ABSTRACT Increasing the use of nitrogen (N) fertilizers will be necessary to enhance grain and pasture yields to satisfy the growing world demand for food. Organic amendments, such as farm dairy effluents (FDE), are an alternative to traditional synthetic fertilizers. However, part of the applied N could be lost as ammonia (NH3) volatilization or nitrous oxide (N2O) emission, decreasing N availability to plants. Nitrification inhibitors, such as dicyandiamide (DCD), suppress the microbial process of nitrification, decreasing soil nitrate concentration and, therefore, N2O emission. Reducing N2O losses from agricultural soils is a key subject for sustainable production. This research aimed to quantify the effect of DCD addition to the FDE on the emissions of N2O and the volatilization of NH3 from the soil. A field trial was carried out in which NH3 volatilization and N2O emission were measured over 49 days after applying FDE, FDE with DCD (DCD), and control (C, without N added) treatments. The amount of N applied as FDE was 120 kg of N ha-1. Accumulated N2O emission during the 49 days after the application was 526, 237, and 174 g N2O-N ha-1 from the soil in the FDE, DCD, and C treatments, respectively. No significant differences were observed in accumulated NH3 volatilization. Pasture yield was higher in DCD treatment, followed by C and FDE. Under low temperatures and high soil moisture conditions, adding DCD to the FDE could be considered an effective alternative to increase pasture yields, decrease N2O emissions, and maintain NH3 volatilization, reducing total N losses to the atmosphere by about 14 %. Adding DCD to the FDE is a promising alternative for the more efficient N use of farm dairy effluents as fertilizer to mitigate N losses, tending to reduce N losses as N2O emissions. More studies are necessary to verify the result of using FDE + DCD under different soils and climates. (N food amendments , (FDE) However NH (NH3 NO O (N2O plants inhibitors (DCD) nitrification therefore production 4 C, (C added treatments 12 ha1. ha1 ha 1. 1 526 237 17 N2ON NON ha- respectively treatment conditions % climates (FDE (NH (DCD 52 23 ON 5 2

Resumen La industria del olivo genera grandes volúmenes de residuos con un impacto negativo sobre el medio ambiente. El objetivo del presente trabajo fue evaluar el efecto del compost y té de compost de alperujo sobre el crecimiento y rendimiento del olivo, cv. ‘Arbequina’, así como su forma de aplicación. El ensayo se realizó en el Departamento Pomán, Catamarca, Argentina, durante 4 años. Se evaluó la aplicación al suelo de compost de alperujo (AS), y tratamientos foliares de un té de compost (AL) obtenido a partir del AS, en comparación con un tratamiento control (C). Estos tratamientos se aplicaron en un lote regado y en otro fertirrigado con AL. Se evaluó el crecimiento de los ramos del año y la evolución de la sección transversal del tronco, contenido de nitrógeno (N), fósforo (P) y potasio foliar; número, tamaño y volumen de los frutos. Los datos se analizaron ajustando un modelo mixto jerárquico con años como bloques aleatorios y los factores Lote y Tipo de fertilización como efectos fijos. Este último se anidó dentro de la interacción Riego:Año. La aplicación de AS y AL repercutió favorablemente en la concentración foliar de N (+17,3 y 24,8%, respectivamente), mientras que el P foliar fue incrementado en un 30,0% por el AS en la parcela con riego. El crecimiento de los ramos del año fue promovido por el AS (+56,2%) en la parcela con riego, mientras que el rendimiento de los frutos aumentó en respuesta al fertirriego con AL, entre el 68,2 y 83,8% según el abono adicional utilizado.

Abstract The olive industry generates a large amount of residues with a negative impact on the environment. The aim of this research was to evaluate the effect of solid compost and compost tea from olive mill waste and their method of application on the growth and yield of olive cv. ‘Arbequina’. The experiment was carried out in the Poman Department, Catamarca province, Argentina, for four years. Treatments were the application to the soil of compost from olive mill waste (solid compost, AS), foliar application of compost tea obtained from AS (compost tea, AL), and the control (C). These treatments were applied in an irrigated plot and in a fertigated plot with AL. Shoot growth, nitrogen (N), phosphorus (P), and potassium foliar content, and the size and number of fruits per plant were evaluated. Data were analyzed with a hierachical mixed model, with years as random blocks and the factors plot and fertilization type as fixed effects. The latter was nested into an irrigation:year interaction. Solid compost and AL application improved foliar N content (+17.3 and 24.8%, respectively), whereas the P foliar concentration under irrigation was increased by 30%. Shoot growth was increased up to 56.2% by AS under irrigation, whereas fruit yield increased in response to AL fertigation (68.2 to 83.8%), depending on the additional organic manure treatment.

