Effects of surface application of calcium-magnesium silicate and gypsum on soil fertility and sugarcane yield

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Soil physical and microbiological attributes cultivated with the common bean under two management systems

Agricultural management systems can alter the physical and biological soil quality, interfering with crop development. The objective of this study was to evaluate the physical and microbiological attributes of a Red Latosol, and its relationship to the biometric parameters of the common bean (Phaseolus vulgaris), irrigated and grown under two management systems (conventional tillage and direct seeding), in Campinas in the state of Sao Paulo, Brazil. The experimental design was of randomised blocks, with a split-plot arrangement for the management system and soil depth, analysed during the 2006/7 and 2007/8 harvest seasons, with 4 replications. The soil physical and microbiological attributes were evaluated at depths of 0.00-0.05, 0.05-0.10, 0.10-0.20 and 0.20-0.40 m. The following were determined for the crop: density, number of pods per plant, number of beans per pod, thousand seed weight, total weight of the shoots and harvest index. Direct seeding resulted in a lower soil physical quality at a depth of 0.00-0.05 m compared to conventional tillage, while the opposite occurred at a depth of 0.05-0.10 m. The direct seeding showed higher soil biological quality, mainly indicated by the microbial biomass nitrogen, basal respiration and metabolic quotient. The biometric parameters in the bean were higher under the direct seeding compared to conventional tillage.

Development of CAN-based distributed control system for variable rate technology in agricultural machinery

The number of electronic devices connected to agricultural machinery is increasing to support new agricultural practices tasks related to the Precision Agriculture such as spatial variability mapping and Variable Rate Technology (VRT). The Distributed Control System (DCS) is a suitable solution for decentralization of the data acquisition system and the Controller Area Network (CAN) is the major trend among the embedded communications protocols for agricultural machinery and vehicles. The application of soil correctives is a typical problem in Brazil. The efficiency of this correction process is highly dependent of the inputs way at soil and the occurrence of errors affects directly the agricultural yield. To handle this problem, this paper presents the development of a CAN-based distributed control system for a VRT system of soil corrective in agricultural machinery. The VRT system is composed by a tractor-implement that applies a desired rate of inputs according to the georeferenced prescription map of the farm field to support PA (Precision Agriculture). The performance evaluation of the CAN-based VRT system was done by experimental tests and analyzing the CAN messages transmitted in the operation of the entire system. The results of the control error according to the necessity of agricultural application allow conclude that the developed VRT system is suitable for the agricultural productions reaching an acceptable response time and application error. The CAN-Based DCS solution applied in the VRT system reduced the complexity of the control system, easing the installation and maintenance. The use of VRT system allowed applying only the required inputs, increasing the efficiency operation and minimizing the environmental impact.

Coffee processing residues as a soil potassium amendment

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comportamento do carbono orgânico e de atributos químicos, físicos e microbiológicos de um solo arenoso em área de conversão pastagem - Eucalipto

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Black carbon affects the cycling of non-black carbon in soil

Black carbon (BC) is an important fraction of many soils worldwide and plays an important role in global C biogeochemistry. However, few studies have examined how it influences the mineralization of added organic matter (AOM) and its incorporation into soil physical fractions and whether BC decomposition is increased by AOM. BC-rich Anthrosols and BC-poor adjacent soils from the Central Amazon (Brazil) were incubated for 532 days either with or without addition of (13)C-isotopically different plant residue. Total C mineralization from the BC-rich Anthrosols with AOM was 25.5% (P < 0.05) lower than with mineralization from the BC-poor adjacent soils. The AOM contributed to a significantly (P < 0.05) higher proportion to the total C mineralized in the BC-rich Anthrosols (91-92%) than the BC-poor adjacent soils (69-80%). The AOM was incorporated more rapidly in BC-rich than BC-poor soils from the separated free light fraction through the intra-aggregate light fraction into the stable organo-mineral fraction and up to 340% more AOM was found in the organo-mineral fraction. This more rapid stabilization was observed despite a significantly (P < 0.05) lower metabolic quotient for BC-rich Anthrosols. The microbial biomass (MB) was up to 125% greater (P < 0.05) in BC-rich Anthrosols than BC-poor adjacent soils. To account for increased MB adsorption onto BC during fumigation extraction, a correction factor was developed via addition of a (13)C-enriched microbial culture. The recovery was found to be 21-41 % lower (P < 0.05) for BC-rich than BC-poor soils due to re-adsorption of MB onto BC. Mineralization of native soil C was enhanced to a significantly greater degree in BC-poor adjacent soils compared to BC-rich Anthrosols as a result of AOM. No positive priming by way of cometabolism due to AOM could be found for aged BC in the soils. (C) 2009 Elsevier Ltd. All rights reserved.

