Soil Bulk Density

RESUMO -A resistência mecânica do solo à penetração pode limitar o crescimento e o desenvolvimento do sistema radicular e diminuir a produtividade das culturas. Os sistemas de manejo do solo apresentam grande influência nas características físicas do solo e estão relacionados com a compactação que é um processo de densificação na qual há um aumento da resistência do solo, reduzindo sua porosidade, permeabilidade bem como a disponibilidade de nutrientes e água. O objetivo deste trabalho foi avaliar os parâmetros físicos de um solo de textura argilosa em dois sistemas de cultivo, o plantio direto e convencional, após feijão irrigado, em Botucatu-SP. Utilizou-se uma unidade móvel -UMAS, com penetrômetro hidráulico-eletrônico para determinação da resistência mecânica à penetração do solo. As amostras foram coletadas na profundidade de 0 a 0,5 m, para determinar à resistência à penetração. E na profundidade de 0 a 0,4 m verificou-se a densidade do solo. Os resultados da resistência mecânica do solo à penetração foram significativos entre os sistemas de plantios e nas camadas estratificadas a cada 0,1 m respectivamente. A densidade do solo foi significativa entre os sistemas de plantios e nas profundidades 0 a 0,2 e de 0,2 a 0,4 m. Nas áreas após o cultivo do feijão irrigado a resistência do solo á penetração, apresentam valores acima de 2,0 MPa, na profundidade de 0 a 0,3 m. PALAVRAS-CHAVE: física do solo, compactação, penetrometros.

Chilopoda and Diplopoda, were studied in two areas located in north-eastern Algeria (anthropized site of Annaba and natural site of El Tarf). Pitfall traps were used to collect individuals during one year (June 2006 to May 2007). In total, 901 Chilopoda and 411 Diplopoda were collected. Spatio- temporal diversities were evaluated for the two taxa. Our results suggest that the soil physico-chemical edaphic parameters such as the quantity of alluvium, the proportion of organic matter or the pH but also climatic parameters such as the amount of precipitation and the relative humidity of air have a significant influence on the abundance and spatial distribution of Chilopoda and Diplopoda with a clear difference of behaviour between the two taxa. The estimation of the intensity of perturbation due to human activities influencing the ecological diversity of the two taxonomic groups studied indicated that Annaba area, which is more anthropized than that of El Tarf, loosed in terms of Chilo...

Lowland sawah is viewed as a sustainable alternative to traditional rice culture in West Africa. Sawah (a bund-demarcated, puddled, leveled, and water-regulated rice field) has received growing research attention lately, but no data exist yet on the system's long-term agronomic impact. In a clayey inland-valley soil in southern Ghana, 10-year-old sawah plots (OSP), fresh sawah plots (FSP), and non-sawah plots (NSP) were maintained under both ponded and nonponded conditions in 2007. The OSP enhanced soil status of exchangeable nutrients compared to NSP. There were relative improvements in soil bulk density, total porosity, and field moisture content (OSP ≥ FSP > NSP), with clear benefits of ponding over non-ponding in OSP. The NSP was so unsustainable that it showed less favourable values of these variables than an adjacent fallowed plot. These soil variables deteriorated with time, with significant differences in FSP. Soil moisture retention data for tension range of 0-300 kPa depicted the importance of puddling and ponding. During 2001-2009, OSP consistently out-yielded NSP by five times on average. During 2007-2009 when all three plots co-existed, grain yields averaged 5.80, 4.80 and 1.10 Mg ha -1 in OSP, FSP and NSP, respectively. In 2007 yields, OSP minus FSP was higher than NSP; in 2008/2009, the opposite prevailed. These results highlight the agronomic benefits of continuous sawah-based rice production. Although the positive effects of puddling on the soil hydrophysical properties were largely responsible for the wide margin in yield between sawah and traditional systems, other yield-enhancing factors, particularly bunds for water control, were also lacking in the latter.

This paper analyses the relationship between presidential power and military influence in Pakistan during the presidency of Farooq Ahmad Khan Leghari (1993-1997). Leghari's time in office saw the enforcement of the 8th Amendment, which empowered the president to dissolve the National Assembly and to appoint the service chiefs. This made him an important player in civil-military relations. This research uses Rebecca Schiff's Concordance Theory and Morris Janowitz's Convergence Theory to find out how far Leghari tried to strike a balance between civilian and military interests. His choice of General Jahangir Karamat as COAS, the establishment of the Council for Defence and National Security (CDNS), and the sacking of Benazir Bhutto's government suggest not only attempts at institutional concordance but also partial convergence of civilian and military roles. However, with the passage of the 13 th Amendment and intensified conflict with Prime Minister Nawaz Sharif, a political deadlock arose. The military leadership offered mediation to defuse the situation, but Laghari opted to resign in December 1997. According to the article, Leghari's presidency was a transitional phase between presidential dominance and parliamentary supremacy in Pakistan's evolving civilmilitary relations.

Soil acidity, a significant form of chemical soil degradation, is one of the most pressing challenges in Ethiopia, particularly in the highlands. It severely impacts agricultural productivity across much of the country. Owing to its impact on crop production and productivity, it is a critical issue that requires immediate attention in most highlands in Ethiopia. This study was conducted at the Lalistu Cheri watershed, which is located in the Sibu Sire District of the western zone of the Oromia region, Ethiopia, with the objective of characterizing and assessing the soil acidity status under different land use types and soil depths. Replicated composite soil samples were collected from three representative land use types (cultivated, grazing, and eucalyptus plantation lands) and two soil depths (0-20 and 20-40 cm) by X-patterns along transects and analyzed via standard laboratory procedures. The results revealed spatial variation in the soil properties among the land use types and soil depths. The soils in both cultivated and eucalyptus plantation land were strongly acidic (pH<5.5), whereas those in grazing land were moderately acidic. The highest (54.89%) and lowest (43.73%) clay contents were recorded in the soils of cultivated and grazed lands, respectively, whereas the sand content was greater (36.11%) in the eucalyptus plantation land. The relatively highest bulk density (1.36 g cm-3) was recorded in the grazed land soils, followed by the cultivated land soils (1.32 g cm-3). Both the exchangeable acidity and aluminum content in all land use types decreased with increasing soil depth, which was consistent with their acid saturations. The organic carbon content ranged from 2.30% at the subsurface layer of the cultivated land to 3.44% at the surface layer of the grazing land soils, whereas the total nitrogen content ranged from 0.19% to 0.30%. Available P ranged from 7.31 mg kg-1 to 12.61 mg kg-1. The highest Ca, Mg, Na, and K contents (8.92, 5.76, 0.30, and 1.26 Cmol (+) kg-1 , respectively) were recorded in the soils of the grazing land. The amount of PBS used ranged from 35.14% to 78.45%. The CEC and ECEC of the soils in the three land use types also increased consistently with increasing soil depth. Micronutrient concentrations decreased with soil depth. The Fe and Mn contents ranged from 0.54 and 4.42 mg kg-1 in the subsurface layer of the grazing land and eucalyptus plantations, respectively, to 10.58 and 12.14 mg kg-1 in the surface layer of the eucalyptus plantations and grazing land soils, respectively. Cu and Zn also ranged from 1.52 and 0.29 mg kg-1 to 3.16 and 0.85 mg kg-1 , respectively. The study suggests that both CL and EPL soils exhibit the highest acidity and require soil management practices, such as lime application, to reduce acidity and improve soil fertility. On the other hand, GL soils show more favorable conditions for nutrient retention and pH.