ABSTRACT The intensification of dairy production systems has resulted in a higher generation of waste. The aim of this study was to evaluate the impact of different doses of farm dairy effluent (FDE) applied to the soil on aerial biomass production, persistence and chemical composition of alfalfa pastures, in Santa Fe province, Argentina. The study was conducted in four randomized complete blocks with four treatments (FDE doses): 0 m3 ha-1 (T0: without FDE), 82 m3 ha-1 (T1: low rate), 151 m3 ha-1 (T2: medium rate) and 282 m3 ha-1 (T3: high rate). The soil application of FDE increased the total aerial biomass produced (ABP) but reduced the persistence of plants. Total nitrogen (Nt) of alfalfa was significantly higher, but phosphorus (P) concentrations did not vary after the application of FDE to the soil . Ca and Mg concentrations in plants were lower in T3 compared to T0, which can be explained by the imbalance produced in the soil after FDE was applied, presenting high levels of Na, K and NH4-N but low levels of Ca and Mg. Soil application of FDE on alfalfa pastures must be carefully planned in terms of composition and amount to be applied in order to increase biomass production, prevent the decrease in persistence, and control changes in the mineral composition of plants.

RESUMEN Las prácticas de manejo pueden alterar la estructura del suelo, influyendo sobre la disponibilidad de agua, la difusión de oxígeno y la resistencia mecánica con consecuencias en la productividad. El intervalo hídrico óptimo (IHO) es una herramienta útil, ya que integra los mencionados efectos. Se plantea que el IHO permite detectar mejor las diferencias entre sistemas de labranza en la disponibilidad de agua. La experiencia se realizó en el sudoeste bonaerense (SOB) en dos sistemas de labranza, siembra directa (SD) y labranza convencional (LC). Las muestras de suelo se tomaron cada 5 cm hasta los 20 cm de profundidad y se determinó retención de agua, resistencia a la penetración (RP) y densidad aparente (DA) para calcular el IHO. En SD se encontraron los valores más altos de RP y DA. El IHO osciló entre 0,024 y 0,095 cm3 cm-3 en SD y 0,007 y 0,110 cm3 cm-3 en LC. El valor de DA donde la θRP reemplazó a θPMP como límite inferior del IHO fue 1,26 g cm-3 para LC y 1,29 g cm-3 para SD, encontrándose 20% de las muestras por encima de este valor en LC y 42 % en SD. LC presentó IHO mayor hasta DA 1,28 g cm-3, a partir de este valor disminuyó más rápidamente que SD quien presentó valores de IHO mayores a densidades superiores. La proyección de los límites críticos, mostraron que se alcanzaría la DA crítica a un valor mayor en SD que en LC (1,49 y 1,40 g cm-3, respectivamente) demostrando mejor condición física de este manejo. Para evaluar la sensibilidad del IHO se utilizaron 3 valores límite de θRP. La pendiente del IHO siempre fue menor en SD, indicando que la amplitud del IHO se reduce más suavemente con el aumento de DA en comparación a LC. Los resultados de este estudio sugieren al IHO como indicador para evaluar la disponibilidad hídrica en suelos del SOB con diferentes manejos.

SUMMARY Management practices can alter soil structure, influencing water availability, oxygen diffusion, and mechanical resistance with consequences on productivity. Least limiting water range (IHO) is a useful tool, since it integrates these effects. It is suggested that the IHO allows showing tillage systems differences in the availability of water. The experience was carried out in the SW of Buenos Aires province (SOB) with two tillage systems, no- (SD) and conventional-tillage (LC). Soil samples were taken every 5 cm up to a depth of 20 cm and water retention, penetration resistance (PR) and bulk density (DA) were determined to calculate the IHO. Highest values of RP and DA were found in SD. The IHO ranged between 0.024 to 0.095 cm3 cm-3 in SD and 0.007 to 0.110 cm3 cm-3 in LC. The value of DA where θRP replaced θPMP as the lower limit of the IHO was 1.26 g cm-3 for LC and 1.29 g cm-3 for SD, with 20% of the samples above this value in LC and 42% in SD. LC presented higher IHO up to Da 1.28 g cm-3, from this value it decreased more rapidly than SD who presented higher IHO values at higher densities. The projection of the critical limits showed that the critical DA would be reached at a higher value in SD than in LC (1.49 and 1.40 g cm-3, respectively), showing better physical condition under no tillage soil. To evaluate the sensitivity of the IHO, 3 cutoff values of θRP were used. The slope of the IHO was always lower in SD, indicating that the amplitude of the IHO decreases more slowly with the increase in DA compared to LC. The results of this study suggest the IHO as an indicator to evaluate the water availability in SOB soils under different tillage.

