Detailed Explanation of Scientific Cultivation and Management Techniques for Sudan Grass

Sudan grass (Sorghum sudanense (Piper) Stapf.) is an annual herbaceous plant of the genus Sorghum in the grass family (Poaceae). It has fibrous roots, and its root system is well developed, penetrating deep into the soil to a depth of up to 2.5 m. The stem is erect and cylindrical, 2-3 m tall and 0.8-2.0 cm thick. It has strong tillering ability and many lateral branches, generally 15-25 per plant, and up to 40-100. It has 7-8 leaves, broadly linear, 60 cm long and 4 cm wide, dark green and smooth on the surface; the leaf sheath is slightly long, completely enclosing the stem, with no auricles. The panicle is relatively loose, with slender branches, and each node bears two spikelets, one sessile, which is a bisexual flower and can set seed; the other stalked, which is a male flower and does not set seed. The fertile spikelet has thick, glossy glumes. The caryopsis is flatly ovate, and the grain is entirely enclosed by the lemma and palea. The seed color varies by variety, including yellow, purple, and black, with a 1000-grain weight of 10-15 g. It is widely distributed in temperate and subtropical zones. In China, it can be cultivated from Hainan Island in the south to Inner Mongolia in the north.

Sudan grass's requirements for the growing environment

It prefers warmth and moisture, has strong drought tolerance, and is not tolerant of cold or waterlogging. The minimum temperature for seed germination is 8-12°C, and the optimum temperature is 20-30°C. Sudan grass can grow in areas with hot summers and moderate rainfall. It has strong drought resistance and a wide range of soil adaptability; it can be cultivated on clay, sandy loam, slightly acidic, and slightly alkaline soils. Sudan grass is a drought-tolerant, high-yielding, high-quality annual superior forage grass suitable for planting in warm, arid regions. Sudan grass has broad adaptability; it prefers warmth and is not cold-tolerant. The minimum temperature for seed germination is 8°C, and the optimum temperature is 20-25°C; seedlings suffer frost injury or are completely frozen to death when exposed to temperatures below 3°C. Growth of mature plants slows when the temperature is below 12°C. Its root system is strong and penetrates very deep, allowing it to use water and nutrients from deep soil layers. Its drought resistance is extremely strong, and it can still achieve relatively high yields when planted in areas with only 250 mm of rainfall.

It is not demanding regarding soil and can be planted in general soils, but it should not be planted on bog soil or shifting sand land. It responds well to water and fertilizer. To obtain high yields, fertilization and irrigation are essential. For the following crop, more fertilizer should also be applied to ensure a bumper harvest. Sudan grass is best sown after the late frost. The growth period is 100-120 days. After entering the tillering stage, it can continue tillering throughout the entire growth process, and from the beginning of tillering, growth speed accelerates, growing 5-10 cm per day and night. During this period, fertilization and irrigation can produce high yields. According to plantings by the Northwest Institute of Animal Husbandry and Veterinary Medicine in 1959 in Huangyang Town, Wuwei, under extensive management, the yield per mu was 1250 kg of fresh grass and more than 50 kg of seed. Under good water and fertilizer conditions, with two cuttings per year, the yield per mu was 3500 kg of fresh grass and more than 100 kg of seed.

Scientific cultivation and management techniques for Sudan grass

Cultivation techniques:

Sudan grass is cultivated mainly for its stems and leaves as feed, so there are no strict limits on sowing and utilization periods. Spring sowing can begin when the soil temperature at a depth of 10 cm in the topsoil reaches 12°C to 14°C. Drilling is mostly used, and the sowing rate is mainly determined by soil moisture conditions, generally 3 jin per mu. For Sudan grass sown in early spring, because temperatures are low and the seedling stage is long, it is easily suppressed by various weeds. When the seedlings are 10-15 cm tall, intertillage and weeding should be carried out once; generally, two intertillages in summer are sufficient. Once Sudan grass has tillered, it is no longer vulnerable to weed damage. Sudan grass has a high demand for nitrogen and phosphorus fertilizers. In addition to applying base fertilizer before sowing, irrigation and fertilization should be carried out in a timely manner at the tillering stage, jointing stage, and after each cutting. 1. Land preparation

