Rolling Pampa Region Research Articles

Size spectra of the edaphic fauna of typical Argiudol soils of the Rolling Pampa Region, Argentina.

Soil-dwelling organisms populate the spaces-referred to as interstices-between the litter on the soil surface and the pores in the soil's organo-mineral matrix. These organisms have pivotal roles in soil ecosystem functions, such as the breakdown and decomposition of organic matter, the dispersal of bacterial and fungal spores and biological habitat transformation. These functions, in turn, contribute to broader ecosystem services like carbon and nutrient cycling, soil organic matter regulation and both chemical and physical soil fertility.This study provides morphological data pertaining to a range of soil organism sizes, specifically in Argiudol soils subjected to varying levels of agricultural activity in the Rolling Pampas Region, one of the world's most extensive and fertile plains.The primary focus is on soil microarthropods-namely, Acari (mites) and Collembola (springtails)-with a body width of less than 2 mm. These organisms constitute the majority of life in the intricate soil pore network. Additionally, the study documents species of earthworms (Oligochaeta, Crassiclitelata), recognised as ecosystem engineers for their ability to create physical channels in the soil matrix and to distribute organic matter. Moreover, the study includes measurements of morphological traits of soil-dwelling "macrofauna" (organisms with a body width greater than 2 mm), which are also implicated in various soil ecosystem functions. These include population regulation by apex predators, organic matter decomposition, biogenic structure formation, nutrient mobilisation and herbivory. In this paper, we report both the geographical locations and individual measurements of key morphological traits for over 7,000 specimens, covering a range of soil-dwelling organisms. These include springtails (Entognatha, Collembola), mites (Arachnida, Acari), earthworms (Oligochaeta, Crassiclitellata) and additional soil macrofauna. All specimens were collected from typical Argiudol soils located in three distinct agricultural systems characterised by varying levels of land-use intensity. To our knowledge, no other dataset exists providing this information for the Argentinian Pampas.

Phosphorus downward movement in soil highly charged with cattle manure

In the rolling pampa region, the intensification of beef cattle feeding operations generates large volumes of solid organic manure which has high concentrations of phosphorus (P). This residue can be reused like organic fertilizer in agricultural practices, increasing crop production and closing the nutrients cycle. However, this practice can cause water pollution if not well managed. The aim was to study the vertical and temporal migration of P and its relations with edaphic properties in agricultural soil that has received a single heavy application of cattle manure. Three treatments were analyzed: (1) Zone 4 (Z4)—plot manured with 1600 tn ha−1 in 2004; (2) Zone 10 (Z10)—plot manured with 500 tn ha−1 in 2010 and (3) Zone control (ZC)—plot free of cattle manure. Water extractable phosphorus—WEP, soil test Bray and Kurtz P—Bray P, total phosphorus—TP, organic carbon—OC, pH and electrical conductivity were quantified. Results indicate high concentration of TP, Bray P and WEP in deeper horizons of impacted plots, showing the mobility of this nutrient. Correlation between TP and OC% were established for Z4 y Z10 in 88 and 84 %, demonstrating that the organic matter that moved in the profile presented high P content. An increase of salinity of 257 and 345 % for Z4 and Z10, respectively, was found in the deepest samples. The quantification of an empirical rate (EARP) showed the downward movement of P reaching 150 cm in Z4 and 90 cm in Z10. The results have shown that application of large volumes of solid manure saturated P retention capacity favoring its movement towards underlying water.

Compactión produced by combine harvest traffic: Effect on soil and soybean (Glycine max l.) yields under direct sowing in Argentinean Pampas

