Managing soil carbon for multiple ecosystem benefits positive exemplars: Latin America (Brazil and Argentina)

Agriculture provides food, fibre and energy, which have been the foundation for the development of all societies. Soil carbon plays an important role in providing essential ecosystem services. Historically, these have been viewed in terms of plant nutrient availability only, with agricultural management being driven to obtain maximum benefits of this soil function. However, recently, agricultural systems have been envisioned to provide a more complete set of ecosystem services, in a win-win situation, in addition to the products normally associated with agriculture. The expansion and growth of agricultural production in Brazil and Argentina brought about a significant loss of soil carbon stocks, and consequently the associated ecosystem services, such as flooding and erosion control, water filtration and storage. There are several examples of soil carbon management for multiple benefits in Brazil and Argentina, with new soil management techniques attempting to reverse this trend by increasing soil carbon (C) stocks. One example is zero tillage, which has the advantage of reducing CO2 emissions from the soil and thus preserving or augmenting C stocks. Crop rotations that include cover crops have been shown to sequester significant amounts of C, both in Brazilian subtropical regions as well as in the Argentinean Pampas. Associated benefits of zero tillage and cover crop rotations include flood and erosion control and improved water filtration and storage. Another positive example is the adoption of no-burning harvest in the vast sugarcane area in Brazil, which also contributes to reduced CO2 emissions, leaving crop residues on the soil surface and thus helping the conservation of essential plant nutrients and improving water storage.

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, validation, and application of a method for the GC-MS analysis of fipronil and three of its degradation products in samples of water, soil, and sediment

A method for the identification and quantification of pesticide residues in water, soil, and sediment samples has been developed, validated, and applied for the analysis of real samples. The specificity was determined by the retention time and the confirmation and quantification of analyte ions. Linearity was demonstrated over the concentration range of 20 to 120 µg L(-1), and the correlation coefficients varied between 0.979 and 0.996, depending on the analytes. The recovery rates for all analytes in the studied matrix were between 86% and 112%. The intermediate precision and repeatability were determined at three concentration levels (40, 80, and 120 µg L(-1)), with the relative standard deviation for the intermediate precision between 1% and 5.3% and the repeatability varying between 2% and 13.4% for individual analytes. The limits of detection and quantification for fipronil, fipronil sulfide, fipronil-sulfone, and fipronil-desulfinyl were 6.2, 3.0, 6.6, and 4.0 ng L(-1) and 20.4, 9.0, 21.6, and 13.0 ng L(-1), respectively. The method developed was used in water, soil, and sediment samples containing 2.1 mg L(-1) and 1.2% and 5.3% of carbon, respectively. The recovery of pesticides in the environmental matrices varied from 88.26 to 109.63% for the lowest fortification level (40 and 100 µg kg(-1)), from 91.17 to 110.18% for the intermediate level (80 and 200 µg kg(-1)), and from 89.09 to 109.82% for the highest fortification level (120 and 300 µg kg(-1)). The relative standard deviation for the recovery of pesticides was under 15%.

Avaliação da erosão hídrica e transporte de sedimentos através do modelo hidrossedimentológico SWAT (Soil and Water Assessment Tool)

Pós-graduação em Geociências e Meio Ambiente - IGCE

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.

Soil greenhouse gas emissions and their relations to soil attributes in a sugarcane area

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

Effects in mechanical properties and structure of the soil tillage with rotary paraplow

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Variation of soil and water volumes in riparian jungle soils of Brazil

The objective of this work is to study the relation between humidity, density, porosity and shrinkage of the floodplain soil and riparian vegetation and their ability to store water. For this purpose, two locations for every type of soils were evaluated. Both were placed at the Agronomy University (Faculdade de Ciências Agronômicas) in São Manuel, State of São Paulo, Brazil. The floodplain soil was vegetated with Southern Cattail (Typha domingensis). In both places, soil samples were collected from several depths: 0, 30, 60 and 100 cm. Results show that lower soil density values (0.15 g/cm3) with organic texture and high porosities values (up to 86.2%) were found in samples with the highest organic material content in the floodplain soil. For this field experiment, flood plains soils (characterised as basin gley soils) presented high volumetric instability with a retratibility of 67.49% and higher water storage capacities compared to riparian stands soils (characterised as fluvic neosoils).

