Winter wheat (Triticum aestivum) is a cereal grain planted in the autumn that requires a winter cold period (vernalization) to stimulate reproductive growth the following spring. Unlike spring wheat, winter wheat is typically harvested in the summer or early autumn of the year after planting. Successfully harvesting this crop at the precise moment of readiness is paramount, as timing directly influences the grain’s quality, maximum yield, and suitability for long-term storage. Maximizing the return requires understanding maturity indicators, preparing machinery, and using meticulous operation techniques.
Assessing Grain Maturity and Optimal Timing
The journey to harvest begins with recognizing two distinct stages of grain maturation: physiological maturity and harvest maturity. Physiological maturity is reached when the kernel achieves its maximum dry weight, meaning no further dry matter will be deposited. This stage is visually confirmed by the kernel losing its green color and a dark layer of cells appearing along the crease, signaling the end of nutrient transfer.
At physiological maturity, the grain’s moisture content (MC) is relatively high, often ranging between 20 and 40 percent. Harvest maturity is the point where the grain has dried down naturally in the field to a moisture level suitable for mechanical harvesting and storage. Visually, the entire plant, including the head and straw, turns a uniform golden yellow color.
The target moisture content for combining winter wheat is between 13.5 and 14.5 percent, which minimizes the need for costly artificial drying. Harvesting above this range increases the risk of mold and spoilage during storage. Harvesting below it can lead to excessive shatter loss in the field and increased kernel damage during threshing. Field moisture meters provide the most accurate measurement, allowing operators to track the drying rate and determine the optimal harvest window.
Pre-Harvest Field and Equipment Preparation
Preparation should begin well before the combine enters the field to minimize delays and mechanical failures. Thorough field scouting is necessary to identify areas of lodged or downed crop, which require adjustments to header operation. Scouting also assesses the presence of green weeds, which interfere with threshing and cleaning, and increase the moisture content of the harvested grain.
The combine requires comprehensive maintenance, starting with the cutting components. Ensure all header knives are sharp and properly aligned to achieve a clean cut and minimize uneven feeding. All belts, chains, and fluids should be checked and replaced or topped off, as mechanical failure during the brief harvest window can result in significant losses.
Logistical support, including grain carts, clean trucks, and labor, must be organized to move the harvested grain efficiently to storage. All machinery should undergo a final safety check, confirming that shields, lights, and fire suppression equipment are functional.
Operating the Combine and Harvesting Techniques
The actual process of harvesting requires continuous attention to combine settings, which must be optimized to balance thoroughly separating the grain while minimizing loss and kernel damage. The combine header should be set to cut just below the heads, typically leaving a stubble height of 8 to 12 inches to reduce the volume of straw processed. Ground speed must be carefully managed; traveling too quickly overloads the machine, leading to grain being carried out with the straw, while moving too slowly extends the crop’s exposure to weather risks.
Optimizing the internal settings preserves yield, aiming to keep losses minimal. The cylinder or rotor speed should be set at the minimum required to fully thresh the kernels from the head, as excessive speed increases the likelihood of cracked or broken kernels. Concave clearance, the distance between the rotor and the concave grate, must be wide enough to prevent grain damage but narrow enough to ensure aggressive threshing. A slightly more open setting is often preferred in high-yielding crops for better material flow.
The fan speed and sieve settings work together to clean the grain sample by blowing light chaff out the back while allowing heavier kernels to fall into the grain tank. If the fan speed is too low, the sieves become overloaded with chaff; conversely, too high a speed will blow good grain out of the machine. Since grain and straw moisture content changes throughout the day, the operator must continually monitor the grain tank sample and the straw discharge to make fine-tuning adjustments.
Immediate Post-Harvest Storage and Management
Immediate post-harvest management is paramount to preserving the quality and value of the grain. If the harvested grain’s moisture content exceeds the safe storage threshold (typically above 14.5 percent), it must be dried or aerated immediately to prevent the rapid growth of mold and fungi. For bulk storage, aeration fans force ambient or slightly warmed air through the grain mass. This controlled drying method also cools the grain to inhibit insect activity and moisture migration.
A crucial step before storage is cleaning the grain to remove foreign material, including weed seeds, broken kernels, and chaff. These impurities reduce the market grade and block airflow during aeration, accelerating spoilage. Using a mechanical cleaner or ensuring the combine’s cleaning shoe is properly tuned minimizes this contamination.
Safe long-term storage requires careful bin preparation. This involves thoroughly cleaning the storage structure to remove all traces of old grain and treating it for residual insect pests. Once the clean, dry grain is placed in the bin, its temperature and moisture must be monitored regularly. Localized hot spots can develop due to insect infestation or moisture build-up, leading to rapid deterioration. Reducing the grain temperature to below 60 degrees Fahrenheit is recommended for extended storage.