ABSTRACT Composting is the most recommended organic waste management technique worldwide. These residues can have various origins, they can even be the result of the industrial processing of agricultural products, such as alperujo, which results from the extraction of oil from olives. This residue, once composted, has the potential to generate a compost of good quality that can be used as an amendment and / or organic fertilizer. However, little information exists regarding the quality of the compost made from alperujo with pruning remains from olive groves. The objective of the present work was to characterize physically, chemically and microbiologically the compost obtained from the composting of olive residues, both in the solid (AS) and liquid (AL) form. In addition, the presence of phytotoxic substances was analyzed through the germination test with different horticultural species. The trials comprised four productive periods. The chemical, physical and microbiological evaluated parameters (organic carbon, pH, electrical conductivity, nitrogen, phosphorus, potassium, soluble cations, polyphenols, biological activity, bulk density, particle density, porosity) are within the range considered adequate in both AS and AL. Phytotoxic effects of LA were not detected in the evaluated species. The results indicate that both fertilizers present highly recommended characteristics for their use as amendment and / or organic fertilizer, and that AL is capable of promoting germination in spinach, parsley, basil and alfalfa.

RESUMEN El compostaje es la técnica de manejo de los residuos orgánicos más recomendada mundialmente. Estos residuos pueden tener variados orígenes, inclusive pueden ser resultado del procesamiento industrial de productos agrícolas, como es el caso del alperujo, que resulta de la extracción de aceite de las aceitunas. Este residuo, una vez compostado, tiene potencial de generar un abono de buena calidad que puede ser aprovechado como enmienda y/o fertilizante orgánico. Sin embargo, escasa información existe respecto de la calidad que poseen los compost elaborados a base de alperujo con restos de poda de los olivares. El objetivo del presente trabajo fue caracterizar física, química y microbiológicamente el abono obtenido del compostaje de los residuos olivícolas, tanto en forma sólida (AS) como líquida (AL). Además, se analizó la presencia de sustancias fitotóxicas a través del test de germinación con diferentes especies hortícolas. Los ensayos comprendieron cuatro períodos productivos. Los parámetros químicos, físicos y microbiológicos evaluados (carbono orgánico, pH, conductividad eléctrica, nitrógeno, fósforo, potasio, cationes solubles, polifenoles, actividad biológica, densidad aparente, densidad de partículas, porosidad) se encuentran del rango considerado adecuado en AS y en el AL. No se detectó efectos fitotóxicos del AL en las especies evaluadas. Los resultados indican que ambos abonos presentan características altamente recomendables para su utilización como enmienda y/o fertilizante orgánico, y que el AL es capaz de promover la germinación en espinaca, perejil, albahaca y alfalfa.

ABSTRACT Several factors interact controlling ammonia (NH3) volatilization contributing to the variability of results reported in the literature. In the milkmaid basin of Santa Fe there is no information on nitrogen loss through NH3 volatilization from dairy cattle slurry (DCS) applied to soil. The objective of this study was to quantify NH3 volatilization from application of different rates of dairy cattle slurry in winter and summer in a soil in the central region of Santa Fe (Argentina). A field experiment was carried out and four treatments were applied. The treatments included the application of three different doses of DCS: D1 = 60 m3 ha-1, D2 = 120 m3 ha-1, D3 = 180 m3 ha-1 and a control treatment without application (D0). The experiment was conducted in summer (February) and winter (July) in a randomized complete design with two replications. The NH3 volatilization was significantly higher in the summer than in the winter. The volatilization initial rates were not affected by the DCS rates applied in the different seasons of the year. The decrease in NH3 volatilization rates was related to the season of the year. The NH3 volatilization rates decrease faster in DCS treatments compared to control. This study demonstrated that NH3 volatilization was strongly related to the season of the year and to a lesser extent with the DCS rates applied.

