Crab pond water plants can not only increase dissolved oxygen, shade and cool down, provide bait, but also transform substances, purify water quality, and provide a suitable ecological environment for the growth of river crabs. Water plants are an indispensable factor to maintain the ecological balance of crab ponds. There are also specific requirements for aquatic plants. The main species of aquatic plants in Yixing Crab Pond are Elephant algae, Yellowgrass and Verticillium vulgaris. Based on the practice and exploration in recent years, the author introduces the problems and solutions encountered in the management of aquatic plants in crab ponds as follows, for your reference.

1. The crab pond water plants grow poorly

1.1 Main reasons. 1. The crab pond is deficient in fertilizer or the water quality is too fertile. The lack of fertilizer in crab ponds generally occurs in the early stage of crab breeding, the water temperature is low, and a large number of snails are placed in the crab pond, and the water quality is thin, especially for newly opened crab ponds and dredged crab ponds, where the mellow soil layer is shallow, the organic matter is low, and the aquatic plants It is difficult to take root and grow; the water quality is too fertile, which reduces the transparency of the pool water, affects the photosynthesis of aquatic plants, and makes it difficult for aquatic plants to grow. 2. Overweight or improper use of medicines in Qingtang. Crab ponds are generally cleaned with quicklime. Due to the excessive dosage, the medicinal properties have not completely disappeared; in addition, the continuous use of copper sulfate in large quantities has caused damage to aquatic plants. 3. There are attachments on the stems and leaves of aquatic plants. Due to poor water quality, the stems and leaves of aquatic plants will adhere to a large amount of pollutants. Microscopic examination found that the attachments of aquatic plants are various algae, ciliates and organic matter, which directly affect the photosynthesis of aquatic plants, causing aquatic plants to shrink or even die.

1.2 Workaround. 1. For newly opened crab ponds and dredged crab ponds, shallow plough for 10-15 cm should be carried out on the bottom of the crab ponds. After 10-15 days of exposure to the sun and freezing, a mellow soil layer is formed, and then fermented organic fertilizer 100 -150 kg/mu, and then plant grass in water. For crab ponds with thin water quality, 50-100 kg/mu of fermented organic fertilizer can be applied. The organic fertilizer is divided into several piles and evenly distributed in the shallow water area around the crab pond. It is frequently turned to allow the fertilizer water to slowly spread to the entire pond; It can be directly applied with 5-8 kg/mu of urea, or 5-10 kg/mu of compound fertilizer can be applied evenly after the water is dissolved to increase the fertility of the pool water and promote the growth of aquatic plants. For crab ponds with excessive water quality, on the one hand, it can be solved by changing the water or increasing the amount of live snails, or using water quality modifiers (zeolite powder, sodium thiosulfate, compound bottom modification, etc.) Use microbial bacteria to completely improve water quality, increase the transparency of pool water, and promote photosynthesis of aquatic plants. 2. The ponds of quicklime clearing ponds should be planted with aquatic plants after the medicinal properties disappear, and the ponds that use a lot of copper sulfate should change the water in time to reduce the concentration of copper ions in the pond water and reduce the toxicity to aquatic plants. 3. There are a lot of algae and organic matter in the stems and leaves of the aquatic plants, which can be activated by 1 kg/mu of EM bacteria. After the rice is activated, add water and sprinkle it on the aquatic plants, and the effect is better. Zinc + 0.2 mg/L copper sulfate + 0.1-0.2 mg/L strong chloroquine was sprinkled in the whole pool. After 3 days, the compound bacteria dominated by photosynthetic bacteria were sprinkled, which had a very good effect.

2. Overgrown growth of aquatic plants in crab ponds

2.1 Main reasons. In the crab ponds dominated by elegans, due to the original pond or too much elegans planted, the pond environment is good and the growth is vigorous. From May to June, some aquatic plants have emerged on the water surface, and the coverage rate of aquatic plants exceeds 70%.

2.2 Solutions. For crab ponds with excessive growth of elegans, the head of elegans should be cut off 30 cm with a drag knife in stages and blocks. Each time a piece is cut, accounting for about 20% of the total area of ​​the crab pond, and the cut off is timely. Fishing out the water plants, the area of ​​the water plants cut each time should not be too large, and the interval between each mowing should not be too long or too short, and the interval should be controlled within 5 days, so that the crab pond environment can be maintained during the mowing period. Stable, to ensure that water plants and river crabs can grow normally during the breeding period. (Han Yongliang, Agricultural Service Center, Yangxiang Town, Yixing City)