Relationships among main soil properties and three N availability indices.

A biological (aerobic incubation for 3 and 6 weeks) and a chemical method [successive extractions with cold 0.1 (H1-N) and 0.5 M HCl (H2-N)] were applied to 21 soils to determine: a) the potentially mineralizable-N; b) the most useful soil variables for predicting soil N availability; and c) their usefulness for predicting N uptake by a greenhouse wheat crop. At t=3, both net N mineralized (NNM) and net N mineralization rate (NNMR) were correlated: a) positively with SOM- and CEC-related variables; and b) positively with soil δ 15N and negatively with soil pH, suggesting that Nmineralization, dominated by nitrification, is associated with NO3 --N losses and soil acidification. At t=6, all previously discussed variables were important for NNM, but not for NNMR, mainly controlled by the available-P content. The importance of H1-N increased with N2-inputs and decreased with NO3 - losses and soil-N. Relationships of H1-N and H2-N with soil CEC and texture showed the strong relations among nutrients content, biological activity and N mineralization, as well as the recalcitrance of clay-bounded SOM. Soil total-N correlations with wheat-N in absolute amount (positive) and as percentage of soil-N (negative) showed an important supply of available-N by N-rich soils, despite their slow N turnover. The best regression models for wheat-N always included 1-2 main available nutrients. The percentage of soil N exported to plant biomass was negatively correlated with noncrystalline Al compounds and soil δ 15N. Mineralized-N and wheat-N pools did not share many correlations with soil properties and seemed to come from different sources; consequently, the former pool, which only explained a quarter of wheat-N variance, was not more useful than soil total-N for predicting it. Only a positive correlation with soil total-N was shared by wheat-N and hydrolysable-N, highlighting that the latter N pools are mainly unrelated. Nevertheless, half of wheat-N variation was explained by its negative relationship with the percentage of soil-N as (H1+H2)-N; a possible explanation is that chemically labile N is also biologically labile, being cumulated because of a limiting factor for microbial N mineralization or plant growth and emerging as a good predictor for wheat-N uptake.Peer reviewe

Mulching and seeding treatments for post-fire stabilization techniques in Laza (NW Spain): medium-term effects on soil quality and effectiveness

The impact of fire and different post-fire stabilisation treatments like mulching and seeding on some selected physical, chemical biochemical and microbiological properties as well as the efficacy of these treatments on control of post-fire erosion was evaluated in a burnt area affected by a high severity wildfire located in Laza (NW Spain). Soil samples were collected from the A horizon (0-2 cm) of the burnt soil 8 and 12 months after the wildfire as well as from the unburnt soil located in an adjacent plot used as control; sediments were periodically collected after precipitation events in the burnt soil with and without different post-fire stabilisation treatments. The results clearly showed that a significant medium-term impact of the wildfire on most soil properties analyzed was still observed 12 months after the fire event and that mulching and seeding treatments did not affect the overall soil quality (physical, chemical, biochemical and microbiological properties) of this burned soil. Sediments data indicated that both stabilisation treatments were effective to control post-fire erosion since, compared to the burnt control, soil losses were reduced by 85% in the mulching treatment and by 30% in the seeding treatment

Recovery of a soil under different vegetation one year after a high intensity wildfire

Studies on soil recovery in fragile ecosystems following high intensity wildfires are scarce. The aim of the present investigation is to evaluate the impact of a high intensity wildfire in an ecosystem under different vegetation (shrubland and pinewood) located at Vilardevós (Galicia, NW Spain) and highly susceptible to suffer soil erosion due to the steep relief and high erositivity of the rainfall. Soil samples were collected from the A horizon (0-5 cm) 1 year after the fire and soil quality was evaluated by analysis of several physical, chemical and biochemical properties measured in the fraction < 2 mm. The results showed marked effects of the wildfire on most properties analyzed even 1 year after the fire; however, a different effect both in the trend (positive, negative) and magnitude were observed, depending on the soil property analyzed. In general, the sensitivity to detect fire induced changes followed the order: biochemical properties > chemical properties > physical properties. The data also showed that the fire impact was different depending on the soil vegetation considered (shrubland and pinewood). Moreover, the data confirmed the slow soil recovery in this fragile ecosystem and, therefore, the need of adopting post-fire stabilisation and rehabilitation treatments in order to minimize the post-fire erosion and soil degradation

