Aeration Porosity Research Articles

Caracterización física y química de sustratos con base en corteza y aserrín de pino

Las características físicas y químicas de los sustratos son importantes para obtener planta en vivero con características morfológicas adecuadas. Se caracterizaron tres sustratos de uso actual en viveros forestales: S1: turba de musgo, vermiculita y perlita; S2: corteza compostada, turba de musgo y aserrín y S3: aserrín de pino, turba de musgo y corteza compostada, todas en proporción 3:1:1 vol., a los cuales se les agregaron 8 g L-1 de fertilizante Osmocote® de 8 meses – 9 meses de liberación. Se utilizaron para la producción de Pinus greggii var. australis Donahue & López. Las características porosidad, pH, conductividad eléctrica y relación carbono/nitrógeno se evaluaron antes y después de la producción de planta, mientras que la granulometría, curvas de retención y liberación de agua solamente antes de la producción. Los intervalos iniciales y finales de porosidad total, aireación y retención de agua fueron de 77% - 83%; 19% - 27% y 54% - 63%, respectivamente. En todos los sustratos la porosidad de aireación disminuyó y la de retención de agua aumentó al final. El agua fácilmente disponible varió de 19% a 30%, S3 presentó el mayor porcentaje. En la granulometría, la mayor proporción de partículas se encontró en diámetros de 0.26 mm a 0.75 mm. Los valores de pH iniciales (4.8 - 5.3) y finales (6.3 - 6.7) fueron ácidos; la CE inicial fue de 0.9 dS - 1.7 dS, menor que la final de 1.7 dS - 2.4 dS. La relación carbono/nitrógeno fue diferente para los tres sustratos, S1 presentó el menor valor (159), S2 con 537 y S3 el mayor (613). Los sustratos alternativos evaluados presentaron características adecuadas para ser utilizados en la producción de planta forestal y sustituir al compuesto por turba de musgo.

Soil respiration and its Q10 response to various grazing systems of a typical steppe in Inner Mongolia, China.

BackgroundAs one of the important management practices of grassland ecosystems, grazing has fundamental effects on soil properties, vegetation, and soil microbes. Grazing can thus alter soil respiration (Rs) and the soil carbon cycle, yet its impacts and mechanisms remain unclear.MethodsTo explore the response of soil carbon flux and temperature sensitivity to different grazing systems, Rs, soil temperature (ST), and soil moisture (SM) were observed from December 2014 to September 2015 in a typical steppe of Inner Mongolia under three grazing systems: year-long grazing, rest-rotation grazing, and grazing exclusion. In addition, plant aboveground and root biomass, soil microbial biomass and community composition, and soil nutrients were measured during the pilot period.ResultsSoil respiration was significantly different among the three grazing systems. The average Rs was highest under rest-rotation grazing (1.26 μmol·m−2·s−1), followed by grazing exclusion (0.98 μmol·m−2·s−1) and year-long grazing (0.94 μmol·m−2·s−1). Rs was closely associated with ST, SM, potential substrate and root, and soil microbe activity. The effects of grazing among two grazing systems had generality, but were different due to grazing intensity. The root biomass was stimulated by grazing, and the rest-rotation grazing system resulted in the highest Rs. Grazing led to decreases in aboveground and microbial biomass as well as the loss of soil total nitrogen and total phosphorus from the steppe ecosystem, which explained the negative effect of grazing on Rs in the year-long grazing system compared to the grazing exclusion system. The temperature sensitivity of Rs (Q10) was higher in the rest-rotation and year-long grazing systems, likely due to the higher temperature sensitivity of rhizosphere respiration and higher “rhizosphere priming effect” in the promoted root biomass. The structural equation model analysis showed that while grazing inhibited Rs by reducing soil aeration porosity, ground biomass and SM, it increased Q10 but had a lower effect than other factors. A better understanding of the effects of grazing on soil respiration has important practical implications.

