Scielo RSS <![CDATA[Journal of soil science and plant nutrition]]> vol. 11 num. 1 lang. es <![CDATA[SciELO Logo]]> <![CDATA[CHANGES IN PHYSICAL PROPERTIES OF A TYPIC HAPLOCAMBID BY ANNUAL CROP CULTURE]]> As an alternative to organic soil amendments used in the Copiapo Valley (northern Chile), this study analyzed the magnitude of changes in physical soil properties associated with different crop rotations on the rows on a grape orchard. The study was performed in the locality of Los Loros, Atacama Region, during the 2006-2008 seasons. In a Typic Haplocambid soil (2-5% slope, coarse loam) with a 6-year old grape plantation, a control and three crop rotations were established, each with four replicates. Soil samples were taken at three depths (0-10; 10-40; 40-60 cm), evaluating bulk density, penetration resistance, aggregate stability, pore size distribution and air and water flux. Crop rotation did not produce statistical differences in soil density compared with the control treatment; nevertheless, soil mechanical strength decreased compared to the control without crops. Aggregate stability increased on the surface horizon when Poaceae and Fabaceae were used separately, but not when they were planted together. Below the surface this effect vanished and no significant differences were observed compared with the control. The leguminous crops promoted a more continuous porous system, with an increase of coarse porosity and a higher air and water flux capability. A longer time period of crop rotation is required to improve the productive potential of grapes. <![CDATA[WATER REQUIREMENTS AND WATER USE EFFICIENCY OF CARROT UNDER DRIP IRRIGATION IN A HAPLOXERAND SOIL]]> Water management efficiency is a key issue for sustainable agriculture development, since it is necessary to get a higher biomass production per unit of applied water. This study aimed to determine both water requirements and water use efficiency (WUE) and their effect on yield and quality parameters in carrots (Daucus carota L.), during the 2006 - 2007 growing season in Chilian, Chile (36° 35' 43.2" S, 72° 04' 39" W, 140 m altitude). The water treatments applied were 25, 50, 75, 100 and 125 % pan evaporation (Epan) in a Haploxerand soil under drip irrigation. The results showed that the highest crop yield was obtained with 100% Epan treatment. However, the highest WUE was found in the 75% Epan treatment equivalent to 3864 m³ ha-1, which is the recommended water application level in irrigation scheduling. Regarding carrot crop yield and quality parameters, statistical differences between the different water treatments were not significant, but the increase of applied water (125% Epan) reduced plant density and root length. This relationship between yield and applied water will allow to improve the management of water resources under water scarcity. <![CDATA[OPTIMAL PARAMETERS FORT <i>In Vitro </i>DEVELOPMENT OF THE HYDROCARBONOCLASTIC MICROORGANISM<i> Proteus </i>sp]]> In México, there are extensive areas polluted by oil spills. Currently, bioremediation technologies have been developed, using microorganisms to clean up oil sites. In this study, we evaluated the development of a hydrocarbonoclastic bacterial strain, using a completely randomized 3x3x4 factor arrangement: three temperatures, three pH, and four nutrients. We collected samples of soil contaminated with 3.45 x 10(5) mg kg-1 (345,000 ppm) Total Petroleum Hydrocarbons (TPH), located at the Ejido José N. Rovirosa, Huimanguillo, Tabasco, México. The samples were grown in a culture medium Nutrient Agar (NA), obtaining a bacterial strain, which was characterized and classified as Proteus sp. The strain was grown in a combined carbon culture medium and then in a liquid mineral medium with crude oil as sole carbon source. Analysis of variance and mean test were performed, using the SPSS-11.0 statistical software. The microorganisms showed the highest population growth in the treatment N2=Triple17pH1=4.029°C with a value of 4.6 x 10(10) CFU mL-1. To reach, by bioaugmentation, the same development of Proteus sp in a conditioned soil would allow us to implement a potential bioremediation strategy for solving the problem of soils contaminated with hydrocarbons in the state of Tabasco in particular, and in Mexico in general. <![CDATA[PREDICTION OF BIOAVAILABILITY OF CHLORPYRIFOS RESIDUES IN SOIL TO EARTHWORMS]]> An incubation test was conducted to investigate the effect of aging on bioavailability of chlorpyrifos in soil and to assess the feasibility of chemical extraction techniques for predicting bioavailability of chlorpyrifos in soil. Chlorpyrifos was spiked into sterilized soil and aged in microcosms for up to 120 days. The earthworms were incubated in the spiked soils, at 0, 7, 14, 30, 60, and 120 days after spiking, for a period of 7 days. After exposure, chlorpyrifos concentrations