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Toxicity induced by heavy metals deteriorates soil fertility status. It also adversely affects the growth and yield of crops. These heavy metals become part of the food chain when crops are cultivated in areas where heavy metals are beyond threshold limits. Cadmium (Cd) and nickel (Ni) are considered the most notorious ones among different heavy metals. The high water solubility of Cd made it a potential toxin for plants and their consumers. Accumulation of Ni in plants, leaves, and fruits also deteriorates their quality and causes cancer in humans when such a Ni-contaminated diet is used regularly. Both Cd and Ni also compete with essential nutrients of plants, making the fertility status of soil poor. To overcome this problem, the use of activated carbon biochar can play a milestone role. In the recent past application of activated carbon biochar is gaining more and more attention. Biochar sorb the Cd and Ni and releases essential micronutrients that are part of its structure. Many micropores and high cation exchange capacity make it the most acceptable organic amendment to improve soil fertility and immobilize Cd and Ni. In addition to improving water and nutrients, soil better microbial proliferation enhances the soil rhizosphere ecosystem and nutrient cycling. This review has covered Cd and Ni harmful effects on crop yield and their immobilization by activated carbon biochar. The focus was made to elaborate on the positive effects of biochar on crop yield and soil health.

El departamento de Sucre, Norte de Colombia se ha caracterizado por su vocación ganadera y agrícola, siendo la agricultura la fuente principal de subsistencia de esta región. En la presente investigación se tuvo como objetivo evaluar la calidad de las fuentes de agua superficiales empleadas en sistemas de riego en 141 unidades productivas agrícolas (Upas) de pequeños agricultores en cinco municipios priorizados del departamento de Sucre, (Norte de Colombia), se analizó una fuente de agua por cada predio, tomándose una muestra para cada fuente de agua. Para ello se determinaron 22 parámetros fisicoquímicos los cuales se compararon con estándares internacionales propuestos por la Organización de las Naciones Unidas para la Alimentación y la Agricultura (FAO) y la Organización Mundial de la Salud (OMS). Se midió salinidad y sodicidad utilizando el diagrama de clasificación de aguas para riego y con un análisis de correlación se determinó el grado de asociación existente entre las 22 variables. Los resultados obtenidos mostraron que los parámetros evaluados clasifican al agua analizada como apropiada para usar en sistemas de riego, el pH presentó valor máximo y mínimo de 9.32 y 4.40 respectivamente, los valores máximos y mínimos de conductividad eléctrica (CE) fueron 669 y 19.80 µS cm-1 respectivamente, los valores máximos y mínimos de sólidos totales disueltos (SDT) fueron: 478 y 11.80 mgL-1 respectivamente y los valores máximos y mínimos de relación de adsorción de sodio (RAS) fueron: 1.72 y 0.01 meq L-1 respectivamente. Las concentraciones de cationes y aniones estuvieron en el rango límite permitido por la FAO y la OMS. Por otro lado, las aguas de acuerdo con el diagrama de clasificación para riego se clasificaron como aguas C1S1 y C2S1, es decir aguas que no presentan restricción para ser usadas en sistemas de riego, agua tipo (I) y tipo (II). The department of Sucre, in northern Colombia, is predominantly a ranching and agricultural region where agriculture is the main source for livelihoods. The purpose of this study was to assess the physicochemical quality of surface water in irrigation systems at 141 farms. A water source for each property, taking a sample for each water source. To this end, 22 physicochemical parameters were selected and compared with the international standards proposed by the United Nations’ Food and Agriculture Organization (FAO) and the World Health Organization (WHO). Salinity and sodicity were measured using the irrigation water classification diagram, and the level of correlation between the 22 variables was assessed by means of correlation analysis. The results