Main measures of field management after alfalfa cutting

Since late June, alfalfa cutting has come to an end in various parts of our city, and strengthening field management after cutting is the key to strive for the next high yield. Agricultural departments at all levels and agrotechnical personnel should take measures to organize and do a good job in field management after alfalfa mowing. The main measures are as follows:

Watering: cut for 3-5 days and irrigate immediately after the stubble healed. The root system of alfalfa is well developed, and the depth of the main root is 3-6 meters, which can absorb deep soil moisture, but watering is an important measure to ensure high and stable yield of alfalfa. It is generally estimated that the water consumption of alfalfa is 800-900 jin per jin of dry matter, so irrigation can greatly increase the yield in the severe drought season and after each mowing. Alfalfa grows fast, the yield is high and the water demand is high after branching. It is necessary to keep the soil moist. In arid areas, irrigation can be carried out under certain conditions, including furrow irrigation and sprinkler irrigation. Watering and replenishing moisture in case of drought after each harvest can increase the annual yield of grass by more than 30%. The water consumption of alfalfa in the first year after sowing is generally 200m 3, which is 50% of the water consumption of grain crops in this area. After that, with the root elongation of alfalfa, the ability of absorbing deep soil water increased, and the water consumption decreased year by year. The survey shows that the water consumption in the second year is 70% of that in the first year, and that in the third year is 50% of that in the first year.

Topdressing: due to the high biological yield and high nutrient consumption of alfalfa, topdressing should be carried out after each harvest, and the main varieties are phosphorus and potassium fertilizer or compound fertilizer, generally applying available phosphorus 6kg, available potassium 7kg and some micro-fertilizers per mu. After cutting, sprinkle it on the surface or apply it in a trench, then water it. Alfalfa has root nodules and can provide nitrogen nutrition for roots, but in areas where the nitrogen content of barren wasteland soil is too low, 10 kg urea is applied after rain, and after seedling or turning green, a large amount of phosphate and potassium fertilizer is needed. In addition to applying 50-60 jin calcium superphosphate per mu as base fertilizer before sowing, the application rate of potassium fertilizer is about 20 jin per mu to ensure the normal growth of alfalfa. A large number of rhizobia in alfalfa roots can fix nitrogen effectively, but nitrogen is needed before nodules are formed at seedling stage. After the seedlings grow up, in order to improve the quality and yield, appropriate amount of topdressing is still needed, especially a large amount of potassium fertilizer is needed to promote nitrogen fixation and absorption. The experiment of topdressing alfalfa for two years showed that there was no obvious increase in grass yield after topdressing nitrogen fertilizer. When the ratio of nitrogen, phosphorus and potassium was applied at 1:2:2, the hay yield could be increased by more than 30%. It shows that the developed root system of alfalfa has formed a large number of root nodules, and topdressing should be dominated by phosphorus and potassium fertilizer. Applying alfalfa compound fertilizer with a dosage of 30-40 kg per mu can be applied at one time when turning green. It can also be applied twice, once in the green period, and again after the third stubble grass is cut, with half of the dosage.

Chemical control: monitor the number and occurrence trend of aphids in the second crop of alfalfa, and carry out chemical control in about 15 days after the emergence of the second crop of alfalfa. 1500 times of imidacloprid wettable powder or 1500 times of cypermethrin + acetamiprid EC or BtA1000 times of biological pesticide can be selected for spray control.