sábado, 6 de mayo de 2017

Publicaciones 2016 en revistas del exterior


Duval M.E., J.A. Galantini, J.M. Martinez, F.M. López, L. Wall. 2016. Sensitivity of different soil quality indicators to assess sustainable land management: Influence of site features and seasonality. Soil & Tillage Research 159: 9-22.
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The turnover rate of labile organic fractions varies continuously due to different soil uses and managements, weather conditions and time of sampling. The aim of this study was to quantify the effect of different agricultural management, season and soil type on soil organic carbon (SOC) and its different fractions. The study was conducted on four sites located in the Argentinean Pampas. In each site, three treatments were defined: Good Agricultural Practices (GAP), Poor Agricultural Practices (PAP) and Natural Environment (NE). During two consecutive years (2010 and 2011) and at two different times (February and September) undisturbed soil samples were taken at0-20 cm depth. Variables assessed included: SOC and its organic fractions: coarse and fine particulate organic carbon (POCc and POCf, respectively), SOC associated with a mineral fraction (MOC), total and soluble carbohydrates (CHt and CHs, respectively), bulk density, and large pores (P>30). Also, indices associated with soil and management variables were determined. SOC reductions caused by agricultural practices were mainly from POCc. This fraction represented 34-52% and 50-74% for PAP and GAP, respectively, of the observed in NE. The carbon pool index (CPI) shows that agricultural treatments induced greater variations in all the labile organic fractions compared with SOC and MOC. In turn, the magnitude of variability was different among fractions, where temporal fluctuations increased according to the following order MOC< SOC <POCf≤CHt<CHs ≤ POCc. Independently of the soil type, the CPI was a sensitive indicator of soil quality in these systems under no-tillage. The multivariate analysis has proven to be an efficient analytical methodology for the identification of soil indicators that respond to agricultural practices, in which chemical properties (POCf and CHt), physical (BD and P>30), and indices (SOC:clay, structural index and intensification sequence index) were the variables that best explained the total variance of information of the four sites. Therefore, these indicators/indices should be included in any minimum data set for evaluating the agricultural soil quality under no-tillage in the studied area.
Keywords: Soil organic carbon; Organic fractions; Multivariate analysis


Galantini, J.A.; M. Duval; J.M. Martinez; V. Mora; R. Baigorri & J.M. García-Mina. 2016. Quality and quantity of organic fractions as affected by soil depth in an argiudoll under till and no-till systems. International Journal of Plant & Soil Science 10 (5) - doi:10.9734/IJPSS/2016/25205
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The turnover rate of labile organic fractions varies continuously due to different soil uses and managements, weather conditions and time of sampling. The aim of this study was to quantify the effect of different agricultural management, season and soil type on soil organic carbon (SOC) and its different fractions. The study was conducted on four sites located in the Argentinean Pampas. In each site, three treatments were defined: Good Agricultural Practices (GAP), Poor Agricultural Practices (PAP) and Natural Environment (NE). During two consecutive years (2010 and 2011) and at two different times (February and September) undisturbed soil samples were taken at0-20 cm depth. Variables assessed included: SOC and its organic fractions: coarse and fine particulate organic carbon (POCc and POCf, respectively), SOC associated with a mineral fraction (MOC), total and soluble carbohydrates (CHt and CHs, respectively), bulk density, and large pores (P>30). Also, indices associated with soil and management variables were determined. SOC reductions caused by agricultural practices were mainly from POCc. This fraction represented 34-52% and 50-74% for PAP and GAP, respectively, of the observed in NE. The carbon pool index (CPI) shows that agricultural treatments induced greater variations in all the labile organic fractions compared with SOC and MOC. In turn, the magnitude of variability was different among fractions, where temporal fluctuations increased according to the following order MOC< SOC <POCf≤CHt<CHs ≤ POCc. Independently of the soil type, the CPI was a sensitive indicator of soil quality in these systems under no-tillage. The multivariate analysis has proven to be an efficient analytical methodology for the identification of soil indicators that respond to agricultural practices, in which chemical properties (POCf and CHt), physical (BD and P>30), and indices (SOC:clay, structural index and intensification sequence index) were the variables that best explained the total variance of information of the four sites. Therefore, these indicators/indices should be included in any minimum data set for evaluating the agricultural soil quality under no-tillage in the studied area.
Keywords: Soil organic carbon; Organic fractions; Multivariate analysis


