato back for the emperor." ”

"Okay, Jinda is really my good general. In that case, immediately go and prepare the fleet, and when you arrive, you will bring back sweet potatoes for me. Li Er said with a smile that Datang lacks everything, but there is no shortage of people who are loyal to the country.

As soon as Zhang Nan heard this, he hurried out to stop him in order to go to the Philippines with so much effort: "Your Majesty, don't worry, just this sweet potato is not worth our trip." ”

"Oh? Listen to what you mean, Qingquan, there are still good things overseas? Li Er asked with interest.

"That's not it, for example, corn, which is also food that yields more than ten stone per mu, and potatoes, which can easily reach thirty stone, and these two things are very good to plant, no matter how bad the land is, there is no need to be afraid of wasting arable land. There are also tomatoes, peanuts, sunflowers, pineapples, jicama, cassava, pumpkin peppers, beans, lima beans, apples, custards, guavas, avocados, cashews, cocoa, American ginseng, papaya, upland cotton and other plants that can be eaten, can weave, and can extract oil. Zhang Nan said with a smile.

After Li Er heard this, he almost threw the map on Zhang Nan's face and asked Zhang Nan to mark these things for himself.

"Then what are you waiting for, hurry up and mark the location of these things for me, and I will send someone to fetch them." Li Er couldn't wait to say.

"Your Majesty, to be honest, except for sweet potatoes, the rest of the places are really difficult for us to go to in Datang." Zhang Nan said with a smile.