Soil health is a critical factor in sustainable agriculture, particularly in fruit production, where fertilization strategies play a vital role in maintaining the soil quality and enhancing fruit production and quality. This study investigates the effects of different fertilization strategies on soil bacterial communities and honey pomelo (Citrus maxima) properties in Ji’an City, Jiangxi Province, China. Three fertilization treatments were compared: conventional fertilization (CF: botanical organic plus chemical compound fertilizers), organic material fermented fertilization (OF: organic material including duck manure fermented fertilizer plus chemical compound fertilizer), and a special honey pomelo fertilizer (SF: organic material fermented fertilizer only during the whole honey pomelo growing season). Soil samples were collected at two depths (0–20 cm and 20–40 cm) from nine plots (three treatments × three replicates) and analyzed for their soil properties, bacterial community diversity and composition, and fruit characteristics. The results indicate that the OF and SF significantly improved the soil pH, soil organic matter (SOM), and nutrient availability compared to the CF. Additionally, the OF and SF treatments led to a 13.6% and 16.6% increase in fruit weight, respectively, and higher bacterial diversity, although no significant differences were observed in fruit quality parameters such as vitamin C, soluble sugar, and titratable acid. Acidobacteriota, Proteobacteria, Actinobacteria, and Chloroflexi were the dominant bacterial phyla. The soil bacterial composition structures were significantly different among the different fertilization strategies, and were well explained by soil properties such as the pH, SOM, total phosphorus, and available nutrients. Our study suggests that applying fermented organic fertilizers which use duck manure as part of the raw materials, either alone or in combination with chemical compound fertilizers, increases honey pomelo fruit production and improves soil health, contributing to the sustainable development of orchards.

Soil organic nitrogen (SON) positively influences crop productivity, greenhouse gas (GHG) emissions, and sustained nitrogen (N) supply. Herein, we observed the effect of different treatments; no fertilizers (CK), chemical fertilizers (nitrogen, phosphorus, and potassium (NPK)), organic manure, and NPK + OM (NPKOM). This study was performed in a randomized complete block design (RCBD) with three replications. The results indicated that NPKOM treatment significantly decreased the nitrous oxide (N₂O) emissions by 19.97% and 17.47% compared to NPK in both years. This was linked with improved soil nutrient availability, soil organic carbon, soil organic nitrogen (SON) storage (10.06% and 12.38%), SON sequestration (150% and 140%), increased soil particulate (44.11% and 44%), and mineral-associated organic N (26.98% and 26.47%) availability. Furthermore, NPKOM also enhanced nitrate reductase (NR: 130% and 112%), glutamine synthetase (GS: 93% and 88%), sucrose phosphate synthase (SPS: 79% and 98%), SSs (synthetic direction; 57% and 50%), and decreased SSs activity in the decomposition direction (18% and 21%). This, in turn, inhibited the decomposition of sucrase and enhanced starch conversion into carbohydrates, thus leading to an increase in rice yield and a decrease in N₂O emissions. All fertilizations, particularly NPKOM, significantly enhanced grain protein contents by increasing N uptake and its availability. Therefore, NPKOM is an effective practice to enhance rice productivity, and SON sequestration and mitigate the N₂O emissions and subsequent climate change.