Pecans are a highly valued nut crop that requires a precise and mechanized process to move them from the tree to the consumer. Primary growing regions in the United States, such as Georgia, Texas, and New Mexico, rely on modern agricultural machinery for efficient harvesting and managing large orchards. This approach is necessary to ensure the quality and integrity of the nuts are maintained throughout the entire process. The journey from the orchard to the processing facility is a multi-step operation where timing and technical control are paramount for a successful yield.
Determining Maturity and Orchard Preparation
The precise moment for harvest is signaled by the natural physiological change of the nut’s protective outer layer, known as the shuck. Growers look for the shuck split, where the hull dries and cracks open into four segments, allowing the nut inside to be exposed and loosened. This visual indicator confirms that the pecan kernel has finished filling and reached peak ripeness inside the shell. Harvesting must wait until the nuts are fully mature and will easily drop or be dislodged from the branches.
Before the mechanical harvest begins, the orchard floor requires careful preparation to ensure efficient collection and minimize contamination. This involves clearing the ground of debris, such as large sticks and fallen limbs, which could damage harvesting machinery. In many commercial operations, the ground is leveled and rolled smooth to create a clean surface. A prepared, flat orchard floor allows sweepers and harvesters to pick up the pecans without collecting excessive amounts of dirt and trash, which would complicate later cleaning stages.
Mechanical Shaking and Collection Techniques
The actual harvest is accomplished using specialized machinery that physically dislodges the nuts from the tree. A self-propelled trunk shaker, equipped with a large, padded clamp, is driven to each tree and grips the trunk. The machine then uses powerful, high-frequency vibrations to shake the tree, causing the mature pecans to fall onto the prepared orchard floor below. Since not all nuts mature simultaneously, a tree may be shaken twice during the harvest season to maximize the yield of high-quality nuts.
Once the pecans are on the ground, a different set of machines handles the collection process. Sweepers are used to move the scattered nuts, leaves, and small debris into long, linear piles called windrows, typically centered between the tree rows. This process often involves multiple passes, first blowing nuts away from the trunk and then consolidating the material into a manageable row. The speed of collection is important, as pecans lying on a wet ground can quickly mold or deteriorate.
The final step in the field is collection, performed by a mechanical harvester or vacuum unit. This machine straddles the windrow and uses rubber-coated fingers or paddles to lift the nuts and debris from the ground. Inside the harvester, a fan creates an air blast to separate the lighter materials like leaves and shucks from the heavier pecans, though some trash remains. The collected nuts are then deposited into a collection hopper or wagon, ready for transport to the cleaning and processing plant.
Cleaning, Drying, and Storage
Immediately after collection, the pecans arrive at the processing facility for cleaning and quality control steps. The nuts still contain a significant amount of foreign material, including sticks, dirt, and unseparated shucks. Cleaning machines use a combination of mechanical screens, which sort by size, and air separation, where a powerful air current lifts out lighter debris. This initial cleaning removes the majority of the trash, preparing the nuts for the next phase.
Drying is a highly technical and crucial step for preserving the pecan’s quality and shelf life. Freshly harvested pecans can have a moisture content as high as 25 to 30 percent, which promotes mold growth and rancidity. To prevent spoilage and darkening of the kernels, the nuts must be reduced to an ideal moisture content of approximately 4 to 4.5 percent. Growers use specialized drying bins or wagons with forced, often slightly heated, air circulating through the nuts.
The forced-air drying process significantly speeds up the reduction in moisture compared to traditional air drying, which could take weeks. Maintaining the correct moisture level is also important for the texture of the kernel, ensuring it is crisp and not “gummy.” Once dried, the in-shell pecans are ready for storage or further distribution. For long-term preservation, pecans are ideally stored in a dry environment at cool temperatures, typically between 32 and 36 degrees Fahrenheit and a relative humidity of about 65 percent.