Efecto de la infestación de Micrapate scabrata (Erichson, 1847) (Coleoptera: Bostrichidae) en la degradación de madera y sus consecuencias en algunas propiedades químicas del suelo

Micrapate scabrata (Erichson) (Coleoptera: Bostrichidae) is a xylophagous beetle native to Chile. Adults and larvae feed on several native host plants, but also on pruned wood of exotic plants. In this study we assessed the impact of artifi cial M. scabrata infestation on Vitis vinifera L. wood degradation and the subsequent changes in soil properties. First, we periodically sampled, during a four-month period, pruned wood from an infested table grape vineyard, fi nding in average 1 adult/10 cm linear wood. Adults were then placed in large Petri dishes containing uninfested wood samples, and maintained in a climatic chamber for six months. At the end of this period, an average of 65.6% of infested wood had been turned mainly into sawdust. Additionally, the impact of leaving M. scabrata infested pruned wood on potted soil for six months, under laboratory conditions, was also evaluated. Afterwards, the surface soil content of macro elements (N-P-K) and organic matter signifi cantly increased, whereas the soil pH decreased. These results document the signifi cant impact of M. scabrata infestation on pruning wood degradation and the benefi ts to the soil if left on the ground in the ecosystem.Micrapate scabrata (Erichson) (Coleoptera: Bostrichidae) es una especie xilófaga y nativa de Chile. Las larvas y los adultos se alimentan de madera de varias especies nativas, y también de madera de poda de plantas exóticas. En este estudio evaluamos el impacto de una infestación artifi cial de M. scabrata en la degradación de madera de Vitis vinifera L. y los cambios subsecuentes en las propiedades del suelo. Para ello, primero muestreamos madera de poda, durante cuatro meses, en un parronal de uva de mesa infestado, y encontramos en promedio 1 adulto/10 cm lineales de madera. Luego se infestó madera de poda sana, dispuesta en placas de Petri, con adultos, las que se mantuvieron en una cámara climática por seis meses. En ese plazo, un 65.6% de la madera infestada fue convertida principalmente en aserrín. Adicionalmente, se evaluó el efecto de dejar madera de poda infestada por M. scabrata en macetas con suelo, durante seis meses, en condiciones de laboratorio. Luego de ese período, se encontró que el contenido de macro-elementos (N-P-K) y materia orgánica en el suelo aumentó signifi cativamente, mientras que el pH disminuyó. Estos resultados muestran el impacto signifi cativo de la infestación de madera por M. scabrata en su degradación y los benefi cios para la condición del suelo si es dejado en superfi cie en el ecosistema

Microbial impact on initial soil formation in arid and semiarid environments under simulated climate change

The microbiota is attributed to be important for initial soil formation under extreme climate conditions, but experimental evidence for its relevance is scarce. To fill this gap, we investigated the impact of in situ microbial communities and their interrelationship with biocrust and plants compared to abiotic controls on soil formation in initial arid and semiarid soils. Additionally, we assessed the response of bacterial communities to climate change. Topsoil and subsoil samples from arid and semiarid sites in the Chilean Coastal Cordillera were incubated for 16 weeks under diurnal temperature and moisture variations to simulate humid climate conditions as part of a climate change scenario. Our findings indicate that microorganism-plant interaction intensified aggregate formation and stabilized soil structure, facilitating initial soil formation. Interestingly, microorganisms alone or in conjunction with biocrust showed no discernible patterns compared to abiotic controls, potentially due to water-masking effects. Arid soils displayed reduced bacterial diversity and developed a new community structure dominated by Proteobacteria, Actinobacteriota, and Planctomycetota, while semiarid soils maintained a consistently dominant community of Acidobacteriota and Proteobacteria. This highlighted a sensitive and specialized bacterial community in arid soils, while semiarid soils exhibited a more complex and stable community. We conclude that microorganism-plant interaction has measurable impacts on initial soil formation in arid and semiarid regions on short time scales under climate change. Additionally, we propose that soil and climate legacies are decisive for the present soil microbial community structure and interactions, future soil development, and microbial responses

Assessment of soil physical properties’ statuses under different land covers within a landscape dominated by exotic industrial tree plantations in south-central Chile

