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Search Results: 1 - 10 of 67030 matches for " Dalvan José; "
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Coluna de areia para medir a reten??o de água no solo: protótipos e teste
Reinert, Dalvan José;Reichert, José Miguel;
Ciência Rural , 2006, DOI: 10.1590/S0103-84782006000600044
Abstract: soil water retention curve (swrc) has been built using several strategies and methodologies. for low tension the use of tension tables has predominated. this paper presents prototypes and test the use of sand suction columns to measure soil water retention from 0 to 100hpa tension. an initial test was set up in a sand column instrumented with tensiometers every 0.1m from top to 1.0m depth. the column was set in a plastic tube 0.25m diameter with devices to have water inlet and to allow water table level. the column was filled with sieved sand, saturated and drained till a given water table depth. the total water potential distribution inside of column and water tension variation at sand surface indicated that, after hydrostatic equilibrium, the depth of water table regulates the potential distribution and the water tension at sand surface is equal to depth of water table. sand column models (low and high cost) were set up and tested. in these columns a tensiometer was installed at sand surface and saturated soil samples in cylinders with tensiometers inside were set on top of sand and on top of filter paper laid on sand. tensiometers located at sand surface and inside of soil samples indicated that tension targets were achieved from 8 to 12 hours at both, sand surface or inside of soil samples.
Varia??o da agrega??o induzida por plantas de cobertura de solo no inverno e plantio direto de milho em um solo podzólico
Basso, Claudir José;Reinert, Dalvan José;
Ciência Rural , 1998, DOI: 10.1590/S0103-84781998000400006
Abstract: a field study was carried out from may of 1993 to may of 1995 at federal university of santa maria campus at the soil science department experimental área, using an experiment installed on a typic hapludalf (yellow-red podzolic) since 1989. the objectives were to evaluate the impact of some winter cover crops on water aggregate stability afterfour andfive year ofno- tiliage system. the cover crops used were: forage pea (pisum arvensis), common vetch (vicia saliva), wild winter pea (lathyrus sativus), ryegrass (lolium multiflorum iam), blue lupine (lupinus angustifolius) and black oat (avena strigosa). the fallow was used as a control treatment. soil samples to measure aggregate stability were extracted from 0 to 5cm depth atfour dates ofeach year: (lst) - cover crops atflowering; (2nd) - after com emergency; (3rd) - com tasseling and; (4th) - com harversting. in 1993/94) growing season the treatment with black oat cover crop induced higher water aggregate stability than other cover crops. however, for the following year ali cover crops inproved the aggregate stabilty to a levei wich was not observed significant dijference among then.
Método alternativo para a determina??o da densidade de partículas do solo: exatid?o, precis?o e tempo de processamento
Gubiani, Paulo Ivonir;Reinert, Dalvan José;Reichert, José Miguel;
Ciência Rural , 2006, DOI: 10.1590/S0103-84782006000200049
Abstract: soil particle density (dp) has been mainly determined using methods which measure solids volume by liquid displacement and its volumetric quantification. the volumetric measurement shows low precision, requires time for complete liquid drainage and is the longer lasting step. the objective of this paper was to substitute the volume displacement measurement step by weighing the volume displaced and to present an alternative method to measure the dp. the dp of 60 soil samples varying in texture and organic matter was determined by volumetric flask and modified volumetric flask, estimating exactness, precision and processing time. the dp averages for both methods were similar, with the modified flask method presenting greater precision and smaller processing time.
Variabilidade espacial da resistência do solo à penetra??o em plantio direto
Silva, Vanderlei Rodrigues da;Reichert, José Miguel;Reinert, Dalvan José;
Ciência Rural , 2004, DOI: 10.1590/S0103-84782004000200010
Abstract: the objective of this work was to characterize the spatial variability of soil resistance to penetration (rp) in no tillage farming, identifying the degree of soil compaction. the rp was determined directly in the field, in systematic way in three soils types. the first experimental area was in santa maria, in hapludalf, with 120g clay kg-1 in the layer of 0-20cm. the second, located in cruz alta, in a haplortox, with 500g clay kg-1 in the 0-20cm layer and the third experimental area located in colonel barros, in a hapludox, with 600g clay kg-1 in the 0-20cm layer. the values of rp were analyzed by descriptive statistics and for geoestatistical techniques. in the three soils, the technique of the krigeagem was used to make surface maps, identifying three classes of rp, the one that, we called degree compaction (ec). in hapludalf, smallest ec was considered the values of rp among 0.58mpa to 0.88mpa, the middleman ec among 0.89mpa to 1.18mpa and largest ec, values of rp between 1.19mpa and 1.50mpa. in haplortox, in the smallest ec the values of rp were selected varying among 1.70mpa to 2.22mpa, the middleman ec, rp among 2.23mpa to 2.75mpa and, in largest ec, values of rp among 2.76mpa to 3.20mpa. in hapludox the values of rp in smallest ec were among 0.20mpa to 1.59mpa, in the middleman ec among 1.60mpa to 2.10mpa and in largest ec, among 2.11mpa to 2.80mpa. in the three areas, the distribution of the soil degree compaction decreased of the headboard area (larger ec) for the center of the farming (smaller ec).
