Nano calcium carbonate promotes phosphorus uptake in wheat by modulating the rate of phosphorus release and facilitating soil bacterial-mediated phosphorus morphological transformation processes†

Abstract

In order to reduce phosphorus (P) losses due to P leaching, enhance the adsorption capacity of soil for P, and ensure environmental safety and optimal crop growth, a multitude of calcium-containing natural minerals and industrial-synthesized materials have been employed in a vast array of applications. However, the potential of nano calcium carbonate (NCC) with high surface electronic activity and a large specific surface area to serve as ideal slow-release P fertilizers has rarely been explored in academic research. In this study, the optimum application rate of NCC and its effect on soil P processes were determined by setting up five different treatments, namely, 0 NCC, 0.15% NCC, 0.30% NCC, 0.45% NCC, and 0.60% NCC, through a soil column leaching experiment as well as a two-year field experiment (2020–2022). The results showed that all treatments of NCC reduced leaching losses of soluble P. Compared with 0 NCC, 0.30% NCC and 0.45% NCC increased soil available P (AP) content and alkaline phosphatase (ALP) activity. In comparison to the 0 NCC, the 0.30% NCC treatment resulted in a notable increase in the relative abundance of several bacterial groups, including Actinobacteria, Acidobacteria, Haliangium, Solirubrobacter, Actinoplane, Nocardioides, Dongia, and Gemmatimonas. Additionally, the relative abundance of ppx, ppa, and phoD was elevated, while the relative abundance of Firmicutes, Bacillus, phnE, and phnC was reduced. The 15% NCC treatment resulted in a notable increase in the abundance of gcd. NCC treatments increased P concentrations in wheat stems, leaves, and spikes. NCC promoted wheat P uptake by regulating the rate of P release, and by activating ALP activity and increasing soil AP content by promoting soil bacterial-mediated mineralization of organic P and solubilization of inorganic P.