RESUMEN Los factores involucrados en la volatilización de amoníaco (NH3) son diversos e interactúan entre sí, lo que genera variabilidad en los resultados reportados en la literatura. En el centro de la cuenca lechera santafesina no existe información sobre las pérdidas de nitrógeno por volatilización generadas a partir de la aplicación al suelo de efluentes líquidos de tambo (ELT). El objetivo de este estudio fue cuantificar la volatilización de NH3 luego de la aplicación de diferentes dosis de efluentes líquidos de tambo en invierno y verano en un suelo de la región centro de Santa Fe (Argentina). El experimento se realizó a campo y se aplicaron cuatro tratamientos que consistieron en la aplicación de tres dosis diferentes (D1= 60 m3 ha-1, D2 = 120 m3 ha-1, D3 = 180 m3 ha-1) de ELT y un tratamiento testigo sin aplicación (D0). El experimento fue realizado en verano (febrero) y en invierno (julio) siguiendo un diseño completamente aleatorizado con dos repeticiones. La volatilización de NH3 fue significativamente mayor en verano respecto de invierno. Las tasas iniciales de volatilización de NH3 no fueron afectadas por las dosis de ELT aplicadas en las distintas estaciones del año. La disminución de las tasas de volatilización estuvo relacionada con la estación del año y decrecieron más rápido en los tratamientos con ELT comparado con el testigo. Los resultados demuestran que la volatilización de NH3 está fuertemente relacionada con la estación del año y en menor medida con la dosis de ELT aplicada.

Soils degradation in central-north region of Santa Fe province and the consequent loss of productivity of the agricultural systems is attributed to two main factors: soil compaction due to tillage and machinery traffic, and loss of chemical fertility. The technological practices of decompaction and fertilization has been propoused to reverse these problems, to increase the resources use efficiency and, consequence, the dry matter production and crop yields. The aim o of this study was to evaluate changes produced in the physical quality of the soil and the yield achieved in the sequence soybean-wheat during the growing seasons 2008/2009 (GS1), 2009/2010 (GS2) and 2010/2011 (GS3) in field conditions with two levels of compaction (decompacted 'd' and without decompacted 'wd') on a soil aquic argiudol in Esperanza (Santa Fe province, Argentina). The experimental design was in randomized complete blocks and three repetitions. Different scenarios differed from the view point of water; where they could be mentioned as: (i) GS1 for very dry to dry soybeans and wheat; (ii) GS2 wet for soybeans and good water reserve in the soil for wheat; (iii) GS3 moderately dry to wet to soybeans and wheat. The results indicate the persistence of the residual positive effect of the initial decompaction on soil resistance penetration (SR) and soil aeration porosity (Ap) after 3 years of work. The treatments -wd- showed a tendency of subsurface improvement in the values soil bulk density (Bd) and SR, which could be due to the effect of the roots of the wheat crop on the soil in the wheat / soybean sequence. The achieved yields improved under conditions d. The year strongly influenced the yield of rainfed crops.

La degradación de los suelos de la región centro-norte de la provincia de Santa Fe y la consecuente pérdida de productividad de los sistemas agrícolas se atribuye a dos factores principales: la compactación -producida por el laboreo y tránsito de la maquinaria- y la pérdida de fertilidad química. Las prácticas tecnológicas de descompactación del suelo y fertilización estratégica han sido propuestas para revertir esos problemas, aumentando la producción de materia seca y el rendimiento. El objetivo general fue evaluar los cambios producidos en la calidad física del suelo y el rendimiento logrado en la secuencia soja-trigo durante 3 años (2008/2009 -C1-, 2009/2010 -C2- y 2010/2011 -C3-), en condiciones de campo con dos tratamientos: descompactado (d) y sin descompactar (sd) sobre un Argiudol ácuico de Esperanza (Provincia de Santa Fe, Argentina). El diseño experimental fue en bloques completos aleatorizados y tres repeticiones. Se diferenciaron distintos escenarios desde el punto de vista hídrico; donde se podrían mencionar como: (i) C1 muy seca para soja y seca para trigo; (ii) C2 húmeda para soja y con buena reserva de agua en el suelo para el trigo; (iii) C3 moderadamente seca para soja y húmeda para trigo. Los resultados obtenidos indican la persistencia del efecto residual positivo de la descompactación inicial sobre la resistencia mecánica (RP) y porosidad de aireación del suelo (Pa) luego de 3 años de realizada la labor. Los tratamientos sd mostraron una tendencia de mejora subsuperficial en los valores de densidad aparente (Ds) y RP, lo que podría deberse al efecto de las raíces del cultivo de trigo sobre el suelo en la secuencia soja-trigo. Los rendimientos logrados mejoraron en las condiciones d. La campaña influyó marcadamente sobre el rendimiento de los cultivos en secano.

The objective of this research was to analyze the effect of the use of plots-nighttime and liming on soil properties in a degraded Aquic Argiudoll. In a field experiment three treatments were established: a) plots-nighttime (N), b) plots-nighttime+liming (NC) and c) control without amendments (T). The pH in NC increased compared to T and N. The CIC and P increased in N and NC respect to T. CIC increased in NC respect to N. Ca ++ increased in NC respect to T and N. No differences were detected in TOC, COP and CE. The IHO was narrower in T.

