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Intensively managed forests of the Southern United States are among the most important sources of wood fiber and timber in this country. There is a great deal of concern that disturbances associated with trafficking by heavy machinery might diminish long-term soil-site productivity. However, determining the effect of harvesting disturbance and silvicultural treatments on the long-term productivity of pine plantations is difficult because, in addition to harvesting effects, growth distributions are affected by changes in climate, silviculture, and genetics. The primary objectives of this study were to determine (1) whether logging disturbances under operationally realistic circumstances affect soil quality, hydrologic function, and loblolly pine (Pinus taeda L.) productivity on wet pine flats, and (2) whether intensive forest management practices mitigate disturbance effects if they exist. Three 20-ha loblolly pine plantations located on wet pine flats in South Carolina were subjected to combinations of wet- and dry-weather harvesting and mechanical site preparations. Changes in soil-site productivity after five years were evaluated using a new rank method. The key advantage of the rank change method is that it is largely independent of the confounding factors (e.g. genetics, silvicultural practices, and climate) that affect comparisons of tree growth and soil quality between growth cycles. After five years, loblolly pine site indexes (base age 25) ranged between 13 and 33 m, and production ranged between 0.5 and 95 Mg ha-1. Soil bulk densities increased from 1.15 to as high as 1.44 g cm-3 after harvesting; by age 7 years it had decreased to approximately 1.25 g cm-3. At the sub-stand scale (0.008 ha), visually assessed soil physical and harvesting residue disturbances had little influence on relative changes in soil-site productivity after five years. Factors that specifically reflect site drainage were the most influential on changes in productivity. At the operational scale (3.3 ha), there were no differences between wet- and dry- harvested sites as long as bedding was applied as a site treatment. These results indicate that when standard site preparation is employed, fertile, wet pine flats such as these are resilient in that they recover from severe, but operationally realistic, harvesting disturbances. / Ph. D.

Soil organic matter (SOM) is a well known indicator of soil quality due to its direct influence on soil properties such as structure, soil stability, water availability, cation exchange capacity, nutrient cycling, and pH buffering and amelioration. Study sites were selected in the Valley region of Virginia with the study objectives to: i) compare the efficiency of density solutions used in recovering free-light fraction (FLF) organic matter; ii) compare different soil organic fractions as sensitive indices of short-term changes in SOM due to management practices; iii) investigate on-farm effects of tillage management on soil organic carbon (SOC) and soil organic nitrogen (SON) stocks; and iv) evaluate the role of SOM in controlling soil available nitrogen (N) for corn uptake. The efficiency of the density solutions sodium iodide (NaI) and sodium polytungstate (SPT) in recovering FLF was the same at densities of 1.6 and 1.8 g cm⁻³, with both chemicals presenting less variability at 1.8 g cm⁻³. The sensitivity of SOM fractions in response to crop and soil management depended on the variable tested with particulate organic matter (POM) being the most sensitive when only tillage was tested, and FLF being the most sensitive when crop rotation and cover crop management were added. The on-farm investigation of tillage management on stocks of SOC and total soil N (TSN) indicated significant increases at 0–15 cm depth by increasing the duration (0 to 10 years) of no-tillage (NT) management (0.59 ± 0.14 Mg C ha⁻¹ yr⁻¹ and 0.05 ± 0.02 Mg N ha⁻¹ yr⁻¹). However, duration of NT had no significant effect on SOC and TSN stocks at 0–60 cm depth. Soil available N as controlled by SOM was modeled using corn (<i>Zea mays</i> L.) plant uptake as response and several soil N fractions as explanatory variables. The final model developed for 0–30 cm depth had 6 regressors representing the different SOM pools (active, intermediate, and stable) and a 𝑅² value of 65%. In summary, this study provides information about on-farm management affects on SOM levels; measurement of such effects in the short-term; and estimation of soil available N as related to different soil organic fractions. / Ph. D.

