Effects of Tillage and N Applications on the Cassava Rhizosphere Fungal Communities

Abstract

Cassava (Manihot esculenta Crantz) is mainly cultivated in marginal land in the south of China where seasonal drought stress occurs frequently and the soil becomes more compact year by year. The study aimed to explore the effect of Fenlong tillage (FLT) combined with nitrogen applications on cassava rhizosphere soil particle composition and fungal community diversity. Conventional tillage (CT) was set as the control. The results indicated that the contents of clay and silt of the cassava rhizosphere soil were influenced by the tillage method, nitrogen (N), and their interaction. There was no difference in the richness and diversity of rhizosphere soil fungal communities among all treatments in 2019, while the richness of FLT was lower than that of CT in 2020. FLT caused a stronger influence on the community structure of rhizosphere fungi than N applications in the first year. The differences in the community structure of all treatments were reduced by continuous cropping of cassava in the second year. The top 10 dominant rhizosphere fungi at the class level of cassava found in 2019 and 2020 were Sordariomycetes, Dothideomycetes, Eurotiomycetes, Agaricomycetes, Intramacronucleata, norank_p__Mucoromycota, unclassified_p__Ascomycota, unclassified_k__Fungi, Pezizomycetes, and Glomeromycetes, which had an important relationship with soil pH, activity of urease, available nitrogen, available phosphorus, organic matter, and clay. These results indicated that FLT created a better soil environment for cassava growth than CT, thus promoting the formation of more stable rhizosphere fungal community structures.

Fenlong-Ridging Deep Tillage Integrated with Biochar and Fertilization to Improve Sugarcane Growth and Yield

“…FT breaks the hardpan under the plow layer and creates a soil layer that is suspended and loosened, which leads to more favorable hydrothermal conditions, increases the availability of nutrients, water, and oxygen, and thus enhances microbial activities, thereby improving plant photosynthetic efficiency and crop yield [43][44][45][46]. FT has the characteristics of deep tillage and rotary grinding, which increase soil porosity and decrease soil bulk density [20,41,47].…”

“…In this study, soil physical qualities, such as soil bulk density and porosity, were improved by FT. There were significant differences in the soil bulk density and porosity between the conventional and FT. A reduction in soil bulk density, an increase in soil porosity and water storage, and an improvement in available N and P after FT treatment indicated that FT could play an active role in the storage of soil nutrients [20,[44][45][46]50].…”

“…Biochar also increased microbial growth and activity, likely due to hydrothermal environment and air conditions [65,66]. Furthermore, FT increased the availability of soil nutrients and microbial growth and activity [44,45]. Overall, the interactions between FT and biochar-based fertilizers can reduce bulk density and increase soil porosity, AN, AP, AK, and SOM.…”

“…FT with biochar significantly increased sugarcane yield as compared with that of the control. This might be because FT and biochar jointly increase soil porosity and promote the formation of soil aggregates [44,45,73,74]. Moreover, a more favorable soil environment promoted the growth of roots and microorganisms, which, in turn, improved the nutrient utilization rate [67,75].…”

Alfalfa with Forage Crop Rotation Alleviates Continuous Alfalfa Obstacles through Regulating Soil Enzymes and Bacterial Community Structures

“…Additionally, the accumulation of self-toxic substances, such as phenolic acids, in soils from continuous cropping inhibits the growth of crops such as cucumbers, strawberries, and tobacco [10][11][12]. Many studies have also shown that continuous cropping significantly increases the relative abundance of fungal pathogens, leading to severe diseases in corn, soybeans, and melons [13][14][15].…”