Short-term effects of grassland set-asides on soil properties in the Fraser River delta of British Columbia

Grassland set-asides (GLSA) in the Fraser River delta are fields that are taken out of crop production and seeded with a mixture of grasses and legumes for 1–4 yr. During this time, the farmer is compensated with a cost-share payment to recover a portion of the financial returns that could have been earned from cash crops. The objectives of this study were to (i) evaluate the effects of GLSA on soil properties during the initial two seasons of enrollment, (ii) determine how GLSA effects differ between fields that were considered productive and unproductive, and (iii) identify soil baseline indicators and preliminary soil thresholds for predicting GLSA vegetation responses. Out of eight fields entering the program, two were considered to be unproductive and exchangeable sodium had the strongest negative relationship to GLSA aboveground biomass (r = −0.61, P = 0.0002). During the second season of GLSA establishment, the mean weight diameter of water-stable soil aggregates was consistently higher in productive GLSAs than paired annual crop rotation (ACR) fields, being 21% higher in April, 14% in July, and 19% in September after crop harvest. After two seasons of GLSA enrollment, both aeration porosity and bulk density were improved by GLSA relative to ACR fields with aeration porosity being 24% greater and bulk density 7% lower in GLSA. The results suggest that GLSA rotations in productive agricultural fields within the Fraser River delta provide an alternative to continued ACR that can improve soil structure and reduce compaction after only two seasons of establishment.

Neoformations (Nodules and Placic Layers) in Surface-Gleyed Loamy Sandy Soils of the Northern Part of the Tambov Plain

In the middle part of the profiles of light gray soils (non-gleyed, deeply gleyed, weakly and strongly gleyed) on silty loamy sandy two-layered deposits of the river terraces in the Tambov Plain, placic layers are formed. Nodules are confined to the arable layer, if surface water stagnation occurs. Angular black nodules of less than 2 mm in size with a high Mn content are specific for weakly gleyed soils, grayish brown nodules of 7–10 mm in size are common in strongly gleyed soils. The Cd and Pb accumulation coefficients in the nodules reach 100–300, those for Co and Mo are 10–100; for Zn and Cu, 2–5; the content of P2O5 is 1.0–1.5%, the content of organic matter in the nodules is 1.8–2.5%, and it has a fulvic nature (Cha/Cfa < 0.4). The placic layer density reaches 1.6 g/cm3, and the aeration porosity is reduced to 3–6%. They are highly acidic, 1.5 to 3 times higher in the contents of clay, Al, Fe, Mn, and trace elements than the enclosing material. A reliable quantitative criterion for the evaluation of the agroecological status of light gray surface-gley soils can be the Fe/Mn ratio in 1 N sulfuric acid extract from the nodules (bogging factor according to Zaidelman and Ogleznev).

Physical and agrochemical properties of alluvial soils with perennial grasses and potatoes seeding

During the research it has been found out that there are notable differences in fertility between soils with perennial grasses and potatoes. It was revealed that a strongly compacted soil layer at a depth of 20-50 cm was formed in potato planting. In the layer of 20-40 cm the density of soil increased by 11.6 to 13.0 %, in the layer of 40-50 cm it was by 8.0 –11.8% in comparison with the optimal. Density decrease in perennial grasses seeding led to increase in the total soil porosity by 3-5% and aeration porosity by 2.8–4.7% compared with soil with potato planting. Perennial grasses cultivating increased moisture storage with full moisture capacity in 0-50 cm layer by 1.8–2.0%, capillary moisture capacity by 8.6–19.3%, and the lowest one by 6.7–19.4% compared to soil with potato planting. The studied soils are characterized by moderate-recovery range. In 0-90 cm soil layer of perennial grasses seeding redox potential is not beyond critical indicators. In potato seeding the optimum and good redox potential values was observed only in 0-30 cm layer. In the lower layers, the figure is reduced to critical. It has been found out that arable and subsurface layers of soil in perennial grasses seeding are characterized by satisfactory water permeability. The 0-20 and 20-40 cm soil layers in potato seeding on the are characterized as unsatisfactory according to permeability, but the 40-60 cm layer is satisfactory, which is associated with an increase in silt and lumpy fraction, structure coefficient decrease and increase of lumpy coefficient. Humus deposits in 0-120 cm layer of perennial grasses seeding were 8.8-12.5% higher compared to soils used for potato planting, and 0-50 cm layer were 9.3–21.7% higher. Perennial grasses reduced the acidity of the soil, increased the number of absorbed bases, increased the amount of mobile forms of nitrogen and potassium.

