Volumen 19, Número 2 (Diciembre, 2001)
Efecto de cationes sobre propiedades hidrofísicas de suelos con diferentes minerales de arcilla
Effect of cations on hydrophysical soil properties in relation to clay minerals
RS Martínez, P Zalba, MB Villamil & N Peinemann
Pág. 85-91
Soil physical properties depend on the composition of exchangeable cations, the concentration of electrolytes, and the kind of soluble salts. Laboratory experiments were conducted to study the variation of soil hydrophysical properties with the use of water solutions of different cationic composition. It was hypothesized that the deleterious effect of monovalent cations on soil hydrophysical properties mainly depends on the kind of divalent cations present in the soil solution and on clay mineralogy. Soil hydraulic conductivity was determined in two soils with illitic and smectitic clay minerals which were leached with solutions of different cationic composition. In these soils, cationic exchange experiments were also carried out. Results show relative hydraulic conductiv- ity (K) in the illitic soil to be more negatively affected by Mg treatments. Soil K decreased further when Ca was replaced by monovalent cations in the smectitic soil. It was concluded that the smectitic soil exhibited the lowest affinity for Na+ and therefore the hydrophysical soil properties were less affected in comparison with the illitic soil.
Texto en PDF
Comportamiento de algunas propiedades del suelo en una sabana del Chaco Semiárido Occidental bajo distintas frecuencias de fuego
Behavior of some soil properties in a savanna of the ‘Chaco Semiárido Occidental’ under different fire histories
CC González, GA Studdert, C Kunst & A Albanesi
Pág. 92-100
Soil properties related to carbon and nitrogen dynamics of a savanna of Elionurus muticus (Spreng) O. Kuntze under three different fire frequencies (‘fire history’) were compared at one point of time. Soil was described as a Torriorthentic Haplustoll. Fire frequencies were characterized as: high (one fire every year), medium or normal (one fire every 3-4 years), and low (one fire every 10 years). Total soil organic carbon (COT) and nitrogen (NOT) contents, particulate organic matter carbon (COP) and nitrogen (NOP) contents, carbon content of the gross organic matter fraction (COG), as well as soil nitrate nitrogen content (N-NO3), soil respiration and soil microbial biomass nitrogen (NBM) were assessed at two soil depths, 0-2.5 cm and 2.5-7.5 cm. Gross organic matter carbon was lower under the high frequency than under the medium and low frequency areas. Total soil organic carbon, NOT, N-NO3 – and NBM were lower under high frequency fires, than under medium and low frequency fires, that did not differ between them. Particulate organic carbon and NOP were also lower under the high frequency, and were more sensitive than COT and NOT to the effects of fire history. There were not differences in soil respiration among fire histories. These results showed that repeated burns reduce soil organic matter as well as soil biological activity and may increase soil susceptibility to erosion processes. However, areas under medium or normal fire frequency maintained organic nitrogen and carbon pools and showed higher nitrogen availability.
