Volumen 18, Número 2 (Diciembre, 2000)
Predicción del agua disponible usando funciones de pedo-transferencia en suelos agrícolas de la región pampeana
Prediction of available soil water using pedo-transfer functions in agricultural soils of the pampean region
F Damiano & MA Taboada
Pág. 77-88
The yield of agricultural crops largely depends on soil available water capacity (CAD), which usually is estimated from the amount of water retained at -33.3 and -1500 kPa matric potential. The soil cartographical information of the pampean region seldom have this information, limiting the construction of crop yields simulation models. The objectives of this paper were: a) to predict CAD from different pedo-transfer functions (FPT) in pampean soils, and b) to represent the spatial distribution of the predicted CAD values. The CAD values were arranged as follows: fine textured soil Series (M. Juárez, Oncativo, Monte Buey and Los Cardos) > medium textured soil Series (Balcarce and Udaondo) > coarse textured soil Series (Anguil and San Claudio) = soil Series with mechanical impedances which limit plant rooting depth (Roldán and Ramblones). None of the four studied FPT predicted reasonably soil CAD in the whole pampean region, but each one of them worked properly in the area where originally calibrated. Predicted CAD values of pampean soils varied between 28 and 180 mm. The lower CAD (18 % of soils) corresponded to Entic Haplustolls and Petrocalcic Calciustolls, at the west of the pampean region, while the higher CAD corresponded to Typic Argiudolls (19 % of soils) mainly at the center-east of the region. The combination of the predicted CAD values and the information existing in already published soil maps allowed us to characterise crop water availability on a regional basis. This information was included in a new 1:500.000 scale soil map.
Texto en PDF
Adsorción de fósforo por suelos ácidos de Misiones (Argentina)
Phosphorus adsorption by acid soils from Misiones, Argentina
S Vázquez & LA Morales
Pág. 89-94
Phosphorus deficiency in acid soils is related to soil ability to fixe this element through adsorption and precipitation reactions. In order to select the best mathematical model for phosphorus adsorption in soils from Misiones (Argentina), A horizons samples from seventeen different soils were analyzed. Adsorption isotherms were determined by Fox and Kamprath method. Data were performed by Langmuir and Freundlich equations, and by a combined model of Langmuir – Freundlich, that resulted the best one. According to the Langmuir – Freundlich the different soils could be grouped into very high, high, medium and low phosphorus adsorption capacity. The Kds coefficient of combined model Langmuir – Freundlich were negatively related with loam, Ca, Sums of bases, and total P, and positively with aluminum-oxalate.
Texto en PDF
Efecto de diferentes enmiendas sobre algunas propiedades edáficas
EFFECT OF DIFFERENT AMENDMENTS ON SOME SOIL PROPERTIES UNDER HORTICULTURE PRODUCTION IN THE HUMID PAMPAS
Sasal C, A Andriulo, J Ullé, F Abrego & M Bueno
Pág. 95-104
The effect of different amendments on some soil properties was studied in the humid Pampas. Soil conditioners (mature farmyard manure, fresh oat, fresh farmyard manure plus fresh oat and calcitic-dolomitic limestone) were applied to a well-structured fertile soil under horticul- ture production. The following properties were studied after two years of experiment start: bulk density, volumetric moisture (at 0, 1, 5, 10, 20 kPa of water suction), textural bulk density, maximal bulk density, compactation susceptibility, infiltration rate (at 0 and 10 mm of water suction), struc- ture stability index, organic matter content, pH and electrical conductivity and earthworm density. Results showed that organic amendments improved permeability and water retention capability by enhancing the stability of soil aggregates. Limestone treatment maintained the values of the chemi- cal, physical and biological properties in the initial situation. For organic amendments, there was an increase of soil carbon content related to the annual amount of carbon added. An increase of a Mg ha-1 of carbon decreased bulk density by about 0,0065 Mg m-3. Fresh treatments (fresh oat, fresh farmyard manure plus fresh oat), with high contents of fibre, decreased the average values of maxi- mal bulk density in 5 and 7% respectively, increasing the corresponding moisture levels in 4 and 5%.