Abstract Soil compaction is caused by the high traffic intensity and tyre ground pressures of tractor and combines in harvesting, especially when these operations are carried out on wet soil or with high ground pressure tyres. Our main objective was to compare the effect of three combine harvester traffic intensities on soil compaction and soybean (Glycine max L.) yields cultivated under direct sowing (DS) in a Typic Argiudoll soil in the east of the Rolling Pampa region, Argentina. The treatments were: (1) combine harvester with high axle load and low ground pressure (C1TLGP), (2) combine harvester with medium axle load and medium ground pressure (C2TMGP) and (3) combine harvester with low axle load and high ground pressure (C3THPG). We hypothesised that the application of the different combine harvester traffic intensities produced soybean yield reductions and subsoil compaction on soil under continuous DS. In the topsoil (0–20 cm), the results show that after three years, the C3THGP treatment aplication produced higher cone index values than for the other treatments. In the subsoil (20–60 cm), the results show that during three growing seasons, the C1TLGP (total load = 152 kN) treatment aplication produced higher cone index values than other treatments The highest average root dry matter per plant (RDM) was found in the first growing season under the C1TLGP treatment. The average dry matter per plant (DMP) measurement was 1.77 g plant−1 in the C1TLGP treatment, followed by 1.55 g plant−1 in the C2TMGP treatment and 1.40 g plant−1 in the C3THGP treatment. The C3THGP treatment resulted in a significantly higher soybean yield (15.3, 21.0 and 22.1% in 2010, 2011 and 2012, respectively) than the C2TMGP and C1TLGP treatments. The main conclusions were that when argiudoll soil under DS system was trafficked with a high axle load >79.70 kN for three years, the cone index peaked in the subsoil to depths below 35 cm and soybean yields were significantly reduced. Soybean seedling emergence was not affected by high topsoil compaction produced by the tyre ground pressure of used combine harvesters. The soybean yield decreased with increased weight of the combine harvester.

Biological water contamination in some cattle production fields of Argentina subjected to runoff and erosion

Grain production has displaced livestock to marginal lands in most of the productive regions in Argentina since 1990. In the fertile Rolling Pampa region, extensive cattle production has been concentrated in lowlands subjected to flooding, salt excess, erosion and sedimentation processes but also in some feedlots recently located in sloping arable lands prone to soil erosion. We studied the concentration of microbiological contamination indicators in runoff water and sediments accumulated in depressions along the tributary network from these lands devoted to cattle production. The aims of this work were: (i) to gather a reliable set of data from different monitoring periods and scales, (ii) to search for simple and sensible variables to be used as indicators for surface water quality advising purposes and (iii) to corroborate previous biological contamination conceptual models for this region. Concentration of pollution indicators in these ponds was related to mean stocking rates from nearby fields and proved to depend significantly on the accumulated water and sediments. Viable mesophiles and total coliforms were found mainly attached to large sediments rather than in the runoff water phase. Seasonal sampling showed that the time period between the last significant runoff event and each sampling date regarding enterococci proved to be a sensible variable for predicting contamination. Enterococci concentration tended to increase gradually until the next extraordinary runoff event washed away contaminants. The mentioned relationship may be useful for designing early warning surface water contamination programs regarding enterococci dynamics and other related microbial pollutants as well.

Agricultural traffic: Motion resistance and soil compaction in relation to tractor design and different soil conditions

Farmers may desire a high cone index soil for tractive purposes or a low cone index (CI) soil for root penetration and seedling emergence. The function of any agricultural tractor is to provide mobility for itself and to power an implement. The aim of this paper was to (a) assess the impact of two tractors with different tyre sizes and axle loads on motion resistance (MR) and on the CI for three different soil mechanic conditions and (b) determine the existing relationships between MR and ground pressure parameters and tyre sinkage. Traffic was simulated with one pass on clay soil for a front-wheel assist tractor (FWA, load=77.7kN) and a four-wheel drive tractor (4WD, load=98.01kN) on three soil conditions: direct sowing systems, ploughed and seedbed. The outlined hypotheses were as follows: (1) there is a direct relationship between the subsoil compaction and the MR force of the FWA and 4WD tractors, and (2) the power loss produced by the MR depends on the soil mechanics. The experiment was conducted in the eastern section of the Rolling Pampa region of Argentina at 34°36′S, 58°40′W. MR, rut depth (RD) and CI were measured. The MR mean values of the 4WD were 9.30, 6.59 and 2.31kN for ploughed, seedbed and direct sowing soil, respectively, whereas the values for the FWA were 10.41, 7.91 and 4.67kN, respectively. For the three soil conditions, no significant differences were found in the RD between the 4WD and FWA. For the topsoil level (0–150mm), one FWA pass caused mean values in the CI of 2150, 1835 and 1780kPa for direct sowing, seedbed and ploughed soil, respectively, whereas for 4WD the values were 1890, 1640 and 1587kPa, respectively. For the subsoil (150–600mm), 4WD caused higher CI values than the FWA. The CI mean values of the 4WD were 2477, 2240 and 1890kPa for direct sowing, seedbed and ploughed soil, respectively, whereas the values for the FWA were 2240, 1870 and 1770kPa, respectively. For the different soil conditions, the subsoil compaction increased as the total axle load increased, independently from the ground pressure. Moreover, for both tractors, a greater MR force was observed in the soil with the lowest bearing capacity. The smallest power loss ratio due to MR and engine power was found with the 4WD.

