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Recent studies show that a labile soil carbon (C) fraction determined with potassium permanganate (KMn[O.sub.4]) reflects the type of soil management. The present study combines the method for determining the active C (AC) pool with an alternative titration of the 0.02 m KMn[O.sub.4] solution with sodium oxalate ([Na.sub.2][C.sub.2]4) for routine laboratory analyses. Three long-term field experiments investigated: (i) different cropping systems and [sup.14]C-labelled organic amendments, (if) three different tillage systems, and (iii) the application of four different kinds of compost. The results showed the depletion of AC in the permanent bare-fallow system of the [sup.14]C-labelled field experiment. When calculating the ratio AC/total organic C (TOC), the depletion of the AC/TOC curve reflected a priming effect, in accord with previous work. We obtained significant positive correlations of AC with TOC, total nitrogen ([N.sub.t]), humic acid-C and remaining [sup.14]C-labelled material. The AC in the tillage systems experiment was significantly (Pc 0.05) different between all three tillage treatments at 0-10 cm depth, and the ratio AC/TOC also revealed a significant difference between minimum and conventional tillage treatments at 10-20 cm. For the compost field experiment, significant differences occurred between plots fertilised solely with N and plots receiving organic amendments. The AC/TOC ratio of the sewage sludge amendment was significantly lower than in all other systems. Correlations of AC with TOC for all samples of the different long-term field experiments revealed different behaviours in different soil types. The correlations of AC with [N.sub.t] showed higher coefficients than with TOC. The applied methodology has a potential for sensitive and reliable detections of differences in soil organic matter characteristics. Additional keywords: [sup.14]C label, compost, cropping systems, SOM, tillage systems, titration., Introduction Global storage of soil organic carbon (SOC) is estimated to be 1502 Pg C in the first metre of soil (Jobbagy and Jackson 2000), including active and more stable [...]

Some topsoil physical properties evolve unfavourably under continuous, no-till fanning. On the Pampa, loam soils under no-till sometimes have lower infiltration rates than those conventionally tilled; this is due to the occurrence of platy and massive structures. In this study, we aimed to identify the soil management practices that promote platy structure formation, and explain the soil physical behaviour linked to the thickness of platy structures in relation to infiltration rate, bulk density and shear strength. Six fields with different numbers of years under agriculture and diverse previous crops (maize or wheat-soybean double crop) were sampled, distinguishing within each field headlands (areas with higher traffic) and centre (lower traffic). Twenty samples were taken at random along a 200-m transect to characterise soil structure (platy, granular or massive) and the thickness of the platy structure. Principal component analysis revealed linkages between previous crop and location in each field and type of structure. ANOVA showed a significant (Pc 0.05) interaction of previous crop x location. The frequency and thickness of the platy structures were lower, and those of granular structures higher, under wheat--soybean double cropping and in the centre of the field. Greater thickness of the platy structure determined lower water infiltration rate (r=-0.337; P Additional keywords: infiltration rate, machinery traffic, no-till, shear strength, structural types., Introduction Physical properties are an important part of the evaluation of soil quality and health (Hussain et al. 1999). Soil structure is generally characterised by form, stability and resilience. Structural [...]

The large amounts of carbon (C) and nitrogen (N) sequestered as organic matter in soils have implications for global and national C and N balances and greenhouse gas emissions. Changes in soil management can affect the amount of C and N stored in soil. We investigated the change in land use from radiata pine plantation to ryegrass--white clover dairy pasture on the total C and N content of Taupo Pumice Soil. Samples were taken at three study sites (Atiamuri, Tokoroa and Wairakei) in North Island, New Zealand. Soils were cored to 60 cm depth and subsampled by soil horizon, and bulk density cores were taken from soil pits. A chronosequence of sites was obtained after conversion from pines to pasture. Long- term pastures (40-80 years) and mature pine plantations were included for further comparison. Regression analyses were completed after logarithmic transformation of the time data. The data were highly variable, but significant (P Additional keywords: deforestation, land use change, pasture chronosequence, soil carbon, soil N, soil storage., Introduction There is increased interest in the amounts of carbon (C) and nitrogen (N) stored in soils, not only because of the benefits of organic matter on soil nutrient dynamics [...]