Texto en PDF
Métodos rápidos de análisis de plantas para evaluar la nutrición nitrogenada del cultivo de trigo
Rapid methods of plant analysis to evaluate wheat nitrogen nutrition
HE Echeverría, RA Strada & GA Studdert
Pág. 105-114
There is a lack of information about the effectiveness of quick methods to evaluate wheat nitrogen nutrition through determinations in the crop. The aim of this work was to determine: a) the relationship between the nitrate concentration at tillering determined in the laboratory on dried stems (BS) and the nitrate concentration determined with a portable reflectometer in the expressed sap (JBT), and b) the relationship between this method and the leaf greenness index (IV) measured in situ with a chlorophyll meter, and wheat grain yield. Two experiments with a randomized com- plete block experimental design and a factorial treatment arrangement, were carried out in 1997. The treatments were the combination of three nitrogen rates (0, 60 and 120 kg N ha-1) and four wheat varieties (similar growing cycle). Nitrate concentration in JBT was related to BS and decreased with plant age and increased with the increase in the nitrogen fertilization rate. The effect of variety was of low impact on both, JBT and BS. The determined thresholds of nitrate concentration in the JBT to achieve approximately 90% of maximum yield were 1,92, 1,34 and 0,58 g L-1 for double ridge, glumme primordium and terminal spikelet, respectively. The IV depended on the nitrogen supply and varied with the varieties. The correlation between nitrogen sufficiency index (ISN) and wheat yield were high (r2 = 0,89) during the tillering. Nitrate concentration in the JBT and ISN in leafs at tillering of wheat are promising estimators of the crop nitrogen nutrition status.
Texto en PDF
Cambios en producción y calidad del forraje otoño-invernal por el agregado de nitrógeno en materiales geneticos de agropiro
Autumn and winter forage production and quality changes by nitrogen applications in tall wheatgrass genetic materials
SI Alonso, JA Fernandez, CI Borrajo & HE Echeverria
Pág. 115-124
Nitrogen applications increase spring tall wheatgrass production, but its effects on production and quality in other seasons, on different genetic materials are unknown for the SE of the Bs. As. province conditions. The objective of this work was to determine the effect of nitrogen applications on autumn and winter forage production and nutritive value, of six tall wheatgrass materials. Forage cuts were made in April, June and August, in treatments with (N100) or without (N0) nitrogen applications. In vitro digestibility (DIVMS), neutral detergent fiber (FDN), total nitrogen percentage (%N), dry matter production (MS), digestible dry matter (MS-Dig) and nitrogen absorption (N- Abs) were evaluated. Nitrogen applications increased tall wheatgrass MS in 60, 110 and 150% for April, June and August forage cuts, respectively. Same results were obtained for MS-Dig. Though the increase due to nitrogen application was higher for the winter forage cut, the greatest MS was obtained in the April cut. The nitrogen application increased the nutritive value. For N0 and N100, the DIVMS was 61,4 and 67,2%, the FDN 55,4 and 51,1%, and the %N 2,1 and 3,3 %, respectively. Phenotypic variability was detected among genetic materials for variables related to forage nutritive value, and it was expressed independently of nitrogen nutritional status. Present information is relevant to crop management and can provide guidelines for selecting germplasm in plant breeding programs, and enhance the positive effect of nitrogen on forage production and nutritive value.
Texto en PDF
Efecto de dos momentos de aplicación de urea sobre la produccion de grano de trigo en Drabble (Buenos Aires, Argentina)
Urea fertilization timing effect on wheat grain yields in Drabble, Buenos Aires, Argentina
M Díaz-Zorita
Pág. 125-131
In the western part of Buenos Aires province (Argentina), many studies show that wheat (Triticum aestivum L.) grain yields increase after nitrogen fertilization, although the best timing for this practice is not clearly defined. The objective of this study was to determine the effects of N fertilization timing using broadcast urea on dryland wheat grain yields. A three years field research on a Typic Hapludoll at Drabble (Buenos Aires) was conducted applying 3 N levels (0, 50 and 100 kg ha-1) at crop emergence or at crop tillering. Wheat grain yields were higher when the N treatments were applied at the emergence of the crops. Response to N fertilization at tillering was significant only in the year with larger rainfall during September. Monthly rainfall in the period June-October was well below that with 50 % chance of recurrence. From the relative availability coefficient and the yield response increment indexes, it was observed that N rates applied at emergence were on average twice as effcective as those applied at tillering for the 3 years.