Texto en PDF
Absorción de nitrógeno por cebada cervecera en dos suelos del sur bonaerense, Argentina
Nitrogen uptake by malting barley in two soils of southern Bs.As. Province, Argentina
MA Lazzari, MR Landriscini, MA Cantamutto, AM Miglierina, RA Rosell, FE Möckel & ME Echagüe
Pág. 101-108
Two experiments were carried out to determine the effect of nitrogen on nitrogen uptake and grain nitrogen concentration of barley grown for malting. First, the effects of fertilizer applications at rates of 0 (0N) and 60 kg N ha-1 (60N) were studied in a pot experiment in a glasshouse using urea labelled with 15N applied at sowing to two soils: Bordenave (B, Typic Haplustoll), and Tres Arroyos (TA, Petrocalcic Argiudoll). Pots were destructively sampled at the fifth leaf, ear emergence, milky kernel and physiological maturity stages. Distribution of 15N and 14N in shoots and roots, and in spikes at maturity, were measured. Maximum aerial biomass uptake was usually reached by the time of milky stage, but continued up to maturity in 60N TA. In 60N B there was evidence of losses of fertilizer and soil nitrogen in shoots, but not in roots, in 60N B between milky and maturity stages. Urea increased the spike yield in 60N TA, and the grain nitrogen concentration in 60N B. Simultaneusly, experiments were carried out in the field in both soils, where urea was applied at rates varying from 0 to 90 kg N ha-1 at TA, and from 0 to 75 kg N ha-1 at B. Plants and soils were sampled at the same growth stages of the pot experiment. Soils samples were analyzed for N-NH + and N-NO3 – (0-60 cm). In all treatments at TA and 75N at B losses of nitrogen from aerial biomass in the last period of growth were detected. The addition of more than 30 kg N (at TA) or 25 kg N ha-1 (at B) increased the percentage of grain protein to higher levels than accepted for malting. A high nitrogen-supplying power of the soil organic reserves was observed.
Texto en PDF
Respuesta a la fertilización con boro y zinc en sistemas intensivos de producción de maiz
Response to boron and zinc fertilization in intensive corn production systems
RJ Melgar, J Lavandera, M Torres Duggan, & YL Ventimiglia
Pág. 109-114
Micronutrient fertilization of corn is not a common practice in cropping systems of Argentina. However, different soil test surveys indicate that boron (B) and zinc (Zn) would be the most fre- quently deficient micronutrients with probabilities of economic responses as result of applications. This work was conduced to evaluate the response of corn to B and Zn applications, relating these responses to its leaf concentration and soil availability. During 1996-2000 fertilization trials were carried out with B in ten locations and with Zn in fourteen locations of the northern pampean region. Increasing rates of B (0 to 1.5 kg ha-1 as sodium borate foliar spray at V4-5 stage ) and of Zn (0 to 6 kg ha-1 as oxisulfate in the sowing line) were applied separately, on high potential yielding corn crops. Results differed among trials since only three of the ten, and five of the fourteen sites where either B or Zn were applied respectively, showed significant differences among the check and treated plots; a site proportion that was not related to soil nutrient availability. For the sites with significant re- sponses, the grain increase was 0,78 and 0,74 Mg ha,-1 obtained with 0,5 and 4 kg of B and Zn ha-1 respectively.
Texto en PDF
Nitrato en la base del tallo del maíz. I: Cambios durante la estación de crecimiento
Basal stalk nitrate of maize. I: Changes during growing season
HE Echeverría, H Sainz Rozas, E Herfurt & SA Uhart
Pág. 115-125
The stalk nitrate concentration on dry basis (NBS) and in sap (NS) have been suggested as an index of nitrogen nutrition of maize. Therefore, it is necessary to describe the evolution of NBS and NS during maize growing season. The evolution of NBS and NS was studied during 1996/97 and 1997/98 growing seasons in a no-tillage system (SD) fertilized with different urea rates (0, 35, 70, 140, 210 and 280 kg nitrogen ha-1 ) at different wheat growing stages (planting and V6) (experiment 1), and under NT and conventional tillage (LC) with different urea rates applied at V6 (0, 70, 140 and 210 kg nitrogen ha-1) (experiment 2). The NBS was determined at six-leaf (V6), twelve-leaf (V12), grain milky (R3) and physiologic maturity (R6), while the NS was determined in V6, V12 and R3. In the Experiment 1, NBS was highest at V12, particularly when nitrogen was applied at planting. The NBS for fertilization at V6 was lower than the fertilization at planting. In the experiment 2, the evolution of NBS showed similar behavior but the oscillations were less marked and differences between tillage systems were not observed. The evolution of NS in the experiments 1 and 2 was the same that NBS in both growing seasons. In all experiments the NS showed high variations between years. At V6, V12 and R3 stages, the NBS and NS were positively associated but the slopes of regression models were different. Therefore, it is necessary to calibrate each methodology separately to determine threshold values above which N addition does not increase maize grain yield.
