Foliar Application of P. II. Yield Responses of Corn and Soybeans Sprayed with Various Condensed Phosphates and P‐N Compounds in Greenhouse and Field Experiments¹

Abstract

Greenhouse and field experiments were conducted with corn (Zea mays L.) and soybeans (Glycine max L. Merr.) to evaluate the growth response of foliar sprays with several condensed phosphates and P‐N compounds. The maximum concentration of P tolerated in solutions of tri‐ and tetrapolyphosphates applied as sprays in the greenhouse was 1.3% with corn and 1.1% with soybeans. The maximum concentration of P tolerated as orthophosphate was 0.5% with corn and 0.4% with soybeans. With soybeans, the yields of plants sprayed with various condensed P compounds significantly exceeded the yields of the unsprayed control, which would not be classed as P‐deficient on the basis of the P content of the leaves. Spraying the plants, however, increased the P concentration in the leaves. Phosphoryl triamide produced the highest yields of above‐ground dry matter of corn plants in an experiment in which several P‐N compounds and condensed phosphates were brushed on the leaves. Several different condensed phosphates were sprayed on corn and soybeans in a field experiment on a fine loamy, mixed, mesic typic haplaquoll (Webster silt loam). An increase in yield of corn that was statistically significant at the 5% level was obtained from spraying. The yields with tri‐ and tetrapolyphosphate were, respectively, 760 and 754 kg/ha above the control yield of 10,234 kg/ha. With soybeans, the increase in yield due to treatment was significant at the 18% level, and the increase was equivalent to 256 kg/ha above the control yield of 3747 kg/ha.

Potential for foliar phosphorus fertilisation of dryland cereal crops: a review

“…The appearance of leaf burn where foliar droplets have been applied has been observed in many studies (Barel and Black 1979b;Parker and Boswell 1980) and generally is not detrimental to the plant. However, some studies have resulted in leaf burn so severe that part or all of the leaf dies, causing a lower yield for foliar-applied treatments.…”

“…Foliar applications of P have been tested on various agricultural crops such as soybeans (Garcia and Hanway 1976;Barel and Black 1979b;Syverud et al 1980;Mallarino et al 2001Mallarino et al , 2005, clover (Bouma 1969, Bouma andDowling 1976), wheat (Arif et al 2006;Mosali et al 2006) and corn (Harder et al 1982;Giskin and Efron 1986;Girma et al 2007). The objectives of such studies have been to identify the best formulation, rate, timing, crop type and sites.…”

“…In a study by Barel and Black (1979b) several times as much P could be added in polyphosphate compounds compared with the orthophosphate form. The maximum concentration of P tolerated in solutions of tri-and polyphosphates as sprays was 1.3% compared with 0.5% orthophosphate on corn leaves.…”

“…The most common adjuvant cited in research is Tween 20Ô (Clor et al 1962;Bouma 1969;Barel and Black 1979b;Syverud et al 1980;Reuveni et al 1996;Ahmed et al 2006). Generally this adjuvant is added to foliar fertilisers at a concentration of 0.1% v/v.…”

Determination of Optimum Rate and Growth Stage for Foliar‐Applied Phosphorus in Corn

“…Harder, Carlson, and Shaw (1982) found that foliar fertilizer applied after silking did not translate into increased grain yield. On the other hand, Barel and Black (1979b) reported an increased grain yield due to foliar P compared with control (untreated check).…”