El objetivo fue analizar el efecto del lote-nochero y la aplicación de carbonato de calcio (CaCO3) sobre las propiedades edáficas de un Argiudol ácuico degradado. Se evaluaron a campo tres tratamientos: a) lote-nochero (N), b) lote-nochero+aplicación de CaCO3 (NC) y c) testigo sin enmiendas (T). El pH en NC aumentó comparado con T y N. La CIC y P se incrementaron en N y NC respecto de T. Sólo la CIC aumentó en NC respecto de N. El Ca++ se incrementó en NC respecto de T y N. No se detectaron respuestas en COT, COP y CE. El IHO fue más estrecho en T.

Resumen La compactación del suelo es un proceso físico complejo que afecta el desempeño del cultivo por limitar la expansión de las raíces y la reducción de agua y asimilación de nutrientes desde el suelo. Debido a la variabilidad espacial de la compactación del suelo, las necesidades de las prácticas de remediación, pueden variar respecto al suelo. Sin embargo, el mapeo de compactación del suelo estimado mediante los datos del índice de cono (IC), es una tarea difícil. El objetivo de este estudio fue el de examinar la variabilidad espacial de los datos del IC en un suelo Typic Argiudoll en el centro de la provincia de Santa Fe, Argentina bajo un sistema de no labranza y el delineamiento de zonas para labranza en sitio específico basado en mapas de probabilidades de ocurrencia de compactación del suelo desarrollada usando el kriging indicador. Se registraron 69 IC georreferenciados y determinaciones volumétricas de agua (SWC) en un área experimental de 70 x 110 m. Los sitios de muestreo fueron distribuidos de acuerdo a una malla psedo- regular, evitando la huella visible de la maquinaria. Se creó una variable indicadora mediante el agrupamiento de los sitios de muestreo en dos grupos según los perfiles de IC dentro de los 30 cm de profundidad. La estructura espacial de los datos de IC agregados por capas de 10 cm y la variable del indicador, fueron evaluados mediante un enfoque basado en el modelo. La alta variabilidad y la pobre estructura espacial observada en los datos IC, fueron atribuidas al efecto de la labranza y al tráfico bajo la escala del muestreo. Esta característica de los datos limitó la aplicación de técnicas de interpolación para este atributo de suelo. Sin embargo, los mapas de probabilidad de ocurrencia de la compactación del suelo en la zona radicular, fueron obtenidos mediante la integración de los datos del índice de cono del horizonte arable (0-30cm), usando el enfoque del kriging indicador. Tales mapas de probabilidad podrían ser útiles para el delineamiento de zonas potenciales para labranza en sitio específico.

Abstract Soil compaction is a complex physical process that affects the crop performance by limiting the expansion of the roots and the reduction of water and nutrients uptake from soil. Due to the spatial variability of soil compaction, the needs for remedial practices may vary within the field. However, mapping soil compaction estimated by cone index (CI) data is a difficult task. The aim of this study were to examine the spatial variability of CI data in a fine-mixed-thermic Typic Argiudoll soil form the center of Santa Fe, province -Argentina under no-till system, and to delineate zones for site-specific tillage based on maps of probabilities of occurrence of soil compaction developed using indicator kriging. Sixty nine georeferenced CI and volumetric water content (SWC) measurements were recorded in a 70 x 110 m experimental area. Sample locations were distributed following a pseudo-regular grid avoiding visible machinery footprint. An indicator variable was created by splitting the sampling locations into two groups based on the CI profiles within 0-30 cm depth. The spatial structure of the CI data aggregated by 10-cm layers and the indicator variable was assessed by a model-based approach. The high variability and poor spatial structure observed in CI data was attributed to the effect of tillage and traffic under the sampling scale. This feature underpinned the application of spatial interpolation techniques for this property. However, maps of the probability of occurrence of soil compaction in the root zone were be obtained by integrating the cone index data of the arable horizon (0-30 cm) using the indicator kriging approach. Such probability maps could be useful for the delineation of potential zones for site-specific tillage.