obtained indicate that based on the measured parameters, the water is classified as appropriate for use in irrigation systems. The maximum and minimum pH values were 9.32 and 4.40, respectively; the maximum and minimum values of electrical conductivity (EC) were 669 and 19.80 µS cm-1 respectively; the maximum and minimum values of total dissolved solids (TDS) were 478 and 11.80 mgL-1 respectively, and the maximum and minimum values of the sodium adsorption ratio (SAR) were 1.72 and 0.01 meq L 1 respectively. Cation and anion concentrations were within the limits allowed by the FAO and the WHO. According to the irrigation water classification diagram, the waters were classified as C1S1 and C2S1, which implies that there are no restrictions for their use in irrigation systems, water type (I) and type (II). Introduccion 12 Planteamiento del problema 13 Justificación 18 Objetivos 21 Objetivos general 21 Objetivos específicos 21 Capítulo I 21 Marco teórico 21 Aguas superficiales 22 Calidad del agua 22 Efectos asociados a la mala calidad de agua de riego 23 Aplicación de fertilizantes 23 Eutrofización 24 Parámetros físicos y químicos que afectan al agua para riego 24 Conductividad eléctrica (CE) 24 Sólidos disueltos totales (SDT) 25 pH del agua 25 Relación de adsorción de sodio (RAS) 26 Salinidad 28 Sodicidad 29 Toxicidad por iones específicos 30 Sodio 30 Diagrama de clasificación agua para riego 31 Estado del arte 32 Área de estudio 39 Capítulo I 42 Metodología 42 Recolección de muestras de agua 44 Procedimiento de toma de muestra: 44 Análisis de calidad en el laboratorio 45 Clasificación de las muestras analizada 47 Análisis de datos por correlación de Pearson47 Determinación de salinidad y sodicidad 47 Diagrama de clasificación de agua para riego 47 Acciones para la conservación de la calidad del agua en las unidades productivas agrícola. 48 Capitulo III 48 Resultados48 Variables fisicoquímicos de la calidad del agua 48 Clasificación del agua para riego analizada 57 Acciones de manejo propuesta para mantener las características de calidad del agua para riego 58 Plan de acción 60 Discusión 63 Capitulo IV 68 Conclusiones 68 Referencias69 Anexos 82 Magíster en Investigación en Desarrollo Sostenible MIDES Maestría

BACKGROUND AND OBJECTIVES: Irrigation system water quality is a complex issue that involves the combined effects of various surface water management parameters. Monitoring of irrigation water quality is essential for the sustainability of crop production and productivity. The department of Sucre, in northern Colombia, is predominantly a ranching and agricultural region where agriculture is the main source for livelihoods. The purpose of this study was to assess the physicochemical quality of surface water in irrigation systems at 141 farms. METHODS: To this end, 141 water samples were taken to determine 22 physicochemical parameters. All in-situ measurements and laboratory analysis were performed using standard methods. The results obtained were compared with the international standards proposed by the United Nations’ Food and Agriculture Organization and the World Health Organization. Salinity and sodicity were measured using the irrigation water classification diagram, and the level of correlation between the 22 variables was assessed by means of correlation analysis. FINDINGS: The results obtained indicate that based on the measured parameters, the water is classified as appropriate for use in irrigation systems. The maximum and minimum pH values were 9.32 and 4.40, respectively; the maximum and minimum values of electrical conductivity were 669 and 19.80 µS/cm respectively; the maximum and minimum values of total dissolved solids were 478 and 11.80 mg/L respectively, and the maximum and minimum values of the sodium adsorption ratio were 1.72 and 0.01 mEq/L, respectively. CONCLUSION: Cation and anion concentrations were within the limits allowed by the Food and Agriculture Organization and the WHO. According to the irrigation water classification diagram, the waters were classified as C1S1 and C2S1, which implies that there are no restrictions for their use in irrigation systems, water type (I) and type (II).