Texto en PDF
Nitrato en la base del tallo de maiz. I I: Diagnóstico de la nutrición nitrogenada
Basal stalk nitrate of maize I I: Diagnosis of nitrogen nutrition
HR Sainz Rozas, HE Echeverría, E Herfurth & GA Studdert
Pág. 125-135
In the southeastern of Buenos Aires Province of Argentina exists little information about the utility of stalk nitrate concentration on dry matter base (NBS) or in sap (NS), as predictors of maize nitrogen nutrition. The relationships between maize relative yield (RR) and NBS and NS were evaluated from 1995/96 to 1997/98 on irrigated no-tillage (SD) maize with different urea rates and fertilization moments (experiment 1), and under SD and conventional tillage (LC) with different urea rates applied at V6 (experiment 2). In 1997/98, the NBS and NS were also evaluated on rainfed maize under NT and CT with different preceding crops (pasture and wheat) and urea rates (experiment 3). In experiments 1 and 3, RR was highly related with NBS (r2= 0.54 to 0.81) and with NS (r2= 0.47 to 0.74) at V6 stage. The NBS sufficiency thresholds (US) for RR= 95% or greater, ranged from 4.3 to 10.4 g N-NO3 – kg-1 , whereas those for NS ranged from 1.2 to 2.4 g NO – L-1 . In experiments 1 and 2, RR 33 was adequately related with NBS or NS at V12 and R3. However, the US values were highly variable among years and fertilization times, especially for NS. At R6, the US of NBS was 0.8 g N-NO -kg-1 and did not show variation among years. The NBS and NS before R6 reflected appropriately nitrogen availability for maize generated by different management practices, but they should be used with caution to make nitrogen-fertilizer recommendations. However, the NBS at R6 could be used for characterizing the degree of nitrogen excess.
Texto en PDF
Predicción de la productividad primaria de pastizales naturales de la Pampa Deprimida utilizando propiedades del horizonte A
Prediction of natural grasslands primary production on the basis of A horizon properties in the Flooding Pampas
P Vázquez; JL Costa; G Monterubbianesi & P Godz
Pág. 136-143
The objective of this work was to develop predictive models of native grasslands dry matter productivity (DM) with nitrogen and phosphorus fertilization in sodic soils of the Flooding Pampas using the properties of A horizon over two growing seasons with contrasting water stress levels (612 mm vs 1046 mm). Total rainfall during the growing season affected the relative weight of A horizon properties on predicting DM. When P was added (40 kg P ha-1) the variables most associated with DM production were pH and sand. The R2 for the dry and the humid period were 0.88 and 0.91, respectively.Whenphosphorusandnitrogenwereapplied(40kgPha-1 and200kgNha-1),gravimet- ric water content at 33 kPa and sand were selected as independent variables in the dry period (R2=0.91), and sodium adsorption ratio (RAS) and clay were selected in the humid period (R2=0.90). Nitrogen use efficiency was better predicted by the gravimetric water content at 1500 kPa and sand in the dry period (R2=0.97) an by sand in the humid period (R2=0.57).
