Can humic acid alleviate the adverse effect of elevated phosphorus application on yield and nutritive contents of maize grown on a calcareous soil?

Abstract

G ROWING maize in calcareous soils requires adequate supply of phosphorus inputs, yet excessive P-applications may affect negatively micronutrients availability in soil, including Zn. Thus, the current study evaluates the ability of humic acid (HA) to counteract the negative effects of applied P on Zn-uptake by maize plants. To achieve this aim, a field experiment was conducted in a calcareous soil (CaCO 3 =268.91 g kg-1) following a split plot design to study the interactions between different P-inputs (100, 125 and 150% of the recommended dose, applied in main plots) and available-Zn in presence and absence of HA (applied in sub-plots at either 2 or 4 kg HA ha-1). Results revealed that increasing the level of P-application raised significantly P availability and consequently its uptake by maize plants; thus, enhanced significantly plant growth parameters and grain yield. In this concern, 125% of the recommended P-dose recorded the highest partial factor productivity values. Likewise, application of HA raised significantly available-P content and improved considerably plant growth and grain yield, especially with increasing the rate of its application. On the other hand, increasing the level of P-fertilizers decreased significantly Zn-availability and uptake by plants; however, in presence of HA, this effect was counteracted. Although, this amendment recorded no significant effect on soil-Zn availability; however, it raised significantly its content in shoots but not in grains. In conclusion, HA improved significantly the productivity of maize grown on a calcareous soil. This amendment not only improved the partial factor productivity of P-fertilizer, but also increased Zn-uptake by maize plants.

Effect of traditional sources of Zn and ZnO-nano-particles foliar application on productivity and P-uptake of maize plants grown on sandy and clay loam soils

“…Soil and foliar applications of Zn fertilizers should be consideredto satisfy plant needs for this nutrient (Singh et al, 2019;Stewart et al, 2019;Zachary et al, 2019 andAkter et al, 2020). Appling Zn as soil fertilizers might undergo precipitation in presence of phosphate fertilizers (Abd El-Aziz et al, 2020); yet, lack of this nutrient may be amended through foliar application without being competed with other soil nutrients on uptake by plant. One of the common Zn-fertilizers is ZnSO 4 which is a highly soluble salt besides being low in price as compared to synthetic chelates and complexes (Gonzalez et al, 2007).…”