Scielo RSS <![CDATA[Revista de la ciencia del suelo y nutrición vegetal]]> vol. 10 num. 2 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[<strong>SOIL GLYCOSIDASE ACTIVITIES AND WATER SOLUBLE ORGANIC CARBON UNDER DIFFERENT LAND USE TYPES</strong>]]> The purpose of this study was to measure the effects of different land uses on soil glycosidase activities (a- and (β-glucosidase, α- and (β-galactosidase), water soluble organic carbon (WSOC) and their relationships. Glycosidase activities showed significant differences under different land use types, the highest one was woodland. (β-glucosidase had the highest activity among the four glycosidases. The activities of these glycosidases decreased with increasing soil depth, being all significantly affected by change of soil depth. Except grassland, the four glycosidase activities intercorrelated each other. Woodland had the highest content of WSOC in the soil depth of 0-20 cm and at increasing soil depth, WSOC content decreased sharply under woodland and grassland. Glycosidase activities had positive and significant relationships with WSOC. Glycosidase activities and WSOC all had significant correlations with soil total organic carbon (TOC) and pH, which were sensitive to different land use types. We found that glycosidase activity indirectly impacts on nutrient recycling and energy flow in soil under different land use types. <![CDATA[<strong>Effects of liming and nitrogen fertilization on the development of <i>Oenothera affinis </i>in a soil affected by copper mining</strong>]]> The Puchuncaví valley (central Chile) has been exposed to aerial emissions from the Ventanas copper smelter. Nowadays, soils in the surroundings are sparsely-vegetated, acidic, nitrogen-deficient, and metal-contaminated. Their remediation is needed to reduce environmental risks. Phytostabilization considers the use of plants which are able to store metals in underground tissues, thus reducing their movement from contaminated soils to the air and water. The success of the treatment depends on application of suitable amendments in order to both limit metal solubility in soils and improve soil conditions for the plant development. We evaluated the effects of liming and nitrogen fertilization on cotyledon emergence, plant survival, biomass production and copper accumulation of Oenothera affinis grown in a soil from the Puchuncaví valley, under controlled conditions. Oenothera affinis is a native Chilean perennial herb, it is drought resistant, it is easy to propagate from seeds, and it produces a large biomass. The soil exhibited pH in salt extract of 4.6 and total copper concentration of 800 mg kg-1. Liming decreased Cu concentrations and Cu2+ activity in the soil solution, but did not affect cotyledon emergence. None of the plants survived in non-limed soils, while plant survival was 100% in the soils with near neutral pH. On the other hand, in limed soils, nitrogen fertilization did not affect biomass production and increased copper concentrations in both roots and shoots. It was concluded that liming is sufficient to improve soil conditions for development of O. affinis in acidic and metal-contaminated soils, allowing by this mean potential utilization of this species for phytostabilization.<hr/>El valle de Puchuncaví (Chile central) ha sido expuesto a las emisiones aéreas provenientes de la fundición de cobre Ventanas. Actualmente, los suelos en las cercanías de la fundición presentan una escasa vegetación, son ácidos, deficientes en nitrógeno y contaminados con metales. Para reducir el riesgo ambiental, es necesario remediar estos suelos. La fitoestabilización considera el uso de plantas capaces de almacenar los metales en sus estructuras subterráneas, reduciendo así su movimiento desde el suelo contaminado al aire y al agua. El éxito del tratamiento depende de la aplicación de enmiendas adecuadas que reducen la solubilidad de los metales en los suelos y, a la vez, mejoran sus condiciones para el desarrollo de la planta. Se evaluó el efecto del encalado y la fertilización nitrogenada sobre la emergencia de cotiledones, supervivencia, producción de biomasa y acumulación de cobre en Oenothera affinis cultivada en un suelo del valle de Puchuncaví bajo condiciones controladas. Oenothera affinis es una hierba perenne nativa, resistente a la sequía, fácil de propagar a partir de semillas y que produce una gran cantidad de biomasa. Los suelos presentaron un pH en sal de 4,6 y una concentración de cobre total de 800 mg kg-1. El encalado disminuyó las concentraciones de Cu y la actividad del Cu+2 en la solución del suelo, pero no afectó la emergencia de cotiledones. Las plantas no sobrevivieron en los suelos no-encalados, mientras que la supervivencia fue del 100% en los suelos con un pH cercano al neutro. Por otro lado, en los suelos encalados, la fertilización nitrogenada no afectó la producción de biomasa y aumentó las concentraciones de cobre tanto en las raíces como en los tejidos aéreos. Se concluyó que el encalado es suficiente para mejorar las condiciones del suelo para el desarrollo de O. affinis en suelos ácidos y contaminados por metales, permitiendo así la potencial utilización de esta especie para la fitoestabilización. <![CDATA[<strong>RELATIONSHIP BETWEEN RADICAL INFESTATION OF<i> Hylastinus obscurus </i>(MARSHAM) AND THE YIELD OF CULTIVARS AND EXPERIMENTAL LINES OF RED CLOVER <i>(Trifolium pratense </i>L.)