Cut-and-come-again, or repeat harvesting, is a practice in which a single planting of greens is harvested on multiple occasions. This is a common practice among small-scale, urban, and home producers in which the outermost leaves are removed, leaving the growing center of the plant intact enabling multiple harvests without compromising plant health. As this practice is not common among large-scale and commercial producers, there are currently no research-based fertilizer recommendations for cut-and-come-again greens. General guidance simply suggests continued, nitrogen-heavy fertilizer applications to ensure repeated harvests. This type of guidance is not easy to follow and could lead to overapplications and nutrient leaching. An experiment was designed to examine eight different fertilizer application strategies to determine which provided better growth and nutritional quality in later collard harvests while limiting nutrient leaching. Fertilizer applications for the cut-and-come-again treatments (CC) ranged from an initial fertilizer application matching local nutrient recommendations, to repeated applications either the initial complete application or a nitrogen side dressing at every third, every other, or at each harvest. A single harvest control grown to maturity (ODM) was also monitored for nutrient leaching. Leachate from collards was collected weekly and the volume measured. Leachate was then tested for pH, conductivity, color, and turbidity using bench top instruments. A portion of the leachate was also filtered and tested for nitrate-nitrogen, ammonia-nitrogen, and phosphate using microplate spectroscopy. Another filtered portion was acidified and tested for mineral nutrient content using ICP-OES. Nutrient management treatment had no effect on leachate volume, which was affected by sample collection time, season, and year, likely due to weather variation and plant growth factors. Nutrient management treatment did have an effect on water quality metrics; however, no metric displayed a dose response. Differences between nutrient management treatments were seen during the spring of 2024 more often than any other growing season. Most metrics were higher in the spring than in the fall, which could be due to poor growth and fewer harvests in the fall, and therefore lower nutrient additions. While the two fall growing seasons were very similar to each other, there were some differences between the spring of 2023 and the spring of 2024, although which had higher nutrient content depending on the nutrient measured. Leachate pH, color, and increased with the number of days after planting in most cases. Leachate conductivity, turbidity, potassium, magnesium, total phosphorus, and sodium decreased with number of days after planting.