Submitted by Angela Maria de Oliveira (amolivei@uepg.br) on 2019-03-25T21:54:20Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Jessica Alves.pdf: 5612043 bytes, checksum: 9bb71d25fb58f8a416e7202f2c27ca77 (MD5) Made available in DSpace on 2019-03-25T21:54:20Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Jessica Alves.pdf: 5612043 bytes, checksum: 9bb71d25fb58f8a416e7202f2c27ca77 (MD5) Previous issue date: 2019-02-14 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Nós mensuramos o rendimento relativo (RR), a diferença de rendimento relativo (DRR) e a eficiência de produção (EP) de trigo, soja, aveia preta e milho, durante os anos de 2012 a 2016; e avaliamos o efeito após 5, 11, 23, 34 e 45 meses da aplicação superficial da dose de corretivos, em diversas camadas do solo (0-5, 5-10, 10-20, 20-40 e 40-60 cm ) de um Cambissolo Háplico, dos atributos: acidez ativa (pH), saturação por bases do solo (V), cálcio (Ca), magnésio (Mg) e potássio (K) trocáveis, o percentual (%) de Ca e Mg na capacidade de troca catiônica a pH 7,0 (CEC) e relações catiônicas (RC) como Ca/Mg e (Ca+Mg)/K. O delineamento experimental utilizado foi o de blocos ao acaso, em parcelas subdivididas, com quatro repetições. Nas parcelas foram estudados o calcário dolomítico (CD) e os corretivos micronizados (CM): calcita (CMG) e dolomita (DMG) micronizada granulada e suspensão carbonatada (SC). Nas subparcelas foram estudadas três doses de cada corretivo a fim de elevar a V para 50, 70 e 90%, além do tratamento controle. Os CM apresentaram maiores RR e EP ao longo do tempo do que CD. Além disso, a maior DRR do CM refere-se ao maior efeito residual e maior/manutenção do rendimento das culturas. Se considerarmos apenas EP, melhores resultados são encontrados na dose que visa V a 61 % para todo os corretivos, mostrando que é o V adequado para o controle da acidez de um Cambissolo Háplico. Apesar do CM apresentarem maior finura do que CD, a eficiência no controle da acidez do subsolo foi ineficiente. No entanto, os CM apresentam menor diferença entre o V estimado e obtido, principalmente na camada de 0-5 cm do que CD. Os corretivos na dose de V entre 50-70 % aumentam a concentração de Ca, Mg e K trocáveis, na camada 0-5 cm e por até 34 meses após a aplicação. Na camada 0-20 cm, as melhores RC ocorreram aos 11 meses após a aplicação. A concentração de K aumentou à medida que diminuiu a % de Mg na CTC. We measured the relative yield (RY), relative yield change (RYG) and production efficiency (PE) of wheat, soybean, black oat and maize, during the years 2012 to 2016; and also evaluate the effect after 5, 11, 23, 34 and 45 months of the surface application of dose of liming materials (LM), in various soil layers (0-5, 5-10, 10-20, 20-40 and 40-60 cm) of a Typic Distrupedt, of attributes: active acidity (pH), soil base saturation (V), exchangeable calcium (Ca), magnesium (Mg) and potassium (K), the percentage (%) of Ca and Mg in the cation exchange capacity at pH 7.0 (CEC) and cationic relationship (CR) as Ca/Mg and (Ca+Mg)/K. The experimental design used was completely randomized blocks in split-plot with four replications. In the plots were studied the dolomitic limestone (DL) and the micronized liming material (MLM): granulated micronized calcite (GMC) and dolomite (GMD) and carbonated suspension (CS). In the subplots were studied three doses of each the LM aiming to increase V to 50, 70 and 90 %, besides of control treatment. The MLM presented major RY and PE along the time than DL. Besides, the major RYG of MLM major residual effect and major/maintenance crops yield. If we consider only PE, better results are found in the dose aiming V to 61 % for all the LM, showing that it is the adequate V for acidity control of a Typic Distrudept. Despite the MLM are more fineness than DL, the effectiveness for control soil acidity in subsoil were inefficient. However, the MLM present lower gap between the V estimated and obtained, manly in the 0-5 cm layer than DL. LM in the V to 50-70 % increased Ca, Mg and K, in 0-5 cm layer, up to 34 months after application. In the 0-20 cm layer, the better CR occurred at 11 months after application. The K increased as it decreased the % of Mg in the CEC.

