| In China, wheat is mainly grown on calcareous soils, which is one of many importantsources of zinc in the human body needs of rural residents. However, the high pH and highCaCO3content in calcareous soil affects the bioavailability of zinc. Soil is a major source oftrace elements in plants, it is very important to improve the utilization of zinc fertilizer incalcareous soils. Therefore, in this paper we explores the impact of different zinc sources andmethods of zinc application on calcareous soil zinc fraction and zinc fertilizer utilization.Through field and pot experiment studied the effect of two zinc sources and two zincapplication methods on soil Zn fractions and zinc fertilizer utilization. The results are asfollows:(1) To increase Zn fertilizer utilization efficiency in potentially Zn-deficient calcareoussoil, the dynamic changes of different Zn fractions after Zn fertilizer application to soil inwheat growth stages (Seedling, tillering, regreening, jointing, filling and harvesting) wasconducted. The field experiment included two Zn sources (Zn-EDTA and ZnSO4) and twoapplication methods (Broadcast and Band). Results showed that Zn fertilizer (Zn-EDTA orZnSO4) application to soil significantly increased the concentrations of soil DTPA-Zn and Znfractions. The order of Zn fractions decreased as follows: Zn weakly bound to organic matter(Wbo-Zn)> carbonate bound Zn (Carb-Zn)> Zn strongly bound to organic matter (Sbo-Zn)>manganese oxides bound Zn (OxMn-Zn)> exchangeable Zn (Ex-Zn). The banded Zn-EDTAand ZnSO4increased soil DTPA-Zn by2and1.2times than that in the broadcast treatments,respectively. Soil Ex-Zn, Wbo-Zn, and Carb-Zn contents positively correlated with soilDTPA-Zn. Compared to the control, Zn-EDTA application significantly increased Ex-Znconcentration and reduced Sbo-Zn concentration. On the other hand, compared to thebroadcast application treatment, the banded Zn application significantly increased theconcentration of soil DTPA-Zn and Zn fractions except for Sbo-Zn. In a word, in potentiallyZn-deficient calcareous soil, the banded Zn application and Zn-EDTA application increasedthe concentrations of available Zn and the efficiency of Zn-EDTA could last to the wheatharvest. (2) The objective of this study was to evaluate Zn fertilizer utilization efficiency and thebehavior of ZnSO4and Zn-EDTA as Zn sources in a potentially Zn-deficient calcareous soil.The greenhouse pot experiment included two Zn sources (Zn-EDTA and ZnSO4) and twoapplication methods (mixed and banding). Zinc behavior in soil was studied bydiethylenetriaminepen-taacetate (DTPA) and sequential extractions. Results showed that themixed ZnSO4application significantly increased grain Zn concentrations compared to that inthe banded ZnSO4application; in comparison, there was no significant difference for grain Znconcentration between the mixed and banded application treatments of Zn-EDTA.Irrespectively of Zn application method, Zn-EDTA had a relatively higher efficiency thanZnSO4in increasing Zn fertilizer utilization. Application of ZnSO4increased all Zn fractionscompared to the control treatment; in contrast, Zn-EDTA application increased theexchangeable Zn (Ex-Zn), carbonate bonded Zn (Carb-Zn), and loose organic matter Zn(Wbo-Zn) contents. In the banded Zn application treatment, Ex-Zn from Zn-EDTA wasdistributed uniformly in the whole bulk soil; however, Ex-Zn from ZnSO4was mainlydistributed in the Zn-fertilized soil section. In conclusion, in this potentially Zn-deficientcalcareous soil, the application of Zn-EDTA either, as band, could increase the contents ofpotentially available Zn and the Zn utilization efficiency to larger extent compared to ZnSO4.Meanwhile, the efficiency of Zn-EDTA could last longer.In conclusion, the chelated zinc fertilizer Zn-EDTA not only reduces the amount offertilizer and thus reduce the waste of resources and soil heavy metal pollution, and improvethe ratio of potentially effective zinc fractions than ZnSO4in calcareous soils. Meanwhile,higher DTPA-Zn content can be maintained until after the wheat harvest, improved zincfertilizer utilization.The results futher show that banding application method more widely toimprove the concentration of soil DTPA-Zn, exchangeable Zn (Ex-Zn), carbonate bonded Zn(Carb-Zn), and loose organic matter Zn (Wbo-Zn) thus improve the zinc absorption rate ofwheat. |
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