Gradients in N-cycling attributes along forestry and agricultural land-use systems are indicative of soil capacity for N supply

Indicators of soil quality associated with N-cycling were assessed under different land-use systems (native forest NAT, reforestation with Araucaria angustifolia or Pinus taeda and agricultural use AGR) to appraise the effects on the soil potential for N supply. The soil total N ranged from 2 to 4 g/kg (AGR and NAT, respectively), and the microbial biomass N ranged from 80 to 250 mg/kg, being higher in NAT and A. angustifolia, and lower in P. taeda and AGR sites. Activities of asparaginase (ca. 50200 mg NH4+-N/kg per h), glutaminase (ca. 200800 mg NH4+-N/kg per h) and urease (ca. 80200 mg NH4+-N/kg/h) were also more intense in the NAT and A. angustifolia-reforested soils, indicating greater capacity for N mineralization. The NAT and AGR soils showed the highest and the lowest ammonification rate, respectively (ca. 1 and 0.4 mg NH4+-N/kg per day), but the inverse for nitrification rate (ca. 12 and 26%), indicating a low capacity for N supply, in addition to higher risks of N losses in the AGR soil. A multivariate analysis indicated more similarity between NAT and A. angustifolia-reforested sites, whilst the AGR soil was different and associated with a higher nitrification rate. In general, reforestation with the native species A. angustifolia had less impact than reforestation with the exogenous species P. taeda, considering the soil capacity for N supply. However, AGR use caused more changes, generally decrease in indicators of N-cycling, showing a negative soil management effect on the sustainability of this agroecosystem.

ISOLATION OF MICROSPORUM GYPSEUM IN SOIL SAMPLES FROM DIFFERENT GEOGRAPHICAL REGIONS OF BRAZIL, EVALUATION OF THE EXTRACELLULAR PROTEOLYTIC ENZYMES ACTIVITIES (KERATINASE AND ELASTASE) AND MOLECULAR SEQUENCING OF SELECTED STRAINS

A survey of Microsporum gypseum was conducted in soil samples in different geographical regions of Brazil. The isolation of dermatophyte from soil samples was performed by hair baiting technique and the species were identified by morphology studies. We analyzed 692 soil samples and the recuperating rate was 19.2%. The activities of keratinase and elastase were quantitatively performed in 138 samples. The sequencing of the ITS region of rDNA was performed in representatives samples. M. gypseum isolates showed significant quantitative differences in the expression of both keratinase and elastase, but no significant correlation was observed between these enzymes. The sequencing of the representative samples revealed the presence of two teleomorphic species of M. gypseum (Arthroderma gypseum and A. incurvatum). The enzymatic activities may play an important role in the pathogenicity and a probable adaptation of this fungus to the animal parasitism. Using the phenotypical and molecular analysis, the Microsporum identification and their teleomorphic states will provide a useful and reliable identification system.

Correlation of soil microbial community responses to contamination with crude oil with and without chromium and copper

Soil microcosms contaminated with crude oil with or without chromium and copper were monitored over a period of 90 days for microbial respiration, biomass, and for dehydrogenase, lipase, acid phosphatase, and arylsulfatase activities. In addition, the community structure was followed by enumerating the total heterotrophic and oil-degrading viable bacteria and by performing a denaturing gradient gel electrophoresis (DGGE) of the PCR amplified 16S rDNA. A significant difference was observed for biochemical activities and microbial community structures between the microcosms comprised of uncontaminated soil, soil contaminated with crude oil and soil contaminated with crude oil and heavy metals. The easily measured soil enzyme activities correlated well with microbial population levels, community structures and rates of respiration (CO2 production). The estimation of microbial responses to soil contamination provides a more thorough understanding of the microbial community function in contaminated soil, in situations where technical and financial resources are limited and may be useful in addressing bioremediation treatability and effectiveness. (C) 2012 Published by Elsevier Ltd.