Relationship between CO2 emissions and soil properties of differently tilled soils

Different tillage technologies have different effects on CO2 emissions from soil. Unfortunately, little information exists about the impact of different types of tillage as compared with no-tillage, and the main controls. The aim of this research is to determine the relationship between physicomechanical, chemical and biological properties of soil and CO2 emissions from differently tilled soils under the climatic conditions of central Lithuania before and after autumn tillage. The studies were conducted in 2009–2012 and 2014 at the Experimental Station of Aleksandras Stulginskis University in Central Lithuania. Different tillage technologies were applied: deep ploughing at 23–25 cm depth (DP); shallow ploughing at 12–15 cm depth (SP); deep cultivation with a cultivator at 25–27 cm depth (DC); shallow cultivation with a disc harrow at 12–15 cm depth (SC); and no-tillage (NT). The correlation of physicomechanical, chemical and biological soil properties with CO2 emissions was determined. During all the experimental period total CO2 emissions from soil in DP, SP, DC, SC and NT technologies were respectively 6.05, 4.25, 4.97, 4.42, 3.94 μmol m−2 s−1 before autumn soil tillage and 29.88, 22.50, 16.73, 13.72, 10.00 μmol m−2 s−1 after autumn tillage. Negative correlation between soil temperature and CO2 emissions before the autumn tillage from soil was evidenced (r = −0.98). A strong negative correlation between soil respiration and total soil porosity was observed. Correlation between aeration soil porosity and CO2 emissions was strong. After autumn tillage, the strongest correlations were found between soil penetration resistance and respiration in the upper (r = −0.75) and deeper (r = −0.71) layers. In autumn, a significant strong correlation (r = 0.78) between soil respiration and aeration porosity was obtained in the upper soil layer under ploughing or cultivation. This study revealed that CO2 emissions were significantly higher immediately after autumn ploughing technologies compared to deep and shallow cultivation and no-tillage.

Soil Water Retention in the Semiarid Region of Brazil

From the physics point of view, soil structure is a dynamic attribute that is affected by genetic conditions and anthropogenic changes and requires an integrated approach. Soil water retention curve is one of the main tools used in soil structure evaluations. The objective of this work was to evaluate the structural and chemical attributes of soils of different classes and agroecosystems in the Terra de Esperança Settlement (Governador Dix Sept Rosado, Rio Grande do Norte, Brazil) to distinguish these environments. Disturbed and undisturbed soil samples were collected in horizons of 10 soil profiles of the soil classes: Cambissolo Háplico (Haplustepts), Latossolo Vermelho-Amarelo (Eutrustox), Chernossolo Rêndzico (Calciustolls), and Neossolo Flúvico (Usticfluvents). The soil physical attributes evaluated were granulometry, soil density, total porosity, aeration porosity, macroporosity, microporosity, field capacity, permanent wilting point, available water, and water retention curve. The results were expressed in averages of four replicates per horizon (in laboratory) by multivariate analysis, which detected the most sensitive attributes for the distinction of the environments. The soil physical attributes of the different classes and its inorganic fractions, especially silt and clay, were determinant to distinguish the environments; they affected the microporosity; aeration porosity; and available water. The source material of the Chernossolo Rêndzico, which is rich in calcium and magnesium, affected its physical attributes, characterized by the predominance of the silt fraction. Clay was the determinant fraction of the Cambissolo Háplico, and Neossolo Flúvico; and the sand fraction on the surface layer, and clay fraction in the Bw horizon were determinant of the Latossolo Vermelho-Amarelo. The more expressive physical attributes were soil density, sand content, macroporosity (Latossolo Vermelho-Amarelo), microporosity, field capacity, available water, permanent wilting point, total organic carbon, mass-based moisture, volume-based moisture, clay, aeration porosity (Cambissolo Háplico, and Neossolo Flúvico), and silt (Chernossolo Rêndzico).

ATRIBUTOS FÍSICOS E BALANÇO HÍDRICO DO SOLO COM FLORESTA OMBRÓFILA MISTA, EM LATOSSOLO VERMELHO-AMARELO, EM TELÊMACO BORBA - PR

