Scientific Journals of INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria)
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Carbon storage as affected by different site preparation techniques two years after mixed forest stand installation
Get PDFAim of study: This study aims at evaluating the impact of site preparation techniques prior to plantation on carbon storage and distribution in a young mixed stand of Pseudotsuga menziesii (PM) and Castanea sativa (CS). Area of study: The experimental field was established near Macedo de Cavaleiros, Northern Portugal, at 700 m elevation, mean annual temperature 12ºC and mean annual rainfall 678 mm. Material and Methods: The experimental layout includes three replicates, where the different treatments corresponding to different tillage intensities were randomly distributed (high, moderate and slight intensity), in plots with an area of 375 m2 each. Twenty six months after forest stand installation, samples of herbaceous vegetation (0.49 m2 quadrat), forest species (8 PM and 8 CS) and mineral soil (at 0-5, 5-15, 15-30 and 30-60 cm depth) were collected in 15 randomly selected points in each treatment, processed in laboratory and analyzed for carbon by elemental carbon analyzer. Main results: The results obtained showed that: (i) more than 90% of the total carbon stored in the system is located in the soil, increasing in depth with tillage intensity; (ii) the contribution of herbaceous vegetation and related roots to the carbon storage is very low; (iii) the amount of carbon per tree is higher in CS than in PM; (iv) the global carbon storage was affected by soil tillage generally decreasing with the increase of tillage intensity. Accordingly, carbon storage capacity as affected by the application of different site preparation techniques should be a decision support tool in afforestation schemes.Keywords: Site preparation; forest species; herbaceous vegetation; carbon storage; mineral soil; Portugal
A comparison of estimation methods for fitting Weibull and Johnson’s SB functions to pedunculate oak (Quercus robur) and birch (Betula pubescens) stands in northwest Spain
Get PDFAim of study: In this study we compared the accuracy of the Weibull and the Johnson’s SB functions for describing diameter distributions in pedunculate oak (Quercus robur L.) and birch (Betula pubescens Ehrh.) stands.Area of study: Galicia (Northwest Spain).Material and Methods: A total of 172 diameter distributions in pedunculate oak and 202 in birch stands were finally evaluated. We compared the accuracy of three commonly used estimation methods of the Weibull and four estimation methods of the Johnson’s SB functions for describing these diameter distributions.Main results. For Quercus robur L. stands, the most suitable methods were the Percentiles followed by Maximum Likelihood for the Weibull PDF and the method of Moments for the Johnson’s SB PDF. For Betula pubescens Ehrh. stands, the best fits obtained with the Percentiles and Maximum Likelihood methods were also superior to the method of Moments, whereas the Conditional Maximum Likelihood and method of Moments provided the best results for the Johnson’s SB PDF, depending on the statistic and the value of the location parameter considered.Research highlights: Both distributions were suitable. The results were better for pedunculate oak than for birch stands.Keywords: Knoebel and Burkhart; location parameter; percentiles; maximum likelihood; moments; mode
Effectiveness of inorganic and organic mulching for soil salinity and sodicity control in a grapevine orchard drip-irrigated with moderately saline waters
Get PDFSoil mulching is a sensible strategy to reduce evaporation, accelerate crop development, reduce erosion and assist in weed control, but its efficiency for soil salinity control is not as well documented. The benefits of inorganic (plastic) and organic (grapevine pruning residues) mulching for soil salinity and sodicity control were quantified in a grapevine orchard (cultivars ‘Autumn’ Royal and ‘Crimson’) drip-irrigated with moderately saline waters. Soil samples were taken at the beginning and end of the 2008 and 2009 irrigation seasons in six vines of each cultivar and mulching treatment. Soil saturation extract electrical conductivity (ECe), chloride (Cle) and sodium adsorption ratio (SARe) values increased in all treatments of both grapevines along the irrigation seasons, but the increases were much lower in the mulched than in the bare soils due to reduced evaporation losses and concomitant decreases in salt evapo-concentration. The absolute salinity and sodicity daily increases in ‘Autumn’ and ‘Crimson’ 2008 and in ‘Crimson’ 2009 were on the average 44% lower in the plastic and 76% lower in the organic mulched soils than in the bare soil. The greater efficiency of the organic than the plastic mulch in ‘Crimson’ 2009 was attributed to the leaching of salts by a precipitation of 104 mm that infiltrated the organic mulch but was intercepted by the plastic mulch. Although further work is needed to substantiate these results, the conclusion is that the plastic mulch and, particularly, the organic mulch were more efficient than the bare soil for soil salinity and sodicity control
Soil-blade orientation effect on tillage forces determined by 3D finite element models