Effects of tannery sludge application on physiological and fatty acid profiles of the soil microbial community

The impact of tannery sludge application on soil microbial community and diversity is poorly understood. We studied the microbial community in an agricultural soil following two applications (2006 and 2007) of tannery sludge with annual application rates of 0.0,2.3 and 22.6 Mg ha(-1). The soil was sampled 12 and 271 days after the second (2007) application. Community structure was assessed via a phospholipid fatty acid analysis, and the physiological profile of the soil microbial community via the Biolog method. Tannery sludge application changed soil chemical properties, increasing the soil pH and electrical conductivity as well as available P and mineral N concentrations. The higher sludge application rate changed the community structure and the physiological profile of the microbial community at both sampling dates. However, there is no clear link between community structure and carbon substrate utilization. According to the Distance Based Linear Models Analysis, the fatty acids 16:0 and 117:0 together contributed 84% to the observed PLFA patterns, whereas the chemical properties available P, mineral N, and Ca, and pH together contributed 54%. At 12 days, tannery sludge application increased the average well color development from 0.46 to 0.87 after 48 h, and reduced the time elapsed before reaching the midpoint carbon substrate utilization (s) from 71 to 44 h, an effect still apparent nine months after application of the higher sludge application rate. The dominant signature fatty acids and kinetic parameters (r and s) were correlated to the concentrations of available P. Ca, mineral N, pH and EC. (c) 2012 Elsevier B.V. All rights reserved.

Introducing Acacia mangium trees in Eucalyptus grandis plantations: consequences for soil organic matter stocks and nitrogen mineralization

Background and aims Eucalyptus plantations cover 20 million hectares on highly weathered soils. Large amounts of nitrogen (N) exported during harvesting lead to concerns about their sustainability. Our goal was to assess the potential of introducing A. mangium trees in highly productive Eucalyptus plantations to enhance soil organic matter stocks and N availability. Methods A randomized block design was set up in a Brazilian Ferralsol soil to assess the effects of mono-specific Eucalyptus grandis (100E) and Acacia mangium (100A) stands and mixed plantations (50A:50E)on soil organic matter stocks and net N mineralization. Results A 6-year rotation of mono-specific A. mangium plantations led to carbon (C) and N stocks in the forest floor that were 44% lower and 86% higher than in pure E. grandis stands, respectively. Carbon and N stocks were not significantly different between the three treatments in the 0-15 cm soil layer. Field incubations conducted every 4 weeks for the two last years of the rotation estimated net soil N mineralization in 100A and 100E at 124 and 64 kg ha(-1) yr(-1), respectively. Nitrogen inputs to soil with litterfall were of the same order as net N mineralization. Conclusions Acacia mangium trees largely increased the turnover rate of N in the topsoil. Introducing A. mangium trees might improve mineral N availability in soils where commercial Eucalyptus plantations have been managed for a long time.

Soil-nutrient availability modifies the response of young pioneer and late successional trees to elevated carbon dioxide in a Brazilian tropical environment

