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

Marciel Redin,Bruno Chaves,Celso Aita,Sandro José Giacomini,Sylvie Recous,Getúlio Elias Pilecco,Ismael Cristiano Pfeifer,Leonardo Mendes Bastos

doi:10.1590/18069657rbcs20170355

Abstract

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 [...]

Highlights

Agricultural soils are important components of terrestrial ecosystems
The dry matter (DM) accumulation in the plant shoots did not distinguish the main crops from the cover crops and the grasses from the non-grasses when millet was discarded from the analysis, due to its very high shoot DM production (Table 3)
Is bias possible in comparison of the various species studied by sampling in the 0.00-0.20 m layer, due to the various root development strategies, for example, between Poaceae and Fabaceae? we observed that most of the root biomass recovered in the 0.00-0.20 m layer was located in the 0.00-0.10 m layer (80-87 % of the total, on average) and that the proportion of fine roots was lower for the Fabaceae species, making their root collection easier

Summary

Introduction

Agricultural soils are important components of terrestrial ecosystems. They allow food production and help in reducing greenhouse gas emissions through C sequestration (Lal, 2004). Even in agricultural systems, which are highly managed compared to natural systems, a better understanding of the allocation of biomass to shoots and roots for annual crops is a key issue to better predict soil C and nutrient dynamics and the effects of agrosystem management on soil C stabilization. This issue is relevant in systems where crop residues are exported and to some extent in no-till agricultural systems, where aboveground residues are left at the soil surface as mulch and where plant roots represent the only entry of organic matter in depth (Zibilske et al, 2005)

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