ABSTRACT Measurements of the soil cone index are widely used to assess soil resistance to root penetration (SR) and to monitor the soil compaction status of agricultural fields. However, soil sampling for SR estimation is a rather challenging task in view of the high spatial and temporal variability of the soil. This study proposed a bootstrapping method to determine the minimum sample size required to estimate the vertical profile of mean soil cone index (CI) values at different levels of precision and confidence. For this purpose, CI data from a Typic Argiudoll under no-tillage before and after chiseling was used. A total of 151 CI profiles were recorded before and after chiseling in a 3,200 m2 (40 × 80 m) no-tillage area at sampling points distributed on a horizontal 5 × 5 m aligned grid and from the top layer to 0.40 m depth by in 0.02 m intervals. A modified bootstrap routine was developed to estimate the sampling distribution of the sample mean and medians of CI values per layer. The minimum sample size to estimate the vertical profile of mean CI values at different levels of precision and confidence was determined from data of the whole soil profile, including the autocorrelation of CI readings in the vertical direction. Tilling increased the variability of this measurement and thus the sampling efforts to achieve the same level of precision and confidence were different before and after the procedure. The standard errors of sample medians estimated by bootstrapping were higher than those corresponding to sample means. In addition, to achieve the same level of precision and confidence, the estimation of the vertical profile of mean CI values based on sample medians required more observations than based on sample means. This study shows that the viability of the bootstrap approach to determine the implications of soil variability on the sampling efforts required for an accurate estimation of the vertical distribution of resistance in soils under different managements.

The flat pampas in the state of Santa Fe in Argentina have soils with high silt content, variable carbon content, and diverse degrees of structural degradation. Aggregate stability has been used as an indicator of the structural condition of the soil. This study aimed to quantify the effect of the addition of crop residues and root activity on the agents of aggregation and mechanisms of aggregate breakdown in soils with different carbon contents and textures cultivated under no-till. An experimental trial was conducted on a loamy soil (Typic Hapludoll, Santa Isabel series) and a silty soil (Typic Argiudoll, Esperanza series) under controlled conditions for 112 days with the following treatments: (i) with and without wheat plant growth and (ii) with and without addition of wheat residues. Soil structural stability by a method allowing for differentiation of aggregate breakdown by slaking, mechanical effect and microcracking, total organic carbon content, particulate organic carbon, glomalin and carbohydrate fractions was assessed. In general, the addition of residues and the presence of plant with active roots increased the presence of all aggregation agents and decreased aggregate breakdown processes in both soils. Soluble carbohydrates and proteins related to glomalin were the most important aggregating agents and their function was to reduce the magnitude of breakdown mechanisms, slaking and microcracking, evidencing a greater impact on the silty soil.

Indicators synthesizing the state of the structural quality and the function of the porous system are useful for assessing soil production capacity as well as the way it may serve natural ecosystems. This research aimed (i) to determine indicators of the state and function of the porous system, (ii) to use them to derive a global index to characterize the soil physical quality, and iii) to establish a reference pore-size distribution curve for Mollisols from the province of Santa Fe (Argentina). Sixty water retention curves (WRC) of A and B horizons of Mollisols, with clay varying between 119 and 538 g kg−1, organic matter between 5 and 40 g kg−1, and soil bulk density between 1.09 and 1.49 Mg m−3, were used. The indicators measured were: pore size distribution, macroporosity (PORp), air capacity (ACt) and plant-available water capacity (PAWC) among others. Soils were classified into four groups according to their physical properties and a reference WRC was determined. From this WRC and considering a total porosity of 0.514 m3 m−3, PORp was 0.035 m3 m−3, ACt 0.153 m3 m−3, field capacity 0.361 m3 m−3, permanent wilting point 0.136 m3 m−3 and PAWC 0.225 m3 m−3. Both the high silt content and low organic matter content confer on the soil characteristics with low stability, excess of small pores and low porosity of the macropore domain. Consequently, the capacity to quickly drain the water excess and allow root proliferation was not optimal, possibly due to the high silt or clay content and the low sand content, characteristic of the soil matrix of these Mollisols.

Muitos solos exibem o comportamento coeso, o qual caracteriza solos que, quando secos, apresentam incremento acentuado de resistência à penetração e sensível redução dessa resistência, quando úmidos, oferecendo sérias limitações à emergência e ao crescimento das plantas. Com os objetivos de avaliar o nível de degradação da estrutura em solos coesos com diferentes classes texturais e estabelecer um índice para determinar o grau de dureza dos solos que apresentam o caráter coeso, foram selecionados seis perfis de solos previamente identificados no campo e localizados em diferentes regiões do país. Testaram-se os índices: S , que determina a qualidade física do solo; e o H , que avalia o grau de dureza e o estresse efetivo sofrido pelo solo durante o secamento. Ambos os índices foram definidos por meio de funções preestabelecidas, utilizando dados da curva de retenção de água no solo. Os resultados comprovaram que o caráter coeso identificado em diferentes solos, na faixa de Tabuleiros Costeiros do Brasil, evidenciou níveis distintos de adensamento (dureza) e pode ser quantificado satisfatoriamente pelo índice H . A utilização do índice S foi adequada para avaliar as condições estruturais dos solos com caráter coeso, classificando-se como bons ou ruins para o cultivo, mas somente quando o solo estava na umidade correspondente ao ponto de inflexão. O índice H comprovou que o aumento da densidade do solo nos solos coesos é proveniente do aumento do estresse efetivo e não da textura do solo. Valores de Ds > 1,48 kg dm-3 permitem o enquadramento do solo como coeso, em razão da organização estrutural ser considerada "ruim".

