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Panosso A.R.,Sao Paulo State University | Marques J.,Sao Paulo State University | Milori D.M.B.P.,Embrapa Agricultural Instrumentation | Ferraudo A.S.,Sao Paulo State University | And 3 more authors.
Soil and Tillage Research | Year: 2011

Soil CO2 emission (FCO2) has been related to soil properties that are strongly influenced by agricultural management. The objective of this work was to study FCO2 and its relation to soil properties in adjacent areas cropped with sugarcane managed with Slash-and-burn (SB) and Green (G) harvest. FCO2 was significantly higher (p<0.01; 2.74μmolm-2s-1 in SB and 2.07μmolm-2s-1 in G) in SB. Total emission in the 70-day period after harvest was also higher in the SB plot (729gCO2m-2) when compared to the G (557gCO2m-2) plot. Organic matter content and carbon stock (0-25cm) were 13% and 20% higher in SB, respectively, when compared to G. Other soil properties that presented significant difference between plots were pH, available phosphorus, sum of bases, cation exchange capacity, texture, and humification index of soil organic matter. The SB plot presented higher spatial variations in the majority of the soil properties, including FCO2, when compared to the G plot. Principal component analysis sustains the distinction of two groups, G soil samples and SB soil samples, separately. Regression analysis was able to explain up to 75% and 45% of the FCO2 spatial variability in SB and G harvested areas, respectively, and indicates that the humification index of soil organic matter, and its interaction with soil bulk density, is an important factor not just to differentiate emissions in each plot. Linear correlation between humification and FCO2 in each management system shows a positive correlation (p<0.10) in the G area and negative correlation (p<0.05) in the SB area. In addition, the interaction between humification index and bulk density relates better than others properties with soil CO2 emission, with this property being the most important to understand the emission variability in the Slash-and-burn area. © 2010 Elsevier B.V. Source

Segnini A.,International Potato Center | Posadas A.,Embrapa Agricultural Instrumentation | Quiroz R.,Environment Division at CIP | Milori D.M.B.P.,Embrapa Agricultural Instrumentation Center | And 2 more authors.
Journal of Soil and Water Conservation | Year: 2011

Carbon accumulation and sequestration in Andean soils are scarcely documented. Carbon contents, carbon stocks, and stability were determined in five Peruvian agroecologies, along a 1,000 km (621 mi) transect covering the arid Pacific coast, the Andean high plateau, and the tropical highland rainforest in the eastern flank of the Andes. It was hypothesized that the carbon stocks and stability varied with land use and altitudinal gradient. Results showed that the soils in the tropical highland rainforest site presented the higher (p > 0.05) carbon contents (134 g kg-1 [13.4%]). Coffee plantations in the tropical highland rainforest and alfalfa under irrigation in the dry valleys presented larger (p > 0.05) carbon stocks (83 Mg ha-1 [37 tn ac-1]) than primary rainforests. The dry lowlands showed the lowest carbon contents (51 g kg-1 [5.1%]) and carbon stocks (40 Mg ha-1 [18 tn ac-1]). Soil organic carbon increased with elevation in the arid environments. In the high plateau potato systems, low carbon contents (68 g kg-1 [6.8%]) and carbon stocks (47 Mg ha-1 [21 tn ac-1]) were found. The soils in both the tropical highland rainforest and the dry valleys presented lower humification index, when compared to other agroecologies. Humification increased with soil depth due to the presence of recalcitrant carbon, while at the surface the presence of labile carbon dominates as a result of a constant input of plant residues. Results suggest that diversified production systems with crops and livestock are more stable for carbon stocks, which might be essential to help farmers adapting to the effects of climate change. Therefore, viable land uses, from the carbon economy perspective, must be promoted to support sustainable agricultural practices for most important ecological conditions. © 2011 Soil and Water Conservation Society. All rights reserved. Source

Steffens C.,URI Integrated Regional University Brazil | Franceschi E.,URI Integrated Regional University Brazil | Corazza F.C.,URI Integrated Regional University Brazil | Herrmann Jr. P.S.P.,Embrapa Agricultural Instrumentation | Oliveira J.V.,URI Integrated Regional University Brazil
Journal of Food Engineering | Year: 2010