Абстракт. Представят се резултати за коефициента на филтрация Кsat на 9 почвени слоя, получени чрез използване на статистически функции за трансформиране на почвени данни и резултати за Кsat от полеви инфилтрационни тестове за същите разновидности. Отчита се съвпадане и съпоставимост на получените по двата метода стойности, което дава възможност за валидиране на модели на миграцията на арсена на по-голяма територия.

O objetivo deste trabalho foi avaliar se a aplicação anual de lodo de esgoto e vinhaça, resíduos empregados com a finalidade exclusiva de fornecer a quantidade necessária de N e K para cana-de-açúcar, causaria alteração em alguns atributos físicos de um Latossolo Vermelho distroférrico argiloso, após as colheitas do 3º e 4º cortes da cultura. O experimento foi conduzido em blocos ao acaso, com três repetições. Os tratamentos foram: (i) dose de lodo de esgoto para suprir 100% do N exigido pela cultura; (ii) dose de lodo de esgoto para suprir 200% do N exigido; (iii) dose de vinhaça para suprir 100% do K exigido; (iv) dose de vinhaça para suprir 200% do K exigido; (v) combinação dos tratamentos (i) e (iii); (vi) combinação dos tratamentos (ii) e (iv); (vii) testemunha (adubação mineral recomendada). Os somatórios das doses dos resíduos foram de 39 e 51 t ha-1 de lodo de esgoto e de 870 e 1.174 m³ ha-1 de vinhaça até o 3º e 4º cortes, respectivamente. Nas camadas de 0-10; 10-20; 20-30;...

Mechanized forest harvest operations induce changes in soil physical properties, which have the potefitial to impzct soil sustai~ability and forest productivity. The assessment of soil compaction and its spatial variability has been determined previously through the identification and tabulation of visual soil disturbance classes and soil physical changes associated with each disturbailce class. This is a time consuming and inaccurate process. The utilization of the GPS provided a means to monitor harvest traffic and transform that information into a detailed map of trafficking. Knowledge of the number of passes (intensity) and their location within the harvest landscape permitted the measurement of soil physical changes in response to the number of machine passes and their spatial structure. Soil bulk density and cone index increased in response to trafficking but the peak values achieved by each varied by sampling time. Soil samples collected immediately after harvest indicated slight response to trafficking but soil samples collected within one year of harvest indicated a greater response, especially in cone index. This was presumably due to differences in soil moisture content at the time of sampling. Spatial structure was evident ifi the portion of the harvest tract which had less soil moisture. Regardless of temporal differences, bulk density exhibited directional dependence while cone index was isotropic.

A study was installed in the Lower Coastal Plain near Washington, North Carolina, to test the hypothesis that incorporating organic matter in the form ofcomminuted forest slash would increase soil carbon and nutrient pools and alter soil physical properties to favour pine growth. Two sites were selected, an organic and a mineral site, to compare the treatment effects on the different soil types. The mulching treatments included a surface broadcast mulch, a surface strip mulch, and a strip mulch and till. On the mineral site, the three treatments resulted in general decreases in soil bulk density, gravimetric soil water content, and soil strength. Soil carbon and nitrogen increased for all the treatments on the mineral site, with some significant differences between the treatments. The broadcast mulch and bed treatment resulted in an almost 100% increase in soil carbon and nitrogen. On the organic site, the treatments did not have a significant effect on soil physical properties or soil carbon and nitrogen. There was a consistent decrease in soil carbon and nitrogen on this site but these changes were not significantly different from those in the control treatment.

A study was installed in an upland hardwood forest to evaluate the site impacts associated with three alternative prescriptions -clearcut, deferment cut, and strip cut. Two methods of site impact assessment were employed: 1) assignment of disturbance classes to selected points within each treatment area and 2) measurement of soil bulk density, gravimetric water content, and soil strength at points previously evaluated for soil disturbance class. Clearcut and deferment cut treatments produced the greatest impacts as evidenced by higher percentage of slightly and highly disturbed areas and increases in bulk density and soil strength. Strip cut KeWtrr$ments had less impact on a stand wide basis but cut strips experienced similar impacts. Hardwood, clearcut, deferment cut, strip cut, soil strength, bulk density, disturbance class. The author(s) is solely responsible for the content of this technical presentation. The technical presentation does not necessarilv reflect the official position of ASAE, and its printing and distribution does not constitute an endorsement of views which may be expres&d T~hnical presentations arc not subject to the formal peer review process by ASAE editorial committcrs; therefore, they are not to lx presented as refcre& publications Quotation from thus work should state that II IS irom a prcsentauon made by (name of author) at the (listed) ASAE mcetmg.

A study was initiated in the Winter of 1998 to examine the utility of employing Global Positioning Systems (GPS) to monitor harvest traffic throughout a loblolly pine plantation and utilize traffic intensity information to assess impacts of select soil physical properties. Traffic maps prepared from GPS positional data indicated the highest concentration of traffic intensities occurred in the landings and skid trails (11 or more) while approximately 94 percent of the site was subjected to 10 or less passes. Estimates of bulk density and gravimetric water content did not approach levels in any traffic intensity class considered to be restrictive to root penetration for either surface or subsurface layers. Soil strength levels for each traffic intensity dass in the surface layer did not indicate the presence of an impenetrable layer but subsoil modification may be necessary to provide a proper environment for regeneration.

A study was installed in an upland hardwood forest to evaluate the site impacts associated with three alternative prescriptions - clearcut, deferment cut, and strip cut. Two methods of site impact assessment were employed: 1) assignment of disturbance classes to selected points within each treatment area and 2) measurement of soil bulk density, gravimetric water content, and soil strength at points previously evaluated for soil disturbance class. Clearcut and deferment cut treatments produced the greatest impacts as evidenced by higher percentage of slightly and highly disturbed areas and increases in bulk density and soil strength. Strip cut KeWtrr$ments had less impact on a stand wide basis but cut strips experienced similar impacts.

Mechanized forest harvest operations induce changes in soil physical properties, which have the potefitial to impzct soil sustai~ability and forest productivity. The assessment of soil compaction and its spatial variability has been determined previously through the identification and tabulation of visual soil disturbance classes and soil physical changes associated with each disturbailce class. This is a time consuming and inaccurate process. The utilization of the GPS provided a means to monitor harvest traffic and transform that information into a detailed map of trafficking. Knowledge of the number of passes (intensity) and their location within the harvest landscape permitted the measurement of soil physical changes in response to the number of machine passes and their spatial structure. Soil bulk density and cone index increased in response to trafficking but the peak values achieved by each varied by sampling time. Soil samples collected immediately after harvest indicated sl...