in the earthworm tissues were determined. Change in chemical extractability of soil-chlorpyrifos was measured using a several solvent systems including methanol, methanol-water (9:1), acetone-water (5:3), and water. The results show that chemical extractability and earthworm bioavailability of chlorpyrifos in soil decreased with aging. The amount of aged and unaged chlorpyrifos recovered from soil varied with the individual chemical extractant and extraction method. Concentrations of chlorpyrifos in Eisenia foetida were significantly higher than in Allolobophora caliginosa, suggesting that the bioavailability of chlorpyrifos was a species-dependent process. The extractability of chlorpyrifos by chemical solvents was significantly correlated with bioavailability fraction of E. foetida and A. caliginosa, showing that these extraction techniques may be efficient for predicting bioavailability of chlorpyrifos in soil. <![CDATA[<strong>NO-LINEAR RESPIRATION DYNAMICS IN A DEGRADED ALFISOL AMENDED WITH DIFFERENT DOSE OF SALMON SLUDGES</strong>]]> No research has been conducted regarding respiration model parameters as a consequence of the application of salmon sludge on degraded Alfisols. In order to investigate kinetic parameters representing the decomposition of salmon sludge by means of respiration rates, sediment samples from a land-farmed pisciculture and a lake-salmon facility were applied to a degraded Alfisol at the Biobio region (Chile). Soil microbiological activity was evaluated on a 60-days laboratory incubation experiment under different salmon sludge addition dose: T1 25 t ha-1; T2: 50 t ha-1; T3: 75 t ha-1; T4: 100 t ha-1; T5: 150 t ha-1. A non-amended soil served as control. C0(2)-C production was determined in samples under closed incubation. A two-component first-order regression model was applied to C0(2)-C curves to obtain kinetic parameter values of C mineralization. The analysis confirmed that microorganisms increased their respiratory activity with time and increased sludge concentration (p ≤ 0.05). A higher microbial activity was noted when soil was amended with land-farmed sludge at 100 and 150 t ha-1, particularly after 30 days of incubation. The model showed that microorganisms needed more time to decompose labile C compounds in the salmon sludge when dose increased above 100 t ha-1. After 60 days of incubation, land-farmed sludge amended at 25 t ha-1 accumulated 44% of C0(2)-C from a labile C source and 56% from a mineralized C pool, whereas at 150 t ha-1 showed a 76% of a labile C and 24% mineralized C. <![CDATA[<strong>STRUCTURAL REMEDIATION OF AN ALFISOL BY MEANS OF SEWAGE SLUDGE AMENDMENTS IN ASSOCIATION WITH YELLOW SERRADELA<i> (Ornithopus compressus </i>L.)</strong>]]> Wastewater treatment generates large amounts of sewage sludge, which when are disposed in highly degraded soils (with a complete loss of the A horizon and a great part of the B horizon), represent an interesting alternative to recover the aggregate level into soil. Within the hierarchy of soil systems, the aggregate level is the one that integrates soil properties that are directly related to soil sustainability. The aim of this study was to determine the effect of different dose of sewage sludge and an annual legume on the structural recovery of a degraded Alfisol. Sludge was added to soil at 0, 15, 30 and 60 t ha-1 in treatments with and without yellow serradela (Ornithopus compressus L.). After 6 months, the following structural indicators were identified: aggregate distribution, water aggregate stability and bulk density (Da). Results showed that the higher the sludge dose the higher the proportion of macroaggregates and their stability, whereas Da decreased. In spite of the short-term study, data showed that there was a positive effect when amendments were combined with O. compressus L. It demonstrated that degradation is likely to be reversed, thus giving to soil more physical support. <![CDATA[EFFECTS OF SALINE WATER ON TOMATO UNDER SUBSURFACE DRIP IRRIGATION: NUTRITIONAL AND FOLIAR ASPECTS]]> A field experiment on the effects of drip irrigation (DI) and subsurface drip irrigation (SDI) with saline water (6.57 dS m-1) on three tomato cultivars (Lycopersicon esculentum Mill., cvs. Rio Tinto, Rio Grande and Nemador) was carried out with the purpose to quantify physiological responses. The aim was to improve irrigation water management under saline conditions of Tunisia. The trial was established in a silt-clayey soil with three regimes of irrigation: 100 %, 85 % and 70 % of crop water requirement. Results evidenced a significant difference between the two irrigation systems for the three cultivars. Growth parameters such as leaf area, chlorophyll content and mineral composition of leaves, petioles, stems and roots were affected significantly by the different treatments, particularly for Rio Tinto