Compara??o entre os métodos do cilindro e do torr?o na determina??o da porosidade e da densidade do solo
Silva, Vanderlei Rodrigues da;Reinert, Dalvan José;Reichert, José Miguel;
Ciência Rural , 2000, DOI: 10.1590/S0103-84782000000600025
Abstract: the objective of this study was to compare and to establish relations between bulk density, total porosity, macro and microporosity values determined by the uhland core method and by the clod method, for no tillage and conventional tillage, with and without grazing. soil samples were collected from a hapludalf, with a loam surface texture, located in santa maria, in brazil. the bulk density values obtained by the clod method were greater than those obtained by the uhland core method. the macroporosity was the soil parameter with the greatest variations when comparing the two methods. thus, comparison it should be avoided to compare management systems, of studies where different methods were used.
Resistência mecanica do solo à penetra??o influenciada pelo tráfego de uma colhedora em dois sistemas de manejo do solo
Silva, Vanderlei Rodrigues da;Reinert, Dalvan José;Reichert, José Miguel;
Ciência Rural , 2000, DOI: 10.1590/S0103-84782000000500009
Abstract: the increase of soil mechanical resistance may limit plant growth and productivity. the objective of this paper was to evaluate the effects of wheel traffic caused by a grain harvester (combine) on penetration resistance for two soil tillage systems. the treatments were: no tillage, no wheel traffic and wheel traffic by a soybean harvester; tillage, no wheel traffic and at wheel traffic by a soybean harvester. soil penetration resistance with a cone penetrograph with electronic readings for each 0.15cm depth, and soil moisture were determined down to a depth of the 40cm, at two soil conditions (dry and wet), on a clayey haplortox (le). the combine front-axle load was 5.0mg and the wheel contact area was 0.283m2, yielding a ground pressure of 0.0884mpa. for high soil moisture the soil resistance difference between treatments was low (smaller than 2,0mpa), not limiting to root growth. however, for the second evaluation, about 30 days after the first, when the soil was drier, soil compaction in the layer from 5 to 17cm caused by wheel traffic was observed. soil water content influenced the values of soil resistance. critical values, considered as penetration resistance greater than 2mpa, were mainly observed for the no tillage system, specially for the 7.5 to 17.0cm layer. the no tillage system had a greater state of compaction than the tilled soil, because of yearly load accumulations. soybean yield was not different between the tillage systems, with an average of 3.15mg ha-1 yield.
Tillage systems and nutrient sources affecting soil cover, temperature and moisture in a clayey oxisol under corn
Veiga, Milton da;Reinert, Dalvan José;Reichert, José Miguel;
Revista Brasileira de Ciência do Solo , 2010, DOI: 10.1590/S0100-06832010000600025
Abstract: tillage affects soil physical properties, e.g., porosity, and leads to different amounts of mulch on the soil surface. consequently, tillage is related to the soil temperature and moisture regime. soil cover, temperature and moisture were measured under corn (zea mays) in the tenth year of five tillage systems (nt = no-tillage; cp = chisel plow and single secondary disking; ct = primary and double secondary disking; ctb = ct with crop residues burned; and ctr = ct with crop residues removed). the tillage systems were combined with five nutrient sources (c = control; mf = mineral fertilizer; pl = poultry litter; cs = cattle slurry; and ss = swine slurry). soil cover after sowing was greatest in nt (88 %), medium in cp (38 %) and lowest in ct treatments (< 10 %), but differences decreased after corn emergence. soil temperature was related with soil cover, and significant differences among tillage were observed at the beginning of the growing season and at corn maturity. differences in soil temperature and moisture in the surface layer of the tilled treatments were greater during the corn cycle than in untilled treatments, due to differences in intensity of soil mobilization and mulch remaining after soil management. nutrient sources affected soil temperature and moisture in the most intense part of the corn growth period, and were related to the variation of the corn leaf area index among treatments
Aggregate stability as affected by short and long-term tillage systems and nutrient sources of a hapludox in southern Brazil
Veiga, Milton da;Reinert, Dalvan José;Reichert, José Miguel;
Revista Brasileira de Ciência do Solo , 2009, DOI: 10.1590/S0100-06832009000400003
