Effect of management systems and cover crops on organic matter dynamics of soil under vegetables

Rodrigo Fernandes De Souza,Nuno Rodrigo Madeira,Flávia Aparecida De Alcântara,Cícero Célio De Figueiredo

doi:10.1590/s0100-06832014000300024

Rodrigo Fernandes De Souza, Nuno Rodrigo Madeira + Show 2 more

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https://doi.org/10.1590/s0100-06832014000300024

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Abstract

Vegetable production in conservation tillage has increased in Brazil, with positive effects on the soil quality. Since management systems alter the quantity and quality of organic matter, this study evaluated the influence of different management systems and cover crops on the organic matter dynamics of a dystrophic Red Latosol under vegetables. The treatments consisted of the combination of three soil tillage systems: no-tillage (NT), reduced tillage (RT) and conventional tillage (CT) and of two cover crops: maize monoculture and maize-mucuna intercrop. Vegetables were grown in the winter and the cover crops in the summer for straw production. The experiment was arranged in a randomized block design with four replications. Soil samples were collected between the crop rows in three layers (0.0-0.05, 0.05-0.10, and 0.10-0.30 m) twice: in October, before planting cover crops for straw, and in July, during vegetable cultivation. The total organic carbon (TOC), microbial biomass carbon (MBC), oxidizable fractions, and the carbon fractions fulvic acid (C FA), humic acid (C HA) and humin (C HUM) were determined. The main changes in these properties occurred in the upper layers (0.0-0.05 and 0.05-0.10 m) where, in general, TOC levels were highest in NT with maize straw. The MBC levels were lowest in CT systems, indicating sensitivity to soil disturbance. Under mucuna, the levels of C HA were lower in RT than NT systems, while the C FA levels were lower in RT than CT. For vegetable production, the C HUM values were lowest in the 0.05-0.10 m layer under CT. With regard to the oxidizable fractions, the tillage systems differed only in the most labile C fractions, with higher levels in NT than CT in the 0.0-0.05 m layer in both summer and winter, with no differences between these systems in the other layers. The cabbage yield was not influenced by the soil management system, but benefited from the mulch production of the preceding maize-mucuna intercrop as cover plant.

Highlights

A number of management and crop systems are being used in the covered by dry grassland vegetation (Cerrado) region of Brazil, with impacts on soil components, above all on the compartments of soil organic matter (SOM)
The treatments consisted of three soil management systems and two plant cover types for straw supply, grown in the summer (December to April) and vegetables planted in the winter
The total organic carbon (TOC) concentrations ranged from 14.7 g kg-1 in CTMM in the 10-30 cm layer to 25.6 g kg-1 in NTMM in the surface layer 0.0-0.05 m, both in the winter, with a gradual decrease with increasing depth (Table 3)

Summary

Introduction

A number of management and crop systems are being used in the Cerrado (savanna-like vegetation) region of Brazil, with impacts on soil components, above all on the compartments of soil organic matter (SOM). The soil acts as a source of carbon (C) to the atmosphere (Bayer et al, 2004), whereas no-tillage (NT) is an alternative to minimize impacts on the soil by different forms of land use. The soil microbial biomass is responsible for biochemical and biological processes in the soil and substantially affected by the environmental conditions (Balota et al, 2008). When the organic residue input to the soil is increased and the amount of roots is large, the microbial biomass is stimulated, increasing the microbial population (Souza et al, 2010)

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