No-till (NT) management has been a successful soil management practice for many decades due to its ability to increase sustainable agricultural production practices through reduced soil erosion. Utilizing this NT conservation practice helps enhance the sustainability of crop production systems. No-till management practices can also improve soil water storage, which optimizes the use of this critical water resource for plant production. No-till management has been found to improve soil organic carbon, soil water retention, plant available water capacity, soil hydraulic conductivity, and water infiltration in soils, resulting in major improvements with water use efficiency. These improvements in soil properties and processes can translate into a more efficient system for sustainable food, fiber and biofuel production for future generations. Conserving and efficiently utilizing soil and water resources is critical for sustaining the world's current growing population. Minimizing soil erosion has been one of the main reasons to utilize NT conservation management systems. No-till systems allow the soil to remain undisturbed, reducing soil detachment and transport, two of the principal mechanisms of erosion . Efforts over the past 50 years in applying NT have been instrumental in reducing soil erosion and improving the long-term sustainability of agricultural management systems (Islam and Reeder 2014). Since NT management systems have been found to reduce runoff

Sweetgum (Liquidambar styraciflua L.) and fescue (Festuca arundinocea Schreb.) were planted after subsolling and sludge applications to depths of 0, 0. 64, 1.27, and 2.54 em to reclaim a borrow pit In the Lower Piedmont of South Carolina. Sludge treatments in combination with subsoiling significantly improved establishment of fescue and growth of sweetgum, but all combinations of fescue with sludge significantly reduced first-year survival of sweetgum. Because survival was stabilized after the first growing season, allelopathy of fescue to sweetgum had little effect in this study . Fifth-year total height growth (0. 74 m) of sweetgum on the nonamended plots was rated not acceptable, but on plots amended at even the lowest rate of sludge, height growth (2.75 m) was acceptable. Total heights (ca 3.6 m) after 5 years on plots amended at the two highest sludge rates were equal to or greater than 5-year heights reported for sweetgum on reforestation sites . The increase in total nitrogen available on the site after 5 years exceeded the amount initially present in the sludge, which suggests either a significant atmospheric contribution or that organic matter enhanced nitrogen fixation.

Biochar additions to soils can improve soil-water storage capability; however, there is sparse information identifying feedstocks and pyrolysis conditions that maximize this improvement. Nine biochars were pyrolyzed from five feedstocks at two temperatures, and their physical and chemical properties were characterized. Biochars were mixed at 2% wt wt j1 into a Norfolk loamy sand (Fine-loamy, kaolinitic, thermic Typic Kandiudult), a Declo silt loam (Coarse-loamy, mixed, superactive, mesic xeric Haplocalcid), or a Warden silt loam (Coarse-silty, mixed, superactive, mesic xeric Haplocambid). Untreated soils served as controls. Soils were laboratory incubated in pots for 127 days and were leached about every 30 days with deionized water. Soil bulk densities were measured before each leaching event. For 6 days thereafter, pot-holding capacities (PHC) for water were determined gravimetrically and were used as a surrogate for soil-moisture contents. Water tension curves were also measured on the biochar-treated and untreated Norfolk soil. Biochar surface area, surface tension, ash, C, and Si contents, in general, increased when produced under higher pyrolytic temperatures (Q500-C). Both switchgrass biochars caused the most significant water PHC improvements in the Norfolk, Declo, and Warden soils compared with the controls. Norfolk soil-water tension results at 5 and 60 kPa corroborated that biochar from switchgrass caused the most significant moisture storage improvements. Significant correlation occurred between the PHC for water with soil bulk densities. In general, biochar amendments enhanced the moisture storage capacity of Ultisols and Aridisols, but the effect varied with feedstock selection and pyrolysis temperature.

Effects of harrowing and fertilisation on tree growth, understory vegetation, forest floor litter and soil properties were studied in a field experiment installed in a 5-year-old first rotation eucalypt plantation. The treatments were harrowing (H), fertilisation (F), harrowing and fertilisation (HF) and a control without any treatments (C), with four replicates. Tree growth, root mass, tree nutrition status, understory vegetation, mass of forest floor litter and soil physical and chemical properties were monitored till the end of the rotation (stand was 14-year old). Effects of treatments on tree growth, root mass and timber production were not significant. Root nutrient concentration differed between treatments only few months after the beginning of the experiment, while differences regarding specific root length and area were observed during the first year. Harrowing (H and HF) led to significantly smaller biomass of understory vegetation (\13.4 g m -2 ) than other treatments (33-61 g m -2 ) during the first 3 years, but at the end of the experiment differences were less important. Forest floor litter mass after 3 years and at the end of the experiment were similar among treatments. Soil bulk density significantly decreased by harrowing (H and HF treatments), but 16 months after treatments were similar. Although soil chemical properties were not significantly affected by treatments, a decrease in base cations occurred during the rotation period. Fertiliser application is a questionable practice under the economic point of view, whereas harrowing can reduce the fuel load only during a short period, without negative effects on productivity and soil quality.

Soil acidity, a significant form of chemical soil degradation, is one of the most pressing challenges in Ethiopia, particularly in the highlands. It severely impacts agricultural productivity across much of the country. Owing to its impact on crop production and productivity, it is a critical issue that requires immediate attention in most highlands in Ethiopia. This study was conducted at the Lalistu Cheri watershed, which is located in the Sibu Sire District of the western zone of the Oromia region, Ethiopia, with the objective of characterizing and assessing the soil acidity status under different land use types and soil depths. Replicated composite soil samples were collected from three representative land use types (cultivated, grazing, and eucalyptus plantation lands) and two soil depths (0-20 and 20-40 cm) by X-patterns along transects and analyzed via standard laboratory procedures. The results revealed spatial variation in the soil properties among the land use types and soil depths. The soils in both cultivated and eucalyptus plantation land were strongly acidic (pH<5.5), whereas those in grazing land were moderately acidic. The highest (54.89%) and lowest (43.73%) clay contents were recorded in the soils of cultivated and grazed lands, respectively, whereas the sand content was greater (36.11%) in the eucalyptus plantation land. The relatively highest bulk density (1.36 g cm-3) was recorded in the grazed land soils, followed by the cultivated land soils (1.32 g cm-3). Both the exchangeable acidity and aluminum content in all land use types decreased with increasing soil depth, which was consistent with their acid saturations. The organic carbon content ranged from 2.30% at the subsurface layer of the cultivated land to 3.44% at the surface layer of the grazing land soils, whereas the total nitrogen content ranged from 0.19% to 0.30%. Available P ranged from 7.31 mg kg-1 to 12.61 mg kg-1. The highest Ca, Mg, Na, and K contents (8.92, 5.76, 0.30, and 1.26 Cmol (+) kg-1 , respectively) were recorded in the soils of the grazing land. The amount of PBS used ranged from 35.14% to 78.45%. The CEC and ECEC of the soils in the three land use types also increased consistently with increasing soil depth. Micronutrient concentrations decreased with soil depth. The Fe and Mn contents ranged from 0.54 and 4.42 mg kg-1 in the subsurface layer of the grazing land and eucalyptus plantations, respectively, to 10.58 and 12.14 mg kg-1 in the surface layer of the eucalyptus plantations and grazing land soils, respectively. Cu and Zn also ranged from 1.52 and 0.29 mg kg-1 to 3.16 and 0.85 mg kg-1 , respectively. The study suggests that both CL and EPL soils exhibit the highest acidity and require soil management practices, such as lime application, to reduce acidity and improve soil fertility. On the other hand, GL soils show more favorable conditions for nutrient retention and pH.