The Argentine Pampas is one of the most important cropping regions of the World. Limited tillage systems, and specially no-till, had widespread in recent years, occupying actually around 70% of the surface devoted to annual crops. We review results produced in field experiments installed along the Pampas to determine the effect of the adoption of these tillage systems on some soil properties and crops yield. It was performed a metanalysis of data from experiments where plow tillage (mouldboard plow), reduced tillage (chisel plow, disk plow or harrow disk) and no-till were compared. Treatments effects were contrasted by paired t-tests between groups of paired data. Soil bulk density and cone penetration resistance of the 0–20 cm layer were higher under limited tillage systems than under plow tillage. Increases of bulk density under no-till in comparison to plow tillage were generally small, averaging 4%, but cone penetration increased by 50% in many soils. The increase of bulk density was greater in soils of initial low bulk density. Neither bulk density increases nor cone penetration changes reached critical threshold for roots development. Aggregate stability and water infiltration rate were higher in soils subjected to limited tillage systems than under plow tillage. The improvement of aggregate stability was higher in poorer structured soils, with an average increase of 70% under no-till in relation to plow tillage. Under no-till infiltration rate doubled in average that of plow tillage. Soil water content during the critical periods of sowing and flowering was generally greater under limited tillage but, conversely, nitrate nitrogen levels were greater in plow tillage. Higher soil water content under no-till in relation to plow tillage may satisfied the evapotranspiration demand of 1–3 days of crops during the critical flowering period, being nitrate nitrogen in average 21 kg ha−1 lower under no-till. Soybean (Glicine max (L.)-Merr.) yield was not affected by tillage system, meanwhile wheat (Triticum aestivum L.) and corn (Zea mays L.) yields were lower under reduced tillage and no-till than under plow tillage without nitrogen fertilization. Wheat and corn no-till yields were 10–14% lower that yields under plow tillage as a mean. When fertilizers were applied, wheat and corn yield differences between tillage treatments generally disappeared. The adoption of limited tillage systems in the Pampas leads to soil improvement but also generates the necessity of increase nitrogen fertilizers utilization to sustain yields of graminaceus crops. Fil: Alvarez, Roberto. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; Argentina Fil: Steinbach, Haydee Sara. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; Argentina

Geographica Pannonica; Vol 19, No 1, 2015. ISSN 1820-7138, The purpose of this study was to evaluate the effect of moisture conditions on the productivity of agricultural crops within the Oltenia Plain, Romania at various time scales. The agro-databases contain the productions of winter wheat, maize and sunflower reported by the National Institute of Statistics and Agricultural Department for the period 1971-2013. The meteorological elements used were represented by the rainfall amount and air-temperature recorded at the six meteorological stations: Drobeta-Turnu Severin, Calafat, Baile?ti, Bechet, Craiova, Caracal and Turnu-Magurele. According to the SPI and De Martonne Index, the driest years, with low rainfall amounts, were 1983-1985, 1993, 2000, 2002, 2007 and 2012, with different degrees of water deficit. Moreover, the years with the lowest productions were recorded in the last half of the analysed period: 1993, 1996, 2000, 2002, 2007 and 2012. The impact of the drought variability of yield on the agricultural crops was evaluated using Bravais-Pearson correlations test, which was statistically significant in the last half of the reference period, while the correlation in the first half of the period it was not statistically significant. This result can be explained by the political system and the gradual degradation of the irrigation system, which determined the addiction on climatic conditions after ‘89 years.