Land use and land cover changes (LULCC) within a highly anthropized Mediterranean landscape dominated by industrial tree plantation leads to degradation of soil physical properties. This process has been more intense in the coastal range of south-central Chile due to its soils, which are highly susceptible to erosion, combined with a long history of intensive land use changes during the last century, transitioning from native forest (NF) to agriculture and the more recent establishment of Pinus radiata and Eucalyptus spp. exotic tree plantations. In this context, the aim of this study was to assess the statuses of soil physical properties over different land cover situations. Historical land cover maps were determined via supervised classifications using the maximum likelihood classifier applied to satellite imagery. Five land use and land cover categories (LULC) were defined according to main land cover transitions asso

Assessment of nitrogen and phosphorus pathways at the profile of over-fertilised alluvial soils. Implications for best management practices

Contrasting soil profiles (coarse-textured and fine-textured) treated with brilliant blue (BB) dye tracer, inorganic nitrogen (N) and phosphorus (P) concentrations along and between stained preferential flow pathways were examined for an irrigated and overfertilised maize monoculture system at the Mediterranean central Chile. The PO4-P concentrations were 2- to 10-fold higher in areas with BB than in areas without BB below 0.5-m soil depth in both soils. This elevated concentration was attributed to transport through cracks in fine-textured soil and finger flow in coarse-textured soil. The highest PO4-P value (13 mg kg(-1)) was found in areas with BB at the fine-textured soil. There were no significant differences in inorganic N concentration between areas with and without BB for both soils, which suggest that the effects of preferential flow are less important for inorganic N forms. There was a strong significant (p < 0.01) positive correlation between PO4-P and NH4-N concentrations in the fine-textured soil, and the amounts retained were clearly proportional to the clay content. Strategies for reducing N and P losses must be placed on good agronomic management of irrigated maize cropping system including accurate calculation of N and P fertiliser rates and establishment of suitable mitigation measures such as cover cropping.FONDECYT 115057

Control of plant-parasitic nematodes using cover crops in table grape cultivation in Chile Control de nemátodos fitoparásitos mediante el uso de cultivos de cobertera en parronales de uva de mesa en Chile

A study to evaluate the effect of a three-year rotation with cover crops for the management of plant-parasitic nematodes (PPNs) was performed in two vineyards producing table grapes (Vitis vinifera L.) in a semiarid region in the north of Chile. In the first vineyard, located in Copiapó valley (trial I), the crops used in the rotations or monoculture were fava bean (Vicia faba) cv. Aguadulce, rape (Brassica napus var. napus) cv L-456, forage turnip (B. rapa var. rapa) cv. Barkant, barley (Hordeum vulgare) cv. Aurora, oat (Avena sativa) cv. Urano-INIA, and mustard greens (Brassica juncea). At the second vineyard employed in the study, located in Huasco valley (trial II), the same crops and varieties were used in a rotation system with the incorporation of crop/goat manure mixtures or manure only at a rate of 10 Mg ha-1. In both studies, two control treatments were included: a nontreated control and a chemical control in which ethoprop was applied at a rate of 7 kg ha-1. The results fro

Preliminary use of a fulvic acid, as a strategy to improve water use in saline soils: Preliminary use of a fulvic acid, as a strategy to improve water use in saline soils

