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Corn is the most important food in China, which has the vital significance in ensuring food security and economic development. The work of topdressing is the important part in the process of corn production. The fertilizer management can effectively improve crop yield at the middle and later stage of maize growth, which can also increase the comprehensive benefit of corn production. However, the current topdressing work of corn is most performed by artificial fertilization. The uniformity of artificial fertilization is worse and the topdressing efficiency is lower, which can be improved by the mechanized fertilizer. So, the mechanized fertilizer would be in urgent need of development. According to the agronomic characteristics of corn layered fertilization, the centralized and pneumatic conveying fertilizer applicator was designed. The fertilizer machine was mainly composed of multi-line concentration distributing device, pneumatic conveying device, control system of fertilization and layered fertilizing device, which can realize long-range and wide-range rapid fertilization. Theoretical analysis and structural parameters of the key components were conducted. The software of control system and the interface of human-machine interaction were developed. The whole fertilizer applicator was assembled completely at last. In order to check the working performance of topdressing machinery, experimental tests concerning the consistency of fertilizer discharge, fertilization accuracy, and depth of fertilization between rows were conducted. Based on the prototype of fertilizer applicator, the tests were carried out according to relevant standards at Malan Farm in Shijiazhuang City of China in July 2019. During the experiment, a 51.5kW tractor was selected as the only power. Granular urea was used as test fertilizer. The experimental results showed that the rotating speed of fertilization wheel had less influence on the consistency of fertilizer quantity among each row. The difference of fertilizer quantity consistency between the deep and shallow fertilization was small at the same speed of fertilization wheel. And the fertilizer quantity was stable and uniform. The variation coefficient of fertilizer quantity consistency was reduced with the increase of rotational speed. And the maximum variation coefficient was 2.64%. With the increase of forward speed, the precision of fertilizer quantity was reduced to 95.42%. And the minimum average depth of deep fertilization of 11.04cm remained stable with the variation coefficient being less than 5.35%, while the stability of depth for shallow fertilization was reduced with the minimum of 6.9cm and the coefficient of variation reached 9.36%. The results indicated that the fertilizer applicator designed can meet the standard requirement of maize topdressing machinery better.