Diversified crop rotation with no‐till changes microbial distribution with depth and enhances activity in a subtropical Oxisol

Abstract

Soil microbial community and enzyme activity regulate carbon and nutrient cycling in soils. No-till has elevated levels of carbon at the soil surface compared to intensively tilled soils. The introduction of crop diversification in agricultural systems increases soil carbon protection and aggregate stability. Thus, the association of no-till with crop diversification may change the soil microbial distribution and enhance activity in comparison with tilled soils with no crop diversification. We tested this hypothesis assessing the soil microbial community and enzyme activity in a long-term (32 yr) experiment with contrasting soil management (no-tillage, (NT) and conventional tillage (CT)) and cropping systems in southern Brazil. Long-term NT increased microbial biomass at 0-5 cm. In contrast, soil microbial biomass was higher in deeper soil layers (10-30 cm) of CT. No-tillage and crop diversification increased the activity of β-glucosidase, acid phosphatase and N-acetyl-glucosaminidase. The benefits of an intensified/diversified crop rotation were offset by soil tillage. The higher abundance of PLFA groups at 0-5 cm and 10-30 cm of respective NT and CT soils were correlated with increased C and nutrient levels (N, Ca 2+ , Mg 2+) and decreased Al 3+. Highlights • Crop diversification increased the soil microbial biomass and individual PLFA groups. • No-till without crop diversification did not change microbial biomass. • No-till with crop diversification increased enzyme activity. • Subsoil fertility restricted microbial responses in a no-till Oxisol.

Linking Cover Crop Residue Quality and Tillage System to CO2-C Emission, Soil C and N Stocks and Crop Yield Based on a Long-Term Experiment

“…The greater t 1/2 of CC residues in NT systems prolongs soil surface protection, temperature control, and conserves soil moisture, thus improving soil health [73,95]. Pires et al [44] reported that NT promoted greater diversity of soil microorganisms and fungal biomass than CT in our experimental site (Table S1). In comparison to fungi, bacteria demand more energy and are less efficient in converting C from substrates to microbial compounds, and therefore could increase residue decomposition and CO 2 -C emissions [96][97][98].…”

“…Conversely, short t 1/2 of legumes leading to short-term CO 2 -C emission and sharp N flush into the soil in CT may hinder formation of N-depending stable organo-mineral interactions, likely restricting SOC and N sequestration [28,76]. In our experimental area, Pires et al [44] found greater arbuscular mycorrhizal fungal biomass as well as N-acetyl-glucosaminidase and B-glucosidase activity (0-0.3 m depth) in NT compared to CT (Table S1), supporting that increasing t 1/2 of legumes benefits fungal communities, consequently increasing SOC and N stocks. Accordingly, previous studies in our experimental site concluded that compared to CT, NT enhanced stabilization of easily degradable organic C by either physical occlusion or by intimate association with soil minerals, probably mediated by microbial compounds [27].…”

“…Studies conducted in the long-term field experiment (began in 1985) in Cruz Alta, Southern Brazil, where the present study was developed, revealed that compared to CT, NT promoted greater: geometric mean diameter of aggregates, aggregates stability and C occlusion in aggregates [37,38]; POM content and quality (lower C/N ratio) as well as C management index [39]; soil C and N sequestration rates and stocks [30,[40][41][42]; soil OM stability [27,38]; total fungal and arbuscular mycorrhizal fungal biomass [43,44]; and grain crop yields [45], and lower CO 2 -C emissions [46], especially in crop rotations including vetch. Most of these studies had specific objectives, which should be interlinked to improve our understanding on mechanisms of SOC sequestration in NT.…”

Soluções tecnológicas emergentes para uma agricultura sustentável: microrganismos eficientes

“…Dentre as práticas agronômicas sustentáveis, as mais comuns são a rotação de culturas, os sistemas agroflorestais, a paisagem heterogênea, o consórcio de culturas e a associação de plantas, práticas essas que favorecem a relação de ME no solo ao aumentar a quantidade de matéria orgânica assim mantendo a "saúde do solo", essencial para uma produção de qualidade. O uso de sistemas de cultivos com espécies diversificadas se mostra cada vez mais útil em diversas regiões, sendo uma prática considerada sustentável, pois em ambientes heterogêneos onde a complexidade genética é maior, a distribuição de pragas e doenças muda, permitindo às culturas um maior rendimento, e isso também pode ser associado à melhorias da qualidade do solo [67][68][69][70].…”

Editorial for the special issue on “opportunities and challenges in no‐till farming”

“…(c) NT in combination with cropping was also studied at Brazilian and Chinese sites. Using a long-term experimental trial (32 years), Pires et al (2020) highlighted for a Brazilian Oxisol that NT when combined with crop rotations increased soil enzymatic activities and individual phospholipid fatty acid groups. By returning the residues, the clay size fraction showed the most substantial increase in SOC, as demonstrated by Zhang et al (2020) based on maize and maize-soybean systems under NT and CT for a Chinese Mollisol (USDA soil taxonomy).…”