Many soils have a hard-setting behavior, also known as cohesive or "coesos". In such soils, the penetration resistance increases markedly when dry and decreases considerably when moist, creating serious limitations for plant emergence and growth. To evaluate the level of structure degradation in hard-setting soils with different texture classes and to create an index for assessing soil hardness levels in hard-setting soils, six soil representative profiles were selected in the field in various regions of Brazil. The following indices were tested: S, which measures soil physical quality, and H , which analyzes the degree of hardness and the effective stress in the soil during drying. Both indices were calculated using previously described functions based on data from the water-retention curves for the soils. The hard-setting values identified in different soils of the Brazilian Coastal Tablelands have distinct compaction (hardness) levels and can be satisfactorily measured by the H index. The S index was adequate for evaluating the structural characteristics of the hard-setting soils, classifying them as suitable or poor for cultivation, but only when the moisture level of the soil was near the inflection point. The H index showed that increases in density in hard-setting soils result from increases in effective stress and not from the soil texture. Values for Bd > 1.48 kg dm-3 classify the soil as hard-setting, and the structural organization is considered "poor".

The use of soil in potting production difficult the crop management and involves the depletion of a nonrenewable resource. Therefore, is necessary to find alternatives for replacement. The objective of this study was to formulate substrates from pine bark (C), leaves of pine (P) and subtropical peat (T) to evaluate their physicochemical properties and quality for growing flowering plants in pots. Seven formulated substrates were evaluated: 1) 1C:1P:1T, 2) 2C:1P:1T, 3) 1C:2P:2T, 4) 2C:1P:2T, 5) 2C:2P:1T, 6) 1C:4P:2T y 7) 2C:4P:1T, one local substrate (leaves of pine + subtropical peat + mineral soil) and one commercial substrate (Blonde and black peat + perlite + vermiculite). Bulk density, total pore space (TPS), water holding capacity (WHC), pore air (PA), particle size, pH and electrical conductivity (EC) was analyzed. Was performed a trial with Viola tricolor var . Yellow, one with Petunia hybrida var. White and one with Salvia splendes var. red. Each trial was composed of nine treatments (substrates evaluated) and 10 repetitions. At the end of the trials the number of buds and flowers, length and stem diameter, shoot and root dry mass were measured. The formulated and commercial substrate presented low bulk density (<0.4 g cm-3). The local substrate was noted for having the highest bulk density and percentage in the size fraction <1 mm due to the presence of soil in its formulation. The particle size >3.35 mm was higher in the substrate 6, 7 and commercial substrate; this explains the high percentage of PA in the first two. The substrates 6 and 7 showed the lowest values in the percentage of the fraction <1 mm, coinciding with lower CRA. All substrates had a suitable pH and EC values (pH: 5.5 – 6.3 and EC: < 1dS m-1 (1+5 v/v)). The substrates formulated obtained floral seedlings quality, but the substrates 1, 2, 3, 4 and 5 were highlighted to achieve greater absolute value in most variables. These substrates had a more balanced water/air ratio (PA <50% and CRA> 35%).

El uso de suelo para la producción en macetas dificulta el manejo del cultivo e implica el agotamiento de un recurso no renovable. Esto genera la necesidad de encontrar alternativas para su reemplazo. El objetivo de este trabajo fue formular sustratos a partir de corteza de pino (C), pinocha (P) y turba subtropical (T) para evaluar sus propiedades físico-químicas y verificar su calidad para el cultivo de plantas florales en macetas. Se evaluaron siete sustratos formulados: 1) 1C:1P:1T, 2) 2C:1P:1T,3) 1C:2P:2T, 4) 2C:1P:2T, 5) 2C:2P:1T, 6) 1C:4P:2T y 7) 2C:4P:1T, un sustrato local (Pinocha + turba subtropical + suelo mineral) y uno comercial (Turba rubia y negra + perlita + vermiculita). En todos se analizó densidad aparente, espacio poroso total (EPT), capacidad de retención de agua (CRA), porosidad de aire (PA), granulometría, pH y conductividad eléctrica (CE). Se realizó un ensayo con Viola tricolor var. Yellow, otro con Petunia hybrida var. White y otro con Salvia splendes var. rojo. Cada uno de ellos constó de nueve tratamientos (sustratos evaluados) y 10 repeticiones. Al finalizar los ensayos se contabilizaron los pimpollos y flores, longitud y diámetro del tallo, masa seca aérea y radicular. Los sustratos formulados y el comercial presentaron baja densidad aparente (<0,4 g cm-3). El sustrato local tuvo la mayor densidad aparente y porcentaje en la fracción granulométrica <1 mm debido a la presencia de suelo en su formulación. La fracción granulométrica >3,35 mm fue mayor en el sustrato 6, 7 y comercial, esto explicó el alto porcentaje de PA en los dos primeros. Los sustratos 6 y 7 presentaron los menores valores en el porcentaje de la fracción <1 mm, coincidiendo con su menor CRA. El pH y la CE de todos los sustratos fueron adecuados (pH: 5,5-6,3 y CE: <1dS m-1 (1+5 v/v)). Los sustratos formulados produjeron plantines florales de calidad, pero se destacaron los sustratos 1, 2, 3, 4 y 5 por lograr mayor valor absoluto en la mayoría de las variables. Estos sustratos presentaron una relación agua/aire más equilibrada (PA <50% y de CRA >35%).

