Anisotropy of Saturated Hydraulic Conductivity in a soil under conservation and no-till treatments

Buda

et al. 2014

Self Cite

SUMMARYThe area under the no-tillage system (NT) has been increasing over the last few years. Some authors indicate that stabilization of soil physical properties is reached after some years under NT while other authors debate this. The objective of this study was to determine the effect of the last crop in the rotation sequence (1 st year: maize, 2 nd year: soybean, 3 rd year: wheat/soybean) on soil pore configuration and hydraulic properties in two different soils (site 1: loam, site 2: sandy loam) from the Argentinean Pampas region under long-term NT treatments in order to determine if stabilization of soil physical properties is reached apart from a specific time in the crop sequence. In addition, we compared two procedures for evaluating water-conducting macroporosities, and evaluated the efficiency of the pedotransfer function ROSETTA in estimating the parameters of the van Genuchten-Mualem (VGM) model in these soils. Soil pore configuration and hydraulic properties were not stable and changed according to the crop sequence and the last crop grown in both sites. For both sites, saturated hydraulic conductivity, K 0 , water-conducting macroporosity, ε ε ε ε ε ma , and flow-weighted mean pore radius, R 0ma , increased from the 1 st to the 2 nd year of the crop sequence, and this was attributed to the creation of water-conducting macropores by the maize roots. The VGM model adequately described the water retention curve (WRC) for these soils, but not the hydraulic conductivity (K) vs tension (h) curve. The ROSETTA function failed in the estimation of these parameters. In summary, mean values of K 0 ranged from 0.74 to 3.88 cm h -1 . In studies on NT effects on soil physical properties, the crop effect must be considered.Index terms: infiltration, crop rotation, water-conducting porosity, no tillage, texture.( RESUMO: ESTABILIDADE DAS PROPRIEDADES HIDRÁULICAS DO SOLO EM UM SISTEMA DE PLANTIO DIRETO EM LONGO PRAZONos últimos anos, o sistema plantio direto (NT) tem aumentado. Alguns autores indicam que os atributos físicos do solo ficam estáveis após anos cultivando nesse sistema, sendo esse fato discutido por outros autores. O objetivo deste trabalho foi avaliar o efeito do último cultivo após a rotação (1º ano: milho; 2º ano: soja; e 3º ano: trigo/soja) sobre a configuração do sistema poroso do solo e das suas propriedades hidráulicas de diferentes tipos de textura (solo 1: franco; e solo 2: franco-arenoso) da região do pampa argentino, em NT por um longo prazo, para determinar se a estabilidade das propriedades físicas do solo independe do momento da rotação. Adicionalmente, foram comparados os procedimentos para avaliar a macroporosidade, bem como avaliada a eficiência da função de pedotransferência ROSETTA, para estimar os parâmetros do modelo de van Genuchten-Mualen (VGM) desses solos. A configuração do sistema poroso do solo e as propriedades hidráulicas não foram estáveis e se alteraram em razão da rotação da cultura e do último cultivo utilizado na rotação em ambos os solos. Nos dois locais, a condutiv...

Section: General Characteristicssupporting

confidence: 76%

Section: General Characteristicsmentioning

confidence: 99%

Section: Last Crop Effects On Soil Hydraulic Properties and On Soil Pmentioning

confidence: 99%

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Stabilization of soil hydraulic properties under a long term no-till system

Buda

et al. 2014

Self Cite

“…The other normally distributed variables were not transformed. show that tillage effects of BD do not persist until harvest (Ferreras et al, 2000;Sasal et al, 2006;Álvarez et al, 2006;Álvarez et al, 2009a, b;Soracco et al, 2010). Table 1 summarizes the statistical parameters of the K data set, calculated using the Ankeny method (Ankeny et al, 1991) In their study, the infiltration rates into Silty-Loam and SiltyClay Loam soils were particularly high under CT (around 23 cm/h).…”

Section: Resultsmentioning

confidence: 99%

Contribution of macroporosity to water flux of a soil under different tillage systems

Balbuena

et al. 2012

SUMMARYIn view of the importance of the macroporosity for the water transport properties of soils, its quantitative assessment is a challenging task. Measurements of hydraulic conductivity (K) at different soil water tensions and the quantification of water-conducting macropores ( M ) of a soil under different tillage systems could help understand the effects on the soil porous system and related hydraulic properties. The purpose of this study was to assess the effects of Conventional Tillage (CT), Chisel Plow (CP) and No Tillage (NT) on M and on K; and to quantify the contribution of macroporosity to total water flux in a loam soil. A tension disc infiltrometer was used at two soil water pressure heads (-5 cm, and 0) to infer M and K, during fallow. Macroporosity was determined based on the flow contribution between 0 and -5 cm water potentials (K 0 , K 5 , respectively), according to the HagenPoiseuille equation. The K 0 values were statistically higher for CT than for NT and CP. The K 5 values did not differ statistically among treatments. The mean K values varied between 0.20 and 3.70 cm/h. For CT, M was significantly greater than for CP a nd N T, follo wi ng t he s am e trend as K 0 . No differences in M were detected between CP and NT. With CT, the formation of water-conducting macropores with persi stenc e unti l p ost -ha rv est wa s p oss ible, while under C P p rep ara tio n, the w aterconducting macropores were not persistent. These results support the idea that tillage affects the soil water movement mainly by the resulting water-conducting macropores. Future studies on tillage effects on water movement should focus on macroporosity.Index terms: Tension disc infiltrometer, no tillage, chisel plow, conventional tillage, effective porosity.(

“…This effect can be determined through the measurement of saturated K in samples taken vertically and horizontally (Soracco et al, 2010;Lozano et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Effects of Compaction Due to Machinery Traffic on Soil Pore Configuration

Villarreal

et al. 2015

Soil compaction has been recognized as a severe problem in mechanized agriculture and has an influence on many soil properties and processes. Yet, there are few studies on the long-term effects of soil compaction, and the development of soil compaction has been shown through a limited number of soil parameters. The objectives of this study were to evaluate the persistence of soil compaction effects (three traffic treatments: T0, without traffic; T3, three tractor passes; and T5, five tractor passes) on pore system configuration, through static and dynamic determinations; and to determine changes in soil pore orientation due to soil compaction through measurement of hydraulic conductivity of saturated soil in samples taken vertically and horizontally. Traffic led to persistent changes in all the dynamic indicators studied (saturated hydraulic conductivity, K 0 ; effective macro-and mesoporosity, ε ma and ε me ), with significantly lower values of K 0 , ε ma , and ε me in the T5 treatment. The static indicators of bulk density (BD), derived total porosity (TP), and total macroporosity (θ ma ) did not vary significantly among the treatments. This means that machine traffic did not produce persistent changes on these variables after two years. However, the orientation of the soil pore system was modified by traffic. Even in T0, there were greater changes in K 0 measured in the samples taken vertically than horizontally, which was more related to the presence of vertical biopores, and to isotropy of K 0 in the treatments with machine traffic. Overall, the results showed that dynamic indicators are more sensitive to the effects of compaction and that, in the future, static indicators should not be used as compaction indicators without being complemented by dynamic indicators.