Effects of different tillage regimes on soil compaction, maize ( Zea mays L.) seedling emergence and yields in the eastern Argentinean Pampas region

Crop establishment depends primarily on the methods used for seedbed preparation and sowing. Our main objective was to evaluate the soil compaction and crop residue effects on maize ( Zea mays L.) seedling emergence and yields in three tillage regimes: direct sowing (DS), chisel plough (ChP) and mouldboard plough (MP). The current study was performed in the eastern section of the humid subtropical Rolling Pampa region, Buenos Aires State (Argentina) between October 2004 and March 2007. The soil of the study site is a typical Argiudoll. We hypothesised that maize yields are affected by different tillage regimes used for seedbed preparation and that the traffic for the three tillage regimes caused subsoil compaction. The variables measured were: (1) cone index (CI) in the 0–450 mm depth profile; (2) root dry matter per plant (RDM); (3) dry matter per plant (DMP); (4) seedling emergence (SE); and (5) maize yields (MY). The results showed that in DS, the high soil compaction level causes smaller yields (decrease between 10.7 and 15.2%) compared with the other two tillage systems. SE was slower under ChP and MP compared with DS, but similar results were achieved 18 days after sowing. The highest RDM average values for three growing seasons were observed in ChP and MP (42.3 and 46.1 g plant −1, respectively) compared to DS (37.1 g plant −1). The study produced the following conclusions. Maize yield was directly related to root dry matter per plant, which was affected by soil compaction. The soil Ap horizon needs to be tilled to improve yields. Despite the greater number of tractor passes in ChP and MP, all systems caused subsoil compaction. SE was not affected by plant residue.

Seedbed compaction produced by traffic on four tillage regimes in the rolling Pampas of Argentina

The main function of primary tillage is to increase the soil's structural macro-porosity, but during secondary tillage operations over these freshly tilled soils, traffic causes significant soil compaction. In terms of soil conservation however, there is evidence that direct sowing is a more sustainable system, even though there is still insufficient information about the rheology of a non-tilled soil under traffic. The objective of this study was to compare the traffic intensity and soil compaction caused by four different tillage regimes currently used by Argentinean farmers (1 direct sowing with a tractor and planter weighing 127 kN and 3 conventional tillage systems with equipment weighing 55.2 kN). The work was performed in the east of the Rolling Pampa region, Buenos Aires State, Argentina at 34°25′S, 59°15′W. Variables measured were: (1) cone index in the 0–450 mm depth profile; (2) bulk density; (3) total soil porosity; and (4) rut depth. (a) Results indicated that in the depth range 0–150 mm with all tillage treatments, bulk density and cone index values generated by tractor traffic were greater than the 1.3 Mg m −3 and 1400 kPa respectively. Similarly in deeper layers these parameters were greater than 1.45 Mg m −3 and 2000 kPa respectively. Measurements revealed that traffic reduced topsoil porosity under direct sowing by an average of 7% and under conventional tillage by 7.6–14.8% confirming that both systems cause both topsoil and subsoil compaction.

Topsoil Properties as Affected by Tillage Systems in the Rolling Pampa Region of Argentina

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.

