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Fertilizer discharge process is a critical part of fertilizer application, as it affects the fertilizer discharge rate and uniformity of fertilizer application. In this study, a spiral grooved-wheel fertilizer discharge device was designed to replace the conventional straight grooved-wheel. Comparisons of the fertilizer discharge performance of the two grooved-wheel types were performed through tests and simulations using the discrete element method (DEM). The discharge performance of the two discharge devices was assessed by measuring the discharge mass rate, discharge uniformity, and the falling velocity of the fertilizer particles. Results showed that under similar conditions, the fertilizer discharge mass rate of the spiral grooved-wheel was higher than that of the straight grooved-wheel. The fertilizer discharge uniformity of the spiral grooved-wheel was much better than that of the straight grooved-wheel. The average falling velocity of fertilizer particles through the discharge spout was higher under the spiral grooved-wheel. The relative errors between the test and simulation results for the discharge mass rates, discharge uniformity, and particle falling velocities of the spiral grooved-wheel were all less than 10%. The developed spiral grooved-wheel exhibited a better performance than the conventional straight grooved-wheel, in all the aspects examined. The results serve as a theoretical basis for guiding the design of high-performance fertilizer applicators., Competing Interests: The authors have declared that no computing interest exist.

Deep fertilization is a beneficial approach for reducing nitrogen losses. However, the effects of various fertilization depths on maize (Zea mays L.) productivity and environmental footprints have not been thoroughly understood. Therefore, a field experiment was conducted to investigate the effects of different fertilization depths of 5 cm (D5), 15 cm (D15), 25 cm (D25), and 35 cm (D35) on maize productivity and environmental footprints. Reactive nitrogen (Nr) losses and greenhouse gas (GHG) emissions were assessed using life cycle analysis. We hypothesized that deep fertilization can obtain lower carbon and nitrogen footprint. The results indicated that deep fertilization decreased the N2O and NH3 emissions while increasing the CH4 uptake. Compared with D5, D15 resulted in an increase in total GHG emissions and carbon footprint (CF), whereas D25 decreased by 13.0% and 23.6%, respectively. Compared with D5, the Nr losses under D15, D25, and D35 conditions was reduced by 11.3%, 17.3%, and 21.0%, respectively, and the nitrogen footprint (NF) was reduced by 16.0%, 27.4%, and 19.0%, respectively. The maize yield under D15 and D25 increased by 5.7% and 13.8%, respectively, compared with the D5 treatment, and the net economic benefits of the ecosystem increased by 7.1% and 17.1%, respectively. In summary, applying fertilizer at a depth of 25 cm can significantly reduce the environmental footprints and increase maize productivity, making it an effective fertilization strategy in the Loess Plateau region of China. [ABSTRACT FROM AUTHOR]

