Objectives We aim to study the effects of the application of different combinations of zinc and phosphate fertilizers on dry matter yield, grain quality, and utilization of phosphorus and zinc. The results will provide a scientific basis for the compatibility of zinc and phosphate fertilizers to develop new zinc-containing phosphate fertilizers.
Methods 0.5 and 5 parts by weight of zinc sulfate heptahydrate (Zn) were combined with 99.5 and 95 parts by weight of phosphate fertilizer (P) using physical (P+Zn) and reactive mixing process (PZn), respectively. A maize pot experiment was carried out with 8 treatments, including the application of the above 4 kinds of zinc-containing phosphate fertilizers (P+Zn0.5, P+Zn5, PZn0.5 and PZn5), common phosphate fertilizer (P) and sulfate heptahydrate (Zn0.5、Zn5), with no fertilization as the control (CK). All fertilizers were applied at the basal level into the soil column (0–30 cm soil layer). After harvesting, maize shoots were collected and divided into five parts (leaf, stem, bract, cob, and grain) to measure dry biomass, P and Zn contents. Soil samples were collected at 0–30 cm, 30–60 cm, and 60–90 cm depth to analyze available P and Zn contents.
Results 1) Compared with common P, both P+Zn and PZn fertilizers increased corn dry matter yield and grain yield by 15.18% and 7.70%, respectively. The effect of reactive mixing (PZn) was better than physical mixing (P+Zn); PZn products increased grain number per panicle than P+Zn. PZn0.5 recorded (P < 0.05) higher yield than PZn5. 2) Compared with common P, PZn0.5 increased P uptake by 8.40% in shoots and 16.67% in grains; the apparent utilization rate, agronomic efficiency, and partial factor productivity of phosphate fertilizer increased by 5.03 percentage point, 41.91%, and 11.64%, respectively. The average phosphate fertilizer utilization rate of PZn0.5 was 4.78 percentage point higher than PZn5. Similarly, the agronomic efficiency and partial productivity of PZn0.5 were 14.57% and 3.58% higher than PZn5. 3) PZn fertilizers (P < 0.05) increased grain zinc accumulation by 21.90% than common P on average, accumulation of zinc in corn shoots by 25.70% than P+Zn fertilizer, and the utilization rate of zinc fertilizer by an average of 7.83 percentage point.
Conclusions Using reaction mixing process to add Zn to phosphate fertilizers showed prospects in increasing maize yield, zinc and phosphorous absorption by maize, Zn and P use efficiencies, and soil available P and Zn contents. Therefore, adding 0.5% zinc sulfate heptahydrate in phosphate fertilizers through reaction is recommended for its positive impact on maize Zn absorption and utilization rate of zinc fertilizer.
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