Search

Microbial inoculant based on beneficial bacteria is a complementary management tool to increase vegetable production. However, its integration with chemical fertilization has been poorly studied. The present study evaluated the effects of microbial inoculant separately and in combination with chemical fertilization on lettuce under greenhouse conditions. An experiment was performed in pots using a completely randomized design. The microbial inoculant was applied at three fertilization levels. Soil response evaluated variables were: available N and P, total soil bacteria, soil enzymatic activities, and N leaching. Agronomic variables measured were: aerial biomass, chlorophyll content, and nutrient foliar contents. Microbial inoculant had a significant impact on soil total bacteria concentration. The application of reduced chemical fertilization and microbial inoculant had a similar effect in terms of soil nutrient availability and soil enzymatic activities as the complete fertilization. Nitrogen leaching was strongly dependent on chemical fertilization rate. Treatment application decreased chlorophyll concentration compared to the control. The application of microbial inoculant and chemical fertilization increased foliar N and P contents improving their uptake. The combined addition of microbial inoculant with chemical fertilization increases the bacteria concentration without altering enzymatic activities, maintaining similar soil nutrient levels and improving N and P uptake in lettuce. Future studies could be performed in lettuce to determine the impact under different growth stages and different soil conditions.

Leafy vegetables constitute an excellent source of fiber, vitamins, minerals, and phytochemicals, producing many benefits to human health. However, nitrate (NO3-N) accumulation constitutes a risk factor for environment and human health. The present study was focused on the evaluation of concentrations and sources of NO3-N in lettuce and spinach under different production systems, located in the Metropolitan region (Chile). Nitrate concentration was determined in vegetable tissue, soil, water, and organic fertilizers, and compared to Chilean and international standards. Results indicated average, dry matter basis, concentrations of 3065 and 4766 mg kg−1 of NO3-N for summer and winter lettuce, respectively. On the other hand, NO3-N concentration for spinach reached 1686 and 1244 mg kg−1, respectively, for the same seasons. The studied species did not show significant differences in NO3-N content. In addition, there was no correlation between the accumulation of NO3-N in vegetable tissue and soil N availability (average of 75 mg kg−1 NO3-N) or NO3-N concentration in irrigation water (average of 8 mg L−1 of NO3-N). Finally, a nitrogen balance determined that in lettuce production systems 240–430% excess N was applied. On the other hand, organic fertilizers used did not comply with the maturity parameters established by the NCh 2880/04, 2016. There were some lettuce samples with high NO3-N contents, without surpassing the maximum allowable concentration. The nitrogen balance for lettuce determined a large excess N application as organic and/or inorganic fertilizers, which was related to larger NO3-N levels found in their tissues.

Integrated Nutrition Management (INM) is a concept developed during the last decade in fruit agroecosystems based on the application of organic matter, biostimulants, and adjusted chemical fertilization to improve soil quality, plant rhizogenesis, and nutrition. Nevertheless, there are few studies on the application of the INM concept on the recovery of decayed orchards. The present study was focused on the evaluation of the effects of INM on soil and plant quality changes as recovery indicators of a decayed pear orchard. Two treatments (T1: conventional, T2: INM) were evaluated under three tree vigor levels, during two growing seasons. Old pear trees were used in a factorial experiment of two treatments (control and INM) x three vigor levels, based on a previous aerial Normalized Difference Vegetation Index (NDVI) image. Soil properties, nutrient leaf contents, and NDVI were evaluated. Soil chemical and biological properties and their spatial variability were determined after two and five years of treatment application, respectively. The INM improved β-glucosidase activity, reduced bulk density, and increased soil porosity. Furthermore, nutrient indices (NDVI x N, K, Ca, Mg, Cu, Fe, and B) were significantly increased under INM. After two years, soil chemical properties and root density were improved by INM. A significantly higher yield, soil organic matter, soluble C, and dehydrogenase activity was observed with INM after five growing seasons. The results indicated that INM is a sustainable alternative for recovering decayed orchards, through the inclusion of good-quality organic matter within the management program.

Se desarrollo y valido una metodologia in vitro para estimar los efectos de la promocion del crecimiento radicular de los suelos tratados con materia organica e inoculantes microbianos, en cultivos, bajo el manejo integrado de nutrientes (INM), contra datos de experimentos previos. Se preparo un suelo con dos tratamientos: a) Control con aplicacion de agua desionizada, yb) INM, que comprende la aplicacion de sustancias humicas e inoculantes microbianos. Los suelos tratados se incubaron durante 72 horas y se extrajeron usando cinco proporciones de extraccion de suelo a agua: 0; 0,05; 0,1; 0,2 y 0,5. Los extractos se analizaron para determinar el pH y la conductividad electrica (CE). Las semillas de rabano y trigo se germinaron e irrigaron con cada solucion. Se realizaron analisis de varianza, regresion y correlacion. La relacion de tratamiento y extraccion afecto significativamente el pH y la CE de los extractos de suelo. La aplicacion de extractos de suelos bajo INM afecto significativamente el crecimiento de radiculas de rabano. El crecimiento de la radicula y el coleoptilo de las semillas de trigo aumento al aumentar la proporcion del suelo en el extracto. El crecimiento maximo se obtuvo con relaciones entre 1: 5 y 2: 5. En los experimentos de validacion, el crecimiento de la semilla de trigo se correlaciono significativamente con el contenido de materia organica del suelo y la actividad enzimatica, lo que confirma que este metodo es sensible para estimar los efectos promotores del crecimiento.