An evaluation of a fulvic acid (FA) was made in a Loam soil, by selecting the best dose to achieve salt displacement under a drip emitter. In trial 1, PVC columns were filled with a loam soil and irrigated with a KCl solution of electrical conductivity (EC) of 12.5 dS m-1. Once the soil solution EC reached the value of the KCl solution, FA doses of 0, 2.1, 5.3 and 10.5 kg ha-1 were applied. The bulk electric conductivity and soil chemical properties were evaluated after 6 irrigation cycles. In trial 2, the same soil salinized with the KCl solution was placed in 0.8 m3 containers. Two irrigations treatments were performed: a control and the best FA dose from trial 1. The displacement of the salt bulb created from irrigation with a dropper in the soil profile was characterized. In trial 1, the dose of 5.3 kg ha-1 reached the lowest EC after the third irrigation. In trial 2, the selected dose reduced EC until 3.75 dS m-1 at 0.3 m depth at the third irrigation, saving 246 L of water compared to control. Additionally, the salinity bulbs were more horizontally extended in the FA treatment. Highlights: Application of FA (5.3 kg ha -1) reduced the water use by 50% compared to leaching carried out exclusively with water. The use of Fulvic acid showed to be an alternative to consider in the recovery of saline soils under drip irrigation when irrigation water is scarce. Little or not residual effect was found after the use of Fulvic acid.An evaluation of a fulvic acid (FA) was made in a Loam soil, by selecting the best dose to achieve salt displacement under a drip emitter. In trial 1, PVC columns were filled with a loam soil and irrigated with a KCl solution of electrical conductivity (EC) of 12.5 dS m-1. Once the soil solution EC reached the value of the KCl solution, FA doses of 0, 2.1, 5.3 and 10.5 kg ha-1 were applied. The bulk electric conductivity and soil chemical properties were evaluated after 6 irrigation cycles. In trial 2, the same soil salinized with the KCl solution was placed in 0.8 m3 containers. Two irrigations treatments were performed: a control and the best FA dose from trial 1. The displacement of the salt bulb created from irrigation with a dropper in the soil profile was characterized. In trial 1, the dose of 5.3 kg ha-1 reached the lowest EC after the third irrigation. In trial 2, the selected dose reduced EC until 3.75 dS m-1 at 0.3 m depth at the third irrigation, saving 246 L of water compared to control. Additionally, the salinity bulbs were more horizontally extended in the FA treatment. Highlights: Application of FA (5.3 kg ha -1) reduced the water use by 50% compared to leaching carried out exclusively with water. The use of Fulvic acid showed to be an alternative to consider in the recovery of saline soils under drip irrigation when irrigation water is scarce. Little or not residual effect was found after the use of Fulvic acid

Pre-compaction and organic conditioning for the recultivation of a coarse-textured soil (Typic xerochrepts) disturbed by sand extraction

La extracción de áridos genera un daño a la estructura del suelo superficial, disminuyendo su capacidad de soporte. Con el objeto de recuperar un suelo agrícola (Typic Xerochrepts, franco arenoso) disturbado por extracción de arenas sub-superficiales, se desarrolló un estudio en la zona central de Chile, en macetas de 20 L, estableciendo tratamientos con dos factores: pre-compactación (sin y con dos niveles crecientes) e incorporación de enmienda orgánica (cama broiler en dosis de 0, 15, 30 y 60 Mg ha-1). Se evaluó el efecto de los tratamientos sobre las propiedades físicas del suelo (densidad aparente, distribución de tamaño de poros, resistencia mecánica, estabilidad de agregados, repelencia al agua) y el rendimiento de materia seca y producción de vainas comerciales de un cultivo de poroto verde (Phaseolus vulgaris L.). La reposición del suelo post-extracción de arena sub-superficial generó una condición de alta porosidad gruesa, baja retención de agua y baja capacidad de soporte; la combinación de la enmienda orgánica en dosis menores a 30 Mg ha-1 y la ausencia de pre-compactación, promueve un asentamiento excesivo del suelo, lo que disminuye los macroporos y aumenta la resistencia mecánica. Sin embargo, la pre-compactación hasta alcanzar niveles de densidad aparente entre 1,05 y 1,15 Mg m-3 y dosis de enmienda de entre 15 y 30 Mg ha-1, favorecen la mejor condición física del suelo, generando una mayor estabilidad de agregados y la máxima producción de materia seca y rendimiento de vainas comerciales.Subsoil extraction of subsurface sandy layers causes damages to soil structure, decreasing its loading capacity. A study was conducted in central Chile in order to reclaim an agricultural soil (Typic Xerochrepts, sandy loam) disturbed by subsurface sand mining. The study was conducted in pots of 20 L, and treatments with two factors were established: pre-compaction (without and with two increasing levels), and the addition of organic amendment (broiler litter in doses of 0, 15, 30 and 60 Mg ha-1). The effect of the treatments was evaluated on soil physical properties (bulk density, pore size distribution, mechanical strength, aggregate stability and water repellency), dry matter yield and pod production of green beans (Phaseolus vulgaris L.). The replenishment of soil after the extraction of subsurface sand generated a condition of high coarse porosity, low water retention and low loading capacity. The combination of the organic amendment in doses lower than 30 Mg ha-1 and the absence of pre-compaction promoted excessive soil settlement, decreasing the macroporosity and increasing the mechanical strength. However, pre-compaction until reaching levels of bulk density between 1.05 and 1.15 Mg m-3 and the amendment dose between 15 and 30 Mg ha-1, promoted the best physical soil conditions, resulting in a high aggregate stability, and maximum dry matter production and yield of commercial pods