The evaluation of the sodium ionic balance by the example of the little-developed area of the Elva River basin in the Russian Federation has been performed in the present research. It has been established that the main role in the element circulation belongs to the lithogenic base due to prevalence of the freely-soluble rocks composing the basin. The contribution of the atmospheric precipitations to the ion delivery and removal within the catchment area is insignificant and makes about 20% which is related to remoteness of the area from the large industrial centers and areas of the seas. It has been discovered that the plant industry plays a small part in the sodium circulation. In general, the anthropogenic transformation of the sodium circulation is primarily associated with the animal industry facilities due to the cattle-feeding with NaCl. © 2014 AENSI Publisher All rights reserved.

Made available in DSpace on 2014-06-11T19:22:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-25Bitstream added on 2014-06-13T19:48:26Z : No. of bitstreams: 1 pivetta_la_me_botfca.pdf: 269979 bytes, checksum: 10bd45eedf903d7012d0a565b5b8ecf1 (MD5) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) A avaliação do sistema radicular de uma cultura é fundamental para o desenvolvimento de práticas agrícolas que visam a otimização da produtividade. Além disso, a distribuição das raízes no perfil do solo não necessariamente condiz com a atividade radicular, que é mais importante no tocante a absorção de água e nutrientes. O objetivo do experimento foi avaliar o efeito de sistemas de manejo sobre o sistema radicular e a produtividade da soja e comparar as metodologias do trado e do elemento não marcado (rubídio), na análise radicular. As avaliações foram realizadas na safra agrícola 2009/2010, em um experimento instalado desde 2003. O delineamento experimental utilizado foi de blocos ao acaso, em esquema de parcelas subdivididas, com quatro repetições. As parcelas foram constituídas pelas culturas de inverno triticale (X Triticosecale Wittmack) e girassol (Helianthus annuus L.), e as subparcelas pelos manejos de primavera envolvendo milheto (Pennisetum glaucum L.), sorgo forrageiro (Sorghum bicolor (L.) Moench) e crotalária júncea (Crotalaria juncea L.), além da escarificação, realizada em 2003 e 2009. Na safra de verão foi cultivada a soja, em todas as subparcelas. As avaliações realizadas foram: densidade de comprimento, área superficial, massa de matéria seca (trado) e atividade radicular (rubídio) da soja, nas distâncias 0,00; 0,11 e 0,22 m da planta de referência, no estádio R4 da cultura, além da produtividade de grãos. Pelo método do trado foram amostradas as camadas 0,00-0,05, 0,05-0,10, 0,10-0,20, 0,20-0,40 e 0,40-0,60 m. O marcador para a atividade radicular, nitrato de rubídio (RbNO3), foi aplicado nas profundidades 0,05, 0,10, 0,20, 0,40 e 0,60 m. A produtividade da soja não foi influenciada pelas culturas de inverno ou manejos de primavera. As culturas de inverno não se diferenciaram em nenhuma das variáveis... The knowledge of root distribution as affected by cropping systems and its role in nutrient acquisition by plants is important in planning crop rotations and soil management that optimize crops yield. Furthermore, root distribution in the soil profile does not necessarily matches root activity, which is more important in water and nutrient acquisition. The objective of this research was to assess the effects of managements systems on soybean root distribution and yields, and compare a direct method (soil core sampling) with an indirect method (with rubidium) in evaluating the root system. Evaluations were carried out in season 2010, in an experiment that has been running since 2003. The experimental design is a complete randomized block with a split-plot arrangement of treatments with four replicates. Plots consist in fall-winter crops triticale (X Triticosecale Wittmack) and sunflower (Helianthus annuus L.), and the subplots in spring crops pearl millet (Pennisetum glaucum L.), forage sorghum (Sorghum bicolor (L.) Moench) and sunn hemp (Crotalaria juncea L.), besides chisel tillage in 2003 and 2009. In summer, soybean (Glycine max L. (Merril) is sowed in all subplots. The evaluations carried out were: soybean root length, surface, dry