Get PDFThis paper investigated the effect of the cutting parameters of a blade on the tillage force components using finite element modeling. A three-dimensional model was carried out with Abaqus Explicit in order to study the interaction between the tool and soil. The soil was modeled with linear forms of the Drucker-Pager model, while the tool was considered as a rigid body with a reference point taken at its tip. The effect of tillage depth and the width of a vertical blade were studied. It was found that the amounts of the draught and vertical forces increase linearly with a slope of 0.037 and 0.0143 respectively when the width increases. The narrow tool (width< 60mm) has a greater effect on the specific draught force than a larger tool. Draught and specific draught force increase with polynomial and linear curve respectively versus the depth. However, this effect was reduced for the vertical force. These results were in a good agreement with previously published works. The second part of this paper is focused on the oblique position of the blade to evaluate the effect of the attack angles on both the tillage forces (draught, lateral and vertical) and the cutting process of the soil during and after its failure. For all considered angles, the draught force presents the highest values compared to the vertical and lateral forces. Results showed that working with small cutting and an average rake angles (30° to 60° and 45° respectively) can produce a good soil inversion
Impact of variation in production traits, inputs costs and product prices on profitability in multi-purpose sheep
Get PDFThe impact of variation in production traits, and inputs costs and product prices on economic efficiency of a multi-purpose sheep breed farmed in a marginal area of Slovakia was examined using a bio-economic simulation model of the program package ECOWEIGHT. Variations in the proportion of milk processed to cheese on farms, sheep product prices and production costs were based on values observed in Slovakia from 2004 to 2010, and variation in ewe performance traits (milk yield, conception rate, litter size, ewe productive lifetime) was based upon breed standards for the Improved Valachian breed. Revenue from government subsidies was not included in farm returns. Profitability ratios of farms were negative for most combinations of production and economic factors (-6 to -37%). Only farms processing milk to cheese, farms with the highest simulated milk yield (180 kg per ewe) and farms receiving the highest simulated milk and cheese prices (0.99 and 8.36 € kg-1) achieved positive profitability’s of 11, 21 and 3%, respectively. Farms reaching the performance level of animals characterised by the breed standard had 9% higher revenue, 3% lower cost and 11 percentage points higher profitability ratio (-6%) than farms with average animal performance, when compared at the same average level of all product prices and costs. To promote economic sustainability of multi-purpose sheep breed enterprises in marginal areas, selection and management to achieve the biological potential of those breeds and increasing the proportion of milk processed to cheese on farms are recommended
A long-scale biodiversity monitoring methodology for Spanish national forest inventory. Application to Álava region
Get PDFAim of study: In this study, a methodology has been designed to assess biodiversity in the frame of the Spanish National Forest Inventory with the aim of evaluating the conservation status of Spanish forests and their future evolution. This methodology takes into account the different national and international initiatives together with the different types and characteristics of forests in Spain. Area of study: Álava province (Basque country, Spain).Material and methods: To analyse the contribution of each of the different indices to the biodiversity assessment, a statistical analysis using PCA multivariate techniques was performed for structure, composition and dead wood indicators. Main Results: The selected biodiversity indicators (based on field measurements) are presented along with an analysis of the results from four representative forest types in Álava by way of an example of the potential of this methodology. Research highlights: The statistical analysis revealed the important information contribution of Mingling index to the composition indicators. Regarding the structure indicators, it is remarkable the interest of using standard deviations and skewness of height and diameter as indicators. Finally it is interesting to point out the interest of assessing dead saplings since they provide additional information and their volume is a particularly useful parameter for analyzing the success of regeneration.Keywords: species richness; structural diversity; dead wood; NFI; PCA
Modeling dominant height growth including site attributes in the GADA approach for Quercus faginea Lam. in Spain