Effect of the number of tractor passes on soil rut depth and compaction in two tillage regimes

The initially high level of soil compaction in some direct sowing systems might suggest that the impact of subsequent traffic would be minimal, but data have not been consistent. In the other hand on freshly tilled soils, traffic causes significant increments in soil compaction. The aim of this paper was to quantify the interaction of the soil cone index and rut depth induced by traffic of two different weight tractors in two tillage regimes: (a) soil with 10 years under direct sowing system and (b) soil historically worked in conventional tillage system. Treatments included five different traffic frequencies (0, 1, 3, 5 and 10 passes repeatedly on the same track). The work was performed in the South of the Rolling Pampa region, Buenos Aires State, Argentina at 34°55′S, 57°57′W. Variables measured were (1) cone index in the 0–600 mm depth profile and (2) rut depth. Tyre sizes and rut depth/tyre width ratio are particularly important respect to compaction produced in the soil for different number of passes. Until five passes of tractor (2WD), ground pressure is responsible of the topsoil compaction. Until five passes the tyre with low rut depth/tyre width ratio reduced topsoil compaction. Finally, the farmer should pay attention to the axle load, the tyre size and the soil water content at the traffic moment.

Soil compaction produced by tractor with radial and cross-ply tyres in two tillage regimes

The aim of this paper was to quantify soil compaction induced by tractor traffic on two tillage regimes: conventional tillage and direct drilling. Traffic was simulated with one pass of a conventional 2WD tractor, using four configurations of cross-ply rear tyres: 18.4–34, 23.1–30, 18.4–38 and 24.5–32, and four configurations of radial tyres 18.4R34, 23.1R 30, 18.4R 38 and 24.5R 32, with two ballast conditions used in each configuration. The experiment was conducted in the east of the Rolling Pampa region, Buenos Aires State, Argentina at 34°25′S, 59°15′W; altitude 22 m above sea level. Rut depth after traffic and soil bulk density and cone index in a 0–450-mm profile were measured before and after traffic. Considering topsoil level, in two tillage regimes, all treatments induced significant values of soil compaction as compared to the control plot without traffic. Subsoil compaction increased as total axle load increased and was independent of ground pressure. For the same tyre configuration, radial tyre caused less soil compaction than the cross-ply.

Effects of supplementary irrigation on chemical and physical soil properties in the rolling pampa region of Argentina.

The effects of supplementary irrigation on soil chemical and physical properties were studied in 21 locations in the north of the rolling pampa region of Argentina. The chemical and physical variables were measured in top soil (0-100 mm) to compare irrigated and non-irrigated soils. Chemical variables were: electrical conductivity (EC), pH, exchangeable sodium percentage (ESP), and organic mater content. Physical variables included structural index (SI) and percolation index (PI) measured in the laboratory, as well as infi ltration, runoff, and soil losses, measured in the field with a small portable rainfall simulator. Water quality was established according to its chemical composition and Riverside USA classifi cation. In irrigated soils, chemical data shows, on average, a slight increase in ESP (from 2.56 to 5.52) and in pH (from 6.13 to 6.45). EC, SI, and PI show the same values in irrigated and non-irrigated soils. The application of a simulated rainfall of 30 mm in 30 min revealed a different soil behavior. Irrigated soils present lower values of water entry and infi ltration rates, and higher values of runoff and soil losses. The variation in chemical and physical soil properties show that within 10 years of supplementary irrigation a slight process of sodication and alkalinization occurs. Water quality and soil chemical data suggest that the sodication process and the increased soil erosion risk must be controlled in order to achieve a sustainable high production system. En 21 localidades del norte de la region pampaena de Argentina se estudiaron los efectos del riego suplementario sobre las propiedades quimicas y fisicas del suelo. Los parametros quimicos y fisicos se midieron entre 0 y 100 mm en los suelos con y sin riego suplementario. Los parametros quimicos del suelo considerados fueron: conductividad electrica (CE), pH, porcentaje de sodio intercambiable (PSI) y materia organica. Los parametros fisicos: estabilidad de estructura indice de percolacion de laboratorio infiltracion a campo, escurrimiento y perdida de suelo, con un micro simulador de lluvia portatil. En suelos bajo riego, los analisis quimicos mostraron un pequeno incremento del PSI, de 2.56 a 5.52 y en pH, de 6.13 a 6.45, respecto a los suelos sin riegos. Sin embargo, la CE se mantuvo en los mismos valores para ambos sistemas. La aplicacion de lluvia simulada de 30 mm por 30 min mostro diferentes comportamientos del suelo. Los suelos bajo riego dieron valores menores de entrada de agua y de tasa de infiltracion, y mayores valores de escurrimiento y perdida de suelo. La variacion de las propiedades quimicas y fisicas de los suelos despues de 10 anos de riego suplementario, muestra que se ha producido un avance moderado de los procesos de sodificacion y alcalinizacion. La calidad del agua de riego y los parametros quimicos de los suelos bajo riego, sugieren que el proceso de sodifi cacion y el incremento del riesgo de erosion deben ser controlados para mantener un sistema de alta productividad.

