Nutrient Management Research Database
General Information
Research Title
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Research Specifications
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Summary/Abstract from Original Source
Nutrient uptake by trees is determined by root interception, soil availability, and tree demand. Fruit trees have low rooting density, especially in the case of dwarfing rootstocks. Mobility in the soil is a key factor in determining nutrient availability, and good management of nutrients requires that supply is matched to demand, in terms of amount, timing and retention in the root-zone, and that nutrients are placed where they can be accessed by roots. Fertigation allows such flexibility in the timing and precision of nutrient supply. The efficiency of N fertigation is closely related to irrigation management. Scheduling irrigation to meet tree evaporative demand mini mizes the drainage of excess water through the root zone and the conseque nt N leaching. Timi ng the N supply to coincide with the period of rapid canopy development avoids excess N application when tree growth is supported by remobilization of stored N. Fertigation gives greater P and K mobility than broadcasting, increasing the potential for timely application of these nutrients in the root zone. P fertigation is beneficial at planting and as a single application at bloom. Fertigation with K can prevent the development of K-defici ency in drip-irrig ated trees on sandy soil. Fertigation with acidic fertilizers th rough drip systems can be detrimental in coarse-textured soils, where it can result in soil acidification and nutrient deficiencies, which can develop in as short a period as three years.
Research Highlights
Design and Methods
This source summarizes the findings on a handful of studies investigating fertigation practices in apple and cherry trees.
Fertigation refers to the application of fertilizer through irrigation systems, particularly drip irrigation or micro-sprinklers.
In all of the studies, water was applied based on measurements of soil water evaporation.
Results
Irrigation Amount
Utilizing soil water evaporation rates to adjust irrigation patterns saved as much as 170 gallons of water per tree.
Nitrogen
As irrigation water moves down through the soil, it carries the highly mobile N with it. This can remove N from the root zone, and make it unavailable to trees.
Apple trees should be fertilized with N during the 6 weeks following bloom, as this is the period of maximum N demand.
Cherry trees fertilized at 56 lbs per acre via a micro-sprinkler system were able to access more N than those fertilized by broadcasting fertilizer on the soil surface at the same rate. Yields did not increase when fertilized at higher rates.
Potassium
The use of acidfiying fertilizers can deplete soil K after 3 years. Daily K fertigation can help remedy this problem.
Potassium Chloride, Potassium Magnesium Sulfate, Potassium Sulfate, and Potassium Thiosulfate did not show any differences in tree K levels.
Phosphorus
Fertigation improves P mobility, especially in sandy soils.
Spreading P fertilization over 8 weekly applications immediately after tree planting was more effective than a single application following planting.