A collaboration between

Acknowledgments

Acknowledgments

Funding provided by:

Guidelines and Webpage Design:

Daniel Geisseler, Ph.D.; UCCE Specialist in Nutrient Management; Department of Land, Air and Water Resources, University of California, Davis

Patricia Lazicki; Department of Land, Air and Water Resources, University of California, Davis

Reviewers:

Roger A. Duncan; Pomology and Viticulture Farm Advisor, University of California Cooperative Extension Stanislaus County

Theodore DeJong, Ph.D.; Professor of Pomology and UCCE Specialist; Department of Plant Sciences, University of California, Davis

Support:

Moradi A. Barzin, Ph.D.; Senior Environmental Scientist FREP, California Department of Food and Agriculture

Amadou Ba, Ph.D.; Branch Chief Feed, Fertilizer, and Livestock Drugs Regulatory Services, California Department of Food and Agriculture

Amrith Gunasekara, Ph.D.; Science Advisor to the Secretary; California Department of Food and Agriculture

Last Update: November, 2015

Additional Information:

Peach, Nectarine Nitrogen Uptake and Partitioning

Peach and Nectarine Production in California

California Fertilization Guidelines

Peach and Nectarine

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Young
Trees

Dormancy
Winter

Bloom
Spring

Fruit Development
Summer

Post-Harvest
Fall

In orchards, leaf analyses are more reliable for the diagnosis of nutrient deficiencies and excesses than soil analyses. Leaf analyses are a vital component in evaluating a allow growers to evaluate their fertilization program.

Sampling Procedure

Interpretation of Results

Dormant Shoot Analysis

N to Young Trees

N Fertilization of Young Trees

Application Rate

Mode of Application

Fertilizer Type

Time of Application

Replant Orchards

Soil Applied N

Soil Applied Nitrogen

A combination of soil-applied and foliar fertilizers is often used.

Application Rate

Crop load drives the demand for nitrogen fertilization. The higher the current crop load, the more nitrogen is needed to replace what will be removed by the developing fruit. Between 2 and 3 lbs N is removed with each ton of peaches harvested ^{[N12, N33, N39]}. Nectarines may remove more per ton of harvest than peaches ^{[N19, N25, N28]}. Niederholzer and coworkers ^[N33] found that the perennial structures of 4-year old 'O'Henry' peaches in Yolo County at a tree density of 427 trees/acre acquired an additional 19 lbs N/acre over the course of a year. Abscised leaves and prunings were found to contain an additional 59 lbs N/acre; however, if left in the orchard 80-90% of this may be assumed to be cycled back into the soil, becoming available again for plant uptake over the course of a few years ^[N41]. For more information see Nitrogen Uptake and Partitioning.

Approximate fertilizer requirements for mature peach and nectarine orchards ^{[N33, N41]}. Assumes that prunings are not removed from the orchard, 2.69 lbs N are removed per ton yield and N use efficiency is 70%.
N application rate to
mature peaches and nectarines

Non-fertilizer N sources, including N supplied by the soil, irrigation water nitrate and organic inputs or cover crops may be significant and should be taken into account. If fall urea sprays are used for bacterial canker control, this N should also be included in the total rate ^[N11] (See Foliar N). Annual rates should be adjusted based on annual leaf analyses (See Tissue analysis).

The values in the table are in line with N recommendations in California: An annual rate of 25 to 75 lbs N/acre is usually enough to maintain adequate N fertility in fresh market peaches and nectarines, depending on the efficiency of the fertilization method ^[N8]. Rates of 50-100 lbs N/acre are more common on processing peaches ^[N34], which are generally higher-yielding ^[N28]. Higher rates will be required for N-deficient orchards ^[N23].

Early varieties usually allocate more N to shoot growth than later varieties ^[N35]. Lower N rates on these varieties are advisable, to avoid excessive vegetative growth and delayed maturity ^{[N6, N35, N39]}.

Nitrate in the Irrigation Water

Mode of Application

Fertilizer Type

Time of Application

Peaches and nectarines take up very little N during dormancy and in spring before leaf-out ^{[N27, N38]}. Unless trees are very N-deficient fertilizer N will not be taken up until active growth resumes and may be lost ^{[N24, N33]}. Soil N applications are therefore most efficient in mid-spring at the beginning of vegetative growth and after harvest, as long as the leaves are still green and temperatures are warm enough for N uptake ^{[N27, N35]}. Because much of the N used for new growth is recycled from the woody parts of the tree, the timing of N application does not normally affect tree performance as long as it is during a period of active uptake ^{[N33, N35]}. No clear differences in N uptake efficiency or yield have been demonstrated between summer, fall or split applications ^{[N24, N33, N39]}. However, split applications are generally considered more efficient than single applications, especially on sandy soils ^{[N8, N33, N40]}.

If fertilizer is broadcast, splitting applications will increase the efficiency ^[N17].

In sandy soils or for late maturing varieties, soil-applied postharvest N is at risk of leaching and polluting the groundwater. Under these conditions, foliar urea application may be a more efficient method for supplying postharvest N (see Foliar N).

Drip-irrigated systems

Nitrogen may be fertigated as long as the trees are actively taking up N. A FREP-funded experiment in Fresno County found no difference in peach growth, yields or groundwater nitrate leaching between a treatment consisting of one May and one September fertigation and a second treatment in which the same amount of N was split between three May and three September fertigations ^[N20]. However, large temporary increases in groundwater nitrate occurred following the single fall application. This suggests that with heavy doses, sandy soils or in wet weather split fall applications or a foliar application may be more efficient than a single large fall application (See Foliar N ).

Early Varieties

Varieties harvested in May or June can become overly vigorous after harvest, and overapplication of N early in the season should be avoided for these varieties ^{[N21, N35]}. Applications in late summer or early fall may be better than heavy spring applications, as they provide enough N to support next year's crop but stimulate post-harvest summer growth less ^[N22]. A FREP-funded study on 'Early Maycrest' peaches in Yolo County found that trees fertilized with 50 lbs N/acre of soil-applied ammonium nitrate in September combined with 50 lbs N/acre of foliar urea in October maintained similar yields but had lower postharvest leaf N and needed less summer pruning than trees receiving the soil application in April, or trees receiving no foliar N and a soil application of 100 lbs N/acre split between April and September ^[N21].

Foliar N

Foliar Nitrogen

While peaches and nectarines need some soil N to support good root function, about 20-50% of their N nutrition may be supplied through the leaves ^{[N8, N22]}. Foliar sprays are an efficient way to supply postharvest N to late- maturing varieties and in sandy soils. They are especially useful under conditions which limit root N uptake, such as nematode infestations, high water tables and cold weather ^{[N10, N11]}.Foliar applications may reduce summer pruning weights in early varieties compared with soil applications ^[N21]. However, there is no evidence that foliar fertilization gives higher yields than soil applications in a healthy orchard ^[N21].

Application Rate

Fertilizer Type

Time of Application

Phosphorus (P₂O₅)

Soil Test

Soil Analysis

Soil samples taken before an orchard is planted provide valuable information about soil conditions, salinity and nutrient availability. Soil analyses for nutrient availability are less common in existing orchards, as decisions are generally based on leaf analyses. ^[P9]. However, soil analyses may be useful to monitor trends in nutrient availability over the years.

Soil Sampling and Analysis

Interpretation of Test Results

Tissue Analysis

Leaf Analysis

In orchards, leaf analyses are more reliable for the diagnosis of nutrient deficiencies than soil analyses. Leaf analyses allow growers to evaluate their fertilization program.