Root and Shoot Contribution to Carbon and Nitrogen Inputs in the Topsoil Layer in No-Tillage Crop Systems under Subtropical Conditions

Abstract

Recycling of carbon (C) and nitrogen (N) from plants into soils is decisive for maintaining soil organic matter and soil fertility. Therefore, we quantified plant biomass and C and N in the shoots and roots from the topsoil layer for a wide range of annual crops grown under subtropical conditions. We grew 26 species, 13 main crops, and 13 cover crops, in the field in standard sowing arrangements. Root biomass was recovered from the 0.00-0.20 m soil layer at flowering, and shoot biomass was measured at flowering for all crops and at maturity only for the main crops. Root dry matter (DM) exhibited an average of 14.9 ± 5.7 % of the total shoot biomass at flowering, and the mean shoot DM to root DM ratio was 6.9 (2.8-15.0) for the 26 crops considered. Leguminous species had less root DM (0.5 to 1.0 Mg ha-1) than grass species (1.1 to 2.3 Mg ha-1). The shoot C to root C ratio varied consistently with DM, while the root N to shoot N ratio varied considerably among species. Proportionally more biomass, C, and N was allocated to the root systems of grasses (Poaceae species) than non-grass species (especially Fabaceae species). The findings of this study contribute to designing rotations to include species that promote cycling of N and have high potential for adding C to the soil through roots. In this sense, the use of intercropped grasses and legumes is a promising strategy, especially for cover crops.

Evaluating Different Catch Crop Strategies for Closing the Nitrogen Cycle in Cropping Systems—Field Experiments and Modelling

“…The RG also showed a high amount of N in the belowground DM, but also a high C:N compared with the other CCs. This is in line with the higher observed allocation of C and N to the root system of grasses compared with non-grass species [47,48], which increases the potential for root-derived C stabilization in soil [49,50]. The lower shoot to root ratio following CE compared to PE is likely due to the lower N supply by the soil [51].…”

Predictive physico-chemical model for soil quality index in a long-term green manure farming system at tropical conditions, North-eastern Brazil

“…Ours results showed that microporosity, macroporosity, soil C stock and exchangeable Al were strongly correlated with root dry biomass. Plant species with high root biomass production (e.g., N. wightii and B. decumbens) can improve rootability (e.g., by releasing exudates and H + ), create biopores, thus in uencing soil microbial activity and soil porosity (Restovich et al 2019), also these plant species may affect the rhizodeposition around the rhizosphere by the allocation of N-and C-rich compounds as described by Redin et al (2018). According to the study done by Rossi et al (2020), plant roots may in uence the input of soil organic carbon into soil pro le, for example, Poaceae presents high ne roots production (e.g., lignin and cellulose rich) which are slowly decomposed by soil organisms, while Fabaceae presents faster ne roots production and decomposition (Jo et al 2020;Forstall-Sosa et al 2020).…”

Summer Cover Crops Shoot Decomposition and Nitrogen Release in a No-Tilled Sandy Soil

“…Rev Bras Cienc Solo 2019;43:e0190027 important to choose short-cycle cash crops (e.g., corn and soybean) for the cultivation of SCCs in succession. Furthermore, root production by cover crops (Redin et al, 2018) and effective input to soil C and N should be evaluated in future studies.…”