matter (soil core sampling), activity (rubidium), at 0.0, 0.11 and 0.22 m from the reference plant, at R4, besides soybean yield. The samples by soil core sampling method were taken at layers 0.00- 0.05, 0.05-0.10, 0.10-0.20, 0.20-0.40 and 0.40-0.60m. The rubidium nitrate was applied at depths 0.05, 0.10, 0.20, 0.40 and 0.60m. Soybean yield was not affected by winter crops or spring managements. Winter crops did not differ in any variable. Among spring managements, the chisel tillage and sunn hemp resulted less soybean root length. The chisel tillage resulted highest soybean root activity at depth 0.10 m, however... (Complete abstract click electronic access below)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Sol compaction effects on soil and plants has been subject of several studies. However, several parameters are used to evaluate soil compaction like bulk density and soil penetration resistance, but these parameters are dependent of soil type and moisture, therefore, the study of a parameter that could compare the different soils would facilitate the soil compaction studies. This work was divided in four chapters. In the first chapter the objective was to evaluate some physical-mechanical parameters of Alfisols and Oxisols submitted to different tillages. Six soils from Rio Grande do Sul state, Brazil, were collected, with clay content varying from 100 to 650 g kg-1. The core samples were collected from 0.08-0.13 m layer, equilibrated to the tension of 33 kPa and submitted to uniaxial compression test with application of successive and static loads. Based on the vertical displacement measured in the consolidometer after application of each load, were evaluated initial (Dsi) and final (Dsf) bulk density, deformation (Def), initial saturation degree (Gsi), initial volumetric moisture (qvi), pre compression stress (sp) and compression index (Cc) by Casagrande s method. Results indicated that managements with larger compaction presented smaller deformation and susceptibility to compaction; managements with recent revolviment of soil presented larger displacement from their compression curves, showing larger susceptibility to compaction; the Oxisol with larger clay content, due ability to retain more water in determined tension and due larger susceptibility to compaction, need to be more careful with traffic of machines than sandy soils. The second chapter aimed to study some physical properties of Alfisols and Oxisols from Rio Grande do Sul state, Brazil, submitted to different tillages and its influence on root growth and soybean yield. R esults showed larger densities in the approximate depth of 0.10 m and the penetration resistance do not appear in layers with uniform resistance, are spaces with larger and smaller resistance; the root evaluation, even visually, it is a good indicative of the soil physical condition and the bulk density and penetration resistance, if appraised with moisture near field capacity, are good indicators of the soil for plant development; crop yield was associated to soil physical conditions. The third chapter had as objective evaluate the effect of the particles size and tillage in the degree of compactness and to verify the best pressure to obtain the reference bulk density. Six soils of Rio Grande do Sul state, Brazil, submitted to different tillages were collected, with clay content varying from 100 to 650 g kg-1. For determination of the bulk density core samples were collected from layers of 0-0.05, 0.05-0.10, 0.10-0.15, 0.15-0.20, 0.20-0.25 and 0.25-0.30 m and for evaluation of the reference bulk density core samples were collected in the layer of 0.08-0.13 m. For determination of the reference bulk density samples were equilibrated to the tension of 33 kPa and submitted to the uniaxial compression test, with application in each soil sample only one load of 200, 400, 800, 1600 kPa and 3200 kPa. It was also obtained the soil compression curve with application of successive loads in each soil sample to compare the results obtained with the samples that was applied only one load. They were evaluated also the macroporosity and soil penetration resistance, yield and root development of soybean. In agreement with the obtained results, the load of 1600 kPa was the best pressure to obtain the reference bulk