Mechanized harvesting operations yield high productivity; however, it damages forest soils seriously. The objective of this study is to determine the impacts of skidding operations on topsoil physical and chemical properties at four different forest floors (tractor road, skid trail, harvesting area and undisturbed area) after a harvesting season. Also, the relationship between soil compaction and soil moisture of these areas were analysed. Soil compaction was estimated with the values of topsoil penetration resistance on two soil depth layers (0-5 and 5-10 cm). In total, 24 soil samples were taken to the laboratory for some physical and chemical analyses. Three soil moisture levels were delineated for the different forest floor areas ranging from 28% to 54%. Significant negative correlation between penetration resistance and bulk density, soil pH and calcium carbonate and significant positive correlation between penetration resistance and organic C, total N and C org /N total ratio were found. It was determined that four study sites shared similar features all having heavy clay (53.5-65.2%) soils. According to soil analysis, the lowest bulk density value (0.89 g/cm 3 ) was found in harvesting area and the highest bulk density value (1.15 g/cm 3 ) was found on the tractor road. Also, the highest content of organic C was found on the skid trail as 5.57% and the lowest content of organic C was on the tractor road as 1.52%. As the soil moisture content increases when penetration resistance decreases, mechanized harvesting operations should be arranged according to precipitation and soil moisture.

Soil CO 2 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; 2.74 mmol m À2 s À1 in SB and 2.07 mmol m À2 s À1 in G) in SB. Total emission in the 70-day period after harvest was also higher in the SB plot (729 g CO 2 m À2 ) when compared to the G (557 g CO 2 m À2 ) plot. Organic matter content and carbon stock (0-25 cm) 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 CO 2 emission, with this property being the most important to understand the emission variability in the Slash-and-burn area.

The dynamics of some physical properties of the soil: bulk density, porosity and percentage of water stable aggregates, which usually are taken as indicators for evaluation of soil quality, have been studied on the flat surfaces of the Canamero's "rana" formation (Caceres, SW Spain). The study shows a high relationship between all these physical soil parameters, the degradation level of the natural vegetation, and years of the soil under tillage. As the deterioration of the natural soil increases the bulk density of the fine earth is increased, diminishing porosity, field capacity moisture content, percentage of water stable aggregates in soil and water infiltration.

The objective of this study was to determine the level of soil spatial variability in an area consisting of the land uses: Quesungual slash and mulch agroforestry system with less than two years (QSMAS&lt;2), Slash-and-burn traditional system (SB) and Secondary forest (SF). Soil samples were taken in three parallel transects of 102 m in length, separated 9 meters. The profile was sampled in the depths from 0 to 5 cm, 5 to 10 cm, 10 to 20 cm and 20 to 40 cm in 6 points (09, 11 am and 05) during 9 days. Coefficient of variation for soil properties varied for bulk density (0.76 and 15.1%), organic carbon (30.4 and 54.3%), volumetric moisture (9.5 and 23.5%), sand (12.8 and 22.5%) and clay (14.0 and 29.2%). The geo-statistical analysis showed that the random component of the spatial dependence was predominant over the nugget effect. The functions of semivariograms, structured for each variable were used to generate maps of interpolated contours at a fine scale. The Moran (I) autocorrela...

O presente trabalho teve como objetivo avaliar o efeito do tipo de preparo do solo em plantas de mandioca. O experimento foi realizado na Universidade Estadual de Maringa, Campus do Arenito em Cidade Gaucha, PR, em solo classificado como Latossolo Vermelho Distroferrico de textura arenosa. O historico da area consiste em lavoura de mandioca sob preparo convencional, a correcao da acidez do solo foi realizada com aplicacao de calcario. Semeou-se aveia preta no inverno e crotalaria juncea no verao e o plantio das manivas foi realizado em 30/09/2016. Foram utilizadasparcelas de 4x25 m, com tres tipos de manejo (pousio, escarificacao a 0,30 m e subsolagem a 0,45 m), compostas por 4 linhas com tres variedades de mandioca (espeto, cultivar uniao e cultivar Santa Helena) formando um esquema fatorial 3x3 com 4 repeticoes. Os parâmetros fisicos obtidos foram a densidade do solo e o teor de agua (0,00-0,20 e 0,20-0,40 m) apos 240 dias do plantio e feita a analise fisiologica das culturas de d...

Intensive agriculture (IA) is widespread in South Italy, although it requires frequent tillage, large amounts of fertilizers and irrigation water. We have assessed the efficacy of reversing IA to sustainable agriculture (SA) in recovering quality of a typical South Italy soil (Lithic Haploxeralf). This reversion, lasting from 2000 to 2007, replaced 75% of nutrients formerly supplied inorganically by farmyard manuring and reduced the tillage frequency. Several chemical and biochemical properties, functionally related to C and N mineralisation-immobilisation processes and to P and S nutrient cycles, were monitored annually from 2005 to 2007 in the spring. Reversing IA to SA decreased soil bulk density, almost doubled the soil organic matter (SOM) as favoured the immobilisation of C and N, increased most soil microbial indicators but decreased contents of nitrate, mineral N and K 2 SO 4 -extractable C. The K 2 SO 4 -extractable C/K 2 SO 4 -extractable organic N ratio suggested that substrate quality rather than the mass of readily available C and N affected biomass and activity of soil microflora. Also, the largely higher 10-day-evolved CO 2 -C-to-inorganic N ratio under SA than IA indicated that higher C mineralisation, associated with higher microbial biomass N immobilisation, occurred under SA than IA. Decreases in most soil enzyme activities under IA, compared to SA, were much higher than concomitant decreases in SOM content. Soil salinity and sodicity were always higher in IA than SA soil, although not critically high, likely due to the intensive inorganic fertilisation as irrigation waters were qualitatively and quantitatively the same between the two soils. Thus, we suggest that the cumulative small but long-term saline (osmotic) and sodic (dispersing) effects in IA soil decreased the microbial variables more than total organic C and increased soil bulk density.

Effective and efficient water resource management is undoubtedly one of the most important policy issues facing agriculture in Hawaii in the years ahead. Substantial amount of water could be saved through optimizing plant water uptake and minimizing excess water looses below root zones. Capacitance sensors have been successful in monitoring water content at multiple depths and at different locations in near real-time. The objectives of this work are to use real-time data from capacitance sensors to: i) determine field soil physical properties, i.e., soil hydraulic conductivities and soil water holding capacity; ii) determine irrigation scheduling setting points, i.e. full points and refill points. Six capacitance probes were used to monitor the soil water content in real-time (every 10 minutes) across the field. Each probe has four soil moisture sensors that monitor the water content at 10, 20, 30 and 50 cm below the soil surface. Soil hydraulic conductivity at 10 and 40 cm was determined across the field. Rain and irrigation were also monitored during the period of the study. Among the three investigated tomato plant varieties, Toro variety treatment had lowest water content in all investigated soil depths compared with the two other treatments. This variety seems to have higher water uptake than Ruby and Atila F1 varieties.