Get PDFAim of the study: To develop a site index model for Quercus faginea Lam. stands.Area of study: SpainMaterial and Methods: Data from 81 growth series collected in plots where Q. faginea was the main species were used for modelling. Different generalized algebraic difference equations (GADA) were fitted from traditionally used models. Richards model was selected and used to expand the parameters with environmental variables.Research highlights: Winter rainfall (WR), annual potential evapotranspiration (PET) and pH were introduced increasing the prediction ability of the GADA. It is strongly recommended to apply the model with ages lower than 80 years because the lack of data above that age makes bias increase and efficiency decrease.Keywords: Site index; Lusitanian oak; environmental variables
A comparative study of fatty acid profiles of fat in commercial Spanish suckling kids and lambs
Get PDFFatty acid profiles are a major contributor to meat quality in small ruminants. Nevertheless, while fatty acid profiles from suckling lambs have been extensively studied they are virtually unknown in suckling kids. Fatty acid profiles of intramuscular and kidney knob fat depots of suckling kids were compared with fatty acid profiles of lambs with a quality label in the Spanish market. Forty suckling kids from Blanca Celtibérica (BC), Moncaína (Mo), Negra Serrana (NS) and Murciano Granadina (MG) breeds and 20 Churra male suckling lambs labelled with ‘Lechazo de Castilla y León’ Protected Geographic Indication were slaughtered at commercial live weights (12 kg). In both depots differences in the unsaturated fatty acid profile were observed between breeds. The most pronounced differences were observed between meat goat breeds (BC, Mo and NS) and lambs, whilst a greater similarity in the fatty acid profile was observed between kids from dairy goat breeds (MG) and lambs. The lowest polyunsaturated fatty acid content was observed in meat goat breeds (approximately 21 to 22% of total fatty acids detected in the intramuscular fat). No significant differences in atherogenic index and desirable fatty acid content (range 68 to 70% of total fatty acids detected) were observed. However, a more favourable (lower than 8.07) n-6/n-3 ratio was observed in meat goat breeds. The use of fatty acid profiles from intramuscular and kidney knob fat could be proposed as a tool to differentiate goat kids and lambs. The fact that intramuscular fat from suckling kids and lambs shows appropriate lipid nutritional indices and their low carcass fatness indicate that moderate consumption of suckling kid and lamb meat may contribute to an overall balanced diet for humans
New pesticides regulation: potential economic impacts of the withdrawal of Pendimethalin in horticultural crops
Get PDFThe Thematic Strategy on the Sustainable Use of Pesticides moves forward towards the sustainability of agriculture fostering the use of Integrated Pest Management (IPM) practices in the European Union (EU). EC Regulation 1107/2009 was adopted in this framework leading to the eventual drop in the Vademecum of authorized substances of some important pesticides which are presently used in EU agriculture. Herbicide Pendimethalin will have to renew its registration in 2016 under the new regulation and there is a high probability that it will be removed. In this study we analyze the potential impact of the prohibition of Pendimethalin in two export driven horticultural crops grown in Southeastern Spain - lettuce and celery - to provide an illustration of possible consequences of the loss of certain active substances due to the new regulation. To do so, gross margin stochastic models are developed and used to generate Monte-Carlo simulations to look at farms’ economic results and their production risks. Econometric models are used to examine consumers’ and producers’ surplus in export markets of lettuce and celery. The results show that the Pendimethalin ban might modify the economic risk profile that the farm faces, affecting the crops’ profitability in the short-term. These changes would pass on to markets through shifts in supply and price and finally to European consumers, who would be the major losers
The capability of alfalfa grazing- and concentrate-based feeding systems to produce homogeneous carcass quality in light lambs over time
Get PDFThe effects of grazing on the carcasses and meat of light lambs are unclear, mainly due to variations in weather conditions and pasture production, which affect the growth of lambs and the quality of their carcasses. The aim of this study was to evaluate the effect of feeding systems, which varied in intensification due to the use of concentrate, on the growth and carcass traits of light lambs and the capability of these feeding systems to produce homogeneous lamb carcasses over the course of several years. The average daily weight gain of grazing lambs, but not lambs fed indoors was affected over years. The colour of the Rectus abdominis muscle and the amount of fat were more variable in grazing lambs (from 2.7 to 6.3) than indoor lambs (from 4.5 to 5.1). Grazing feeding systems without concentrate supplementation are more dependent than indoor feeding systems on the year. This climatologic dependence could lead to slaughter of older grazing lambs (77 days) to achieve the target slaughter weight when temperatures are low or the rainfall great. All feeding systems evaluated produced light lambs carcasses with a conformation score from O to R- that is required by the market. Even the potential change in fat colour found in both grazing treatments was not enough to change the subjective evaluation of fat colour