[pt] A exploração do ecossistema pelo homem tem provocado mudanças ambientais na Terra, como liberação de gases poluentes, aumento da temperatura do planeta, desmatamento, degradação do solo, entre outros. Têm se elaborado novas técnicas que buscam melhorar a qualidade química e física do solo, a recuperação da biodiversidade e ainda contribuir para diminuir os efeitos das mudanças climáticas. O biocarvão é produzido a partir de pirólise de resíduos orgânicos, que pode ser aplicado ao solo para melhorar a qualidade, além de ser uma técnica de mitigação do efeito estufa. O objetivo desse trabalho foi avaliar o efeito da aplicação do biocarvão, produzido de Gliricidia, nos parâmetros físico e químicos do solo em Seropédica, no período de julho de 2017 a julho de 2018. O biocarvão foi incorporado ao Planossolo Háplico sob um coqueiral. O delineamento do experimento utilizado foi em blocos casualizados em esquema fatorial, sendo os fatores com e sem aplicação de biocarvão (10 t ha-1), com 12 repetições em cada tratamento. O biocarvão foi aplicado em faixa de 80 cm, na projeção da copa dos coqueiros. Foram determinados pH, P, Ca, Mg, Al, H+Al, K, Na, Cu, COT, M.O, nas profundidades 0-5, 5-10, 10-20cm, no intervalo de três meses, durante o período de um ano. A propriedade física do solo analisada foi a retenção de água nas potências 0, 60, 100, 330 e 1500 kPa. O uso do biocarvão como condicionador do solo não aumentou significativamente o pH, retenção de água e nos teores de carbono orgânico total e na CTC. Contudo nota-se que o biocarvão pode ser promissor para aumentar o carbono do solo e consequentemente mitigar o efeito estufa. / [en] Ecosystem exploration by humans has led to environmental changes on Earth, such as the release of polluting gases, rising global temperatures, deforestation, soil degradation, and so on. New techniques have been developed that seek to improve the chemical and physical quality of the soil, the recovery of biodiversity and also contribute to reduce the effects of climate change. Biocarbon is produced from pyrolysis of organic waste, which can be applied to the soil to improve the quality, besides being a greenhouse mitigation technique. The objective of this work was to evaluate the effect of biochar, produced of Gliricidia, on the physical and chemical quality of the soil in Seropédica, from July 2017 to July 2018. The biochar was incorporated to the Solonetz under a coqueiral in Seropédica. The experimental design was a randomized complete block design in a factorial scheme, with the factors with and without application of biochar (10 t ha-1), with 12 replicates in each treatment. pH, P, Ca, Mg, Al + 3, H + Al, K, Na, Cu, COT, M.O at depths 0-5, 5-10, 10-20cm were evaluated at three months intervals. The soil physical property analyzed was the water retention at powers 0, 60, 100, 330 and 1500 kPa. The use of bio-carbon as a soil conditioner increased the water retention and total organic carbon contents in the 0-5 cm depth, increasing the organic matter content. The use of biochar as a soil conditioner did not significantly increase pH, water retention and total organic carbon content and CTC. However, it is noted that biochar can be promising to increase soil carbon and consequently mitigate the greenhouse effect.

<p>Rural people around the 4 km2 Orathupalayam Dam in southern India live in one of India’s most polluted areas. The people were once restricted mainly by scarcity of water but today they cannot drink their well water or cultivate their soil. The dam, created to store floodwater from the Noyyal River, also stores effluent water from the more than 700 dyeing and bleaching industries situated in the town of Tiruppur, 20 km upstream. Although most industries have treatment plants they do not treat total dissolved solids (TDS) and thus NaCl becomes one of the major components of the effluent. 75 to 100 million litres of effluents are released every day.</p><p>Through water sampling in open and bore wells, and with the help of GPS, ArcView and Surfer it could be concluded that high TDS levels and concentrations of Cl-, Ca2+, Mg2+ and Na+ were associated with the dam. A definite spatial pattern of the spreading of polluted water could be determined. Water from the dam was fed to the ground water all around the dam and also affected the groundwater more than 4 km to the southeast. Soil samples and interviews with farmers made it clear that land irrigated with dam water or affected well water soon became uncultivable. The water destroyed the soil structure and seeds did not germinate after irrigation with polluted water.</p><p>Through interviews it could be concluded that the local people around the dam paid a large part of the externalities of the polluting activities of the textile industries in terms of negative health effects and lost agricultural land, water resources, fishing and working opportunities. These problems have mostly been caused by the high salt concentration in the effluents but it is unclear to what extent other substances have caused or might cause harmful effects to the environment, people and animals.</p>