To indentify the best soil management practices, it is necessary to quantify the modifications to the soil structure. Three different management practices were compared for short time: superficial tillage, medium tillage and conventional deep tillage. Tests were carried out over a sandy loam soil in the Higher Institute of Agronomy of Chott Meriem (Tunisia). Tillage was followed by a first resumption 10 days after tillage and a second one 20 days after. The studied parameters were measured at initial state and after each operation. Soil structure was characterized by its resistance to penetration using an electronic penetrometer and its bulk density. In soil tilled by conventional system with mouldboard ploughing, soil resistance decreased for a depth of 50 cm. In contrast, medium tillage with discs plow showed higher values of soil resistance in both the surface layer (10 cm) and the plowing depth (20 cm). Superficial tillage using discs harrow (Offset), showed higher values of soi...

Rainfall simulations were conducted on a loess derived silt loam soil (Henan province, P.R. China) under conventional tillage. This tillage practice is widespread and involves the turning of the plough layer and the wheat stubble in July (primary tillage), followed by a secondary tillage operation in October. Soil samples were collected and in situ measurements were done before each rainfall simulation in order to analyse soil physical properties after successive simulated rainfall events. The purpose of this study was to determine rainfall induced changes in saturated hydraulic conductivity, bulk density, penetration resistance, water retention and soil erodibility. The results only showed significant differences in soil bulk density and erodibility when applying successive rainfall events. Penetration resistance and water retention (at matric potentials VÀ 3 kPa) were not significantly affected and soil surface sealing was not observed. This was also confirmed by the infiltration measurements, where no significant differences in saturated hydraulic conductivity were found. From a soil conservation point of view, this study indicated that the primary tillage operation

O Intervalo hídrico ótimo (IHO) é muito utilizado como indicador agronômico de qualidade física do solo, contudo pouquíssimas pesquisas relacionaram o IHO com crescimento e produção de plantas. Os escassos resultados são insuficientes para confirmar ou negar a eficiência do IHO, porém apontam para a discordância entre IHO e produção das culturas. O objetivo deste estudo foi analisar a correlação do IHO com as variáveis de crescimento e com a produção de grãos da cultura de milho (Zea mays L.) de oito cultivos (quarto na safra 2010/11 e quatro na safra 2011/12) em Latossolo Vermelho distroférrico típico, com diferentes estados de compactação. Os tratamentos consistiram de plantio direto, que recebeu escarificação e compactação adicional. Foram medidos a altura de plantas (Ap), o índice de área foliar (IAF), a profundidade efetiva de raízes (Ze), o rendimento de grãos e o peso de 1000 grãos nos oito cultivos de milho. O IHO foi determinado para seis combinações de resistência do solo à penetração e potencial matricial (RP:ψ ψ ψ ψ ψ), usadas nos limites inferiores: (2:-0,8), (3:-0,8), (4:-0,8), (2:-1,5), (3:-1,5) e (4:-1,5), expressos em MPa. O IHO esteve fracamente associado com Ap, IAF e Ze. Os coeficientes de correlação variaram entre -0,20 e 0,36 e a maioria das correlações não foi significativa. Além disso, a melhor relação linear explicou apenas 17 % da variação da altura das plantas em função da variação do IHO. Não houve correlação entre IHO e produção de grãos de milho. Esses resultados indicaram que, embora o IHO seja sensível à compactação do solo, ele não é um índice agronômico robusto para orientar o manejo da compactação para culturas, cujo objetivo principal é a produção de grãos. Termos de indexação: compactação do solo, plantio direto, densidade crítica. (1) Recebido para publicação em 17 de janeiro de 2013 e aprovado em 30 de agosto de 2013.

A field experiment was carried out on sugarcane plant-ratoon system to develop nutrient management strategies for sustaining soil health, quality and sugarcane production at Research Farm, Dr. Rajendra Prasad Central Agricultural University, Pusa, Bihar. Trials were conducted to test the efficiency of various fertilizers in sugarcane on solubility of applied inorganic fertilizer during spring season in calcareous soil. The pooled data revealed that number of millable cane (NMC), cane and sugar yield varied significantly due to integrated use of organic and inorganic fertilizer with bio-fertilizer in combination both in plant and ratoon crops. The significant increase in NMC, cane and sugar yield was recorded in the treatments receiving organic and inorganic fertilizer in combination with bio-fertilizer over control. The highest number of NMC (103.0 × 10 3 ha-1), cane yield (85.8 t ha-1) and sugar yield (11.21 t ha-1) was recorded in treatment T9 i.e 75% NPK of RDF + Acetobacter

Carbon stock assessment is important to estimate carbon stock potential of forest. In Ethiopia, assessment of carbon stock potential of forest begun in recent years. Though, different studies have been made in Ethiopian forests, Gambo Plantation Forest has not yet been studied. So, the aim of this study was to analyze the carbon stock potential of selected tree plant species in Gambo plantation forest. A systematic random sampling method was used to take samples. Sampling plot of (20m x 20 m) was established for each species. The diameter was measured at breast height to estimate biomass of trees in sampling plots. Tree height was recorded by using a measuring hypsometer. Soil and Litter samples were collected from the field with five sub-plots within each major plot. Results revealed that the total mean carbon stock of the Gambo plantation forest was 795.51t/ha of which above ground carbon share 407.07, below ground carbon 80.37, litter fall carbon share 1.43 and soil organic carbon was 306.64 (up to 30cm depth). The ultimate result implies that Gambo plantation forest is a reservoir of high carbon stock. The presence of high range value of carbon stock in the sites indicates its potential to mitigate climate change by absorbing greenhouse gases from the atmosphere. Effective forest revenue system should be in place, and revenues generated from all marketed forest goods and services should be reinvested in the sector for the sustainable production and forest management.

The management of cracking clay soils has important influence on irrigation efficiency. To determine the effects of different irrigation water managements on yield and water use efficiency of rice (Oryza sativa L.) in cracked paddy soils, a field experiment was conducted on a silty clay soil, a typical swelling soil of Guilan province, northern part of Iran. The experiment was a randomized complete block design with factorial arrangement of treatments with three replications. The main treatment was crack width (3-4 mm, 1.5 cm and 2.5 cm) which are called C 0 , C 1.5 and C 2.5 , respectively. The subtreatment was irrigation (D 0 , irrigation to fill up the cracks and up to the start of ponding; D 2.5 , irrigation to fill up the cracks and up to 2.5 cm of ponding at the soil surface; D 5 , irrigation to fill up the cracks and up to 5 cm of ponding at the soil surface). The results showed that the effects of crack width, depth of irrigation water and their interaction on rice grain yield and water use efficiency were significant at 5% and 1% level, respectively. The highest grain yield (3.279 ton ha -1 ) belonged to the D 5 C 0 and the lowest grain yield (2.04 ton ha -1 ) belonged to D 0 C 2.5 . The reduction of depth of ponding (D 0 vs. D 5 ) caused 36.5% improvement in water use efficiency. On cracked paddy soils, based on the development of crack width, the irrigation schedule can be planned to save water without considerable reduction of crop yield. The results of this study can be applied to cracked paddy soils of the study area in order to save irrigation water.

