Production and Decomposition of Cover Crop Residues and Associations With Soil Organic Fractions

José Carlos Mazetto Júnior,Zigomar Menezes de Souza,Venâncio Rodrigues e Silva,Danyllo Denner de Almeida Costa,Ernane Miranda Lemes,José Luiz Rodrigues Torres

doi:10.5539/jas.v11n5p58

Abstract

The decomposition of plant residues, the changes in the total organic carbon (TOC) and the fractions of soil organic matter (SOM) occur differently in irrigated areas. The objective of this study was to quantify the biomass production, the decomposition of cover crops residues and relate them with the changes n the content and fractions of SOM in an irrigated area of vegetable crops. Six types of cover crop treatments were evaluated: brachiaria (B); sunn hemp (S); millet (M); B + S; B + M; S + M, plus an additional treatment (native area), with 4 repetitions. The production of fresh (FB) and dry biomass (DB), the rate of plant residue decomposition, TOC, SOM fractions and the coefficient of SOM (QSOM) were quantified. It was observed that the greatest and the lowest volume of crop residues were from the B and S cover crop, respectively. The cover crops in monoculture presented great decomposition rates and short half-life when compared to mixtures of cover crop. The TOC and QSOM were great in the 0 to 0.05 m soil layer, and in the M + S cover crop mixture, when compared to the 0.05 to 0.1 m soil layer and to other cover crops. Among the SOM fractions, the humin predominated in the most superficial soil layer (0 to 0.05 m).

Highlights

IntroductionThe no-tillage system (NTS) has grown exponentially up to 30% a year, reaching a total area cultivated of 32 million hectares in the season 2014/2015 (Motter & Goelzer, 2015)
Along with the technological innovations adopted for agricultural production in the Brazilian Cerrado (Savannah like biome), the no-tillage system (NTS) is one of the most expressive and the one that has brought many changes to the previous system of crop production.The NTS has grown exponentially up to 30% a year, reaching a total area cultivated of 32 million hectares in the season 2014/2015 (Motter & Goelzer, 2015)
Among the plant species used as cover crops for NTS in Cerrado, brachiaria, millet and sunn hemp are well adapted to its edaphoclimatic conditions and produce great amounts of biomass (Torres et al, 2017; Pacheco et al, 2017; Ceballos et al, 2018)

Summary

Introduction

The NTS has grown exponentially up to 30% a year, reaching a total area cultivated of 32 million hectares in the season 2014/2015 (Motter & Goelzer, 2015). This expansion has always been associated with the development of new technologies for crop management, like crop rotation and the selection of plants adapted to the edaphoclimatic conditions of the Cerrado region. The cultivation of brachiaria (signalgrass), millet and sunn hemp as cover crops provide greater soil coverage and nutrient cycling than other plants used at this biome (Torres et al, 2008; Carvalho et al, 2011; Assis et al, 2016; Pacheco et al, 2018)

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