Concerns were raised over the past decades, on the degradation condition of arid and semi-arid rangelands in South Africa, mainly in areas under communal land management. Baseline information on soil quality is essential to monitor changes in land conditions and assess impacts of land uses and management over time. The objectives of this study, initiated within the framework of the Desert Margins Program, were to characterize and establish baseline indicators of soil quality health, and to investigate the potential effects of grazing and exclusion management (hypothesized as grazing effect) on selected soil properties in the western Bophirima District in South Africa. Soils were characterized for physical, chemical, enzymatic activity and microbial biomass properties, and grazing effects were evaluated on selected properties. The aboveground herbaceous species composition and biomass production were also determined. Sandy, poor fertile soils (low organic carbon and phosphorus) characterized all sites. Various levels of enzymatic and microbial biomass were recorded at the sites. Grazing had no significant effects on most of soil chemical properties, but did affect selected enzymatic activities, site-specifically. No significant differences of grazing effects were observed on soil microbial biomass. The inconsistent responses of soil properties across the sites prompt to caution regarding the generalization and/or extrapolation of grazing effects to other areas, without consideration of the prevailing environmental and management characteristics to each site. Notwithstanding the alarming plea about degradation at these communal sites, indicators of soil quality did not significantly differ between communal and surrounding commercial and/or game managed areas, despite their apparent vegetation degradation. The results showed that rangeland under the communal management were characterized by increaser species of low grazing value, but this situation did not necessarily interpret severe soil degradation as tacitly described. Soil degradation depends on land use, management and environmental conditions, and references are needed to assess degradation. Important interrelationships between the aboveground vegetation and soil belowground activity were observed. This emphasized the need to integrate both soil and vegetation into rangeland monitoring, as these interrelationships and associated ecological processes sustain rangeland health. Further research is needed to re-examine the "inferred degradation of rangelands in communal areas, taking into consideration their history, and using appropriate baselines and references sites. Only then, can degradation trends and hotspots be identified and thereof, appropriate management decisions (through participatory research) taken locally to combat degradation and sustain long-term rangeland resources uses. / Thesis (Ph.D. (Environmental Science))--North-West University, Potchefstroom Campus, 2007.

Le sol fait face à de nombreuses pressions anthropiques qui menacent son fonctionnement et sa capacité à fournir des services essentiels au bien-être humain. Pour évaluer l’effet de ces perturbations et proposer de nouvelles voies de gestion des sols, il est nécessaire de développer des méthodes d’évaluation de la qualité des sols opérationnelles. La qualité des sols a été définie comme « la capacité des sols à fonctionner […] » (Karlen et al., 1997). Cependant, la littérature scientifique se focalise plutôt sur son état et ses propriétés que sur son fonctionnement. En effet, la qualité des sols est généralement appréhendée comme une somme de propriétés édaphiques, chimiques et biologiques qui ne tiennent pas compte des nombreuses interactions de cet écosystème. Cette étude propose un nouveau cadre conceptuel d’évaluation fonctionnelle de la qualité des sols basé sur la mesure directe des fonctions portées par les assemblages biologiques du sol. A partir de ce cadre, un nouveau set d’indicateurs, nommé Biofunctool®, a été développé. Biofunctool® permet de renseigner trois fonctions du sol (transformation du carbone, cycle des nutriments et maintenance de la structure) à partir de douze indicateurs, bords de champ et de faible technicité. Le set d’indicateurs a été appliqué dans divers sites expérimentaux en Asie du Sud Est et a permis de relever l’impact i) de la transition entre une culture annuelle et une culture pérenne, ii) de l’évolution du développement de cultures pérennes et iii) d’une couverture du sol avec légumineuses en plantation d’hévéa sur la qualité des sols. L’évaluation locale et fonctionnelle de la qualité des sols a pu ensuite être extrapolée à une échelle plus globale grâce à un modèle prédictif. Ce modèle permet de répondre à une forte attente d’intégration d’un indicateur fonctionnel de qualité des sols dans les modèles d’évaluation environnementale à une échelle globale comme l’Analyse Cycle de Vie. / Soils are currently threatened by many human activities that jeopardize soil functioning and its ability to provide ecosystem services, vital for human well-being. In order to assess human impacts and to propose new management practices to protect soils, it is necessary to implement assessments of soil quality. Soil quality was defined by Karlen et al. (1997) as “the capacity of soil to function […]”. However, in the literature, most of study focus on assessment of soil properties and intrinsic states rather than focusing on the soil functioning and the multiple interactions within the complex system. This study proposes a new integrative approach of the soil quality from direct assessment of the functions carried out by the soil biological assemblages, namely Biofunctool®. Biofunctool® allows for assessing three soil functions (carbon transformation, nutrient cycling, structure maintenance) based on twelve functional, in-field and low-tech indicators. Biofunctool® was applied over several case studies in Thailand to assess the impact of various land management on soil quality. The results pinpointed the impact of the conversion from an annual cropping system to a perennial one on soil; it also raised the evolution of soil quality over perennial tree stands and the impact of cover crop in rubber tree systems. The local assessment of soil integrative quality was then scaled up, to be integrated within the Life Cycle Assessment framework through a predictive model approach. The model developed allows to meet the current demand in defining integrative indicators of soil quality adapted to global scale environmental frameworks.