Tennis is played on many different surfaces including natural grass, which plays fast because of low ball bounce (i.e., coefficient of restitution [COR]) and low ball‐to‐surface friction (coefficient of friction [COF]) that increase the pace (ball speed) of tennis. Effects of various C3 turfgrasses on COF and COR have not been investigated. Our objectives were to evaluate eight cultivars of various species randomized within three official size tennis courts: (a) ‘Keeneland’ Kentucky bluegrass (Poa pratensis L., KB), (b) ‘Rubix’ KB, (c) ‘Villa’ velvet bentgrass (Agrostis canina L., VBG), (d) ‘Puritan’ colonial bentgrass (Agrostis capillaris L., CL), (e) ‘007’ creeping bentgrass (Agrostis stolonifera L., CB), (f) fine fescue (Festuca sp., FF) mixture, (g) ‘Karma’ perennial ryegrass (Lolium perenne L, PR), and (h) ‘Wicked’ PR. Friction was measured using a weighted sled and ball bounce (BB) to derive COR was measured using a vertical drop height of 254 cm. Bounce (i.e., COR) to satisfy...

O objetivo deste trabalho foi avaliar a distribuição espacial de alguns atributos físicos do solo e verificar suas alterações no desenvolvimento da seringueira consorciada com leguminosas. O experimento foi instalado em Argissolo Vermelho-Amarelo no Polo Regional de Desenvolvimento Tecnológico dos Agronegócios do Centro-Norte, localizado em Pindorama (SP). Foram avaliadas: infiltração de água a 0,10 e a 0,20 m de profundidade, macro e micro porosidade e densidade do solo nas camadas 0-0,10; 0,10-0,20; 0,20-0,40 e 0,40-0,60 m. O desenvolvimento das plantas de seringueira foi avaliado medindo-se o perímetro do caule e o aumento desta medida no período de quatro anos (1996-1999). Os dados foram submetidos à análise de estatística descritiva para verificação de parâmetros de tendência central e dispersão. Foram utilizados métodos geoestatísticos incluindo semivariogramas, krigagem e mapas de isolinhas para a avaliação da variabilidade espacial. Houve dependência espacial de moderada a f...

Soil structure plays a major role in the design of new crop management systems. For instance, the transition from conventional to no-tillage changes soil structure, which, in turn, has implications on crop yield greenhouse gas emissions, and pesticide and nitrate leaching. Modelling soil structure at field scale faces two main issues: (1) the spatial variability and (2) the temporal variability. Here, we review how spatial variability of soil structure is taken into account in water transfer models at field scale. We discuss the effects of soil structure on hydraulic properties. We present options to model soil structure effects using pedotransfer functions or calculations based on pore network geometry. Then we review studies on water transfer. Here, we show the utility of one-dimensional (1-D) and 2-D models, and the range of soil profile partitions. In the second part, we study a mean to model the temporal variation of soil structure. We propose an indicator of soil structure dynamics based on the proportion of compacted clods in the tilled layer. This indicator was measured from the observation face of soil pits. We studied this indicator in a long-term field experiment involving various risks of compaction. The results showed that this indicator gave a more precise description of the time course changes in soil structure than the mean soil bulk density measured on the same experimental plots. Lastly, we discuss the principles of a model that predicts the evolution of this indicator under different soil tillage and climatic conditions. This model can be used to evaluate the effects of different crop management systems on soil structure and soil water transfer. soil structure / crop management / tillage / water transfer / model

Soil structure plays a major role in the design of new crop management systems. For instance, the transition from conventional to no-tillage changes soil structure, which, in turn, has implications on crop yield greenhouse gas emissions, and pesticide and nitrate leaching. Modelling soil structure at field scale faces two main issues: (1) the spatial variability and (2) the temporal variability. Here, we review how spatial variability of soil structure is taken into account in water transfer models at field scale. We discuss the effects of soil structure on hydraulic properties. We present options to model soil structure effects using pedotransfer functions or calculations based on pore network geometry. Then we review studies on water transfer. Here, we show the utility of one-dimensional (1-D) and 2-D models, and the range of soil profile partitions. In the second part, we study a mean to model the temporal variation of soil structure. We propose an indicator of soil structure dynamics based on the proportion of compacted clods in the tilled layer. This indicator was measured from the observation face of soil pits. We studied this indicator in a long-term field experiment involving various risks of compaction. The results showed that this indicator gave a more precise description of the time course changes in soil structure than the mean soil bulk density measured on the same experimental plots. Lastly, we discuss the principles of a model that predicts the evolution of this indicator under different soil tillage and climatic conditions. This model can be used to evaluate the effects of different crop management systems on soil structure and soil water transfer. soil structure / crop management / tillage / water transfer / model

The purpose of this investigation was to evaluate mechanical harvest impacts on soils in a western juniper (Juniperus occidentalis) woodland parcel of about 14.7 acres. The project site is located on property owned by the Lost River Ranch, about six air miles southwest of Bonanza, Oregon. This is the first study to examine the effects of mechanical harvest on the soils of a western juniper woodland parcel. Western juniper entirely dominated the pre-harvest overstory, ranging from 25-35 stems/acre in the lowest density area to 120-160 stems/acre in the highest density area. Shrub cover was sparse and groundcover consisted of a dense carpet of cheat grass (Bromus tectorum). Juniper canopy cover was estimated from aerial photographs to be less than 10% in the low density area and greater than 60% in the high density area. Average age of the junipers on site was 80-90 years at stump height. No trees were cored that were older than 90 years. Average diameter at breast height was 12-14 in...

The study was carried out during three consecutive seasons (2005/06, 2006/07 and 2007/08) under rain-fed conditions, to investigate the effect of some tillage methods and sowing dates of sorghum (Sorghum bicolor L.) on soil moisture content, bulk density and sorghum grain yield in northern Gedarif area, at the pilot farm of the Faculty of Agricultural and Environmental Sciences, University of Gedarif, Gedarif, Sudan. The experiment was laid out in a split plot design with three replicates. Main plots were assigned to three tillage methods; which were: Zero tillage (ZT), offset disc as post harvest tillage(PHT) and farmers practice which was wide level disc (WLD) as control, while sub-plots were assigned to two sowing dates which were early sowing date (S1) and late sowing date (S2). Post-harvest tillage treatment (PHT) resulted in significantly higher soil moisture content in the three growing seasons compared to the other two treatments. Combined analysis indicated that ZT resulted in significantly higher soil bulk density in comparison with WLD and PHT treatments for the three depths. The 3-years average grain yield for PHT, WLD and ZT were 1113 kg/ha, 976 kg/ha and 885 kg/ha, respectively. The respective increase in yield was 26% and 14%.

We evaluated the effects of individual Quercus emoryi trees on precipitation distribution and microenvironment in a semi-arid savanna in south-eastern Arizona, U.S.A. Tree size was explicitly considered, with trees varying in crown area from 5 to 70 m 2 . Throughfall (the proportion of precipitation falling through the tree crown) was influenced by tree size and precipitation event size for precipitation events less than 30 mm. Non-linear regression indicated an exponential relationship between precipitation event size and stemflow, with precipitation event size explaining 66% of the variability in stemflow. Tree size was linearly related to stemflow, and accounted for an additional 6% of the variability. Soil moisture and temperature varied between sampling locations and between trees, although tree size had no apparent effect. Soil temperatures were lower beneath tree canopies in summer and higher in winter, compared to grassland zones. Regardless of tree size, trees had no measureable influence on soil bulk density or relative soil surface elevation.