Duval M., J.A. Galantini, Julia E. Capurro, J.M. Martinez, F.M. López. 2016. Use of different winter cover crops species in soybean monoculture: effects on soil organic carbon and its fractions. Soil & Tillage Research 161:95-105 doi:10.1016/j.still.2016.04.006
 ISSN: 0167-1987
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The current agricultural production systems in the Pampas Region have been significantly simplified by cultivating large land areas under no tillage (NT), where soybean is the predominant crop. These systems with long periods of fall-winter fallow and poor annual input of carbon (C) into the soil lead to soil degradation, thereby affecting physical and chemical properties. A 6-year cover crop study was carried out on a Typic Argiudoll under NT in the south of Santa Fe, Argentina. Various winter species were used as cover crops: wheat (W), oat (O), vetch (V), an oat + vetch mixture (O + V) and a control (Ct) treatment without a cover crop. We examined the influence of cover crops on the following soil organic C-fractions: coarse particulate organic carbon (POCc), fine particulate organic carbon (POCf) and mineral-associated organic carbon (MOC) from 2008 to 2011. Aboveground carbon input by the cover crops was related to the June to October rainfalls. In general, the W and O treatments supplied a higher amount of C to the soil; these gramineous species produced 22 and 86% more biomass than O + V and V. The water cost of including cover crops ranged from 13 to 93 mm compared with Ct. However, this water-use did not affect soybean yields. On average, gramineous species (pure stand or mixture) supplied more than 3.0 Mg C ha−1 year−1 to the soil, whereas V supplied less than 2.0 Mg C ha−1 year−1. Increase in the mean annual C-input by residues into the soil (cover crop + soybean) explained most SOC variation (R2 = 0.61; p < 0.05). This relationship was more evident with labile soil organic fractions, both for POCc (R2 = 0.91; p < 0.001) and POCc + POCf (R2 = 0.81; p < 0.001). The stratification ratios of SOC (SI, 0–5:10–20 cm) reflected differences among treatments, where >2.0 for W; 1.7 for O, O + V and V, and <1.5 for Ct. Soil physical fractionation by particle size showed that cover crops affected the most dynamic fraction directly associated with residue input (POCc) at 0–5 and 5–10 cm. At 0–5 cm, the effects were observed in the most transformed fractions (MOC and POCf) 4 years after the experiment started, whereas at 0–20 cm, differences in the labile fractions (POCc and POCf) were found at the end of the experiment (6 years). Although C-input by the cover crops fueled decomposition of labile soil organic fractions, concentration of surface SOC and its associated fractions (POCc, POCf and MOC) was modified after 6 years. This effect became noticeable during the third year when the plots under cover crops showed a higher SI than the traditional fallow.
Keywords Wheat; Labile fractions; No-tillage

Zalba P., N.M. Amiotti, J.A. Galantini, S. Pistola. 2016. Soil humic and fulvic acids from different land use systems evaluated by E4/E6 ratios. Communications in Soil Science and Plant Analysis 47 (13-14) 1675-1679. Doi 10.1080/00103624.2016.1206558
ISSN: 0010-3624 (Print) 1532-2416 (Online)
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Changes in land-use systems such as the introduction of trees on agricultural land can give rise to changes in the physicochemical properties of the soils, also affecting the quantity and quality of organic matter incorporated into the system. The present study assesses humic substances (HS) in the soil such as humic acid (HA) and fulvic acid (FA) by looking at the relationship between the optic densities determined at 465 and 665 nm (E4/E6 ratio). Topsoil samples (0–20 cm) from pine woodlands 60 years of age were compared with agricultural soils of similar age in the central-south region of the Province of Buenos Aires, Argentina. The pH of the topsoil from beneath the pine trees was highly acidic (5.0 vs. 6.2) and a significant increase in the level of organic carbon (OC) was registered. The carbon to nitrogen (C/N) ratio was also higher (by one order of magnitude) beneath the pine trees, although the humification conditions of the soil organic matter (SOM) were good in the soils of both studied land-use systems. The E4/E6 ratio was higher in the HA and FA 2 (second extraction) beneath the pines, indicating a smaller molecular size of the HS bound to the clay minerals. This fact can be attributed to the higher concentration of hydrogen ions beneath the pines and consequently the loss of polyvalent cations, mainly calcium. The most labile organic molecules (FA 1 – first extraction) were of a larger size in soils beneath the pines, most likely owing to a specific characteristic of the Pinus genus, although the fraction in question constitutes a minority fraction among the HS. Clear differences were established between the E4/E6 ratios in HA and FA, making this a highly useful method for determining molecular changes in HS as a result of changes in land use.
KEYWORDS: Fulvic acid, humic acid, pinus afforestation



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