Effects in mechanical properties and structure of the soil after tillage with rotary paraplow

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Microbial biomass and soil chemical properties under different land use systems in Northeastern Pará

O aumento da produção agrícola na Amazônia brasileira tem ocorrido devido, em grande parte, à expansão da fronteira agrícola, utilizando áreas já antropizadas ou avançando sobre a vegetação primária. Ao mesmo tempo, os sistemas agrícolas, na pequena produção, continuam utilizando o fogo no preparo da área, o que leva à perda da capacidade produtiva dos solos em curto espaço de tempo, forçando a abertura de novas áreas. Este trabalho avaliou o efeito de métodos de preparo do solo e tempo de pousio que envolvem queima e trituração da vegetação, com permanência na superfície ou incorporada ao solo, com ou sem adubação mineral, em duas épocas do ano sobre os atributos químicos e biológicos do solo. O experimento foi instalado em 1995 em um Latossolo Amarelo do campo experimental da Embrapa Amazônia Oriental, no nordeste do Estado do Pará. O delineamento experimental foi em blocos casualizados, arranjados em esquema fatorial 2 x 6, sendo dois sistemas de manejo e seis tratamentos, estudados em duas épocas de coleta. Os sistemas de manejo envolveram as culturas de arroz (Oriza sativa), seguido de feijão-caupi (Vigna unguiculata) e mandioca (Manihot esculenta). Um sistema constou de dois ciclos de cultivo seguidos, deixando em pousio por três anos; e o outro, de um ciclo de cultivo, deixando em pousio por três anos. Os tratamentos foram: corte e queima da vegetação, com adubação NPK (Q+NPK); corte e queima da vegetação, sem adubação NPK (Q-NPK); corte e trituração da vegetação, deixando-a na superfície do solo, com adubação NPK (C+NPK); corte e trituração da vegetação, deixando-a na superfície do solo, sem adubação NPK (C-NPK); corte e trituração da vegetação, com incorporação e com adubação NPK (I+NPK); e corte e trituração da vegetação, com incorporação e sem adubação NPK (I-NPK). As coletas de solo foram realizadas na estação mais chuvosa (abril de 2006) e na menos chuvosa (setembro de 2006), na profundidade de 0,0-0,1 m. Em cada parcela, foram coletadas 10 amostras simples para compor uma amostra composta. O sistema de manejo mais intensivo apresentou maiores teores de C microbiano (Cmic) e N microbiano (Nmic), ao passo que o sistema menos intensivo mostrou maio teor de C orgânico. Os tratamentos que apresentaram maior teor de Cmic e Nmic foram aqueles em que houve corte, trituração e deposição da biomassa na superfície do solo. Os atributos químicos nos dois sistemas de manejo encontram-se em faixas que enquadram os solos como de baixa fertilidade; no entanto, P e K (no período chuvoso) foram mais elevados no sistema de manejo menos intensivo.

Spatial and Temporal Variation of Archaeal, Bacterial and Fungal Communities in Agricultural Soils

Background: Soil microbial communities are in constant change at many different temporal and spatial scales. However, the importance of these changes to the turnover of the soil microbial communities has been rarely studied simultaneously in space and time. Methodology/Principal Findings: In this study, we explored the temporal and spatial responses of soil bacterial, archaeal and fungal beta-diversities to abiotic parameters. Taking into account data from a 3-year sampling period, we analyzed the abundances and community structures of Archaea, Bacteria and Fungi along with key soil chemical parameters. We questioned how these abiotic variables influence the turnover of bacterial, archaeal and fungal communities and how they impact the long-term patterns of changes of the aforementioned soil communities. Interestingly, we found that the bacterial and fungal b-diversities are quite stable over time, whereas archaeal diversity showed significantly higher fluctuations. These fluctuations were reflected in temporal turnover caused by soil management through addition of N-fertilizers. Conclusions: Our study showed that management practices applied to agricultural soils might not significantly affect the bacterial and fungal communities, but cause slow and long-term changes in the abundance and structure of the archaeal community. Moreover, the results suggest that, to different extents, abiotic and biotic factors determine the community assembly of archaeal, bacterial and fungal communities.

EROSION LOSSES FROM RUNOFF: INTERACTION OF SOIL COVER AND EROSION CONTROL PRACTICE

The flow of sediment from cropped land is the main pollutant of water sources in rural areas. Due to this fact, it is necessary to develop and implement technologies that will reduce water and sediment discharges. Accordingly, an experiment was conducted in the Department of Biosystems Engineering - ESALQ / USP, Piracicaba - SP with the objective to evaluate the effect of different soil cover (bean, grass and bare ground) and erosion control practices (wide base terraces and infiltration furrows in slopes (no practices to control erosion)) while measuring water losses in runoff. The statistical design adopted was randomized blocks in a 3x3 factorial scheme resulting in 9 treatments with 3 replicates (blocks). The period of rainfall data collection was December 6, 2007 to April 11, 2008. A 21.1 cm diameter rain gauge was installed in the experimental area. Terraces were the most efficient practices for reducing erosion losses in the treatments with infiltration furrows being better than the control treatment. Bean was more effective than grass in reducing erosion. Bare ground was the least efficient.

