If proper fertilizers are applied during the August expansion period of Astragalus membranaceus, the yield can exceed 4,000 kilograms per mu.

In the first half of July, remember to remove the flower buds in batches. One week before removing the buds, apply 5 to 7.5 kilograms of urea per acre. After removing the buds, apply another 17.5 to 22.5 kilograms of urea and spray a layer of photosynthetic nutrient film fertilizer. The nutrient absorption speed will be directly doubled. 
Once the flowering period is over, astragalus will completely shift to its underground growth stage. At this point, potassium fertilizer becomes the most effective, specifically responsible for making the roots and stems grow thick and strong. 
During the August growth expansion period, instead of using the old-fashioned single fertilizer, we should directly switch to the special growth-expanding fertilizer for astragalus, which contains active factors, moderate elements, and organic active substances. 
This kind of fertilizer can directly act on the root and stem cells, stimulating them to divide and elongate. It also enables the products of photosynthesis in the leaves to all go downwards, without wasting any nutrients at all. 
The usage is also very simple: Mix 500 grams of the special fertilizer with 500 kilograms of water. Spray it on the leaves and it can cover 5 acres of land. Spray it three times in a row, with an interval of 7 days each time. After that, you will see the roots and stems growing thicker and thicker, and the size of the plants will be particularly uniform. 
From the end of August to the beginning of September, continue to closely monitor the seedling condition and add about 5 kilograms of urea. Combine it with spraying phosphoric acid potassium and plant electronic fertilizer. Spray once every 15 days. 
If you notice weak seedlings that have turned yellow in the field, simply spray 0.2% diammonium phosphate on the leaves. The effect of saving the seedlings will be immediate. 
Don't underestimate trace elements. This is actually a key factor for increasing production that many people are unaware of. 
In most of the areas where astragalus is grown in our country, zinc deficiency is a problem. Sprinkling 1 kilogram of 98% zinc sulfate on each mu (about 5,567 square meters) of land during the seedling stage can increase the yield by at least 19%, and in some cases up to 27.7%. The grade of first-class products can be directly increased by 24.9%, and the weight of each root stem can increase by up to 14.7%. No matter how you calculate it, this is a profitable investment. 
When fertilizing, remember to apply the fertilizer in a concentrated manner, in small amounts and multiple times. Do not pour concentrated or hot fertilizers directly on the roots. When turning the soil, dig 10 centimeters deep and 10 centimeters wide small trenches to apply the fertilizer, keeping a moderate distance from the roots. This way, the roots will not be burned and the nutrients can be fully absorbed. 
Water management should not be overlooked either: During the period when tubers are growing and expanding in August, water is needed. In case of drought, water should be applied promptly. But after rain, if the soil becomes waterlogged, it must be drained within half an hour. If left to stand for too long, significant losses may occur. 
One last reminder: Do not apply any fertilizer to the fields for the first 50 days before harvest. Otherwise, the quality of the medicinal herbs will not meet the standards, and they will not fetch high prices. All the previous efforts will be in vain.