Nutrient Deficiency
As turfgrasses are cultured for aesthetic reasons, only under extreme nutrient deficiency cases or fertility misapplications (i.e. not overlapping properly) do we actually see symptoms of nutrient deficiency. The typical turfgrass fertilizer contains nitrogen (N), phosphorus (P), and potassium (K). Subsequently, these three nutrients and iron (Fe) are the most common nutrients found to be deficient in turfgrass culture. Furthermore, deficiencies of each has its own identifiable characteristic.
Nitrogen Deficiency
General yellowing or chlorosis initially in the older leaves is a symptom of nitrogen (N) deficiency. Subsequently, tips will die back, and shoot density and tillering will decrease. This is the most common observed in turfgrasses. Nitrogen deficiency occurs because of the relatively high requirement of nitrogen by most turf species. Also, most soils do not have the ability to meet this requirement without fertilizer applications.
Turf diseases also are affected by nitrogen fertility. Brown patch may be more active under high levels of nitrogen fertility. In contrast, dollar spot and rust are more active under low levels of nitrogen fertility. By maintaining an adequate nitrogen level, disease management can be enhanced.
Phosphorus Deficiency
A common leaf symptom of phosphorus (P) deficiency is a dark green color that progresses to a purplish to reddish purple color, mostly in the older leaves, is a common leaf symptom of phosphorus (P) deficiency. A phosphorus deficient turf may appear wilted and be confused with one suffering from drought stress.
While leaf symptoms associated with phosphorus deficiency may not be evident, turf performance can be affected greatly. Seedling establishment has been shown to be improved by phosphorus fertility. This is the most evident stage at which fertility problems are observed. A high phosphorus fertilizer is recommended for newly seeded areas.
Potassium Deficiency
Yellowing of older leaves followed by tip dieback and necrosis along the leaf margin are signs of potassium (K) deficiency. Typically, symptoms are rare with the exception of sand media greens.
Symptoms more likely appear as increased susceptibility to other stresses. Overall turf may appear chlorotic and have lower spring quality and heat resistance. Potassium deficiency is rarely reported. However, it has been suggested that mild deficiencies are rather common. Among various turf species, adequate potassium has been shown to increase establishment and spring performance. Also, it aids in increasing stress tolerance to cold, heat, and wear.
Iron Deficiency
Interveinal chlorosis occurring initially in the younger leaves is a sign of iron (Fe) deficiency. To illustrate, In extreme cases, leaves can appear almost white. Iron deficiency results in the loss of an upright growth habit. Turf stands can appear matted and are often difficult to mow. Iron deficient turf may appear as a mosaic of chlorotic patches. Soil conditions leading to iron deficiencies include high soil pH (reduced availability), high soil phosphorus leaves (increases pant growth efficiency, i.e. tillering), high soil nitrogen levels (leads to rapid growth rates), sandy soils, and cold wet soils.
Many products are available for foliar applications of iron. Color enhancement may occur within hours of the application. In addition, it will last two to three weeks during wet periods and several months during cool, dry periods. Under high maintenance conditions, iron toxicity can cause a blackening of leaf tissue, but usually the injury is temporary. Selecting grasses adapted to more alkaline soils also will decrease the problem.
Reference
L. J. Giesler. (1997). Abiotuc Turf Injury. In F. Baxendale, Ph.D., & R. Gaussoin, Ph.D., Integrated Turfgrass Management for the Northern Great Plains (pp. 171-173). Location: Nebraska
