In the archives of Qing Dynasty in the Archives of Xinjiang Uygur Autonomous Region, there is an essay written by Zuo Yu to Turpan Hall on March 25th, 4th year of Guangxu (1878), which requires all localities to "publish and brush ten essentials of cotton planting and agricultural books", "persuade people", "eradicate poppies" and "urgently plant cotton". It fully reflects his great attention to eradicating poppies and planting cotton in Gansu and Xinjiang provinces.
Turpan in April is already very warm, which is very suitable for sowing cottonseed. Zuo's article and Ten Essentials of Cotton Planting published with it are very timely, which shows that Zuo knows a lot about agricultural production. Although he lives in Lanzhou and Suzhou, thousands of miles away, he knows the mountains, rivers, geography and climate conditions in Xinjiang like the back of his hand, and he can distribute the ten essentials of cotton planting to Turpan Hall without missing the farming season.
Zuo hates poppy and thinks it is a "beige book", while he thinks cotton is a "good flower" and planting cotton is a good thing for people's livelihood. Therefore, he is "impolite" to those local officials who neglect their duties and production.
Turpan Hall distributed the ten essentials of cotton planting in time, saying that we should "follow various methods and sow in time". From this, we can also see the reverence of lower-level officials for Left. This move was criticized by later generations as "endless benefits."
There are 80,000 troops left to recover Xinjiang. It is difficult to supply food for so many troops only by relying on sparsely populated and backward provinces in the northwest. The main solution can only be to cultivate land on the spot. Xinjiang has a history of reclamation since the Han Dynasty. Due to years of war, reclamation has been intermittent. Zuo's reclamation in Xinjiang not only solved the problem of military grain, but also promoted the development of agriculture, especially grain industry in Xinjiang.
Left also pays attention to repairing rivers and roads in the arid areas of northwest China, and "widely planting elms" along the river and along the road. Later generations praised: "thousands of miles away, green as a curtain." Although it is a bit excessive, it can also be seen that the results are not ordinary. When Yang Changrui, the governor of Zhejiang Province, came to Xinjiang, he wrote a poem "Ode to Zuo Gong's Westbound Journey to Gan Tang", in which there are two sentences: "The newly planted willow is 3,000 Li, which led to Yumen Pass", and he strongly praised Zuo for pushing "widely planted elm" to Xinjiang.
The recovery of Xinjiang made Zuo Tang Zong go down in history; Pay attention to people's livelihood and let Zuo Tang Zong live forever in the hearts of people of all ethnic groups in Xinjiang.