Methane emission from soil under long-term no-till cropping systems

Methane (CH4) emission from agricultural soils increases dramatically as a result of deleterious effect of soil disturbance and nitrogen fertilization on methanotrophic organisms; however, few studies have attempted to evaluate the potential of long-term conservation management systems to mitigate CH4 emissions in tropical and subtropical soils. This study aimed to evaluate the long-term effect (>19 years) of no-till grass- and legume-based cropping systems on annual soil CH4 fluxes in a formerly degraded Acrisol in Southern Brazil. Air sampling was carried out using static chambers and CH4 analysis by gas chromatography. Analysis of historical data set of the experiment evidenced a remarkable effect of high C- and N-input cropping systems on the improvement of biological, chemical, and physical characteristics of this no-tilled soil. Soil CH4 fluxes, which represent a net balance between consumption (-) and production (+) of CH4 in soil, varied from -40 +/- 2 to +62 +/- 78 mu g C m(-2) h(-1). Mean weighted contents of ammonium (NH4+-N) and dissolved organic carbon (DOC) in soil had a positive relationship with accumulated soil CH4 fluxes in the post-management period (r(2) = 0.95, p = 0.05), suggesting an additive effect of these nutrients in suppressing CH4 oxidation and stimulating methanogenesis, respectively, in legume-based cropping systems with high biomass input. Annual CH4 fluxes ranged from -50 +/- 610 to +994 +/- 105 g C ha(-1), which were inversely related to annual biomass-C input (r(2) = 0.99, p = 0.003), with the exception of the cropping system containing pigeon pea, a summer legume that had the highest biologically fixed N input (>300 kg ha(-1) yr(-1)). Our results evidenced a small effect of conservation management systems on decreasing CH4 emissions from soil, despite their significant effect restoring soil quality. We hypothesized that soil CH4 uptake strength has been off-set by an injurious effect of biologically fixed N in legume-based cropping systems on soil methanotrophic microbiota, and by the methanogenesis increase as a result of the O-2 depletion in niches of high biological activity in the surface layer of the no-tillage soil. (C) 2012 Elsevier B.V. All rights reserved.

NATURAL REGENERATION IN ABANDONED FIELDS FOLLOWING INTENSIVE AGRICULTURAL LAND USE IN AN ATLANTIC FOREST ISLAND, BRAZIL

The time required to regrowth a forest in degraded areas depends on how the forest is removed and on the type of land use following removal. Natural regeneration was studied in abandoned old fields after intensive agricultural land use in areas originally covered by Brazilian Atlantic Forests of the Anchieta Island, Brazil in order to understand how plant communities reassemble following human disturbances as well as to determine suitable strategies of forest restoration. The fields were classified into three vegetation types according to the dominant plant species in: 1) Miconia albicans (Sw.) Triana (Melastomataceae) fields, 2) Dicranopteris flexuosa (Schrader) Underw. (Gleicheniaceae) thickets, and 3) Gleichenella pectinata (Willd.) Ching. (Gleicheniaceae) thickets. Both composition and structure of natural regeneration were compared among the three dominant vegetation types by establishing randomly three plots of 1 x 3 m in five sites of the island. A gradient in composition and abundance of species in natural regeneration could be observed along vegetation types from Dicranopteris fern thickets to Miconia fields. The gradient did not accurately follow the pattern of spatial distribution of the three dominant vegetation types in the island regarding their proximity of the remnant forests. A complex association of biotic and abiotic factors seems to be affecting the seedling recruitment and establishment in the study plots. The lowest plant regeneration found in Dicranopteris and Gleichenella thickets suggests that the ferns inhibit the recruitment of woody and herbaceous species. Otherwise, we could not distinguish different patterns of tree regeneration among the three vegetation types. Our results showed that forest recovery following severe anthropogenic disturbances is not direct, predictable or even achievable on its own. Appropriated actions and methods such as fern removal, planting ground covers, and enrichment planting with tree species were suggested in order to restore the natural forest regeneration process in the abandoned old fields.

Parasitological risk assessment from wastewater reuse for disposal in soil in developing countries

The purpose of this work is to analyze the parasitological risks of treated wastewater reuse from a stabilization pond in the city of Piracicaba, in the State of Sao Paulo (Brazil), and the level of treatment required to protect public health. Samples were taken from raw and treated wastewater in stabilization ponds and submitted to a parasitological, microbiological and physicochemical analysis. The study revealed on treated wastewater the presence of Ascaris sp. and Entamoeba coli with an average density of 1 cysts L-1 and 6 eggs L-1, respectively. For Ascaris, the annual risks of infection due to the accidental ingestion of wastewater irrigation were 7.5 x 10(-2) in 208 days and 8.7 x 10(-2) in 240 days. For Total Coliforms and Escherichia coli in treated wastewater, the average density was 1.0 x 10(5) MPN/100 ml and 2.7 x 10(4) MPN/100 ml respectively, representing 99% and 94% removal efficiency, respectively. For BOD, COD, TS and TSS removal efficiency was 69, 80, 50 and 71%, respectively. The removal efficiency for nitrogen; ammonia nitrogen and total phosphate was 24, 19 and 68%, respectively. The average density of helminths eggs in treated wastewater is higher compared to the density of the limit value of <= 1 egg L-1 and tolerable risk is above the level recommended by the World Health Organization. Multiple barriers are necessary for the reduction of organic matter, chemical contaminants and parasites from treated wastewater. Standards for the sanitary control of treated wastewater to be reused in agricultural irrigation areas should be compiled for developing countries in order to minimize public health risks.