density in the uniaxial compression test using core samples, independent if applying just the load of 1600 kPa or from the load of 1600 kPa of the soil compression curve; the largest soybean yield was obtained with degree of compactness of 82% for Alfisols and 85% for Oxisols and the degree of compactness was a good indicator of the physical conditions of the soil, presenting good relationship with soil penetration resistance, macroporosity, root growth and soybean yield; the degree of compactness looks like independent from particle size, based especially in the results of crop yield and macroporosity in function of degree of compactness. The fourth chapter aimed to study the effect of different compaction states on the soil physical properties and growth and yield of soybean, corn and wheat. An experiment was set in the Cooperativa Regional Tritícola Serrana Ltda (COTRIJUÍ) , Ijuí city, Rio Grande do Sul state, Brazil, in an Oxisol. The completely randomized experimental design was used, in a bifactorial with split plots, with three repetitions. The main plots had three compaction states (PDC no tillage during six years + four passes of a machine with mass of 10 Mg in the agricultural year 2003/2004; PD no tillage during six years; Escarif no tillage during six years + chisel and harrowing in the agricultural year 2003/2004) and the split plots had soybean and corn. The soil physical properties (macroporosity, microporosity, total porosity, bulk density and soil penetration resistance) and development and yield of soybean, corn and wheat were measured. The results showed that the additional compaction presented increment of the soil resistance to penetration until the depth of 0.12 m; soil compaction influenced negatively soil physical properties; soybean and wheat were sensitive to compaction, soybean and corn had reduced heights and the wheat and soybean had their root system reduced length, for the additional compaction; soil compaction affected crop yield of corn, soybean and wheat, been the larger yields verified in no tillage and the smaller in treatments with additional compaction; the larger wheat yield was observed in the succession with soybean A compactação do solo é tema de vários estudos que visam avaliar seus efeitos no solo e na planta. Vários parâmetros são utilizados para avaliar a compactação do solo, como densidade do solo e resistência à penetração, mas esses parâmetros são dependentes do tipo e da umidade do solo; portanto, o estudo de parâmetros que comparam diferentes solos facilita o estudo sobre compactação do solo. Este trabalho foi dividido em quatro capítulos. No primeiro capítulo o objetivo foi avaliar alguns parâmetros físico-mecânicos de Argissolos e Latossolos submetidos a diferentes sistemas de manejo. Foram coletados seis solos do Rio Grande do Sul, com granulometria variando, aproximadamente, entre 100 a 650 g kg-1 de argila. As amostras com estrutura preservada foram coletadas na profundidade de 0,08-0,13 m e equilibradas à tensão de 33 kPa, e submetidas ao teste de compressão uniaxial com aplicação de cargas sucessivas e estáticas. Baseado no deslocamento vertical medido no consolidômetro após a aplicação de cada carga foram avaliados a densidade do solo inicial (Dsi) e final (Dsf), deformação (Def), grau de saturação inicial (Gsi), umidade volumétrica inicial (qvi), e pressão de pré-consolidação (sp) e índice de compressão (Cc) determinados pelo método de Casagrande. Os resultados indicaram que manejos com maior estado de compactação inicial apresentaram menor deformação e menor suscetibilidade do solo à compactação; sistemas de manejo com revolvimento do solo recente apresentaram maior deslocamento de suas curvas de compressão, mostrando maior suscetibilidade à compactação; o Latossolo Vermelho distroférrico típico, pela capacidade de reter mais água a uma determinada tensão e pela maior suscetibilidade à compactação, necessita de maior cuidado com o tráfego de máquinas do que solos arenosos. O segundo capítulo objetivou estudar algumas propriedades físicas de Argissolos e Latossolos do Rio Grande do Sul submetidos a diferentes sistemas de manejo do solo e suas influências no crescimento radicular e rendimento da cultura da soja. Os resultados mostraram que independente do solo e manejo, de modo geral