Automatic Sprinker Systems, Virginia
New Technology: Fertigation Quick Facts…
- The most common nutrient applied by fertigation is nitrogen. Other nutrients include phosphorus, potassium, sulfur, zinc and iron.
- Anhydrous ammonia is not recommended for sprinkler systems.
- Applications of phosphorus in irrigation water are subject to precipitation problems.
The application of nutrients through irrigation systems is called “fertigation,” a contraction of fertilization and irrigation. The most common nutrient applied by fertigation is nitrogen. Elements applied less often include phosphorus, potassium, sulfur, zinc and iron.
This technique can reduce fertilizer application costs by eliminating an operation. It may also improve nutrient efficiency by applying them closer to when the plant needs them. Also, it could conceivably reduce leaching or denitrification (gaseous) losses of nitrogen and lower the luxury uptake of nutrients by plants.
A rule of thumb is that nutrients that are not absorbed by the soil (anion forms) and that move with soil water are best for sprinkler application. This may limit the list to nitrogen, sulfur and some of the chelated micronutrients (ZnEDTA, FeEDDHA, CuDTPA). Phosphorus, potassium and inorganic forms of micronutrient cations may be soluble in water. However, because of immobilization in the soil they may accumulate in the top 1 to 2 inches of the soil surface and not be distributed throughout the root zone.
Applications of Nitrogen Solutions in Water
In irrigated agriculture, water applications of nonpressure urea-ammonium nitrate (UAN) solutions have become increasingly popular as a means of improving nitrogen use efficiency. The nitrogen sources will not cause salts to precipitate out of the irrigation water. Losses due to leaching are minimized by split or multiple nitrogen applications as compared to applications prior to seeding, particularly on sandy soils. The amount of various nitrogen fertilizer required to give 20, 30 and 40 pounds of nitrogen per acre are given in the table below.