Objetivou-se no presente trabalho caracterizar os atributos físico-hídricos do solo e quantificar, em um ano, as componentes de um balanço hídrico, realizado para Floresta Ombrófila Mista em Latossolo Vermelho-Amarelo, textura arenosa, em Telêmaco Borba - PR. O experimento foi instalado na Fazenda Monte Alegre, pertencente à empresa Klabin Florestal, em área com mata nativa em estado avançado de regeneração. Foram caracterizados os seguintes atributos físicos do solo: massa específica, condutividade hidráulica saturada, curva de retenção da água, porosidade de aeração e capacidade de água disponível (CAD). As amostras indeformadas foram coletadas em uma trincheira, em cinco camadas. As amostras deformadas foram retiradas semanalmente, em oito pontos dentro da área experimental, em cinco camadas. Os valores de umidades do solo e precipitação interna foram coletados e registrados semanalmente ao longo do ano. O armazenamento de água no solo foi calculado empregando a regra do trapézio. A drenagem interna (D) e a ascensão capilar (AC) foram estimadas com a equação de Darcy-Buckingham. Os valores de massa específica, micro, macro e porosidade total do solo enquadraram-se nas faixas consideradas adequadas para solos de textura arenosa. O solo apresentou alta condutividade hidráulica, característica de solos bem drenados. Em média, o armazenamento não atingiu o ponto de murcha permanente ao longo do ano. A D média foi maior nos meses com maior precipitação, sendo o valor total anual médio de 94,9 mm ano–1. O valor médio da evapotranspiração real foi de 1355,9 mm ano-1, média de 3,7 mm dia-1.

Soil salinity and matric potential interaction on water use, water use efficiency and yield response factor of bean and wheat

We studied the effects of soil matric potential and salinity on the water use (WU), water use efficiency (WUE) and yield response factor (Ky), for wheat (Triticum aestivum cv. Mahdavi) and bean (Phaseoulus vulgaris cv. COS16) in sandy loam and clay loam soils under greenhouse conditions. Results showed that aeration porosity is the predominant factor controlling WU, WUE, Ky and shoot biomass (Bs) at high soil water potentials. As matric potential was decreased, soil aeration improved, with Bs, WU and Ky reaching maximum value at −6 to −10 kPa, under all salinities. Wheat WUE remained almost unchanged by reduction of matric potential under low salinities (EC ≤ 8 dSm−1), but increased under higher salinities (EC ≥ 8 dSm−1), as did bean WUE at all salinities, as matric potential decreased to −33 kPa. Wheat WUE exceeds that of bean in both sandy loam and clay loam soils. WUE of both plants increased with higher shoot/root ratio and a high correlation coefficient exists between them. Results showed that salinity decreases all parameters, particularly at high potentials (h = −2 kPa), and amplifies the effects of waterlogging. Further, we observed a strong relationship between transpiration (T) and root respiration (Rr) for all experiments.

