Effects of Nitrogen Addition on Soil Microbial Functional Diversity and Extracellular Enzyme Activities in Greenhouse Cucumber Cultivation

Abstract

Greenhouses, commonly used for vegetable production, are experiencing large nitrogen (N) inputs in North China, which leads to soil acidification, increases soil N availability, and affects microbial community structure and composition. However, it remains unclear how N enrichment influences soil microbial functional activities in this region. In this study, we conducted a two-year pot experiment in a greenhouse to evaluate the effects of four different rates of N addition (0, 334, 668, and 1002 kg N ha−1 year−1) on cucumber soil properties, extracellular enzyme activities, and community level physiological profiles (CLPP). We found that high-N addition (1002 kg N ha−1) caused a massive accumulation of inorganic nitrogen and soil acidification, which was not beneficial to soil microbial activities. The color development (AWCD) values for the metabolism of microbial carbon sources and the activities of soil extracellular enzymes also showed a significant decrease in high N(N3) treatment. Additionally, the activity of leucine aminopeptidase (LAP) and polyphenol oxidase (PPO) of N3 decreased by 36% and 50% compared to the N0 and could be a good predictor for microbial functional diversity and microbial biomass carbon (MBC). Structural equation modeling (SEM) confirmed that the reduction of microbial functional diversity is mainly coregulated by the decline of soil pH and the change of cucumber BGB (belowground biomass) resulting from soil C and N imbalance. Overall, excessive N-fertilizer amendment can be more dangerous to microbial community functional diversity, especially for carbohydrate utilization which adversely affects cucumber yield in current intensive management.

Nutrient Recovery from Poultry Wastewater by Modified Biochar: An Optimization Study

“…The specific surface area of BS biochar was about 171.251 m 2 /g with a pore volume of 0.267 cm 3 /g. This was comparable with other research on the specific surface area such as wood biochar and rice husk biochar (57.1 and 4.38 m 2 /g) [41], corncob (23.3 m 2 /g) [42,43], rape (184 m 2 /g) [43,44], Chinese cabbage (124 m 2 /g) [43,45,46], peanut straw (99.1 m 2 /g) [44,45], rice husk (273.6 m 2 /g), and wood (11 m 2 /g) [43]. Moreover, other research on various biochar materials indicated specific surface area and pore volumes of sugarcane bagasse by MgCl2 soaking (1440.4 m 2 /g and 1.574 cm 3 /g) [47], oilseed rape straw by co-pyrolysis of coal gangue (144.59 m 2 /g and 0.069 cm 3 /g) [48], sludge by slow pyrolysis (1.850 m 2 /g) [49], sludge by dewatering with Fenton and slow pyrolysis (4.890 m 2 /g) [49], and sewage sludge by pyrolysis under CO2 (109 m 2 /g and 0.085 cm 3 /g) [50].…”

Analysis of Disinfection in Greenhouse Soils with Medium-Temperature Steam Produced by Solar Energy

“…Some species of the genus Cordyceps are capable of affecting the behavior of their host insect. Cordyceps unilateralis, for example, causes ants to perch on top of a plant before they die, ensuring the maximum distribution of spores from the fruiting body that sprouts from the insect carcass [60,61].…”

Snow-cover loss attenuates the effects of N addition on desert nutrient cycling and microbial community

“…URE ( P < 0.001), Invertase ( P < 0.01), and AprX ( P < 0.01) as typical hydrolytic enzymes showed high sensitivity to N addition ( Miralles et al., 2021 ), which suggests that soil enzymes have adapted to survive drought stress in arid areas, making them more nutrient-dependent ( Ren et al., 2020 ). POD and PPO as oxidative enzymes increased significantly with N addition, perhaps this is because they are produced by fungi ( Wang et al., 2022 ), which have a high tolerance for acidity and are sensitive to N availability ( Talbot et al., 2015 ). Previous research has demonstrated that after the removal of the snow-cover, frequent freeze-thaw cycles caused the death of soil microorganisms, which resulted in the temporary release of enzymes and nutrients.…”