Effects of supplementary irrigation on chemical and physical soil properties in the rolling pampa region of Argentina

AbstractR. Mon, C. Irurtia , G. F. Botta , O. Pozzolo , F. Bellora Melcon , D. Rivero , and M. Bomben. 2007. Effects of supplementary irrigation on chemical and physical soil properties in the rolling pampa region of Argentina. Cien. Inv. Agr. 34(3):187-194 . The effects of supplementary irrigation on soil chemical and physical properties were studied in 21 locations in the north of the rolling pampa region of Argentina. The chemical and physical variables were measured in top soil (0-100 mm) to compare irrigated and non-irrigated soils. Chemical variables were: electrical conductivity (EC), pH, exchangeable sodium percentage (ESP), and organic mater content. Physical variables included structural index (SI) and percolation index (PI) measured in the laboratory, as well as infi ltration, runoff, and soil losses, measured in the fi eld with a small portable rainfall simulator. Water qualit y was established according to its chemical com position and Riverside USA classi fi cation. In irri gated soils, chemical data shows, on average, a slight increase in ESP (from 2.56 to 5.52) and in pH (from 6.13 to 6.45). EC, SI, and PI show the same values in irri gated and non-irri gated soils. The a pplication of a simulated rainfall of 30 mm in 30 min revealed a different soil behavior. Irri gated soils present lower values of water entry and infi ltration rates, and higher values of runoff and soil losses. The variation in chemical and physical soil properties show that within 10 years of supplementary irrigation a slight process of sodication and alkalinization occurs. Water quality and soil chemical data suggest that the sodication process and the increased soil erosion risk must be controlled in order to achieve a sustainable high production system.

Traffic alternatives for harvesting soybean ( Glycine max L.): Effect on yields and soil under a direct sowing system

This initially high level of soil compaction in some direct sowing systems might suggest that the impact of subsequent traffic would be minimal, but data have not been consistent. Soil compaction is caused by the high traffic intensity and weight of tractor and combines in harvest operations, especially when these operations are carried out on wet soil or with high-pressure tyres. Traffic effects on the yield of soybean and on some physical soil properties were studied over a period of 3 years. After this period, the reduction of traffic intensity from 38 to 15 Mg km −1 ha −1 produced an increase on the yields of 29.2% from the base year improving the incomes by US$134 ha −1 besides the reduction of fuel consumption of 35.5%. With the results obtained in this work it can be assumed that traffic reduction at harvest has a good potential to increase yields and reduce soil compaction under direct sowing system on the Rolling Pampa Region, Argentina.