This work reports the development of gas sensors with three different techniques applied to sensor coating with conducting polymer polyaniline (PANI) by: in situ polymerization, RESS (rapid expansion of supercritical solutions) of polyaniline doped with dodecyl benzene sulphonic acid (DBSA) in pressurized fluid, and precipitation. The two latter sensors were obtained through micro/nanoparticle deposition onto interdigitated line patterns of graphite deposited on tracing paper using the supercritical fluid technology. It is shown that sensors produced exhibited different behavior with regard to moisture and also to vapor-phase atmosphere of acetone, ethanol, n-hexane and ethyl acetate. Results demonstrate that sensors produced by precipitation and RESS seem to be promising to detect the ripeness of banana thus indicating a potential technology to be further explored towards developing accurate methods for monitoring the maturation of fruits. © 2010 Elsevier Ltd. All rights reserved. Source

Vaz C.M.P.,Embrapa Agricultural Instrumentation | Jones S.,Utah State University | Meding M.,University of Arizona | Tuller M.,University of Arizona
Vadose Zone Journal | Year: 2013

Eight commercially available electro-magnetc water content sensors were evaluated in seven well-characterized soils ranging from sand to clay textures, including an organic soil. Factory supplied calibrations were compared and sensor response to soil properties demonstrated. Soil-specific calibrations yielded measurement accuracies from 0.015 to 0.025. An increasing number of electromagnetc (EM) sensors are deployed to measure volumetric soil water content (q) for agricultural, ecological, and geotechnical applications. While impedance and capacitance sensors generally operate at frequencies between 20-300 MHz, time domain-refectometry (TDR) and-transmissometry (TDT) function in the GHz range. In general, lower frequency sensors are less expensive but more sensitive to confounding effects of salinity, temperature, and soil textural variations. To simplify sensor application, factory-supplied calibrations are often provided for different porous media types such as mineral, organic, and saline soils, or soilless-substrates. The objective of the presented study was to evaluate the performance of eight commercially available EM moisture sensing systems (TDR 100, CS616, Theta Probe, Hydra Probe, SM300, Wet2, 5TE, 10HS) in seven well-characterized and texturally varying soils using a standardized approach. The validity of factory supplied-calibraton relatonships was evaluated and the influence of soil properties on the EM responses for q measurements was observed. Results indicate that the factory-supplied calibraton relatonships for groups of mineral and organic soils in general performed well, but some inconsistences were identified and suggestions for improvement are discussed. Soil-specific calibrations from this study yielded accuracies of around 0.015 m3m-3 for 10HS, SM300, and Theta Probe, while lower accuracies of about 0.025 m3 m-3 were found for TDR100, CS616, Wet2, 5TE, and the Hydra Probe. These results are based on mineral soils having a large variaton in texture, electrical conductvites below 2 dS m-1, organic mater below 10%, and specific surface areas of less than 50 m2 g-1. © Soil Science Society of America, 5585 Guilford Rd., Madison, WI 53711 USA. All rights reserved. Source

Moretti C.L.,Embrapa Vegetables | Mattos L.M.,Embrapa Vegetables | Calbo A.G.,Embrapa Agricultural Instrumentation | Sargent S.A.,University of Florida
Food Research International | Year: 2010

Temperature increase and the effects of greenhouse gases are among the most important issues associated with climate change. Studies have shown that the production and quality of fresh fruit and vegetable crops can be directly and indirectly affected by high temperatures and exposure to elevated levels of carbon dioxide and ozone. Temperature increase affects photosynthesis directly, causing alterations in sugars, organic acids, and flavonoids contents, firmness and antioxidant activity. Carbon dioxide accumulation in the atmosphere has directly effects on postharvest quality causing tuber malformation, occurrence of common scab, and changes in reducing sugars contents on potatoes. High concentrations of atmospheric ozone can potentially cause reduction in the photosynthetic process, growth and biomass accumulation. Ozone-enriched atmospheres increased vitamin C content and decreased emissions of volatile esters on strawberries. Tomatoes exposed to ozone concentrations ranging from 0.005 to 1.0 μmol/mol had a transient increase in β-carotene, lutein and lycopene contents. © 2009 Elsevier Ltd. Source

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