The aim of this work was to determine the impact of three levels of [CO2] and two levels of soil-nutrient availability on the growth and physiological responses of two tropical tree species differing in their ecological group: Croton urucurana Baillon, a pioneer (P), and also Cariniana legalis (Martius) Kuntze, a late succession (LS). We aimed to test the hypothesis that P species have stronger response to elevated [CO2] than LS species as a result of differences in photosynthetic capacity and growth kinetics between both functional groups. Seedlings of both species were grown in open-top-chambers under high (HN) or low (LN) soil-nutrient supply and exposed to ambient (380 mu mol mol(-1)) or elevated (570 and 760 mu mol mol(-1)) [CO2]. Measurements of gas exchange, chlorophyll a fluorescence, seedling biomass and allocation were made after 70 days of treatment. Results suggest that elevated [CO2] significantly enhances the photosynthetic rates (A) and biomass production in the seedlings of both species, but that soil-nutrient supply has the potential to modify the response of young tropical trees to elevated [CO2]. In relation to plants grown in ambient [CO2], the P species grown under 760 mu mol mol(-1) [CO2] showed increases of 28% and 91% in A when grown in LN and HN, respectively. In P species grown under 570 mu mol mol(-1) [CO2], A increased by 16% under HN, but there was no effect in LN. In LS species, the enhancement of A by effect of 760 mu mol mol(-1) [CO2] was 30% and 70% in LN and HN, respectively. The exposure to 570 mu mol mol(-1) [CO2] stimulated A by 31% in HN, but was no effect in LN. Reductions in stomatal conductance (g(s)) and transpiration (E), as a result of elevated [CO2] were observed. Increasing the nutrient supply from low to high increased both the maximum rate of carboxylation (V-cmax) and maximum potential rate of electron transport (J(max)). As the level of [CO2] increased, both the V-cmax and the J(max) were found to decrease, whereas the J(max)/V-cmax ratio increased. In the LS species, the maximum efficiency of PSII (F-v/F-m) was higher in the 760 mu mol mol(-1) [CO2] treatment relative to other [CO2] treatments. The results suggest that when grown under HN and the highest [CO2], the performance of the P species C. urucurana, in terms of photosynthesis and biomass enhancement, is better than the LS species C. legalis. However, a larger biomass is allocated to roots when C. legalis seedlings were exposed to elevated [CO2]. This response would be an important strategy for plant survival and productivity of the LS species under drought stresses conditions on tropical environments in a global-change scenario. (C) 2011 Elsevier B.V. All rights reserved.

Isolation of Microsporum gypseum in soil samples from different geographical regions of Brazil, evaluation of the extracellular proteolytic enzymes activities (keratinase and elastase) and molecular sequencing of selected strains

A survey of Microsporum gypseum was conducted in soil samples in different geographical regions of Brazil. The isolation of dermatophyte from soil samples was performed by hair baiting technique and the species were identified by morphology studies. We analyzed 692 soil samples and the recuperating rate was 19.2%. The activities of keratinase and elastase were quantitatively performed in 138 samples. The sequencing of the ITS region of rDNA was performed in representatives samples. M. gypseum isolates showed significant quantitative differences in the expression of both keratinase and elastase, but no significant correlation was observed between these enzymes. The sequencing of the representative samples revealed the presence of two teleomorphic species of M. gypseum (Arthroderma gypseum and A. incurvatum). The enzymatic activities may play an important role in the pathogenicity and a probable adaptation of this fungus to the animal parasitism. Using the phenotypical and molecular analysis, the Microsporum identification and their teleomorphic states will provide a useful and reliable identification system.

Carbon flux, nutrient retention efficiency and the curvature of respiration depth-profiles in the ocean water column

Trabajo realizado por: Packard, T. T., Osma, N., Fernández Urruzola, I., Gómez, M

Summer drought reduces total and litter-derived soil CO2 effluxes in temperate grassland - clues from a 13C litter addition experiment

Current climate change models predict significant changes in rainfall patterns across Europe. To explore the effect of drought on soil CO2 efflux (FSoil) and on the contribution of litter to FSoil we used rain shelters to simulate a summer drought (May to July 2007) in an intensively managed grassland in Switzerland by reducing annual precipitation by around 30% similar to the hot and dry year 2003 in Central Europe. We added 13C-depleted as well as unlabelled grass/clover litter to quantify the litter-derived CO2 efflux (FLitter). Soil CO2 efflux and the 13C/12C isotope ratio (δ13C) of the respired CO2 after litter addition were measured during the growing season 2007. Drought significantly decreased FSoil in our litter addition experiment by 59% and FLitter by 81% during the drought period itself (May to July), indicating that drought had a stronger effect on the CO2 release from litter than on the belowground-derived CO2 efflux (FBG, i.e. soil organic matter (SOM) and root respiration). Despite large bursts in respired CO2 induced by the rewetting after prolonged drought, drought also reduced FSoil and FLitter during the entire 13C measurement period (April to October) by 26% and 37%, respectively. Overall, our findings show that drought decreased FSoil and altered its seasonality and its sources. Thus, the C balance of temperate grassland soils respond sensitively to changes in precipitation, a factor that needs to be considered in regional models predicting the impact of climate change on ecosystems C balance.