Siheyuan, integrating everything, cultivating the city

He collected a lot of data and finally told Li Xiangqian: "This pest is really special. It carries a rare pathogen that is extremely harmful to plants."

"Then what should we do?" Li Xiangqian asked anxiously.

However, despite all the work, Li Xiangqian still had many doubts in his heart. Although it seemed that the problems in the fields had been alleviated, he knew that the real challenge was far from over. He decided to check the water flow, which was originally part of the courtyard, nourished by streams and canals, and full of greenery. However, the water flow in the water flow seemed to be a little abnormal recently, which made Li Xiangqian suspicious.

Li Xiangqian walked on the path, the gravel under his feet making a slight sound under his steps. The gurgling water in the stream was originally a peaceful scene, but at this moment it became a hidden worry in his heart. He glanced at the vegetation by the water from time to time, trying to find any abnormal signs. The grass by the water became greener because of the change of seasons, but Li Xiangqian felt that the green seemed to hide some kind of uneasy omen.

"The water flow at the stream seems to be wrong." Li Xiangqian thought silently in his heart, "Maybe this is the root of the problem."

He squatted down and reached out to touch the mud by the water, feeling the faint wetness coming from the mud. However, this wetness was not as natural as before, and it had a strange fishy smell. He put his finger in front of his nose and took a deep breath. The fishy smell shocked him, making him even more worried about the situation at the water flow.

"Could there be something wrong with the water source?" he said to himself. "No, I have to find someone to check the water source."

Li Xiangqian walked to the source of the water flow, where there was a small well, which was used to supply water to the courtyard. He squatted down and carefully observed the inside of the well. The water surface at the well mouth reflected a layer of light green, which made him feel uneasy.

"What are these green things?" Li Xiangqian was full of doubts. "Could it be that the plants in the water have been contaminated?"

He picked up a wooden stick from the well, carefully put it into the well, and stirred the water. Green substances kept floating in the water, emitting a strange smell. He scooped up the green substances on the stick, put them on a clean cloth, and carefully observed the composition of these substances. They showed a sticky texture and felt uncomfortable to the touch.

"These are definitely not normal plants." Li Xiangqian's uneasiness grew. "These things may be the breeding grounds for pests and pathogens."

He decided to contact Professor Zhang and ask for professional help. The moment he dialed the phone, his heart beat faster, expecting to get expert guidance. The ringing of the phone was particularly clear in the silent field, and finally Professor Zhang's voice came from the other end of the phone.

"Li Xiangqian, what's wrong?" Professor Zhang's voice was a little tired, but still full of concern.

"Professor Zhang, I found something unusual in the water flow. It may be the source of pollution." Li Xiangqian reported briefly, "I think these green substances may be the key to the problem."

"Okay, I'll be right there." Professor Zhang's tone became serious. "The situation at the water flow is indeed worthy of attention. We need to conduct a thorough inspection of the water source."

Soon after, Professor Zhang came to the water flow. He brought professional tools and testing equipment to carefully check the well and the water flow. Li Xiangqian stood aside, full of expectation and nervousness, hoping to find the root cause of the problem as soon as possible.

After Professor Zhang finished the examination, he said solemnly: "This green substance is some kind of algae. It may have multiplied in large numbers due to water pollution. This algae will not only pollute the water source, but also affect the ecosystem in the water."

"Then what should we do?" Li Xiangqian asked anxiously.

"First, we need to thoroughly clean the water source to remove all pollutants," said Professor Zhang. "Then, we need to use some specific chemicals to inhibit the growth of algae. At the same time, we need to monitor the water quality regularly to ensure there are no other potential problems."

"I understand." Li Xiangqian nodded, "I'll take action right away."

He began to clean up according to Professor Zhang's instructions. The whole process was tedious and time-consuming, but Li Xiangqian did not slack off. He knew that only by thoroughly solving the problem of the water source could the spread of pests be effectively prevented. He cleaned the sludge in the well and used special chemicals to treat the water source. In the process, his sweat kept dripping, but he felt an unprecedented determination.

As time went by, Li Xiangqian kept an eye on the changes in the fields while dealing with the water pollution. After a period of observation, he found that the plants in the fields gradually returned to a healthy state, and the number of pests also decreased significantly. Although this does not mean that the problem has been completely solved, at least he sees a glimmer of hope.

However, despite the gradual improvement of the external environment, Li Xiangqian's worries have not diminished. He knows that the emergence of pests and water pollution are only part of the problem. The real challenge lies in how to ensure that the ecological balance of the entire courtyard is not destroyed. Whenever night falls, he often sits in the yard, looking up at the stars, thinking about future plans.

"I have learned a lot from this experience," Li Xiangqian said silently in his heart, "No matter what difficulties we encounter, as long as we work hard to solve them, we will definitely find a way out."

He continued to work hard, taking good care of his fields and staying in touch with experts to ensure that any new problems could be addressed promptly. In the process, he gradually learned how to stay calm under pressure and how to find solutions in difficult situations.

One evening, while working in the fields, Li Xiangqian discovered a new sign of disease. Some strange spots appeared on a green spinach leaf, as if covered by some black powder. Li Xiangqian felt nervous again, and he knew that this might mean that a new problem was quietly happening.

"What is this?" he thought to himself. "Are we going to face more challenges?"

He decided to take immediate action, conduct a detailed inspection of the spinach leaves, and prepare to send samples to Professor Zhang. Although he was full of uneasiness, Li Xiangqian still maintained a firm belief that as long as he kept working hard, he would be able to find a solution to the problem.

Li Xiangqian stood in the field, his eyes cast solemnly on the originally lush potato seedlings.