绿洲边缘夹粘沙丘持水特性

PDF HTML阅读 XML下载 导出引用 引用提醒 绿洲边缘夹粘沙丘持水特性 DOI: 10.5846/stxb201705250970 作者: 作者单位: 中国科学院西北生态环境资源研究院 中国生态系统研究网络临泽内陆河流域研究站 中国科学院内陆河流域生态水文重点实验室,中国科学院西北生态环境资源研究院 中国生态系统研究网络临泽内陆河流域研究站 中国科学院内陆河流域生态水文重点实验室,中国科学院西北生态环境资源研究院 中国生态系统研究网络临泽内陆河流域研究站 中国科学院内陆河流域生态水文重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41630861，41501577） Water retention of the clay interlayer of dunes at the edge of an oasis Author: Affiliation: Northwest Institute of Eco-Environment and Resources, CAS,Northwest Institute of Eco-Environment and Resources, CAS, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:夹粘沙丘是指剖面中分布有一层红褐色粘化层的沙丘，其夹粘层埋藏深度常在120-500cm左右，厚度在40-100cm之间，粘粉粒含量达到90%以上。夹粘沙丘人工梭梭固沙植被郁闭度在0.5以上，明显高于相同水热条件下的植被生产力，这可能与夹粘层通过改变土壤持水性及水分状况，从而提高了土壤水分承载力有关。以河西走廊绿洲边缘夹粘沙丘为研究对象，在测定0-8.0m剖面土壤物理性质和土壤水分特征曲线的基础上，计算了土壤孔隙分布和持水特性，研究了剖面中土壤持水性的变化规律及其影响因素。结果表明：（1）夹粘层土壤含水量最高，上覆沙土土壤含水量最少且随深度增加而增加，下伏沙土受地下水毛管作用影响水分含量较高；（2）土壤机械组成决定了不同土层的持水特性，土壤中粘粉粒含量越高，田间持水量和饱和含水量就越大，夹粘层的土壤持水性远高于沙土层；（3）夹粘层是沙丘土壤水分暂时贮存的重要土层，可以为植被提供深层土壤水分，这对绿洲边缘人工固沙植被的生存和繁衍有重要影响，而土壤持水性和毛管作用的强弱决定了夹粘层对沙丘水分调节能力的强弱。本研究为深入理解绿洲边缘雨养固沙植被斑块状分布的机理提供了一定的理论依据。 Abstract:A sandwich dune's profile consists of layers with different soil textures, the upper and lower of which are sandy soil layers, and there is a fine soil pan between the surface and the subsoil. The clay interlayer is composed of silty loam containing over 90% silt and clay. Deposits of this layer occur at depths of 120-500cm and it ranges in thickness from 40 to 100cm. In arid areas with precipitation of less than 200mm, artificial sand-fixing vegetation coverage is approximately 10% to 15%; however, the vegetation coverage of the study area with 117mm mean annual precipitation is approximately 65%, which does not meet the zonal water and heat conditions. Water retention is considered to play an important part in affecting the water conditions and soil water carrying capacity of dunes. With regards to water retention, Betti et al. have analyzed the effects of soil texture on water retention, revealing that when the sand content is increased, water retention becomes weaker, and the soil layer has a significant effect on the water-holding capacity, and their studies have focused on analysis of the water-holding capacity of homogeneous soil. In order to study the characteristics and mechanisms of the response of the clay interlayer to water retention, we measured the soil water characteristic curve based on the centrifuge test, particle size measured by Mastersizer-2000, and pore distribution based on the measured soil water characteristic curve and the calculated equivalent porosity at different depths of a sandwich dune. Our results show the following patterns. (1) The soil moisture content of the clay interlayer was the highest, soil water content increased slightly with depth in the surface soil, and the soil moisture of the subsoil was higher than in the surface, which was affected by the capillary action of groundwater. (2) Field capacity, wilting coefficient, saturated water content, total porosity, and aeration porosity were significantly correlated with soil physical properties, such as bulk density, sand content, clay content, and particle size. Sandy soil layers were at 0-4.0m and 4.6-8.0m. The soil water characteristic curves of these profiles were steep and the soil was loose (aeration porosity, 14%-27%) with poor soil water retention. The layer at 4.0-4.6m was an interbedded layer of silty loam, the soil water characteristic curves of which was smooth and the soil water content was high when the soil water suction was high.This type of soil had less aeration porosity, leading to higher soil water-holding capacity than the upper and lower sandy layers. Furthermore, correlation analysis showed that capillary porosity was not significantly correlated with soil physical properties, but was weakly related to soil water content, and increased significantly only at both the interface between the sandy layer and silty loam layer, and the water table. To a certain extent, the distribution of soil porosity affected the soil moisture content and water conveyance between the clay interlayer and the sand layer. In conclusion, soil textures lead to considerable differences in soil water retention of dunes at the edge of an oasis. The clay interlayer can hold more water compared with all profiles, which improves the water conditions of the dune. (3) The soil pan is the region where water collects, and provides water resources for plants. It plays an important role in the improvement of sand-fixing vegetation of dunes at the edge of an oasis. Further, the ability of the clay interlayer to regulate the water conditions of dunes depends on soil water retention and soil capillarity. In conclusion, our findings should provide strong support for future understanding of the mechanism of spatial patterns of artificial sand-fixing vegetation. 参考文献 相似文献 引证文献

The Effects of Fresh and Composted Chicken Manures on Some Soil Characteristics

ABSTRACTThe effects of fresh and composted chicken manures on some soil characteristics were investigated. Fresh and composted chicken manures were mixed with the soil at the rates of 0%, 1%, 2%, 3%, and 4%, and then were incubated for 90 days. At the end of this incubation period, some soil physical properties closely related to soil aggregation (such as hydraulic conductivity, water stable aggregates, aeration porosity, and available water) and some soil chemical characteristics (such as organic carbon, total nitrogen, pH, and electrical conductivity, EC) were determined. As doses of both manures in the soil mixtures increase, the amounts of water stable aggregates, hydraulic conductivity, and aeration porosity increased, whereas the available water content decreased. Increasing doses of both manures increased the amount of the soil organic carbon and total nitrogen. Application of both manures to the soil increased the EC values, but it was limited in the composted chicken manure.

Comparison of Selected Soil Properties following Grassland Set-Aside and Annual Crop Rotations in the Fraser River Delta of British Columbia

Selected soil properties were compared after 2–6 yr of grassland set-aside (GLSA) management and an annual cropping system (potato). In general, GLSA and nearby arable cropping fields had similar soil properties, with some improvements of aeration porosity, aggregate stability, bulk density, and mechanical resistance following short-term GLSA management.