Texto en PDF
Evaluación de sedimentos marinos afectados por efluentes cloacales como sustrato vegetal
Evaluation of marine sediments with sewage sludge used as plant substratum
ME Vázquez, A Pellegrini, G Millán, R Carrizo & JW Lanfranco
Pág. 132-139
With the purpose of evaluating possible use of marine sediments with sewage sludge that is now poured in Bahía Encerrada, Usuahia, Tierra del Fuego, as plant substratum, and the environmental risk, were performed chemical analysis, microbiological and a biological test with plants (Lolium multiflorum, Festuca arundinacea, Tynopiron ponticum) that were cultivated in the greenhouse under controlled conditions of growth. The variables evaluated were: place of the bay where the sediment comes from, plant species and different mixtures with the upper horizons of a Typic Argiudoll soil. The plant shoot biomass accumulated along 3 months in 100 g pots was analysed. There was a statistically significant difference (P less than 0.01) for the interaction between the origin of the sediment and their proportion in the mixture with soil. A multiple comparison analysis of the simple factors indicated that sediment contents equal or higher than 50%, independently of its origin, affected plants growth negatively. For those treatments with 25% of sludge more distant of the dumping place, comparable results were found and it was also found an increase of the plant shoot biomass in relation with the non added sediment control. The main restrictions for the agronomic use of the sludges were their high salinity, sodium adsortion relation (SAR), and sulphate content, and the unbalanced bases ratio. Water had also microbiological restrictions because of the high number of total Coliformes and the presence of fecal Coliformes. A useful destination is possible only with a previously treatment of the sediment to ensure their sanitarian aptitude.
Texto en PDF
Fijación de nitrógeno en alfalfa y su transferencia al pasto ovillo asociado
Nitrogen fixation in alfalfa and its transfer to orchardgrass in mixed sward
G Sierra, A Lazzari & A Gargano
Pág. 140-143
A pot experiment was conducted a) to determine the biological N2-fixation by alfalfa (Medicago sativa L.) grown in monoculture and associated with orchardgrass (Dactylis glomerata L.), and b) to assess the potential transfer of fixed nitrogen from the legume to the companion grass. To calcu- late the proportion of nitrogen in the legume derived from the air (%NDDA) the isotope dilution technique was used. Labelled ammonium sulfate in destilled water solution was injected into each pot and provided in split applications. Plants were submited to five harvests. Generally, the dry matter and nitrogen yields of alfalfa and orchardgrass were higher were grown in association. A higher %NDDA was observed in the legume when mixed, ranging 84-94% from the second to fourth harvest. In this period no nitrogen transfer was detected. At harvests first and fifth the differ- ence in atom % 15N enrichment between pure and mixed grass were statistically significant but a direct transfer of N from alfalfa is negligible.
Texto en PDF
Caracterización química y biológica de un Hapludol bajo diferentes manejos
Chemical and biological characterization of an Hapludoll under different managements
F Covacevich & HE Echeverría
Pág. 144-148
The aim of this work was to characterize chemical and biologically three productive soils management systems: conventional agriculture (AC), intensive livestock (GI) and organic livestock (GO). The determinations were made seasonally from spring 1998 until winter 1999, on three adjacent experimental plots at Balcarce, Argentina. The lowest pH values (5,3 ± 0,1) were found at the AC system. Both the available soil P and the organic matter (MO) decreased with soil depth. The lowest and highest soil P was found at the GO and AC, (9,8 ± 1,2 and 24,6 ± 4,7, respectively). However the MO was highest at GO and it was lowest at AC (6,6 ± 0,4 and 5,6 ± 0,2, respectively).
The ammonium (NH4 +) content was always low (1,39 ± 0,6). The mycorrhizal colonization was higher in orchardgrass and ryegrass plants (49,6 ± 12,4 and 29,2 ± 3,4, respectively) under GO than in orchardgrass and ryegrass plants (22,1 ± 12 and 20,0 ± 8,2, respectively) under GI. The mycorrhization was mostly negatively correlated with the available soil P and N-NO3 -, but positively with the MO. Mycorrhizal colonization did not correlated with pH, N-NH4 +, NBM nor with NOL.
Texto en PDF