Descompactación de suelos en siembra directa: efectos sobre las propiedades físicas y el cultivo de maíz
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Abstract:
No-tilled soils have higher penetration resistances and bulk density values than tilled soils. Shallow compaction may be alleviated using deep tillage practices. The objectives of this study were to determine the effects of soil alleviation on: 1- soil physical properties at maize sowing and harvest, 2- root abundance, maize yield and its components. Three experiments were conducted during the 2004/05 growing season. The experiments had a complete block design, with 2 treatments (control and deep-tilled) and 3 replicates, and were located at Junin, San Gregorio and Chivilcoy. Soil bulk density, soil water content, soil penetration resistance and infiltration rate were determined at maize sowing and harvest. At flowering maize root abundance, intercepted photosynthetic active radiation and leaf greenness were determined. Additionally, yield and its components were measured. Soil alleviation increased infiltration rate at sowing (P<0,05), but there were no differences at harvest. Soil alleviation reduced penetration resistances at sowing by 54%, 28%, 42 % at Junin, San Gregorio and Chivilcoy, respectively (P<0,05). Deep tillage increased root abundance at flowering at Junin and Chivilcoy (P<0,05). Maize yield showed a positive and statistically significant increase with soil alleviation. However, its magnitude was only 6,5% more than control yield. This result was in accordance with a 3% increase in intercepted photosynthetic active radiation. Yield response to subsoiling was positively related with the original soil bulk density at each site. Although the measured changes might improve water use efficiency, little impact on yield was observed due to a relatively humid cropping season. More research is needed in order to establish crop response in a wide range of water availability and soil compaction conditions.Keywords:
Conventional tillage
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Infiltrometer
Permeameter
Infiltration (HVAC)
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Macropore
Infiltration (HVAC)
Soil Compaction
Temporal scales
Soil Management
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Macropore
Soil structure
Infiltration (HVAC)
Bulk soil
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Abstract Disc permeameters are designed to measure hydraulic properties of field soils containing macropores and preferential flow paths and are particularly useful in soil management studies. We present here designs for disc permeameters for both positive and negative water supply heads. The effects of the water supply membrane and soil contact material on permeameter performance are examined using approximate quasi‐analytic solutions to the flow equation. This analysis provides approximate criteria for the selection of membrane and soil contact materials. Limitations to performance caused by restricted air entry are considered and design criteria are given also. We present in situ tests of the disc permeameter for the early stages of one‐dimensional infiltration and an example of the deterministic variation of sorptivity of a field soil with supply potential. Finally, we use ponded and unsaturated sorptivities measured in situ with disc permeameters to find the saturated hydraulic conductivity and flow‐weighted mean characteristic pore dimension of a field soil.
Permeameter
Sorptivity
Infiltration (HVAC)
Macropore
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Improved topsoil structural quality is expected under no‐till farming, but soil physical constraints can develop under continuous no‐till. Our objectives were: to evaluate the properties of loam, silty loam, and silty clay loam soils under various management practices on a regional scale; to clarify the relationship between soil organic matter pools and soil physical properties; and to find a minimum set of topsoil properties to characterize trends established by tillage. Thirty‐nine loam, silty loam, and silty clay loam soils were sampled from cropped fields managed using conventional tillage (CT) and no‐till (NT) as well as six undisturbed soils (uncropped). The A horizon thickness did not differ among soil textural groups and was 4 cm thicker in uncropped soils. Total and particulate organic C were significantly affected by management (uncropped > CT = NT, P < 0.001). Soil structural instability of uncropped soils (0.317 mm) differed from CT soils (0.723 mm) but not from NT soils (0.573 mm). Soil structural instability was negatively related to total and particulate organic C, and no relation was found with the resistant organic C pool. Water infiltration rate was the only topsoil property affected by a significant texture × management interaction. Lower infiltration rates in NT silty soils were caused by platy structural forms with horizontal pores. Soil penetration resistance (0–5 cm) was 0.77 MPa higher in NT than in CT soils. A minimum set of topsoil properties to evaluate tillage management includes structural instability, total or particulate organic C, infiltration rate, and penetration resistance.
Topsoil
Soil structure
Infiltration (HVAC)
Soil texture
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