</strong>]]> Red clover (Trifolium pratense L.) is a valuable forage legume grown alone or in mixture with grasses in temperate regions of the world. Red clover is adapted to a wide range of soil types, pH levels, environmental and management conditions. However, the main limitation of this species is the lack of persistence related to the high mortality of plants. In Chile the main biotic factor affecting survival of plants is the root borer Hylastinus obscurus (Marsham) (Coleóptera; Scolytidae). In 1989, a red clover (T. pratense L.) breeding program was started at Carillanca Research Center of the Institute of Agricultural Research (INIA), Chile, with the main objectives of improving the survival of plants, forage yield and persistence. In 2002 a research line to study the interaction between the root borer and the plant was started. This paper describes briefly the improvement obtained in survival of young plants after twenty years of breeding and the importance of root borer population regarding forage yield. Experiments were conducted at Carillanca Research Center under irrigated conditions, comparing under cutting the dry matter yield of new synthetic lines and Redqueli-INIA with Quinequeli-INIA. The experimental lines Syn Int IV, Syn Pre III, Syn Int V and Syn Int VI were more productive than the cultivars Redqueli-INIA and Quiñequeli-INIA at the second season. The evaluation of the biological parameter allowed identifying a tolerant line, Syn Pre I, and three potential new varieties: Syn Pre III, Syn Int V and Syn Int VI. This is the first report showing an inverse relation between dry matter yield of red clover and root borer population (P<0.05). Moreover, we report the first evidence that H. obscurus start the colonization of red clover plant of 6-month-old. <![CDATA[<strong>BIOCHEMICAL PROPERTIES IN VASCULAR EPIPHYTES SUBSTRATE FROM A TEMPERATE FOREST OF CHILE</strong>]]> The temperate forests of south-central Chile belong to the association Lapageria aextoxiconetum Oberdorfer vegetation, dominated by Aextoxicon punctatum R. et P., elderly and multi-layered, where the strata are emergent, dominant and co-dominant, shrub and herbaceous epiphytes. This work is the first report of measurements of some biochemical properties in samples from vascular epiphytes substrate in temperate forests. We evaluated the most frequent ecological situations: bifurcated trees (BT), dead standing trees (SDT) and medium gap border trees (MGBT), ES were compared with the surrounding soil forest land (SS) as control. The microbial biomass and enzyme activities of substrate were higher in ES of BT, situation probably due to optimal micro-environmental conditions (moisture and humidity, temperature, organic matter (OM) content and nutrient availability); similarly, lower levels of activity were found in ES in MGBT situation. We found a statistically significant correlation (P≤0.05) between evaluated microbial biomass and enzymatic activities. Furthermore, the biochemical properties were influenced by factors such as moisture, temperature, pH and OM content and all of these factors correlated significantly (P≤0.01) among them. These results demonstrate a difference between ES and SS in BT that should be explored to gain insights in understanding the processes of decomposition using the natural microcosms that ES provides. <![CDATA[<strong>GROWTH OF <i>Inga vera </i>WILLD. SUBSP. <i>Affinis </i>UNDER RIZOBIA INOCULATION</strong>]]> Nitrogen, in general, is the largest limiting plant growth nutrient in the tropics and is required as a synthetic fertilizer to improve plants productivity. Therefore, studies aiming in understanding and using nitrogen fixation by leguminous trees have been done as a low-cost alternative for chemical fertilizer. Native legume trees such as Inga vera have been recommended in the rehabilitation of degraded areas due their ability to establish symbiosis with nitrogen fixation organisms replacing nitrogen fertilization. These species are able to increase soil organic matter, nitrogen and phosphorus availability. Thus, the present study aims to assess the inoculation effects of native rhizobia strains on