Zinc application in conjunction with urea as a fertilization strategy for improving both nitrogen use efficiency and the zinc biofortification of barley

Abstract

BACKGROUND: Intensive cropping systems have caused widespread Zn deficiency, low nutritional quality of cereals and environmental problems. The aim of the microplot field experiment reported in this paper was to assess the option of using Zn in conjunction with urea fertilization in order to reduce N rate and to maintain the yield level and grain quality but minimizing environmental risks. Barley (Hordeum vulgare L.) was cultivated in a calcareous soil under semi-realistic conditions. Combinations of four Zn levels, applied by spraying aqueous solutions of ZnSO 4 , and three N levels, applied by spreading granular urea, were tested. RESULTS: Zn and N showed a synergistic effect, increasing yield and Zn content in all plant parts and protein content in grain.A low Zn dosage of 5 kg ha −1 was sufficient to significantly increase the amount of bioavailable Zn in soil and significantly raise its concentration in plant material and also the protein content in grain. The remobilization of Zn from leaf tissue to grain was dependent on the availability of Zn and was only crucial when its bioavailability was low. CONCLUSIONS: A Zn dosage of 5 kg ha −1 enhanced the agronomic efficiency of N by 15.5 kg grain kg −1 N. The Zn applied to the soil permitted a reduction in the rate of N with only a small decrease in barley grain yield and nutritional value. However, due to the interannual variability in rainfall, which is characteristic of Mediterranean climates, further studies will be necessary to confirm and extend these results.

Strategies to mitigate N2O emissions and improve crop quality. Effect of Zn-N co-fertilization and N-enhanced efficiency fertilizers on microbial communities

“…This positive effect of Zn and N fertilization on Zn biofortification that was observed for most of the Zn treatments has also been described in several previous experiments using ZnSO4 (ZnSul) (e.g. Gonzalez et al, 2019;Kutman et al, 2010;Xue et al, 2012). These authors suggested that grain proteins act as Zn sinks, which could explain this synergistic effect.…”

“…Our study, therefore, demonstrates that Zn-N coapplication can be a sustainable strategy for enhancing crop quality and yields and increasing N use efficiency in Zn-deficient soils. Gonzalez et al (2019) and Xue et al (2012) also observed this synergistic and positive effect on Zn biofortification through Zn-N co-fertilization as a result of grain proteins acting as Zn sinks. Future studies should look at whether it is possible to reduce the N rate to below the recommended rate by using Zn fertilizers in wheat.…”

Zinc–nitrogen interaction effect on wheat biofortification and nutrient use efficiency

“…Co‐fertilization with N also increased the Zn concentration in each part of the plant (grain, stem, and leaf) in winter wheat. This positive effect of Zn and N fertilization on Zn biofortification that was observed for most of the Zn treatments has also been described in several previous experiments using ZnSO 4 (ZnSul) ( e.g ., Kutman et al., ; Xue et al., ; Gonzalez et al., ). These authors suggested that grain proteins act as Zn sinks, which could explain this synergistic effect.…”

“…The absorption and mobility of Zn from the rhizosphere to the grain is dependent on different proteins and other N compounds, including amino acids and peptides ( Palmer and Guerinot , ). When Zn availability in soil was high or sufficient due to Zn foliar application to the crop, a positive effect of N was observed on Zn biofortification ( Gonzalez et al., ). A link has also been reported between the remobilization of N and Zn from senescing leaf tissues into wheat grain ( Waters et al., ).…”

Zn-DTPA-HEDTA-EDTA Application: a Strategy to Improve the Yield and Plant Quality of a Barley Crop While Reducing the N Application Rate

“…Various authors have studied the effects of applying Zn-N combinations using inorganic sources of Zn, such as ZnO, ZnSO 4 , or Zn(NO 3 ) 2 (Cakmak et al 2010;Erenoglu et al 2011;Gonzalez et al 2019;Kutman et al 2010). All these studies have focused on the impact of applying Zn-N combinations on N and Zn concentrations in plants in just one way: N fertilization combined with soil Zn applications has a significant interaction on grain Zn and N concentrations.…”