How to manage summer-sown soybeans by classification? These key points must be mastered

Because the time for rush harvesting and rush sowing of summer-sown soybeans is very tight, some farmers applied base fertilizer before sowing, while others went to the field with bare seeds because they had no time to apply base fertilizer. According to surveys, at present, some soybeans have entered the branching stage, the earliest sown ones have entered the flowering stage, some soybeans are growing rather vigorously and the field has already become closed and shaded, while some are growing weakly, with yellow leaves and thin seedlings, and symptoms of fertilizer deficiency and nutrient deficiency have already appeared. In the face of summer-sown soybeans with different growth conditions, management should be differentiated according to the situation and carried out by classification.

1. Do the accounting and comparison. Although the growth period of summer soybeans is relatively short, the yield is generally 100-150 kg per mu. If management is strengthened, the yield per mu can exceed 150 kg; if management is abandoned, the yield per mu will hardly exceed 100 kg. The yield difference is at least more than 50 kg, and the income difference per mu is 150-200 yuan, while the average fertilizer input per mu is less than 50 yuan. Therefore, strengthening management is very necessary.

2. Quickly topdress fertilizer for soybeans with fertilizer deficiency. Although soybeans have rhizobia that can fix part of the nitrogen in the air, the amount is limited, so fertilizers should be quickly supplemented for weakly growing soybeans. First, during the flowering and podding stage, combined with intertillage and weeding, apply 5-7.5 kg of urea per mu, because this is the period when fertilizer demand is greatest and fertilizer supply is most vigorous; second, for those not treated with ammonium molybdate seed dressing, use 10 g of ammonium molybdate per mu and spray it with 40 kg of clean water; third, spray 1%-2% superphosphate or 0.3%-0.5% potassium dihydrogen phosphate solution 1-2 times each; fourth, for those with boron deficiency symptoms, spray 0.1%-0.2% Sule boron; fifth, use active liquid fertilizers such as Huimanfeng or Zhuangfuxing, 100 mL per mu, and spray with 50 kg of clean water.

3. Immediately carry out chemical control for vigorously growing summer soybeans. First, at the early flowering stage, spray 50 kg of 0.5 mg/L triacontanol solution, which can shorten the distance between the upper internodes and leaf petioles of soybean plants, reduce leaf area, enhance light transmission, shorten the nutrient transport distance, and help nutrients transform into pods. Second, at the early flowering stage, spray triiodobenzoic acid, which can promote branching, dwarf the plant type, increase the podding rate, and help early maturity and increased yield. Use 5 g of triiodobenzoic acid per mu, dissolve it in an appropriate amount of alcohol, and after it turns yellow, add 50 kg of water and spray; or at the early flowering stage, spray 50 kg of a diluted paclobutrazol solution at a concentration of 200-250 g/L, which helps soybeans grow steadily, increase chlorophyll content, and accumulate dry matter. Third, from full flowering to the early podding stage, use 5 g of sodium bisulfite per mu, add 50 kg of water, and spray, which can inhibit photorespiration and promote steady growth of soybeans.

Yu Hongzhang