Exploring the Role of Nitrogen in Integrated Pest Management Strategies

Integrated pest management (IPM) programs have been developed for almost all agricultural and ornamental crop production systems over the past two decades. But only recently have IPM and organic management systems been considered a truly primary approach in professional turfgrass management. The reasons for the dramatic increase in organic approaches are centered on public concern for the environment that has resulted in legislation at both the state and federal levels. A multitude of research reports and on-site experiences have shown that switching partially or even wholly to organic management techniques have resulted in renewed and greatly increased turfgrass performance while reducing or eliminating pesticide and synthetic fertilizer use. One of the more significant problems associated with organic turfgrass management, particularly on golf courses, is the inability to develop and maintain the high levels of overall turf quality and aggressiveness with natural organic fertilizers. Natural organic fertilizers are inherently low in available nitrogen levels ranging between 2 percent and 8 percent with only blood meal, bat guano and feather meals approaching the 10 percent to 12 percent levels. Although feather meals tend to be high in nitrogen content, the nutrient is in a protein form that is slow to degrade and yield the needed results. Relatively low nitrogen levels found in natural organic products make it necessary to apply high amounts of material to achieve the desired seasonal effects because all natural organics depend upon soil microbial activity for nitrogen/mineral release. As such, when soil temperatures are low in the spring and fall, release rates are limited at a time when cool-season turfgrasses are at their peak of performance and need higher levels of nitrogen to develop root zones and lateral stems. This is particularly the case when using materials lower than 6 percent nitrogen having a comparatively high carbon/nitrogen (C/N) ratio, which would result in even slower mineral release. To overcome this problem, the industry has developed organically based fertilizers that have increasing levels of inorganic nitrogen added to meet the high nitrogen demands. These bridged products have been successful but cannot be considered 100 percent natural organic. Inorganically amended materials, however, do not have the same ability as purely natural organic materials to stimulate increases in soil microbial activities and populations. These are