ASSESSMENT OF CARBON STOCK IN GOKARNA FOREST, KATHMANDU, NEPAL Sagar Dhakal*, Sanu Raja Maharjan, Prakash C Aryal *Correspondence: sagardhakal2043@gmail.com 1 Department of Environmental Science, GoldenGate International College, Kathmandu, Nepal Abstract Assessment of carbon stock in urban forest is essential to obtain the carbon sequestration rate and has important role in urban environment with play vital role to conserve biodiversity. This study was conducted in Gokarna protected forest, Kathmandu, to explore the forest carbon stock. A total of 60 circular plots of random sample with size of 250 m were sampled for study. The biomass of standing trees was estimated by using allometric equation of trees, measuring their diameter & height. A total of 844 trees were measured belonging to 52 species. The total tree biomass was found to be 548.92t/ha. The aboveground tree carbon and belowground tree carbon were found 214.99 (t/ha) and 42.99 (t/ha) respectively. On the basis of IVI val...

Soil biota such as earthworms, arbuscular mycorrhizal fungi (AMF) and plant roots are known to play a major role in engineering the belowground part of the terrestrial ecosystems, thus strongly influencing the water budget and quality on earth. However, the effect of soil organisms and their interactions on the numerous soil physical properties to be considered are still poorly understood. Shrinkage analysis allows quantifying a large spectrum of soil properties in a single experiment, with small standard errors. The objectives of the present study were, therefore, to assess the ability of the method to quantify changes in soil properties as induced by single or combined effects of leek roots (Allium porrum), AMF (Glomus intraradices) and earthworms (Allolobophora chlorotica). The study was performed on homogenised soil microcosms and the experiments lasted 35 weeks. The volume of the root network and the external fungal hyphae was measured at the end, and undisturbed soil cores were collected. Shrinkage analysis allowed calculating the changes in soil hydro-structural stability, soil plasma and structural pore volumes, soil bulk density and plant available water, and structural pore size distributions. Data analysis revealed different impacts of the experimented soil biota on the soil physical properties. At any water content, the presence of A. chlorotica resulted in a decrease of the specific bulk volume and the hydrostructural stability around 25%, and in a significant increase in the bulk soil density. These changes went with a decrease of the structural pore volumes at any pore size, a disappearing of the thinnest structural pores, a decrease in plant available water, and a hardening of the plasma. On the contrary, leek roots decreased the bulk soil density up to 1.23 g cm À3 despite an initial bulk density of 1.15 g cm À3 . This increase in volume was accompanied with a enhanced hydro-structural stability, a larger structural pore volume at any pore size, smaller structural pore radii and an increase in plant available water. Interestingly, a synergistic effect of leek roots and AMF in the absence of the earthworms was highlighted, and this synergistic effect was not observed in presence of earthworms. The structural pore volume generated by root and AMF growth was several orders of magnitude larger than the volume of the organisms. Root exudates as well as other AMF secretion have served as carbon source for bacteria that in turn would enhance soil aggregation and porosity, thus supporting the idea of a self-organization of the soilplant-microbe complex previously described.

Magellanic moorlands range from Tierra del Fuego to temperate southern Chile and grow on poorly drained soils, deficient in plant nutrients, leached by high rainfall (2,000 -6,000 mm/yr). The climate is strongly influenced by the Pacific Ocean to the west. Mean annual temperatures reach 5-6°C. Neither longer frost nor drought periods are frequent. In Chiloé Magellanic moorland is restricted today to plateaus on the Cordillera de Piuchué, surrounded by scrub and woodland on better drained sites. Palynological studies show that these moorlands are remnants of vaster bog areas covering Chiloé island during the late glacial and early postglacial periods. A typical moorland complex has different floristic zones. Important ecological factors are the water regime and the nutrient supply. From an ombrotrophic bog center dominated by Donatia fascicularis, the vegetation changes to increasingly minerotrophic fen zones with other cushion plants, such as Astelia pumita, sedges like Schoenus antarcticus, rushes and grasses with a !ayer of Sphagnum magellanicum underneath. The ecotone between moorland and forest is covered by shrubs like Baccharis magellanica and Tepualia stipularis. The nutrient supply of the moorland was characterized by the total and plant-available contents of K, Na, Ca, Mg, Fe, Mn and Al as well as the C/N ratio and the effective cation exchange capacity (CEC) of the peat soils. The results show that only the cushion bog of Dona tia has nearly ombrotrophic conditions, whereas the Astelia mire and the Schoenus fen are strongly influenced by mineral seepage water. In addition to nitrogen, which could not be investigated in this study, phosphorus is the most important limiting factor for moorland vegetation. Man has disturbed the fragile equilibrium between woodland and moorland, by fire and logging. The enhanced runoff from deforested woodland favors the invasion of sorne moorland plant species.

A study was carried out for three consecutive seasons (2005/06, 2006/07 and 2007/08) under rain- fed condition, to investigate the effectof some tillage systems on surface runoff and soil erosion in northernGedarif. The study was conducted at the pilot farm of the Faculty ofAgricultural Sciences and Environment, University of Gedarif ,in thenorthern area of Gedarif State ( Latitude 12° 45′ N, Longitude 35° 15′ Eand 540 m above sea level ). The experimental design was randomizedcomplete block with three replications. Treatment were three tillagesystems: No tillage or zero tillage (ZT), offset disc as post harvest tillage(PHT) and wide level disc, farmers practices as control ( WLD ). Raingauge was used to measure the rainfall, whilst the surface runoff and soillosses were measured using runoff plot technique. Total recorded annualrainfall was 368.1mm (2005), 463.6 mm (2006) and 495.2 mm (2007)which was spread over 32, 30 and 32 rainy days during the first , secondand third growing seasons, respectively. The results showed that thesecond season had the best distribution and satisfaction pattern. Itrecorded 15 %, 36 %, 26 % and 5 % for July, August, September andOctober, respectively, compared to 24 % ,53 % 13 % and 2 % ; and 29% ,41 % , 21 % and 1 % for first and third seasons in the same months.Zero tillage treatment showed more runoff and soil loss than PHT andWLD. In terms of accumulation, ZT produced more runoff by 28 % and 9% and soil loss by 53 % and 28 % over PHT and WLD respectively forfirst season ,30 % and 13 % runoff and 28 % and 13 % soil loss for thesecond season and 55 % and 23 % runoff and 105 % and 24 % soil lossfor third season . The post harvest tillage reduced average annual runoffand soil loss to the lowest values compared to the Wide level disk andZ T.

An adequate supply of plant-available nutrients and an appropriate chemical composition of soils in tree pits are important factors affecting the health and life span of trees in urban environments. We used Multivariate Adaptive Regression Splines (MARS) to explore relationships between nutrient availability, soil organic matter (SOM), soil pH, land use, soil age (time since tree transplanting from nursery to the tree pit), street width, and tree pit cover material in Montreal, Quebec, Canada. Soil was collected to a depth of 20 cm from tree pits along commercial and residential streets and analyzed for concentrations of plant available K, Ca, Mg, P, and N, concentration of Na, SOM content and soil pH. Mulching with wood chips and soil age influenced the availability of K, P, and N in the tree pit soils. Sodium concentration was positively correlated with soil pH, possibly due to the displacement of H + by Na + originating from de-icing salt. Soil organic matter content was positively correlated with Mg and Na concentrations in tree pit soils in commercial zones, and with K and Ca concentrations in those of residential zones. Soil from tree pits located along wide streets in commercial zones had high concentrations of Na and Ca, possibly due to higher volumes of traffic on those streets splashing more de-icing salt, and increased weathering of buildings and sidewalk by deicing salt. The information presented here can be a valuable baseline for managing nutrients in tree pits, in order to mitigate the stresses that can shorten the life of street trees.

