Can We Approach Complete Dependence on Foliar-applied Urea Nitrogen in an Early-maturing Peach?

Abstract

<jats:p>The suspected contributory role of soil fertilization to nitrate pollution of groundwater has encouraged exploration of novel fertilizer management strategies. Foliar-applied urea has long been used to supplement soil N applications, but there have been no apparent attempts to replace soil N applications completely in deciduous orchard culture. Two experiments were conducted to study the effect of foliar-applied low biuret urea on productivity and fruit growth of the early maturing peach [<jats:italic>Prunus persica</jats:italic> L. Batsch (Peach Group)] cultivar, Early Maycrest. In a 3-year experiment, a total foliar urea regime was compared to an equivalent amount of N applied to the soil. The foliar treatment supplied adequate amounts of N to the various organs of the tree including the roots, shoots, and fruit buds, but mean fruit weights were lower than in the soil-fertilized treatment. In a 2-year experiment, a 50%-50% combination treatment of soil-applied N in late summer with foliar-applied N in October, maintained yields and fruit weight equal to the soil-fertilized control. Some soil-applied N appears necessary for optimum fruit growth. Soil N application may be needed to support root proliferation and associated processes, but we did not determine a threshold amount of soil-applied N needed. The combination treatment also reduced excessive vegetative growth which is characteristic of early maturing peach cultivars. Therefore, this combination treatment offers promise as a viable commercial practice for maintaining tree productivity and controlling excessive vegetative growth in peach trees.</jats:p>

Foliar N application reduces soil NO3−-N leaching loss in apple orchards

“…It has also been reported that complete dependence on foliar-applied urea N reduced fruit size of an earlymaturing peach (Johnson et al, 2001). However, we found no reduction in fruit size with foliar N application in this experiment.…”

“…We used a low urea concentration (5 g/l) and multiple applications (7 sprays) during the growing season (from mid-May to mid-August, once every two weeks), while they sprayed with a high urea concentration (43 g/l) two-three times in October. A 50%:50% foliar:soil N combination treatment in their experiment maintained yield and fruit weight equal to the soil fertilized treatment, which suggested some soil-applied N was necessary for optimum fruit growth, but they did not indicate the threshold amount of soil-applied N required (Johnson et al, 2001). In our experiment, the ground was not covered when urea was sprayed, and about 12-15% of sprayed N fell to the ground as calculated from the volume of solution collected on the ground during the spray (data not shown).…”

“…Foliar application of nitrogen has been suggested as an N-conservation alternative compared with conventional soil fertilization (Bondada et al, 2001;Embleton and Jones, 1974;Swietlik and Faust, 1984). Adequate amounts of N in various tissues including roots, shoots and buds can be obtained by applying only foliar urea to earlymaturing peach trees (Johnson et al, 2001). Embleton and Jones (1974) reported that foliar applied N was as effective as soil applied N for citrus production.…”

“…E-mail: dongs@agr.gc.ca application for fruit trees (Weinbaum, 1988). This benefit argues for a shift from soil applied N to complete dependence on foliar application for N supply in orchards (Embleton and Jones, 1974;Johnson et al, 2001).…”

Foliar Applications of Urea Affect Nitrogen Reserves and Cold Acclimation of Sweet Cherries (Prunus avium L.) on Dwarfing Rootstocks

“…Urea is the most widely used form of N for foliar applications because of its rapid absorption, low phytotoxicity, and high solubility (Bondada et al, 2001;Yamada et al, 1965). Johnson et al (2001) showed that N for normal growth of peach (Prunus persica Batsch.) buds, shoots, and roots can be supplied adequately by foliar urea applications during the growing season.…”