Root abundance of maize in conventionally-tilled and zero-tilled soils of Argentina

Abstract

SUMMARYMaize root growth is negatively affected by compacted layers in the surface (e.g. agricultural traffic) and subsoil layers (e.g. claypans). Both kinds of soil mechanical impedances often coexist in maize fields, but the combined effects on root growth have seldom been studied. Soil physical properties and maize root abundance were determined in three different soils of the Rolling Pampa of Argentina, in conventionally-tilled (CT) and zero-tilled (ZT) fields cultivated with maize. In the soil with a light Bt horizon (loamy Typic Argiudoll, Chivilcoy site), induced plough pans were detected in CT plots at a depth of 0-0.12 m through significant increases in bulk density (1.15 to 1.27 Mg m -3 ) and cone (tip angle of 60 º) penetrometer resistance (7.18 to 9.37 MPa in summer from ZT to CT, respectively). This caused a reduction in maize root abundance of 40-80 % in CT compared to ZT plots below the induced pans. Two of the studied soils had hard-structured Bt horizons (clay pans), but in only one of them (silty clay loam Abruptic Argiudoll, Villa Lía site) the expected penetrometer resistance increases (up to 9 MPa) were observed with depth. In the other clay pan soil (silty clay loam Vertic Argiudoll, Pérez Millán site), penetrometer resistance did not increase with depth but reached 14.5 MPa at 0.075 and 0.2 m depth in CT and ZT plots, respectively. However, maize root abundance was stratified in the first 0.2 m at the Villa Lía and Pérez Millán sites. There, the hard Bt horizons did not represent an absolute but a relative mechanical impedance to maize roots, by the observed root clumping through desiccation cracks.Index terms: zero tillage, conventional tillage, soil compaction, root growth.( O crescimento das raízes do milho é alterado negativamente quando o solo apresenta camadas compactadas superficiais (trânsito de maquinário) ou subsuperficiais (camada argilosa). Os dois tipos de impedimentos mecânicos muitas vezes coexistem nos campos sob cultura de milho, porém seus efeitos combinados no crescimento das raízes do milho foram raramente estudados. As propriedades físicas do solo e a abundância de raízes de milho foram estudadas em três diferentes solos da região do Pampa Ondulado, na Argentina, que foram cultivados em parcelas próximas com milho em preparo convencional e em plantio direto. No solo com um horizonte Bt incipiente (Argiudol típico franco, local Chivilcoy), as compactações induzidas pelo preparo foram identificadas nas parcelas sob preparo convencional na profundidade de 0-12 cm por meio de significativos incrementos na densidade aparente (1,15 e 1,27 Mg m -3 ) e na resistência à penetração com penetrômetro de cone (ponta com ângulo de 60° ), com valores de 9,37 e 7,18 MPa, no verão, nas parcelas sob preparo convencional e plantio direto, respectivamente. Isso ocasionou diminuição da abundância nas raízes do milho entre 40 e 80 % sob preparo convencional, se comparado com plantio direto, abaixo das compactações induzidas. Dois dos solos estudados tinham horizontes Bt fortemente estrutura...

Tillage Effects on Corn Soil-plant-water Continuum in Alfisols of Southern Ohio

“…Compaction in one portion of the soil profile may decrease RLD in underlying non-compacted layers. Taboada and Alvarez (2008) observed 40-80 % decrease in root abundance below 10 cm depth under CT. In general, root elongation rate decreases in response to both increasing penetrometer resistance and decreasing matric potential of soil (Bengough et al, 2011).…”

Effects of soil compaction on cereal yield

“…Soil compaction measurements of Taboada and Alvarez (2008) and Nyéki et al (2013) synchronize in the case of sandy loam and silty loam soils. Several authors proved that soil compaction effects on cereal yields taking into account the clay content change (Filipovic et al 2006;Franke et al 2008;Chen and Weil 2011;Ijoyah et al 2012;Nyéki et al 2013).…”

“…The experiments of Taboada and Alvarez (2008) resulted in no diffence between conventionally-tilled and zerotilled systems in levels of soil (soil profiles), and maize root systems of distribution and frequency (maize root abundance and distribution). In contrast, Salem et al (2015) attributed soil compaction and a potential reduction in maize yield to the tillage method, although the greatest bulk density reduction was observed under conventional tillage and measured cone index was the largest in zero tillage.…”

“…The soil resistance has influence on the cereals root (Czyž et al 2001;Wolkowski and Lowery 2008;Lipiec et al 2012) in turn on the whole plant's physiological maturation, growth and yield, and additionally affects the nutrient intake, independent of the culture. In spite of that, in the deeper soil layer subsoil compaction is not present; the surface compaction affects the root exploration and growth Taboada and Alvarez (2008). Maize seedlings were affected significantly by compaction treatments in Taser and Kara (2005) and the shoot ratio in Wolfe et al (1995), respectively.…”

“…yield prediction), because this conception is not clearly established in most cases. In some studies contradictions are presented between the bulk density and compaction (Lapen et al 2002;Taboada and Alvarez 2008), while other references found positive correlation (Smith et al 1997;Szőllősi 2003;Kumar et al 2012;Lipiec et al 2012).…”