Abstract: the ability of a soil to keep its structure under the erosive action of water is usually high in natural conditions and decreases under frequent and intensive cultivation. the effect of five tillage systems (nt = no-till; cp = chisel plowing and one secondary disking; ct = primary and two secondary distings; ctb = ct with crop residue burning; and ctr = ct with removal of crop residues from the field), combined with five nutrient sources (c = control, no nutrient application; mf = mineral fertilizers according to technical recommendations for each crop; pl = 5 mg ha-1 y-1 fresh matter of poultry litter; cm = 60 m3 ha-1 y-1 slurry cattle manure; and sm = 40 m3 ha-1 y-1 slurry swine manure) on wet-aggregate stability was determined after nine years (four sampled soil layers) and on five sampling dates in the 10th year (two sampled soil layers) of the experiment. the size distribution of the air-dried aggregates was strongly affected by soil bulk density, and greater values of geometric mean diameter (gmdad) found in some soil tillage or layer may be partly due to the higher compaction degree. after nine years, the gmdad on the surface was greater in nt and cp compared to conventional tillage systems (ct, ctb and ctr), due to the higher organic matter content, as well as less soil mobilization. aggregate stability in water, on the other hand, was affected by the low variation in previous gravimetric moisture of aggregates, which contributed to a high coefficient of variation of this attribute. the geometric mean diameter of water-stable aggregates (gmdws) was highest in the 0.00-0.05 m layer in the nt system, in the layers 0.05-0.10 and 0.12-0.17 m in the ct, and values were intermediate in cp. the stability index (si) in the surface layers was greater in treatments where crop residues were kept in the field (nt, cp and ct), which is associated with soil organic matter content. no differences were found in the layer 0.27-0.32 m. the effect of nutrient sources on gmdad
Varia??o na temperatura do solo em três sistemas de manejo na cultura do feij?o
Silva, Vanderlei Rodrigues da;Reichert, José Miguel;Reinert, Dalvan José;
Revista Brasileira de Ciência do Solo , 2006, DOI: 10.1590/S0100-06832006000300001
Abstract: soil temperature is a property that directly affects crop growth and is influenced by the energy balance on the soil surface. thus, soil management systems influence soil temperature because they change soil surface conditions. the objective of this study was to determine the effect of three soil management systems on soil temperature throughout the snapbean cycle. a field experiment was arranged in a randomized block (split plot) design with four replicates, on a soil classified as hapludalf. the treatments were continuous no-tillage for 7 years (pd); no-tillage revolved by disc moldboard ploughing (pdar); and no-tillage revolved by chiseling (pdesc). the soil temperature was monitored throughout the snapbean cycle. an automated data collection system collected information every 10 minutes with thermopar (copper-constantan) sensors installed at depths of 0.025 m and 0.10 m. soil bulk density and snapbean yield were determined. the lowest maximum temperature and the lowest daily amplitude were observed for pd. the pdar system showed a maximum temperature of 42.2 °c, the pdesc system of 43.7 °c, and the pd of 36.1 °c at 0.025 m depth. the daily soil temperature variation during a day with 12 hours of sunlight at the beginning of the snapbean development (02/12/2002) indicated that the peak temperature was reached at about 15 o'clock, with values of 40 oc in pdar and 30 oc in pd, at the 0.025 m depth. when the plants shaded the soil, there were no differences in soil temperature among management systems. the differences in soil temperature were not reflected in the snapbean yields since the effects of high soil temperature are observed at seed germination.
Variabilidade espacial da resistência do solo à penetra o em plantio direto
Silva Vanderlei Rodrigues da,Reichert José Miguel,Reinert Dalvan José
Ciência Rural , 2004,
Abstract: O objetivo deste trabalho foi caracterizar a variabilidade espacial da resistência do solo à penetra o (RP) em solo sob plantio direto, identificando estados de compacta o. Determinou-se a RP diretamente no campo, de forma sistemática, em três classes de solos. A primeira área experimental está localizada em Santa Maria, em um Argissolo Vermelho-Amarelo, com 120g kg-1 de argila na camada de 0-20cm. A segunda está localizada no município de Cruz Alta em um Latossolo Vermelho distrófico, apresentando 500g kg-1 de argila na camada de 0-20cm, e a terceira área experimental está localizada em Coronel Barros, em um Latossolo Vermelho distroférrico típico, com 600g kg-1 de argila na camada de 0-20cm. Os valores de RP foram analisados via estatística descritiva e por geoestatística. Nos três solos, utilizou-se a técnica da krigagem para desenhar mapas de superfície, identificando três classes de RP, a qual, chamamos de estados de compacta o (EC). No Argissolo, o menor EC foi considerado os valores de RP entre 0,58MPa e 0,88MPa, o EC intermediário entre 0,89MPa e 1,18MPa e o maior EC, valores de RP entre 1,19MPa e 1,50MPa. No Latossolo Vermelho distrófico, no menor EC foram selecionados os valores de RP variando entre 1,70MPa e 2,22MPa, o EC intermediário, RP entre 2,23MPa e 2,75MPa e, no maior EC, valores de RP entre 2,76MPa e 3,20MPa. No Latossolo Vermelho distroférrico típico, os valores de RP no menor EC foram entre 0,20MPa e 1,59MPa, no EC intermediário entre 1,60MPa e 2,10MPa e no maior EC, entre 2,11MPa e 2,80MPa. Nas três áreas, a distribui o dos estados de compacta o diminuiu da área de cabeceira (maior EC) para o centro da lavoura (menor EC).
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