Application and Use of Fertilizers
Achieving the maximum biological efficiency in using fertilizers depends on time of application and their placement. The lower cost of fertilizer relative to labor and other application costs has encouraged higher rates of fertilizer use as well as less attention to effective placement and proper time of application. Factors that influence decisions about when to apply a fertilizer and where to place it include nutrient mobility and fixation in the soil; plant needs and the location of roots; losses by volatilization and leaching; the amount of soil moisture and temperature of soils; and salt effects on germination. Sufficiency recommendations are based on the soil-test correlation. The soil-test value is used to predict or estimate the amount of fertilizer needed to achieve the desired yield goal. Broadcast application is the spreading of the fertilizer uniformly over the entire soil surface. Foliar application can be used for the quick correction of a nutrient deficiency in plants.