as maiores densidades foram encontradas na profundidade aproximada de 0,10 m; os níveis de resistência do solo à penetração não se apresentam em camadas uniformes, ocorrem espaços de maior e menor resistência; a densidade do solo e a resistência à penetração se avaliada com umidade próxima à capacidade de campo, mostraram-se bons indicadores do solo para desenvolvimento da planta e a avaliação do sistema radicular, mesmo que apenas visual, é um bom indicativo da condição física do solo; o rendimento esteve associado às condições físicas dos solos. O terceiro capítulo teve como objetivo avaliar o efeito da textura e do manejo do solo no grau de compactação e verificar a melhor pressão para se obter a densidade referência. Foram coletados seis solos do Rio Grande do Sul submetidos à condições de manejo distintas, com granulometria, aproximadamente, entre 100 e 650 g kg-1 de argila. Para a determinação da densidade do solo foram coletadas amostras com estrutura preservada nas camadas de 0-0,05; 0,05-0,10; 0,10-0,15; 0,15-0,20; 0,20-0,25 e 0,25-0,30 m e para avaliação da densidade referência foram coletadas amostras com estrutura preservada na camada de 0,08-0,13 m. Para a determinação da densidade referência, as amostras foram equilibradas à tensão de 33 kPa e submetidas ao teste de compressão uniaxial, com aplicação em cada amostra de solo carga única de 200, 400, 800, 1600 kPa e 3200 kPa. Também foi obtida a curva de compressão do solo com aplicação de cargas sucessivas em cada amostra de solo para poder comparar os resultados obtidos com as amostras em que foi aplicada carga única. Foram avaliados também a macroporosidade e a resistência do solo à penetração, e o crescimento radicular e o rendimento da cultura da soja. Os resultados obtidos mostraram que a carga de 1600 kPa foi a melhor pressão para se obter a densidade referência no teste de compressão uniaxial utilizando amostras de solo com estrutura preservada, independente de ser obtida de aplicação de carga única ou da curva de compressão do solo; o maior rendimento da soja é obtido com grau de compactação, em média de 82% para os Argissolos e 85% para os Latossolos; o grau de compactação mostrou-se um bom indicador das condições físicas do solo, apresentando boa relação com rendimento da cultura da soja, resistência à penetração, macroporosidade e desenvolvimento radicular; o grau de compactação parece ser independente da ranulometria do solo, baseado principalmente nos resultados de rendimento e macroporosidade em função do grau de compactação. O quarto capítulo objetivou estudar o efeito de diferentes condições de compactação sobre as propriedades físicas do solo e crescimento e rendimento das culturas soja, milho e trigo. Para isso, foi conduzido um experimento no campo tecnológico da Cooperativa Regional Tritícola Serrana Ltda (COTRIJUÍ), município de Ijuí (RS), em um Latossolo Vermelho distroférrico típico. Foi utilizado o delineamento experimental inteiramente casualizado, em um bifatorial com parcelas subdivididas, com três repetições, tendo nas parcelas principais três estados de compactação (PDC - Plantio direto há seis anos que recebeu compactação adicional por quatro passadas de máquina com massa de 10 Mg no ano agrícola 2003/2004; PD - Plantio direto há seis anos; Escarif - Plantio direto há seis anos, sendo escarificado e gradeado no ano agrícola 2003/2004) e nas subparcelas as culturas de verão soja e milho e trigo no inverno. Foram avaliadas as propriedades físicas do solo macroporosidade, microporosidade, porosidade total, densidade do solo e resistência do solo à penetração e o crescimento e rendimento das culturas soja, milho e trigo. Os resultados mostraram que a compactação adicional apresentou incremento da resistência do solo à penetração até a profundidade de 0,12 m e afetou negativamente as propriedades físicas do solo; as culturas milho, soja e trigo foram sensíveis à compactação, tendo a altura das culturas soja e milho e comprimento radicular das culturas soja e trigo, reduzidos pela compactação adicional; a compactação do solo influenciou o rendimento das culturas soja, milho e trigo, sendo os maiores rendimentos verificados no plantio direto e os menores no tratamento com compactação adicional, e o maior rendimento do trigo foi observado na sucessão com soja