Reduced carbon stock levels in Australian soil due to cropping provide a significant opportunity for carbon sequestration, and the recent initiative to consider soil carbon in domestic emissions trading requires a scientific assessment of soil carbon levels under a range of cropping soil management practices. Some of the previous research in southern and western New South Wales (NSW) showed that the rate of carbon decline in cropping soils is slowed under minimum tillage when the stubble is also retained. However, such comparison is rare in the NSW North-West Slopes and Plains region, particularly on the red soils (Chromosols) which are one of the major soil types in the region. We surveyed 50 dryland Chromosols, 72 dryland Vertosols, and 25 irrigated Vertosols on commercial farms across this region to examine the effects of conventional tillage, minimum tillage, and irrigation on total soil organic carbon. Samples of 0.1 m segments to 0.3 m depth were analysed for total organic carbon and other soil properties. Mid-infrared scans were used to predict the particulate, humus, and resistant soil organic carbon fractions. Bulk density was used to calculate total organic carbon stock for each segment, and equivalent soil mass (ESM) for 0-0.3 m. In Vertosols, for 0-0.3 m ESM, total organic carbon and particulate organic carbon were not different between management practices, whereas humic organic carbon and resistant organic carbon were consistently lower under conventional tillage. However, in 0-0.1 m, total organic carbon was greater under minimum tillage (15.2 Mg [ha.sup.-1]) than conventional tillage (11.9Mg [ha.sup.-1]) or irrigation (12.0Mg [ha.sup.- 1]), reflecting less soil surface disturbance under minimum tillage. In Chromosols, only total organic carbon was higher under minimum tillage than conventional tillage in the 0-0.3 m ESM (39.8 v. 33.5 Mg [ha.sup.-1]) and in 0-0.1 m (19.7 v. 16.9 Mg [ha.sup.-1]). The strong influences of rainfall, temperature, bulk density, texture, and management history on soil carbon stocks suggested that these environmental and management factors require further consideration when gauging soil carbon sequestration potential under current and novel tillage practices in key regional locations. Additional keywords: carbon accounting, conservation tillage, soil carbon sequestration., Received 25 January 2013, accepted 4 June 2013, published online 20 December 2013 Introduction Soil is a significant global carbon (C) reservoir (Lal 2004). Because C is the main constituent [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2008.01.007 Byline: Paola Gatto (a), Alessia Zocca (b), Andrea Battisti (b), Maria Joao Barrento (c), Manuela Branco (d), Maria Rosa Paiva (c) Abstract: This paper assesses the private and social profitability of current strategies for managing processionary moth (Thaumetopoea pityocampa) in Portuguese pine forests, looking at economic and environmental costs and benefits. Costs include the expenses for forest treatment and the social costs of threats to human health (dermatitis amongst others); benefits are assessed in terms of both revenue and social benefits such as carbon fixation and recreation. The evaluation was done using Cost Benefit Analysis (CBA) as an analytical framework. While this tool is currently applied to forest and environmental assessment and specific applications to pest management strategies are to be found in agricultural economics, rather few attempts have been made in the field of forest pest management. In order to assess and compare with-without options, a case-study was analysed for the Setubal Peninsula, south of Lisbon, an area where extensive stands of maritime pine (Pinus pinaster) grow. The exercise has shown that CBA can be a valuable tool for assessing the economic and social profitability of pest management. The results demonstrate that the loss of revenues in the no-management option is not sufficient to make pest management profitable for private forest owners in the short-term. Conversely, a social profit is gained as pest management minimizes health risks for humans and avoids possible recreational losses. Author Affiliation: (a) Department of Land and Agro-Forestry Systems, University of Padova, Agripolis, Viale dell'Universita, 16, 35020 Legnaro, PD, Italy (b) Department of Environmental Agronomy - Entomology, University of Padova, Agripolis, Viale dell'Universita, 16, 35020 Legnaro, PD, Italy (c) Department of Environmental Sciences and Engineering, FCT, New University of Lisbon, Portugal (d) Department of Forest Engineering, ISA, Technical University of Lisbon, Portugal Article History: Received 17 December 2005; Revised 13 September 2007; Accepted 3 January 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2006.04.019 Byline: David A. Lobb (a), Edward Huffman (b), Donald C. Reicosky (c) Keywords: Tillage; Soil management; Environmental indicators; Soil erosion; Tillage erosion; Crop residue cover Abstract: Tillage has been and will always be integral to crop production. Tillage can result in the degradation of soil, water, and air quality. Of all farm management practices, tillage may have the greatest impact on the environment. A wide variety of tillage equipment, practices and systems are available to farmers, providing opportunities to enhance environmental performance. These opportunities have made tillage a popular focus of environmental policies and programs such as environmental indicators for agriculture. This paper provides a very brief examination of the role of tillage in crop production, its effect on biophysical processes and, therefore, its impact on the environment. Models of biophysical processes are briefly examined to demonstrate the importance of tillage relative to other farm management practices and to demonstrate the detail of tillage data that these models can demand. The focus of this paper is an examination of the use of information on tillage in Canada's agri-environmental indicators initiative, National Agri-environmental Health Analysis and Reporting Program (NAHARP). Information on tillage is required for several of the indicators in NAHARP. The type of data used, its source, and its quality are discussed. Recommendations regarding the collection of tillage data and use of tillage information are presented. Author Affiliation: (a) Soil Science, University of Manitoba, Winnipeg, Canada (b) Research Branch, Agriculture and Agri-Food Canada, Ottawa, Canada (c) Agricultural Research Service, United States Department of Agriculture, Morris, MN, USA Article History: Received 30 October 2004; Revised 21 April 2006; Accepted 27 April 2006