Good preceding crops for Sudan grass are legumes, wheat, and root and tuber crops. For spring-sown Sudan grass, the plowing depth should be no less than 20 cm. Sudan grass likes fertilizer and can achieve high yields under high-fertility conditions. Organic fertilizer is usually used as base fertilizer, applied at 1000-1500 kg per mu and plowed into the soil together with land preparation.

2. Sowing

Sun-drying the seed for 4-5 days 10-15 days before sowing can increase the germination rate. For spring sowing of Sudan grass in the north, the earlier the sowing, the higher the yield. Sow when the soil temperature stabilizes at 10-12°C. In the south, spring sowing is done in February to March, and for summer sowing, it is done immediately after the previous crop is harvested. In the middle and lower reaches of the Yangtze River, sowing is done around late April. When Sudan grass is rotated with Italian ryegrass, the sowing period can be delayed, but not later than late May. In cold regions, to allow Sudan grass to supply forage earlier and mature fully before frost, sprouting before sowing can also be adopted. Soak the seed in warm water for 8-12 hours 7-10 days before sowing, then pile it up in a place at 20-30°C, cover it with plastic sheeting, water it 1-2 times a day, and sow when half of the seeds show slight whitening. Drill sowing with 30 cm row spacing and a sowing rate of 2.5-3 kg per mu. Mixing Sudan grass with fodder soybean, peas, cowpea, hyacinth bean, wild soybean, and others can improve fresh grass yield and quality, but these leguminous crops have poor regrowth, so mixed sowing should be mainly based on Sudan grass. For drilling, the row spacing for forage harvest is about 35 cm, with 1.5-2 kg sown per mu; the row spacing for seed harvest is 45-60 cm, with 1-1.5 kg sown per mu.

3. Field management

Sudan grass seedlings are slender and weak and not tolerant of weeds, so intertillage and weeding should be carried out promptly after emergence. Carry out intertillage and weeding once every 10-15 days. In pure Sudan grass stands, spraying with 0.5 percent 2,4-D herbicide solution 2-3 times during the seedling stage can eliminate broadleaf weeds. Sudan grass grows rapidly from the tillering stage to the booting stage, and its fertilizer needs gradually increase. In addition to applying base fertilizer, in principle, topdressing should be applied after each cutting and utilization, generally 10 kg of ammonium sulfate per mu each time or a certain amount of decomposed human and livestock manure and urine. Irrigate at the right time. Sudan grass is susceptible to damage from armyworms, stem borers, aphids, and others. For those cut and used as green feed, if aphid damage occurs, cut and use immediately; seed fields should be noted for timely control. Sudan grass is a warmth-loving crop; it can overwinter safely in the subtropics and dies after frost in the temperate zone. The minimum temperature for seed germination is 8-10°C. It likes light and is not tolerant of shade; insufficient light not only reduces tillering and yield but also results in poor quality. After tillering, Sudan grass has strong drought tolerance, but sufficient water can significantly increase fresh grass yield and quality. Sudan grass is not demanding regarding soil and can be planted in various soils, growing best on sandy loam or clay loam. Under general cultivation conditions, the fresh grass yield of Sudan grass is 4000-6000 kg per mu, and the forage supply period is from late June to the end of September. Because it has relatively many stems, when feeding cattle and sheep, it is generally cut and used before heading; when feeding fish, rabbits, and geese, it is generally cut and used when the plant height is 70-80 cm. The crude protein content from jointing to before heading is 8-10 percent, and its palatability is poorer than other forage grasses. For Sudan grass silage, cut at the booting to heading stage. If ensiled together with mixed-sown leguminous forage, high-quality silage can be obtained.