Sorghum (milo) is a cereal grain and forage crop recognized globally for its resilience and versatility. As one of the world’s top five cereal crops, it is cultivated for human food, animal feed, and ethanol production. Its superior ability to withstand dry conditions makes it a reliable crop for arid and semi-arid regions. The deep, fibrous root system extracts moisture from soil layers inaccessible to many other grains.
Preparing the Field and Selecting the Cultivar
Successful sorghum production begins with optimizing the growing environment and selecting the appropriate seed type. Sorghum is a warm-season crop requiring a long, hot growing season, with optimal temperatures ranging between 77 and 86°F (25 to 30°C). It grows best in well-drained loam soils but can tolerate heavier clay soils and some soil salinity. Soil preparation involves either conventional tillage for a fine seedbed or no-till methods requiring careful planter management for good seed-to-soil contact.
The choice of cultivar is determined by the crop’s intended final use. Grain sorghum (milo) is harvested for its seed and is the most common type grown in the United States. Forage sorghum is selected for high biomass yield, often reaching 8 to 15 feet, and is used for silage or hay. Sweet sorghum is grown for its sugar-rich stalks, processed into syrup or used in biofuel production.
Planting should be delayed until the soil has warmed sufficiently to ensure rapid and uniform emergence. The minimum daily soil temperature at planting depth should reliably reach 60 to 65°F (about 15°C). Planting into cooler soil can result in slow germination, making the seedlings more vulnerable to disease and early-season pests.
Planting Techniques and Timing
Planting requires precision, as sorghum has a smaller seed size and weaker seedling vigor compared to corn. Seeds are typically planted shallowly, at an optimal depth of 1 to 2 inches (2.5 to 5 cm). On sandy or dry soils, planting slightly deeper may be necessary to reach moist soil. Heavy clay soils require a shallower depth, usually no more than one inch, to prevent emergence issues.
Row spacing decisions are often governed by the expected moisture conditions. A 30-inch row spacing is common, balancing light interception with soil moisture conservation. In environments with high yield potential and sufficient water, narrower rows of 10 to 15 inches can lead to higher yields. This reduced spacing allows the crop canopy to close more quickly, which also helps suppress weed growth by shading the soil.
Mid-Season Care and Management
Ongoing management focuses on providing necessary nutrients and protecting the young crop from competition. Sorghum requires less supplemental water than corn due to its drought tolerance, but water stress can still severely limit final yields. The most sensitive period for water availability is the reproductive phase, specifically from the boot stage to two weeks past flowering, when the grain head is forming and filling.
Fertilization, particularly with nitrogen, is managed similarly to corn, though the total amount applied is typically lower, reflecting sorghum’s lower yield goal. Growers aim to supply nitrogen at a rate of 1.0 to 1.3 pounds per bushel of expected yield. Split applications of nitrogen are recommended to maximize efficiency and minimize the risk of loss due to heavy rainfall.
Weed control is critical during the first few weeks after planting because young sorghum seedlings are poor competitors. Heavy weed infestations early on can reduce yields by up to 20%. Herbicide options are limited compared to other major row crops, necessitating safener-treated seed for pre-emergent herbicides like Dual Magnum. Common pests include the sugarcane aphid, headworms, and sorghum midge. Diseases like grain mold and leaf blight are managed through resistant varieties and crop rotation.
Harvesting and Post-Harvest Handling
The final stage of the crop cycle is determined by the grain’s moisture content and physical maturity. Grain sorghum reaches physiological maturity when the hard starch has filled to the base of the kernel, with moisture content typically between 25% and 30%. Waiting too long to harvest increases the risk of lodging, shatter loss from the head, and bird damage.
Most grain sorghum is harvested using a combine, often beginning when the grain moisture is between 20% and 25% to minimize field losses. Harvesting at this moisture level requires artificial drying, but it avoids the risks associated with leaving the crop in the field longer. Forage sorghum, in contrast, is cut and chopped for silage or hay.
The harvested grain must be dried to a safe moisture level for long-term storage to prevent spoilage and mold growth. Grain is typically dried to 12% to 14% moisture content. Drying uses natural air or heated air systems, and proper aeration is essential to maintain quality.