Effects of microbial fertilizers on tomato yield, N₂O emission, and nitrogen utilization in greenhouse soils

This study aims to explore the effects of the fertilization strategies on the soil N₂O emission and nitrogen use of greenhouse tomatoes. A reasonable fertilization model was proposed to reduce the soil emission for the high yield of tomatoes in a greenhouse. A field trial was also conducted at the A-Cheng Experimental Research Base of the Northeast Agricultural University, Heilongjiang Province, China in 2023. Among them, the soil N₂O emission was monitored using a static box-gas chromatography. A systematic analysis was made to explore the patterns of soil nutrient contents, crop yield and nitrogen utilization efficiency. The soil N₂O emission and nitrogen use of tomato were then determined under different fertilizer treatments. A series of experiments were carried out on two types of fertilizers (compound and microbial fertilizers) and three nitrogen dosages (0, 120 and 180 kg/hm²). Five treatments were set as CK (no fertilizer), CF (constant compound fertilizer), RCF (reduced compound fertilizer), OF (constant microbial fertilizer), and ROF (reduced microbial fertilizer). The results showed that: 1) The total N₂O emission of microbial fungal fertilizer was reduced by 51.94% and 71.45% under the macronutrient and reduced nitrogen application, respectively, while the N₂O emission per unit of yield was reduced by 27.11%-47.75% (P<0.05), compared with the compound fertilizer. 2) The application of bacterial fertilizer increased the soil pH from 5.58 to 6.03, compared with the soil base value. There was the great potential to the soil acidification. Mycorrhizal manure was elevated the MBC and MBN, which increased by 20.47%-80.08% and 8.84%-59.15%, respectively, compared with the compound fertilizer. As the experimental period progressed, the total nitrogen content of the fungal fertilizer showed a continuous upward trend, and then increased by 8.49%-118.25% and 9.37%-122.03% under normoxic and reduced conditions, respectively, compared with the compound fertilizer. 3) The fungal fertilizer increased the tomato yield by 9.09%-13.68%, the agronomic efficiency of nitrogen fertilizer was improved by 25.85%-56.21%, and the nitrogen fertilizer utilization by 12.19%-17.99%, compared with the compound chemical fertilizer treatment under equal nitrogen. In conclusion, the reduced application of microbial fertilizers can be expected to serve as a promising fertilization strategy for less nitrogen losses and high yields of greenhouse tomatoes. Some recommendations can be given in greenhouse tomato systems for the green and sustainable production.