Uptake of phosphorus from surfactant solutions by wheat leaves: spreading kinetics, wetted area, and drying time

Abstract

The delivery and uptake of nutrients at the surface of plant leaves is an important physicochemical phenomenon that depends on leaf surface morphology and chemistry, fertilizer formulation chemistry (including adjuvant and associated surfactants), wetting dynamics, and many other physical, chemical and biological factors. In this study, the role of spreading dynamics in determining uptake of the macronutrient phosphorus from phosphoric acid fertilizer solution in combination with three different adjuvants was measured in the absence of droplet run-off and splashing. When run-off and splashing losses were zero, spreading and drying rates had a small to negligible effect on the uptake efficiency. The results suggest that uptake may be much less sensitive to the specific choice of adjuvant and long time-scale spreading behaviour than one might intuitively expect.

Assessment of foliar-applied phosphorus fertiliser formulations to enhance phosphorus nutrition and grain production in wheat

“…An increase in biomass due to increased uptake of P from foliar application has previously been reported (Sherchand and Paulsen 1985;Mosali et al 2006;McBeath et al 2011). The high recovery (>60% in most cases) of the foliar pathway found in this study is consistent with findings from other studies that used foliar P at rates relevant for field applications (McBeath et al 2011;Peirce et al 2014Peirce et al , 2016. The efficiency of foliar P uptake was not affected by formulation, with only potassium phosphate having lower efficiency, owing to crystallisation of the fertiliser on the leaf surface, which was subsequently washed off the leaves.…”

“…The role of adjuvants in the translocation of foliar P once it enters the plant cells is still relatively unknown, although Stolzenberg et al (1982) showed that there was little movement of a labelled surfactant and its metabolites away from the initial application site. Although the type of adjuvant was not important for either uptake or translocation of foliar-applied P when used in combination with phosphoric acid as the P source (Peirce et al 2016;Peirce et al 2019), it is not known what interactions may occur between adjuvants and other P sources.…”

“…However, yield responses to phosphoric acid have been inconsistent. This is despite the foliar uptake of P from phosphoric acid being high (>90% of the applied P) (Peirce et al 2016). There is scope to investigate the effectiveness of other P formulations as foliar fertilisers because the accompanying cation and formulation pH can affect foliar P uptake (Koontz and Biddulph 1957).…”

“…An adjuvant is defined as any chemical added to a foliar spray solution that modifies the spray characteristics of the solution or aids in increasing the penetration of the leaf by the active ingredient (Hazen 2000). The use of adjuvants is especially important for wheat crops, because the hydrophobic nature of the wheat leaves render them difficult to wet with hydrophilic foliar sprays (Holloway 1969;Netting and von Wettstein-Knowles 1973;Peirce et al 2016). The use of adjuvants can initially influence the deposition of the foliar fertiliser (through altering the spray characteristics including the droplet size) on the plant foliage (Spanoghe et al 2007;Zabkiewicz 2007).…”

Oblique drop impact onto a deep liquid pool

“…In agriculture, e.g. in pesticides crop spraying [4], oblique drop impact and the subsequent splashing and droplet rebound [5] is important. In industrial applications oblique impact occurs in e.g.…”