nodulation, dry matter production, nitrogen and phosphorus leaf incorporation in I. vera seedlings. With this purpose, four strains were obtained from inga nodules and tested in a greenhouse. The inoculation of I, vera seedlings with native rhizobium strains promoted an increase in shoot dry mass as well as in leaf nitrogen content. According to symbiotic efficiency equation, this approach ranged from 50 to 80% indicating that the nitrogen fertilization for this species can be partially replaced by rhizobia inoculation. <![CDATA[SOIL NUTRIENT CONTENTS AND ENZYMATIC CHARACTERISTICS AS AFFECTED BY 7-YEAR NO TILLAGE UNDER MAIZE CROPPING IN A MEADOW BROWN SOIL]]> No tillage is being populanzed for the rainfed maize production in Northeast China. In order to evalúate its effects on the nutrient contents and enzymatic charactenstics in upland soils of Northeast China, surface (0-20 cm) meadow brown soil samples were collected from the plots under no tillage and conventional tillage in a 7-year field experiment under maize cropping in Shenyang, with the soil pH, contents of total C, N, P and S and available N, activities of α- and (β-galactosidase, α- and (β-glucosidase, urease, protease, phosphomonoesterase, phosphodiesterase, and arylsulphatase, and kinetic parameters of (β-glucosidase, protease, phosphomonoesterase, phosphodiesterase, and arylsulphatase determined. Comparing with conventional tillage, no tillage increased the contents of soil total C, N, and S and available N, the activities of test enzymes, and the Vmax/Km of soil urease, protease, and phosphomonoesterase, but decreased the activity of soil α-galactosidase and the VmaxKm of soil (β-glucosidase significantly. All the results suggest that long term no tillage for the maize production on meadow brown soil of Northeast China could enhance soil nutrients storage and the turnover of soil N and P, but had definite negative effects on the transformation of soil C. <![CDATA[<strong>EFFECT OF LIQUID COW MANURE ON CHEMICAL AND BIOLOGICAL PROPERTIES IN AN ANDISOL</strong>]]> The aim of this work was to establish the effect of the dose of liquid cow manure (LCM) on some chemical properties and biological activity in an Andisol. This study was carried out under laboratory conditions using an Andisol and LCM from a dairy farm located in the South of Chile. The dose of LCM were the equivalent to 0 (SO), 100 (S100), 200, (S200) and 300 (S300) thousand L ha-1. This amount is equivalent to regular agronomic LCM applications. The chemical characterization indicated that the LCM addition modified all the tested Andisol chemical properties. These begin to return to the initial conditions from 10 days on, with the exception of EC, K and DOC. The C-C0(2) evolution indicated that LCM incorporation at increasing dose enhanced the respiratory activity. Enzyme activity was greater in the amended soils than in SO. The results of this study indicated that the period of time necessary for the LCM amended soils returning to a similar behavior to SO is more than 10 days, with a strong correlation between the chemical properties of the amended soils and their biological activity, mainly C-C0(2) evolution. <![CDATA[<strong>NITROGEN SOIL BUDGETS IN CONTRASTING DAIRY GRAZING SYSTEMS OF SOUTHERN CHILE, A SHORT-TERM STUDY</strong>]]> In recent years, the intensification of livestock production in Southern Chile has resulted in a high potential for environmental damage through nitrogen (N) losses, creating the need for the evaluation of N flows from these systems. The aim of the research was to determine N budgets and N use efficiency in two grazing systems in Southern Chile. For this, inputs and outputs were measured during one year on two grazing systems (heavy grazing, HG; and light grazing, LG). Also, a control treatment with no grazing (C) was considered. The annual N soil budget was determined by the difference between all N inputs (£ inputs) and all N outputs (X outputs). The results of the experiment indicate that HG treatments received the biggest N input (427, 359 and 288 kg N ha-1 yr-1 for HG, LG and C treatment, respectively), however this treatment also had the biggest N losses (406 kg N ha-1 yr-1), with a nitrogen recovery efficiency from fertilizer of 71%. In addition, herbage dry matter yield (DM) was greater in the HG than in the LG and C treatments (10.4; 8.1 and 7.1 t N ha-1 yr-1, respectively). Also, N concentration in the forage was higher in this treatment (2.9%) than in the LG (2.7%) and C (2.5%) treatments. The results indicate that HG increases N use efficiency in pastures in Southern Chile, increasing the herbage production and quality, but also increasing the potential for N losses to the wider environment. Farmers should consider this when choosing the appropriate grazing system.