80-річчя академіка НАН України В.І. Старостенка

Qualitative and quantitative changes in soil and fertilizer-derived organic N fractions were assessed during a cropping season in an intertropical Alfisol, under maize and pasture, fertilized with15 N-urea. Before the sowing, after fertilizing and after the harvest, the organic N of top soil samples was fractionated by a two-step acid hydrolysis under reflux (H1 = 1 M HCl for 3 h; H2 = 3 M HCl for 3 h). The total hydrolysable N (HN) from H1 decreased significantly during the cropping season in both maize and pasture soils. Contrastingly, the content of HN from H2 and that of non-hydrolysable N did not vary significantly during the cropping season. The easily hydrolysable fractions, especially amino acid N, amino sugar N and amide N, were the most active N pools and the major source of N potentially available for plants. The urea-derived N that remained in the soil was mainly in organic forms at both 7 and 108 d after fertilizing (70–82% and 93–98%, respectively), higher figures being found in pasture than in maize soil. The total amount of urea-derived HN decreased significantly during the crop period in both maize and pasture soils. This decrease was largely due to the decline in HN from H1. The amount of non-hydrolysable urea-derived N was significantly higher in pasture than in maize soil and it decreases in the former and increases in the latter, during the cropping season. During the crop period, the decrease of urea-derived organic N was 4.6 to 9.1 times higher than that of native organic N. Shortly after fertilizing, the proportion of urea-derived N in the easily hydrolysable (H1) organic fractions was higher than that of soil N, whereas the reverse was true for the slowly hydrolysable (H2) or insoluble fractions. These differences were less marked, but still significant, at the end of cropping. The easily hydrolysable organic N fractions were more sensitive than total N to the impact of land use intensification and are, therefore, a more useful index for early detection of soil biological degradation.Peer reviewe

Anales de Edafología y Agrobiología Tomo 34 Número 3-4

Estudio de la materia orgánica del ranker atlántico. I. Caracterización general, por P. Rodríguez Seoane, T. Carballas y F. Guitián Ojea.-- Movimiento y distribución de sales solubles en suelos calizos, por F. G. Fernández, M. Caro y A. Cerda.-- The availability of added and native phosphorus to barley grown in sorne Egyptian soils .containing different levels of calciurn carbonate, by M. H. Nafady.-- The measurernent of soil pH in calciurn chloride solutions, by M. H. Nafady.- Nuevas aportaciones al conocimiento del género Mnema (nernatoda) y su distribución en los suelos españoles, por María Arias.-- Estudios bioquímicos y fisiológicos en aceituna. III. Variaciones en el crecimiento de hojas y frutos, por J. P. Donaire, A. J. Sánchez-Raya, J. López Corge y L. Recalde.-- Importancia de la rnicorrización espontánea en ensayos de nutrición vegetal en suelos deficientes en fósforo, por R. Azcón y J. M. Barea.-- Andosoles canarios. J. Características generales de estos suelos, por E. Fernández Caldas y M. L. Tejedor Salguero.-- Andosoles canarios. II. Intergrados andosol-tierra parda oligotrófica. Características morfológicas y quírnkas, por M. L. Tejedor Salguero y E. Fernández Caldas.-- Andosoles canarios. lll. Jntergrados andosol-tierra parda otigotrófica. Catacterísticas físicas, por E. Fernández Caldas y M. L. Tejedor Salguero.-- Andosoles canario;. IV. In ter grados andosol-tierra parda ohgotrófica. Características mineralógicas. Interpretación y clasificación, por C. Rodríguez Pascual, P. Quantin, M. L. Tejedor Salguero y E. Fernández Caldas.-- Estudios recapitualtivos.-- La vid una revisión de las condiciones del cultivo, por C. González O. y M. Lachica.—Notas científicas.-- Nota sobre la determinación del carbono orgánico en suelos, por J. F. Gallardo.—Notas.-- Ampliación de la Comisión Permanente de la Junta de Gobierno del Patronato Alonso de Herrera.-- Nombramiento de Secretario del Centro de Edafología y Biología Aplicada de Tenerife.-- Nombramientos en el Instituto de Alimentación v Productividad Animal.-- Cambio de representantes del Patronato Alonso de Herrera en la Comisión Asesora de la Investigación Científica y Técnica.-- Convenio con ASPA.-- Dimisión del Director del Centro de Edafología y Biología Aplicada del Segura de Murcia.-- Nombramientos de representantes en los C. R. l. D. A. S.-- Designación de Jurados para Premios del C. S. l. C.-- Informes del Secretario Adjunto del C. S. I. C. sobre reuniones en Europa.-- Convenio entre la Estación Experimental del Zaidín y la Universidad de Nápoles.-- Donación de terrenos a la Diputación de Badajoz.-- Seminario Oleícola Internacional.-- Congreso de la Unión Fitopatológica Mediterránea.-- Situaciones de personal.-- Reunión de la Comisión de Protección Vegetal.-- Día Forestal Mundial.-- Congresos y reuniones internacionales y viajes.-- Premio Agrícola Aedos.-- BibliografíaPeer reviewed2019-08.- CopyBook.- Libnova.- Biblioteca ICA