Innovative fertilizer management is the most effective strategy for increasing crop yields and reducing environmental pollution. Deep fertilization reduces NH 3 emissions and increases crop yield, but its effects on N 2 O emissions are still unclear. Nitrification or urease inhibitors trigger cross-contamination of N 2 O and NH 3. Little is known about whether innovative fertilizer management strategies can reduce nitrogen emissions while maintaining higher yields. We conducted field experiments using maize in the semi-humid and drought-prone areas of the Loess Plateau in China from 2019 to 2021. To further verify the research results, experiments were conducted in semi-arid and drought-prone areas in 2022 and 2023 using surface fertilization (SF), surface fertilization with nitrification (SNI) or urease inhibitor (SUI), deep fertilization (DF), and deep fertilization with urease and nitrification inhibitor (DUN) as experimental treatments. The trends were similar at the three experimental locations over five years, where the ability of DF to reduce emissions was equivalent to those of SNI for N 2 O and SUI for NH 3. However, the increase in the crop productivity was significantly higher under DF than SUI and SNI. Compared with SF, DF significantly reduced the N 2 O and NH 3 emissions by 39.85 % and 46.08 %, respectively, and significantly the increased maize yield, N uptake, and nitrogen use efficiency (NUE) by 16.86 %, 15.83 %, and 32.79 %. The innovative fertilizer management strategies combined the advantages of inhibitors and deep fertilization, and they obtained the highest maize yield and NUE, as well as the lowest N 2 O and NH 3 emissions and gaseous nitrogen loss intensity (GNLI) among all treatments. Compared with SF, DUN reduced the urease, nitrate reductase, nitrite reductase, and hydroxylamine reductase activities by 22.03 %, 58.81 %, 52.72 %, and 50.27 %, respectively, the soil NO 3 –-N and NH 4 +-N contents by 82.94 % and 53.71 %, and N 2 O and NH 3 emissions by 80.79 %, and 79.33 %. DUN increased the maize yield and NUE by 23.30 % and 46.91 %, respectively, and decreased the GNLI by 84.69 %. DUN reduced the concentration of substrates for producing gaseous nitrogen by regulating the activities of soil nitrogen circulating enzymes to significantly reduce the nitrogen loss, and it achieved the highest maize yield (11,818.10 kg ha–1) and NUE (46.62 %) with the lowest GNLI (0.71 g N kg–1 grain). Innovative fertilizer management strategies can help to balance economic and environmental benefits in the Loess Plateau region of China. Our findings provide a reference for obtaining higher maize productivity with low environmental pollution in the Loess Plateau region of China. • Effects of deep fertilization and inhibitors on maize productivity and gaseous nitrogen losses comprehensively evaluated. • Nitrification inhibitor reduced N 2 O emissions but not NH 3 emissions. • Urease inhibitor reduced both N 2 O and NH 3 emissions. • Deep fertilization reduced N 2 O and NH 3 emissions. • Deep fertilization with inhibitors obtained higher maize productivity with the lower environmental cost. [ABSTRACT FROM AUTHOR]

There is an urgent need to address the contradiction between food security and climate change, and achieve the highest crop productivity at the lowest environmental cost. Scientific fertilization is the key to solving this problem. Deep placement of fertilizer (DPF) is an effective fertilization strategy for improving crop productivity and reducing gaseous N losses, but its effectiveness varies among agricultural systems and appropriate fertilization depths have not yet been determined. In this study, we synthesized 99 global studies (120 locations) and conducted a three-year field experiment to evaluate the effects of DPF on the crop yield, nitrogen use efficiency (NUE), and nitrous oxide (N 2 O), and ammonia (NH 3) emissions, and explored their responses to different climates, field management practices, and environmental factors. DPF could increase the grain yield by 13.5%, and NUE by 33.8%, and reduce N 2 O emission by 16.2%, and NH 3 emissions by 86.6%, respectively. Random forest analysis showed that the fertilization depth and nitrogen application rate were the most important factors that determined the impacts of DPF on the crop yield, NUE, and N 2 O and NH 3 emissions, but their effects also depended on the climate conditions, field management practices, and soil environmental factors. Meta-regression modeling showed that the effects of DPF on the crop yield and NUE increased but then decreased as the fertilizer application depth and nitrogen application rate increased, and the effects on N 2 O and NH 3 emissions tended to increase gradually. The meta-analysis also demonstrated that under DPF, the emission factors for N 2 O and NH 3 decreased by 35.8% and 84.5%, respectively. According to the meta-analysis, the global N 2 O and NH 3 emissions under DPF can be reduced by 0.23 and 5.46 Tg N·year–1 respectively. The results obtained based on global meta-analysis and a three-year experiment demonstrated that DPF obtained higher grain production with lower environmental costs, and the most suitable fertilization depth was identified as 15–25 cm. The results obtained in this study provide valuable insights into food security and environmental costs under effective fertilization management. • DPF strategy achieved higher grain yield with lower environmental costs compared to traditional fertilization methods. • The N 2 O and NH 3 reduction effects enhanced with the increase of fertilization depth. • Fertilization depth significantly affected the effects of DPF on grain yield and NH 3 emission. • Nitrogen application rate significantly affected the effects of DPF on nitrogen use efficiency and N 2 O emission. • The most suitable fertilization depth for maize production was 15-25 cm. [ABSTRACT FROM AUTHOR]