Volumen 17, Número 1 (Junio, 1999)
Contracción al secado de agregados en diferentes fases de degradación de un suelo franco limoso de la pampa ondulada
The shrínkage characteristic of soíl aggregates in different degradation phases of a sílty loam of the rolling Pampa, Argentina
OA Barbosa, MA Taboada & DJ Cosentino
Pág. 1-7
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Sortívídad y conductividad hidráulica saturada de Udoles del sudeste bonaerense, Argentina
Sortivity and saturated hydraulic conductivity of udolls soils in south eastem of Buenos Aires province, Argentina
FN Cabria & JPh Culot
Pág. 8-19
Sortivity and saturated hydraulic conductivity were estimated for three representative soil series in the south eastern Pampa of the Buenos Aires province. The goodness of fit of severa1 equations in calculating sortivity (S) and final infiltrability (i,) of soils was assessed and errors estimated when truncated algorithms were applied. Infiltration data were obtained using a double ring infiltrometer device. S and i, were calculated from the Philip two terms equation arid the truncated algorithm of Swartzendruber with one to five coefficients. The Philip equation overestimated S and underestimated ic. During hydration, the magnitude and direction of surface tensible force changed. It is suggested that A, B. C. ….N coefficients of Swartzendruber equation represent the directional and magriitudirial changes in the evolution of sortivity. Iu the soils under study tliese clianges are influenced by the iiiitial water content arid by the modifications iri the design of the pore space resulting from differential expansibility of matrix elements. In three soils, final infiltrability calculated through Swartzendruber algorithm was equivalent to saturated hydraulic conductivity (K) measured through the Klute method.
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Evaluación de la nutrición nitrogenada de girasol cultivado en Balcarce (Buenos Aires, Argentina)
Nitrogen nutrition of sunflower cultivated in Balcarce, Buenos Aires, Argentina
LJ Sosa, HE Echeverría G A Dosio & LAN Aguirrezabal
Pág. 20-26
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Cambios en la fijación-liberación de potasío en Argíudoles con distintos tipos de arcillas y saturación potásica
Changes in the potassium fixation-líberation in Argiudolls with different types of clays and potassium saturation
MG González, G Moreno, ME Conti & AM de la Horra
Pág. 27-30
An experimeiit was coiiducted to asses the potassium kinetics of two different soils, an Aquic Argiudoll (AA) with high smectite contents ind low potassium saturation, and a Typic Argiudoll (AT) with low illite coiiteiits aiid high potassium saturation. Samples were fertilized with different rates of potassium, and incubated under four different humidity and ternperature cycles. In order to estabiish fixation-release cycles, residual value of potassium B value and Q/I curves were deterrnined. Fertilization increased the exchangeable and non-exchangeable potassium forrns in both soils, but did not affect tlie B value, which was characteristic of each orie of them ,showing fixed potassium liberation potential. because of previous fertilizatioris of soils. Potassium replacement was higher in AA than in AT in all treatments. The AA soil had a higher potassium buffer capacity and a lower residual B values thaii AT, sliowiiig that a riegative con-elation between potassium saturation and fixatioti capacity exists.
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Efectos de seis años de labranzas en un Hapludol del noroeste de Buenos Aires, Argentina
Six years of tillage in an Hapludoll from tbe northwestem of Buenos Aires, Argentina)
M Díaz-Zorita
Pág. 31-36
The objective of this research was to select tillage systems for the sustainable management of corn-soybean sequences in soils of the Northwestern of Buenos Aires, Argentina. Evaluation of soil chernical (Total organic carbon, total nitrogen, available phosphorus, pH) and physical properties (actual and maximum bulk density, soil resistance, aggregate distribution, and wet aggregate stabiliiy) was carried out in 1996 from tillage experiments established in 1990 on a Typic Hapludoll. Tillage treatments included: moldboard plowing (LC), chisel plowing (LV) and no-ti11(SD). After six years of continuous cropping total organic carbon contents (COT) in the 0- 30 cm layer decreased 18.9 96 and 7.3 96 under LC and LV, respectively. No differences in COT between the initial condition and SD were found. Phosphorus (Bray Kurtz 1) content in the 0-3 cm layer was lower under SD than LV or LC. Soil pH was not affected by the different tillage systems. There were no significant differences in corn or soybean yields arnong tillage systems. SD was shown to be a benefitial management practice conserving the soil fertiliiy of Typic HapludolB during agricultura1 cycles, in the Northwestern of Buenos Aires, Argentina.