Repercussao dos incendios florestais na qualidade do solo

Trabajo presentado en el XVI Encontro Luso-Galego de Química, celebrado en Aveiro (Portugal), del 10 al 12 de noviembre de 2010Peer reviewe

Estímulos y obstáculos de las investigadoras de mi generación

Trabajo presentado en las Xornadas Mulleres Universitarias Galegas Compromiso e Igualdade, celebradas en Santiago de Compostela (España), en octubre de 2010Peer reviewe

Inorganic and organic N pools in soils burned or heated: immediate alterations and evolution after forest wildfires

Variation in the inorganic and organic N contents and in the resistance of organic N to step-wise acid hydrolysis (four steps of increasing hydrolytic intensity) was analysed in burned soils sampled (0–5 and 5–10 cm depth) at different times after high severity forest wildfires, as well as in one soil heated in the laboratory at 150, 210 or 350 °C. Ammonium content increased in the 0–5 and 5–10 cm soil layers immediately after burning and after heating at 150, 210 or 350 °C. The positive effect of burning on NH4+-N persisted for several months and was particularly intense 1 year after burning. Two, 5 and 10 years after wildfire, NH4+-N in burned soils was similar or slightly higher than in the corresponding unburned soils. Nitrite and nitrate were very low or undetectable in most burned and unburned samples analysed. Organic N strongly decreased in one of the soils immediately after wildfire and in the soil heated at 350 °C; conversely, in the other recently burned soil and in samples heated at 150 and 210 °C, organic N was slightly higher or similar to that in the corresponding unburned soils. During the 2 years after wildfire, organic N changed little and in soils sampled 5 and 10 years after burning the organic N contents were close to those of the unburned control soils. Independent of the variation in organic N content, the lability of organic N dramatically changed after burning or heating, this change remaining for at least 2 years after wildfire. The amount of N solubilised by acid hydrolysis strongly decreased in both 0–5 and 5–10 cm soil layers after wildfire and in soils heated at 210 or 350 °C. This decrease was mainly due to the loss of labile N (solubilised after hydrolysis with 1 and 3 N HCl), while the hydrolysable N obtained with 6 N HCl changed little or even increased. On the contrary, the amount and/or percentage of N resistant to acid hydrolysis (residual N) increased in recently burned soils and in soils heated at 210 or 350 °C (except in the 5–10 cm layer of one soil). In the months following burning, differences in the lability of organic N between the burned and unburned soils decreased, especially in the 0–5 cm soil layer, although 2 years after wildfire the effect of burning on the organic N compounds was still detectable. In soils sampled 5 or 10 years after wildfire, the amounts and percentages of the residual N and of different fractions of hydrolysable N were similar to those of the unburned soils. The relationship between the reduction in hydrolysable N and the alteration of N mineralisation (previously studied) was also analysed.This work was funded by the Xunta de Galicia and by the Spanish Ministerio de Educación y Ciencia.Peer reviewe

Incorporation of the degradation products of 14C,15N-glycine in various forms of organic carbon and nitrogen in two acid soils

The incorporation of the degradation products of 14C,15N-glycine in the endogenous organic matter of two Cambisols, one developed over acid schists and the other over gabbros, was studied by aerobic incubation for 42 days at 28°C, of unenriched samples and samples enriched with glycine, and analysis of the C and N organic forms in the samples. The incorporation of exogenous C depended on soil type and on the nature of the added substrate. Thus, the addition of glycine increased the proportion of water-soluble C, stimulated microbial oxidation of unhumified organic matter and favoured the synthesis of early humification compounds at the expense of unmineralized and unhumified organic matter; and also favoured the formation of organo-clay compounds (possibly due to adsorption of the glycine or its metabolites on clay) and (where stabilizing agents were present) of insoluble humin. In both soils, the distribution of endogenous N was unaffected by incubation. 15N from glycine was incorporated mainly among identifiable forms (NH+4, amides, hexosamines and α-amino acids) in the schist soil, which may possibly be related to ammonification being the dominant mineralization process. In the gabbro soil, 15N from glycine was incorporated mainly in hydrolyzable unidentified forms which is probably related to the dominance of nitrification in the mineralization process. The virtual absence of isotoplc excess in the hydrolysis residue and the large isotoplc excesses in the first two hydrolysis stages (the shortest and gentlest) showed that added N was considerably more labile than endogenous N. The step-wise hydrolysis procedure used extracted the more labile soil N much more selectively than does conventional continuous hydrolysis.This research was supported by Conselleria de Education y Ordenacion Universitaria de la Xunta de Galicia (Spain).Peer reviewe