and Nemador, being Rio Grande the more adapted. The fruit was the organ less affected. Strong accumulation of Na+ and Cl- accompanied a reduction in Ca2+, K+, Mg 2+ and P content in the case of DI. The distribution of these last necessary elements for plants nutrition under a strong accumulation of Na+ and Cl- depends on the cultivar and changes from one organ to another. SDI can be included as an effective option for tomato production in Tunisia. <![CDATA[IDENTIFICATION OF AGRONOMIC MANAGEMENT UNITS BASED ON PHYSICAL ATTRIBUTES OF SOIL]]> Oil palm (Elaeis guineensis Jacq) is an alternative for the development of productive systems in the tropics. By determining the spatial variability of physical characteristics of soil, specific recommendations for certain areas within a zone can be made. Geostatistical analysis can determine the existence and characteristics of the spatial distribution and is an appropriate tool for analyzing the spatial variability of soil properties. The aim of this study was to determine areas with homogeneous physical characteristics in order to establish agricultural management units, using geostatistical techniques. For this study, 62 samples were collected in 10.6 ha in the municipality of El Reten (Magdalena, Colombia). The properties analyzed were: content of sand, silt and clay, particle density, bulk density, total porosity, gravimetric and volumetric water content, hydraulic conductivity and infiltration rate. All properties showed spatial correlation, with adjustments to semivariograms theoretical models, mostly to the spherical model, with ranges between 84.87 and 218.60 m and moderate to strong spatial dependence. The contour maps obtained through ordinary kriging, allowed for the identification of the relationship between the different physical properties of the soil and subsequent classification to determine the Agronomic Management Units (AMU). <![CDATA[<strong>HOW SOIL FORMING PROCESSES DETERMINE SOIL-BASED VITICULTURAL ZONING</strong>]]> The aim of this study was to elucidate the soil forming processes of representative vineyard soils, and to discuss the implications on a soil-based viticultural zoning at very detailed scale. The study area is located in Priorat, Penedes and Conca de Barbera viticultural areas (Catalonia, North-eastern Spain). The studied soils belong to representative soil map units determined at 1:5,000 scale, according to Soil Taxonomy classification. The soil forming processes, identified through morphological and micromorphological analyses, have significant effects on some soil properties. For example, the different processes of clay accumulation in soils developed from granodiorites in Priorat or gravel deposits in Conca de Barbera, are primarily responsible for significant differences in clay content, available water capacity and cation exchange capacity. These soils properties, especially those related to soil moisture regime, have a direct influence on vineyard management and grape quality. However, soil forming processes are not always reflected on soil classification, especially in soils modified by man. We show that climate or geology alone cannot be used in viticultural zoning at very detailed scale, unless soil forming processes are taken into account. <![CDATA[SOIL FERTILITY EVALUATION OF COFFEE <i>(Coffea </i>spp.) PRODUCTION SYSTEMS AND MANAGEMENT RECOMMENDATIONS FOR THE BARAHONA PROVINCE, DOMINICAN REPUBLIC]]> Reported yields in most coffee farms of the Barahona province in the Dominican Republic are relatively low (< 290 kg ha-1 parchment coffee). In general, coffee producers do not use diagnostic techniques such as soil testing. This fact prevents them from identifying the limiting factors (especially nutrients), complicates the work of coffee cultural management practices, and potentially reduces productivity and coffee quality. This study was designed to diagnose the fertility level of soils in coffee farms in the area of Barahona in 96 farms within an area of 637 hectares and design a nutrient management strategy. Soils from each farm were sampled and analyzed for soil fertility parameters. A survey was provided to farmers that permitted the collection of information regarding yields, management practices, and landscape features. Soils in the area were predominantly clayey. Soil pH varied between 4.61 and 7.69 and soil organic matter ranged between 3.29 and 10.9%. Exchangeable potassium levels were classified as deficient in all areas. The clustering of results identified two main components, which accounted for 76% of the variability of the data and the grouping into five communities by similarity of features. The results show that soil testing of this coffee coffee-growing region can be used as a tool to diagnose the soil fertility status and guide them in implementing management and fertilization recommendations.