Texto en PDF
Pérdida de nutrientes por erosión hídrica en dos suelos del Caldenal Pampeano
Nutrient losses due to water erosion in two soils of the Pampa´s Caldenal
EO Adema, FJ Babinec & N Peinemann
Pág. 144-154
In the Caldenal region, overgrazing causes important soil losses due to water erosion. The magnitude of this process is related to soil properties and vegetation cover. The objective of this study was to evaluate nutrient losses due to water erosion on an Entic Haplustoll and a Typic Ustipsamment. Treatments were: natural vegetation, clipped vegetation with residue reduction, and bare soil. Evalu- ations were carried out in March and September using a rainfall simulator (28 mm in 30 min) over 2 m 2 runoff plots. Organic carbon (OC), total nitrogen (N) and available phosphorus (P) were determined onsediments. Average sediment OC and N content was higher in the Haplustoll (59.5g.kg-1 and4.3 g.kg-1) than in the Ustipsamment (37.6 g.kg-1 and 2.2 g.kg-1). P was lower in the Haplustoll (29.8 mg.kg-1) than in the Ustipsamment (40.2 mg.kg-1). Losses of N and P were significantly higher in March than in September. In the bare soil, nutrient losses were higher in the Haplustoll than in the Ustipsamment, while with vegetation cover, erosion was of lesser importance, and similar for both soil types. Organic carbon was the soil constituent that suffered the highest losses due to water erosion.
Texto en PDF
Comparación de dos técnicas de cuantificación de infección micorrítica
Comparison of two techniques for determining mycorrhizal infection
F Covacevich, HE Echeverria & LAN Aguirrezabal
Pág. 155-158
Our aims were to compare the techniques for determining root mycorrhizal infection pro- posed by Giovanetti-Mosse and by Trouvelot et al. Data were extracted from a glasshouse experi- ment where wheat plants were grown in pots filled with a Petrocalcic Paleudoll soil. Treatments were nitrogen and phosphorus fertilization levels and three sampling depths. Mycorrhization (M) esti- mated by both methods ranged from 0 to about 68 %. Arbuscules (A) estimated by both methods ranged from 0 to about 61 %. There were found positive (up to r2= 0,77) relationships between M and A. Similarly, there were found positive (up to r2= 0,76) relationships when M or A estimated by the two methods were correlated. Mycorrhization estimated by the Giovanetti-Mosse method showed M% values lightly highest from the estimated by Trouvelot et al. (MTrouvelot(%)= 0,98 MGiovanetti (%)– 4,1; r2= 0,81). Arbuscules showed a similar trend (A (%)= 0,82 A (%) – 4,2 r2= 0,76).
Texto en PDF
Nodulación y nutrición nitrogenada en sojas convencionales y resistentes a glifosato inoculadas con Bradyrhizobium japonicum
Nodulation and nitrogen nutrition in conventional and glyphosate resistant soybean inoculated with bradyrhizobium japonicum
FA Montero, KM Filippi & MA Sagardoy
Pág. 159-162
Numerous glyphosate resistant soybean ( Glycine max L. Merrill) cultivars are cropped in Argen- tina, though sufficient information about the symbiosis capacity of B. japonicum with each cultivar is lacking. Therefore, our objective was to evaluate different parameters of nodulation and nitrogen nutrition in four conventional and fifteen glyphosate resistant soybean cultivars originated from seeds inoculated with liquid inoculant containing B. japonicum E109. The assay was conducted in a growth chamber under controlled conditions (22-25 oC, 16 h of light, 8 h of dark, soil at field capacity). The soil used was B. japonicum free. After six weeks (V3 soybean growing stage) different parameters related to nodulation were measured. When all cultivars were tested together significant differences were found in nodule number per plant, nodule dry mass per plant, shoot and root dry mass per plant, dry mass per nodule, and total nitrogen concentration and content. The number of nodule per plant was similar in glyphosate resistant and conventional soybean cultivars. However, the nodule dry mass per plant, shoot and root dry mass per plant, dry mass per nodule, and total nitrogen concentration and content was 4.8 to 14.2 % higher in conventional than in glyphosate resistant cultivars. Considering all resistant and non resistant cultivars together, significant relationships between nodule dry mass and shoot accumulated total nitrogen, between nodule dry mass and shoot dry mass, and between shoot dry mass and shoot accumulated total nitrogen were determined. Under the conditions of this assay the compatibility between B. japonicum E109 and each conventional or glyphosate resistant soybean cultivar was different because a width range of nodulation and nitrogen nutrition were observed.
Texto en PDF