The application of dairy cattle slurry (DCS) to the soil is a practice that is spreading quickly in the milkmaid basin of Santa Fe. The objective of this study was to evaluate the effect of adding several rates of DCS on the soil physical properties. The experiment was carried out on a Typic Argiudoll and consisted of three treatments with three replications randomly distributed :control, without DCS (T0), application of 80 m³ ha-1 (T80) and 160 m³ ha-1 (T160) of DCS. The DCS was spread before seeding ryegrass and sorghum. Measurements were performed before grazing the ryegrass (M1) and before harvesting the sorghum (M2). Undisturbed soil samples (cylinders) were collected to determine soil bulk density (Bd), pore size distribution, least limiting water range (LLWR) and soil critical bulk density (Bdc). Undisturbed soil samples were also collected with a shovel to evaluate the size aggregates distribution and the mean geometric diameter (MGD). Water infiltration and hydraulic conductivity were measured with tension infiltrometers. Treatments M1, T80 and T160 showed higher water infiltration and conduction through bio and macropores. The size aggregates distribution and the MGD did not show significant differences among treatments. In M2, a Bd decrease and a macroporosity increase was observed, mainly in T160. The three treatments showed similar Bdc, but with a different range of variation of Bd and percentage of cases registered outside of the LLWR. The evaluated indicators showed different sensitivity to identify alterations in soil structure induced by the application of DCS. The soil-crop-weather interaction notably influenced the changes of the soil physical properties. Therefore, it is necessary to carry out long-term studies to corroborate these results.

La aplicación de efluentes líquidos de tambo (ELT) al suelo es una práctica que se está extendiendo rápidamente en la cuenca lechera santafesina. El objetivo de este trabajo fue evaluar el efecto de aplicar al suelo dosis variables de ELT sobre sus propiedades físicas. El ensayo se realizó en un suelo Argiudol típico y consistió de tres tratamientos con tres repeticiones distribuidos en un diseño completamente aleatorizado-testigo, sin aplicación de ELT (T0), aplicación de 80 m³ ha-1 (T80) y 160 m³ ha-1 (T160) de ELT. Se realizaron dos aplicaciones de ELT, previo a la siembra del raigrás y del sorgo. Las mediciones se efectuaron antes del pastoreo del raigrás (M1) y previo al corte del sorgo (M2). Muestras no disturbadas (cilindros) se colectaron para determinar densidad del suelo (Ds), distribución de poros por tamaño, intervalo hídrico óptimo (IHO) y densidad de suelo crítica (Dsc). Muestras inalteradas se extrajeron con pala para evaluar la distribución por tamaño de agregados y el diámetro medio geométrico (DMG). La infiltración y conductividad hidráulica se midió con tensioinfiltrómetros. En M1, T80 y T160 presentaron mayor infiltración y conducción de agua por bio y macroporos. La distribución de agregados por tamaño y el DMG no mostraron diferencias entre tratamientos. En M2 se observó una disminución en Ds respecto de M1 y un incremento de la macroporosidad, principalmente en T160. Los tres tratamientos presentaron similar Dsc pero con diferente rango de variación de Ds y porcentaje de casos registrados fuera del IHO. Los indicadores presentaron diferente sensibilidad para identificar alteraciones de la estructura del suelo inducidas por la aplicación de ELT. La interacción suelo-cultivo-condiciones atmosféricas ejerció notable influencia sobre los cambios ocurridos en las propiedades físicas, por lo que es necesario realizar estudios a largo plazo para corroborar los resultados de este estudio.