Light tractor traffic frequency on soil compaction in the Rolling Pampa region of Argentina

Direct seeding production in Argentina requires frequent traffic with farm machinery, in example 6–12 passes. The initially high level of soil compaction in some no till systems might suggest that the impact of subsequent traffic would be minimal, but data have not be consistent. Our objective was to quantify soil mechanical behavior related to compaction from farm machinery traffic on Typic Argiudoll under wheat ( Triticum aestvium L. Merr.), soybean ( Glycine max L. Merr.) rotation in the northeastern Rolling Pampa region at Argentina. Treatments included five different traffic frequencies (0, 6, 8, 10 and 12 passes of a two wheel-drive, 52 kW tractor running repeatedly on the same track). Total weight of the tractor was 3.1 Mg, with 1.0 and 2.1 Mg on the front and rear axles using 7.50 × 16 and 18.4 × 34 tyres, respectively. The speed of tractor traffic was 5.5 km h −1. Variables measured were: (1) soil bulk density, (2) cone index in the 0–600 mm depth profile and (3) rut depth. Only 10 and 12 tractor passes produced significant increases in cone index and dry bulk density throughout the soil profile. Dry bulk density and cone index increased with number of passes. All frequencies compacted the top soil generating physical soil conditions that would be unsuitable for seedling emergence. Although soil had high bulk density prior to traffic treatments, a significant increment of compaction still occurred due to the high traffic frequencies applied.

PA—Precision Agiculture: Wheel Traffic Influence on Poplar Regeneration and Grass Yield

All transport in forest stands occurs on the ground that at the same time is used as a growth substrate, not only for timber production but for grass as well in several Argentine production systems. Heavy traffic will damage the ground vegetation, affect tree roots and compact the soil to a degree where the tree roots have difficulty in regenerating in the damaged zone. The main objective of this research was to evaluate changes in soil compaction, introduced by traffic, during harvesting operations in a timber forest where grass production is also used for cattle feeding. Four experimental variables were measured: changes in bulk density in the profile, changes in penetration resistance, grassland yield and forest plantation regeneration after harvesting traffic. The work was performed in the south of the Rolling Pampa region, Argentina. The soil was a fine clayey, illitic, thermic Typic Argiudoll. Treatments consisted of four different traffic intensities, due to different passes of a tractor pulling a trailer on the inter-row area of the plantation, during harvesting operations. Increasing the number of traffic passes, increased the depth at which differences in cone penetration resistance values began to be significantly higher.The increments in bulk density values after traffic were not so evident as those in penetration resistance values, but the same tendencies were shown. The least traffic intensity, corresponding to only one pass, resulted in a reduction of grass yield (40·3%) in comparison with the control (no traffic) treatment, although there was no effect on tree regeneration. Traffic within the plantation impacted principally on tree shoot mortality, with a maximum of 51·5%, measured 1 year after traffic, recorded in the ten pass treatment. Grassland production within the plantation, after harvesting operations, was directly associated with forest regrowth.

Influence of the axle load, tyre size and configuration on the compaction of a freshly tilled clayey soil

Enhancement of the potential root growth volume is the main objective of farmers when they establish a conventional tillage system. Therefore, the main function of primary tillage is to increase soil’s structural macroporosity. In spite of this, during secondary tillage operations on these freshly tilled soils, the traffic on seedbeds causes significant increases in soil compaction. The aim of this paper was to quantify soil compaction induced by tractor traffic on a recently tilled non consolidated soil, to match ballast and tyre size on the tractors used during secondary tillage. The work was performed in the South of the Rolling Pampa region, Argentina. Secondary tillage traffic was simulated by one pass of a conventional 2WD tractor, using four configurations of bias-ply rear tyres: 18.4×34, 23.1×30, 18.4×38 and 18.4×38 duals, two ballast conditions were used in each configuration. Soil bulk density and cone index in a 0 to 600 mm profile were measured before and after traffic. Topsoil compaction increased as did ground pressure. Subsoil compaction increased as total axle load increased and was independent from ground pressure. At heavy conditions, topsoil levels always showed higher cone index values. From 150 to 450 mm depth, the same tendency was found, but with smaller increases in the cone index parameter, 22 to 48%, averaging 35%. Finally, at the deepest layer considered, 600 mm, differential increases due to the axle load are great enough as to be considered similar to those found in the upper horizon, 36 to 64%, averaging 55%. On the other hand, bulk density tended to be less responsive than cone index to the traffic treatments. Topsoil compaction can be reduced by matching conventional bias-ply tyres with an optimized axle weight.