Abstract
To meet future requirements for food production, sustainable intensive agricultural systems need to optimize nutrient availability to maximize yield, traditionally achieved by maintaining soil pH within an optimal range (6-6.5) by applying lime (calcium carbonate). However, a field trial that applied recommended liming rates to a sandy loam soil (increasing soil pH from 5.5 to 6.2) decreased pod yield of field bean (Vicia faba L. cv. Fuego) by ~30%. Subsequent pot trials, with liming that raised soil pH to 6.3-6.7, reduced stomatal conductance (g(s)) by 63, 26, and 59% in V. faba, bean (Phaseolus vulgaris), and pea (Pisum sativum), respectively. Furthermore, liming reduced shoot dry biomass by 16-24% in these species. Ionomic analysis of root xylem sap and leaf tissue revealed a decrease in phosphorus concentration that was correlated with decreased g(s): both reductions were partially reversed by adding superphosphate fertilizer. Further analysis of pea suggests that leaf gas exchange was reduced by a systemic increase (roots, xylem sap, and leaves) in the phytohormone abscisic acid (ABA) in response to lime-induced suboptimal plant phosphorus concentrations. Supplying synthetic ABA via the transpiration stream to detached pea leaves, at the same xylem sap concentrations induced by liming, decreased transpiration. Furthermore, the g(s) of the ABA-deficient mutant pea wilty was unresponsive to liming, apparently confirming that ABA mediates some responses to low phosphorus availability caused by liming. This research provides a detailed mechanistic understanding of the physiological processes by which lime application can limit crop yields, and questions the suitability of current liming recommendations.
Highlights
Modern intensive agricultural practices that rely heavily on applying supplementary mineral fertilizers may accelerate naturally occurring soil acidification processes that can impair crop productivity (Bolan et al, 2003; Matsuyama et al, 2005)
The gs of the abscisic acid (ABA)-deficient mutant pea wilty was unresponsive to liming, apparently confirming that ABA mediates some responses to low phosphorus availability caused by liming
Soil samples taken 16 weeks after agricultural lime application showed that soil pH increased from ~5.5 to 6.2 (Fig. 1A), slightly less than the pH 6.5 target
Summary
Modern intensive agricultural practices that rely heavily on applying supplementary mineral fertilizers may accelerate naturally occurring soil acidification processes that can impair crop productivity (Bolan et al, 2003; Matsuyama et al, 2005). Liming responses are not always positive, and yield reductions can occur even at recommended application rates. This has been attributed to changes in tissue Ca:Mg ratios (Carran, 1991), Mg fixation within the soil (Sumner et al, 1978), or reduced P availability (Haynes, 1982; Maxwell et al, 2012).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