The Pisco and wine industry in Chile generates about 400,000 tonnes/year of grape pomace as organic wastes (OWs). This material can be composted and used as organic fertilizer or amendment in grape orchards located in inceptisol soils with a very low organic matter as a strategy to increase soil and grape quality. The maturity and the stabilization of compost define the potential use of OWs as an amendment. Therefore, the objectives of the present study were focused to evaluate the evolution of chemical, microbiological, biochemical and phytotoxicity parameters during the composting process using grape marc and other components. The experimental study consisted of nine opened piles constituted by grape pomace, goat or horse manure. The piles were evaluated for 180 days in winter-spring seasons and mechanical turns were carried out every 10 days. The results indicated that humic to fulvic acids content ratio (Ha/Fa) could be used as process evolution indicator. The potential enzymatic activity of alkaline phosphatase and β-glucosidase, and microbiological functional groups like cellulolytic, amylolytic and phosphate solubilizing bacteria were strongly correlated with production of fulvic and humic acids (p ≤ 0.01). The compost derived from treatments complies with Chilean National Standard - NCh 2880/04, 2016 for the quality of organic amendments including low phytotoxicity with a radish germination %> 92% and absence of Salmonella sp., and fecal coliforms

Este estudio evaluo el efecto del manejo integrado de nutricion (MIN) en la disponibilidad de nutrientes y actividades enzimaticas del suelo durante la etapa de enraizamiento en Vitis vinifera . Los efectos de compost (C), fertilizante mineral (FM) e inoculante microbiano (IM) se evaluaron a traves de siete tratamientos y un testigo en un diseno completamente al azar con cuatro unidades experimentales por tratamiento: T 1 (C + IM + FM), T 2 (C + FM), T 3 (IM + FM), T 4 (C + IM), T 5 (FM), T 6 (C), T 7 (IM) y testigo (T). Indicadores quimicos y bioquimicos se evaluaron a traves de la prueba comparacion de promedios (LSD, p ≤ 0,05). Los resultados indicaron que la aplicacion de C y FM incremento la concentracion de P durante los primeros 30 dias (64,8 y 69,9 mg kg -1 ), el N aumento al dia 60 en T 1 (178,1 mg kg -1 ) y alcanzo su concentracion maxima el dia 30 en T 2 (433,3 mg kg -1 ). La mayor actividad potencial de la β glucosidasa fue de 113,8 µg ρ-nitrofenol g -1 h -1 al dia 60 en T 1 , determinandose tambien que la adicion de compost aumenta la actividad deshidrogenasa y fosfatasa alcalina en T 1 el dia 30 (62,6 µg de TFF g -1 24 h -1 y 155,7 µg ρ-nitrofenol g -1 h -1 ). Los resultados sugieren que la aplicacion de MIN durante el trasplante de V. vinifera incrementa la disponibilidad de nutrientes y las actividades enzimaticas en el suelo.

The Normalized Difference Vegetation Index (NDVI) is a simple indicator that quantifies aerial biomass in fruit crops, which is correlated with the fruit yield and quality produced by an orchard. Therefore, knowing the NDVI values would allow predicting productive parameters above mentioned, which in turn would help planning operational activities such as harvesting. In this study, we estimated the NDVI of a Chilean table grape orchard based on past data using data mining techniques. For this purpose, we developed a three-step method, obtaining NDVI predictions with high accuracy.

Spatial variability of Chilean vineyards, in terms of yield and quality, is high, which fully justifies site-specific management, particularly differential harvest. In this study, the most common zoning tools (NDVI and ECa measurements) were evaluated and compared. Comparisons also included a calibrated GVI. Two contrasting large field experiments (pruning, irrigation, and N fertilization treatments) were established in vineyards to (1) evaluate two vegetation indices: (i) a non-calibrated airplane-based NDVI and (ii) calibrated satellite-based GVI and to (2) evaluate the ECa measurements. The GVI was also assessed at the commercial level, in different vineyards and valleys. The GVI was more sensitive in discriminating grape yields and quality while the NDVI failed to adequately sense vigor patterns and fruit quality in the more homogeneous site. Thus, a calibrated GVI can be recommended as a better tool than NDVI for defining management zones as well as making spatial and temporal comparisons among fields and seasons. In general, ECa explained few differences in the alluvial soil properties and did not predict differences in plant vigor as measured by either vegetation indices, therefore ECa by itself was not a good estimator of the most commonly measured soil properties for establishing management zones in these fields with low variability in terms of EC and other soil characteristics.

Two Chilean soils were used to evaluate the performance of the nitrification inhibitor 3,4-dimetilpirazol phosphate (DMPP) added to ammonium-sulfate-nitrate (ASN) in comparison with traditional nitrogen (N) sources and different N-application forms. Two experiments were conducted: In the first, broccoli (Brassica oleracea var. italica) plants were cultivated in pots under greenhouse conditions, and received a N-fertilization equivalent to 150 Kg N ha−1 as ASN+DMPP (one application), urea (two splits), and sodium-potassium nitrate (three splits). In the second, ryegrass (Lolium spp.) plants were grown in pots under shading conditions. In this case, ASN+DMPP and urea were applied at N rates equivalent to 150 and 300 Kg N ha−1 in a single application. In the first experiment, ASN+DMPP increased dry-matter production, maintained a higher N content in the soil (at least until the middle of the growing period), and improved fertilizer N-use efficiency (FUE) in one soil. There were no significant differ...