Journal of Hunan Ecological Science

【Objective】This study aims to explore the effects of nano zero-valent iron (nZVI) and the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on the soil-crop systems of Brassica rapa var. chinensis under tap water and wastewater irrigation conditions, to optimize agricultural irrigation and nitrogen fertilizer management. 【Method】A pot experiment was conducted with eight treatments, in- volving the application of nZVI and DMPP under tap water and rice-fish symbiosis wastewater irrigation conditions. Parameters such as yield, quality, resistance indicator of Brassica rapa var. chinensis, abiotic property, enzyme activity, nitrogen transformation rate of the soil, and the soil-plant system multi- functionality were measured. 【Result】Under different irrigation conditions, the application of nZVI im- proved the Brassica rapa var. chinensis yield to some extent. The applications of DMPP and nZVI reduced the nitrate content in Brassica rapa var. chinensis, with the best results under tap water irriga- tion. Application of DMPP alone or in combination with nZVI increased the acidic soil pH under different irrigation conditions. The combined applications of DMPP and nZVI significantly reduced soil NO - 3-N content and increased soil NH + 4-N content. Under tap water irrigation, nZVI increased soil β- glucosidase, chitinase, acid phosphatase, and arylsulfatase activities, but nZVI and DMPP had no signif- icant effects on soil enzyme activities under wastewater irrigation. Under tap water irrigation, the applica- tions of the nZVI and DMPP improved system multifunctionality to some extent, however, under wastewater irrigation, only the alone application of nZVI increased system multifunctionality to a certain degree. 【Con- clusion】Under tap water irrigation, nZVI and DMPP improved the Brassica rapa var. chinensis yield and quality, enhanced soil quality, and optimized soil environment by increasing soil enzyme activities. The complex components in wastewater might inhibit the effectiveness of DMPP. In practical agricultural pro- duction, nZVI and DMPP should be reasonably selected and applied according to different irrigation water sources to improve crop yield and quality, soil health and soil-plant system multifunctionality.

Brassica rapa var. chinensis; nano zero-valent iron ( nZVI); 3, 4-dimethylpyrazole phosphate (DMPP); system multifunctionality