A field experiment was conducted under rainfed environment of Pothowar region of Pakistan to assess physical properties of soil as influenced by various green manure legumes (sesbania, cluster bean and rice bean) and different P levels (0, 30, 60, 90 kg P 2 O 5 /ha). Highest fresh biomass was observed in sesbania (23 t/ha) followed by cluster bean (19 t/ha) and lowest in rice bean (17 t/ha). Maximum crude protein content was found in sesbania (17%) followed by rice bean (10%) and cluster bean (8%). Green manuring crops, on average reduced soil bulk density (5%), enhanced total porosity (8%), and macropores and large mesopores (28%). Maximum reduction (7%) in soil bulk density, and an increase (11%) in total soil porosity and available water (17%) was observed in plots where sesbania was incorporated as green manuring crop. The order of effectiveness in improving bulk density, macro and mesopores was sesbania > cluster bean > rice bean. Sesbania produced greater number of macro and large mesopores about 41% increase over control followed by cluster bean (29%) and rice bean (16%). Phosphorus application showed meager positive impact on various soil physical properties but did not significantly increased porosity or reduced bulk density. Significant differences in volume fraction in pore space suggest that pore space on a volume basis was much higher in sesbania-amended soil than in other treatments.

This research project is aimed at assessing the soil organic carbon (SOC) sequestration potential of reclaimed minesoils (RMS). The experimental sites, owned and maintained by the American Electrical Power, are located in Guernsey, Morgan, Noble, and Muskingum Counties of Ohio. These sites, characterized by age chronosequences, were reclaimed with and without topsoil application and are under continuous grass or forest cover. During this quarter, water infiltration tests were performed on the soil surface in the experimental sites. Soil samples were analyzed for the soil carbon and nitrogen contents, texture, water stable aggregation, and mean weight and geometric mean diameter of aggregates. This report presents the results from two sites reclaimed during 1978 and managed under grass (Wilds) and forest (Cumberland) cover, respectively. The trees were planted in 1982 in the Cumberland site. The analyses of data on soil bulk density (ρ b), SOC and total nitrogen (TN) concentrations and stocks were presented in the third quarter report. This report presents the data on infiltration rates, volume of transport and storage pores, available water capacity (AWC) of soil, particle size distribution, and soil inorganic carbon (SIC) and coal carbon contents. The SIC content ranged from 0.04 to 1.68% in Cumberland tree site and 0.01 to 0.65% in the Wilds. The coal content assumed to be the carbon content after oven drying the sample at 350 0 C varied between 0.04 and 3.18% for Cumberland and 0.06 and 3.49% for Wilds. The sand, silt and clay contents showed moderate to low variability (CV < 0.16) for 0-15 and 15-30 cm depths. The volume of transmission (VTP) and storage pores (VSP) also showed moderate to high variability (CV ranged from 0.22 to 0.39 for Wilds and 0.17 to 0.36 for Cumberland). The CV for SIC was high (0.7) in Cumberland whereas that for coal content was high (0.4) in the Wilds. The steady state infiltration rates (i c) also showed high variability (CV > 0.6) and ranged from 0.01 to 0.98 cm min-1 in Cumberland and 0.1 to 1.68 cm min-1 in Wilds. The cumulative ____________________________ Shukla and Lal-C-MASC Oct 04

Knowledge of the spatial variability of soil physical properties is important for site-specific soil management. The objectives of this study were to characterize the field-scale spatial variability of cone index (CI), soil bulk density (D b), moisture content (K v), and sand and clay contents in the A horizon of a Lihen sandy loamy soil (sandy, mixed, frigid Entic Haplustoll), and to describe the relationship among these soil physical properties. This study was conducted on a grassland site of approximately 4.75 ha that has been in rain-fed crested wheatgrass-alfalfa hay production for over 20 years. Soil bulk density was determined from samples collected using a core sampler, whereas CI was measured by inserting a digital penetrometer into the soil at three different locations within a 300-mm radius from where the D b samples were extracted. The measurements were made on a 16 Â 36-m grid sampling system, which created 72 individual grid cells. Soil properties were measured at the center of each grid cell at depths of 50 to 100 mm and 200 to 250 mm. Soil parameters were modeled as normally distributed random variables. Cone index at 50 to 100 mm and 200 to 250 mm depths, D b , K v , and sand and clay contents exhibited medium to strong spatial dependence that was well described using either spherical or exponential models. The semivariogram for clay content shows a small range of spatial dependence and nearly zero nugget effect. Positive correlations indicated that direct relationships existed between D b and CI (r = 0.57, P G 0.01) at 50 to 100 mm depth and between K v and content of clay (r = 0.58, P G 0.01) in the soil. Spatial variability of soil physical properties was attributed to a combination of previous farming practices, vegetation history, erosion, and weather conditions. The degree of variability in soil physical properties was concluded to be of sufficient magnitude to influence the spatial distribution of crop yield, thus having considerable implications regarding the implementation of site-specific management practices.

Resumo-O objetivo do trabalho foi avaliar os efeitos dos tipos de manejo de solo e das rotações de culturas nos atributos físicos restritivos de duas camadas de solo situadas entre 0 a 20 cm na produção vegetal de culturas de grãos. O experimento foi conduzido em Passo Fundo, em Latossolo Vermelho distrófico, com 25 anos de cultivo. Os tratamentos consistiram em três tipos de manejo de solo (plantio direto-PD; preparo mínimo com escarificador de hastes-PM; e preparo convencional com arados e grades, no inverno-PC), nas parcelas, e três rotações de culturas (trigo e soja-R1; trigo, soja, ervilhaca e sorgo-R2; e trigo, soja, ervilhaca, sorgo, aveia branca e soja-R3), nas sub-parcelas. Foram avaliados o rendimento de grão (RG), a massa seca da parte aérea (MS) das culturas e os atributos físicos densidade do solo, porosidade total, macroporosidade, microporosidade e criptoporosidade, resistência do solo à penetração, argila dispersa em água e condutividade hidráulica do solo saturado em duas camadas de solo (0 a 6,7 e 6,8 a 20 cm). O efeito dos manejos de solo e das rotações de culturas não influenciou os atributos físicos do solo, ainda que estes mostrassem restrições ao desenvolvimento das culturas. Estes fatores, porém, podem ter influenciado o RG das culturas de trigo e de sorgo, além da MS dessas culturas e a da soja. Em todos os tratamentos, os resultados dos atributos físicos indicaram haver uma camada (0 a 6,7 cm) não compactada e outra (6,8 a 20 cm) compactada. Na camada de 0 a 6,7 cm, as diferenças nos atributos físicos entre os tratamentos não foram importantes. Palavras-chave: plantio direto; compactação; resistência à penetração.