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Indicadores de deterioro en suelos de la Pampa Ondulada
Soil deterioration indexes in the Rolling Pampa
S Unicariet & RS Lavado
Pág. 37-44
The intensive land use in the Rolling Pampa promoted different rates of soil chemical and physical deterioration. Aggregate stability is known to be a good index of soil detenoration. Our objective was to compare soil physical, cliemical and biological indexes of soil quality and their relationship with maize yields. Two fields differing in land use intensity were selected on farms. Soils with short cropping history (CC), long cropping history (CL) and a non-disturbed site. considered as the pristine soil condition (CP) were sampled. Organic carbon, organic nitiogen, tiitrogen mineralizatioii, extractable phosphorus. copper, zinc and boron, inorganic sulfate, exchangeable cations (calcium, magnesium and potassium), cation exchangeable capacity, pH aiid water stable soil aggregation were determined. Maize grain yield was used as a biological index in two successive years. The more intense land use promoted a greater decrease of coi1 aggregation than organic carbon and total nitrogen. As compared to CP, iiitrogen mineralizatioii iii CL, was reduced to a 50 %, while plant availability of phosphorus, zinc and boron was reduced by 77%, 57% and 55% respectively. Otlier soil properties differed significantly from both detenorated and pnstine conditions but not between CC and CL. Exchangeable cation capacity, calcium and pH did not differ between treatments. Maize graiti e l d was only sigiiificaiitly different in the first year of experirnentation. Mean weight diameter of aggregate was associated negatively with corn yields (r– 0.63) being the only coi1 property that presented significant differences among treatments in both years (P less than 0.05). Soil stable aggregation and extractable phosphorus explained 53 % of tlle variation of maize grain yield.
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Cambios en el contenido de fósforo asimilable en los suelos del este de la Provincia de La Pampa, Argentina
Changes in avaílable soíl phosphorus in the Eastem La Pampa, Argentina
J Montoya, AA Bono, A Suárez, N Darwich & F Babinec
Pág. 45-49
Available soil phosphorus coiiteiit (Bray-Kurtz 1) iu fifteen departmeiits of the Eastern Region of La Pampa Proviiice, Asgeiitiiia, obtaiiied betweeii 1993 aiid 1996 were compared to the 1980 ‘S data. TIie results showed aii importaiit iiicrease iii the areas with pliosphorus deficieiicy. Agicultuse iiiteiisificatiori, use of low aptitude laiids aiid the lack of the repositioii OS iiutrient to the soil have lowered available pliosphorus Icvels. iti maiiy situatioiis, tliese critical lcvels may limit crop productioii.
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Contenidos y formas de fósforo en suelos desarrollados sobre materiales aluviales de Tucumán, Argentina
Contents and forms of phosphorus in alluvial soils from Tucuman, Argentina
NC Molina, R Blanco, A Cabrera & J Arcia
Pág. 49-53
Five soils of alluvial ongin of the orders Mollisol and Entisol, cropped with sugar cane were aiialyzed for total, orgaiiic, iiiorgaiiic mobile and resistant phosphorus. Iti al1 profiles calcium phosphates aid orgaiiic pliosphorus were the major forms. Relative calcium phosphate contents increased with depth, while organic phosphorus decreased. Aluminum and iroii phosphates were secoiidary forms iii al1 profiles. Soil pH was the maiii determining variable in dishibution of phosphorus inorganic forms. Relative resistant phosphorus was more or less coiistant in each profile with low values for three profiles developed on dehital parent material from the Aconquija mountains and high for two profiles developed oii alluvial pareiit material originated by local transport in Chacopampeana aeolian plain. Total phosphorus was low in the last two profiles and relatively high in the fust tluee: this was interpreted as inherent differences of parent material linked to geomorphological and geographic position.
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Boro extraíble en suelos del sudoeste bonaerense
Extractable boron in soils of southwestem Buenos Aires, Argentina
MM Ron, SG de Bussetti & T Loewy
Pág. 54-57
The objective of tliis communication was to obtain preliminary information on levels of soil boron in tlie area and its relation with other soil properties. Boron extracted by ammoiiium acetate was determiiied in 28 soil samples of tlie area. Extractable boron (BE) was in average 42 pg g-l. The fiuer textured soils had a slightly higher BE on average. 20 % Udols and 40 % Ustols were iiot higher than tlie tentative critica1 leve1 of 0,35 pg E’,reported in the literature. No significant relations were found betweeii BE aiid pH. BE iiicreased with M 0 aiid SE iii tlie Ustols. but oiily tlie association witli SE was significant. BE was significantly correlateci to 7c clay and surface hydroxyls ( O X ) iii both suborders. This was explaiiied thougli the relationship of these properties with adsorbed boron.
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Influencia de enmiendas orgánicas sobre el aluminio de cambio de un Oxisol
Influence of organic manures on the exchangeable aluminum of an Oxisol
AE Castillo, RM Carbonell & S Vazquez
Pág. 58-59
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