Cover Crops Effects on Soil Chemical Properties and Onion Yield

Rodolfo Assis De Oliveira,Paulo Emílio Lovato,Claudinei Kürtz,Arcângelo Loss,Luciano Colpo Gatiboni,Gustavo Brunetto,Monique Souza,Vilmar Müller Júnior,Jucinei José Comin,Bruno Salvador Oliveira

doi:10.1590/18069657rbcs20150099

Abstract

Cover crops contribute to nutrient cycling and may improve soil chemical properties and, consequently, increase crop yield. The aim of this study was to evaluate cover crop residue decomposition and nutrient release, and the effects of these plants on soil chemical properties and on onion (Allium cepa L.) yield in a no-tillage system. The experiment was carried out in an Inceptisol in southern Brazil, where cover crops were sown in April 2012 and 2013. In July 2013, shoots of weeds (WD), black oats (BO), rye (RY), oilseed radish (RD), oilseed radish + black oats (RD + BO), and oilseed radish + rye (RD + RY) were cut at ground level and part of these material from each treatment was placed in litter bags. The litter bags were distributed on the soil surface and were collected at 0, 30, 45, 60, 75, and 90 days after distribution (DAD). The residues in the litter bags were dried, weighed, and ground, and then analyzed to quantify lignin, cellulose, non-structural biomass, total organic carbon (TOC), N, P, K, Ca, and Mg. In November 2012 and 2013, onion crops were harvested to quantify yield, and bulbs were classified according to diameter, and the number of rotted and flowering bulbs was determined. Soil in the 0.00-0.10 m layer was collected for chemical analysis before transplanting and after harvesting onion in December 2012 and 2013. The rye plant residues presented the highest half-life and they released less nutrients until 90 DAD. The great permanence of rye residue was considered a protection to soil surface, the opposite was observed with spontaneous vegetation. The cultivation and addition of dry residue of cover crops increased the onion yield at 2.5 Mg ha-1.

Highlights

In southern Brazil, and in the Itajaí Valley, onion (Allium cepa L.) is typically grown in a conventional tillage system (CTS), in which losses of soil, water, and nutrients are increased by water erosion (Castro et al, 2011)
The great permanence of rye residue was considered a protection to soil surface, the opposite was observed with spontaneous vegetation
The dynamics of dry matter (DM), total organic carbon (TOC), lignin, cellulose, and non-structural biomass loss, as well as N, P, K, Ca, and Mg mineralization, up to 90 days after distribution (DAD) were explained by the exponential decay model (Table 2; Figures 2 and 3)

Summary

Introduction

In southern Brazil, and in the Itajaí Valley, onion (Allium cepa L.) is typically grown in a conventional tillage system (CTS), in which losses of soil, water, and nutrients are increased by water erosion (Castro et al, 2011). Nutrients are gradually mineralized during cover crop decomposition, which reduces leaching and favors greater uptake by onion plants. During decomposition of plant residues, microbial populations use organic C as an energy source (Brunetto et al, 2014), and N, P, K, Ca, and Mg are mineralized and they eventually return to the soil, increasing their availability and uptake during the onion cycle (Souza et al, 2013; Martins et al, 2014)

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Results