Effect of soil salinity on the wheat and bean root respiration rate at low matric suctions

Water logging and salinity often occur together because rising water table brings salt to the surface. We studied the effects of a range of low soil matric suctions (or nearly paddy condition) (2–33 kPa) and salinity (EC = 0.7–8 dS m−1 for bean and 2–20 dS m−1 for wheat) on the root respiration (Rr) in two sandy loam and clay loam soils at greenhouse condition. Results showed that the aeration porosity mainly controls Rr especially at 2 kPa matric suction. As matric suction increases, soil aeration rises and consequently the Rr reaches maximum values (7.9 μmol m−3 s−1 for bean and wheat) at 6 and 10 kPa suctions in clay loam and sandy loam soils, respectively. Using a mechanistic soil respiration model reveals that these matric suctions, h, are corresponded to the aeration porosities of 0.18 m3 m−3 in sandy loam and 0.16 m3 m−3 in clay loam soils. Bean and wheat Rr remains nearly constant at higher suctions (h > 10 kPa) in sandy loam and decreases slightly in clay loam soil. Gas diffusivity and the root surface area may explain the variation of the Rr between the sandy loam and the clay loam soils. Results showed that the salinity (EC = 6–8 dS m−1 for bean and EC = 16–20 dS m−1 for wheat) amplifies the effect of aeration stress at 2 kPa matric suction in both soils. We also observed a strong correlation between root surface area, Rs, and the Rr for all experiments. We concluded that the aeration deficit is not only major factor determining differential plant respiration under adverse stress conditions, and the salinity has a pronounced impact on differences in crop physiological responses.

Changes in balk density and porosity of chernozem typical under different cultivation systems

Abstract The changes of density, total porosity and aeration porosity of chernozem typical under different tillage were studied. It was established that the density of 0–30 cm layer of chernozem typical was in the range of optimal values for corn. The density of the soil increased during corn vegetation. The most optimal density values were under different-depth cultivation to 25–27 ≿m with periodical loosening of soil to 50 ≿m (1,16–1,28 g/cm 3 ). The highest parameters of bulk density was at the variant of shallow soil cultivation to 10–12 ≿m. Total porosity parameters were the lowest in variant of sallow soil cultivation to 10–12 ≿m. Variant of different-depth cultivation to 25–27≿m had total porosity parameters as under plowing, and the most optimal values were under different-depth cultivation to 25–27 ≿m with periodical loosening of soil to 50 ≿m. All types of tillage provide a good soil porosity soil at the time of seedlings, except shallow soil cultivation. As for aeration porosity, it was for all the best under the cultivation of corn for grain and was over 20%. The highest yield of corn was at variant of different-depth cultivation to 25–27 ≿m with periodical loosening of soil to 50 ≿m.

DISTURBANCES CAUSED BY FLOODS IN THREE PHYSICAL PROPERTIES OF A VERTISOL SOIL IN THE EAST REGION OF CUBA, CULTIVATED WITH SUGARCANE (Saccharum spp.)

In Cuba the 40,3 % of cultivated lands is located in poorly drained soils, with tendency to increase, compounded by the effects of current climate change, which in this region of Cuba are becoming with more frecuency in extreme climatic events such as droughts and floods. The researh was developed with the objective of determing the influence of flooding in a Vertisol soil in three physical properties in the Cauto River Valley, of the Granma province. It was considered the presence or absence of flooding as the principal factor on large plots, each one divided into 30 plots of 48 m2, to facilitate take replicate samples. Two samplings, one at the beginning of the experiement and the other five months later, when the soil flooded concluded. The average of the bulk density, total porosity and aeration porosity values with their standard errors were plotted by bars, while statistically discriminated with the use of the Student t test. It is concluded that prolongated water excess in the soil increased bulk density and makes it significally decreases the total aeration and porosity, which affects physical fertility of these soils and a decrease of the sugarcane yield, the principal crop in Cuba yet.

Pore network of an Inceptisol under different uses and relativized S-index as an indicator of soil physical quality

Abstract The objective of this work was to evaluate soil porous media quality under different uses, as well as to propose a new index to monitor changes in its structure due to management: the Srelative index. An Inceptisol under irrigated banana cultivation and secondary forest, in the Brazilian Apodi Plateau, was evaluated at three soil layers (0.0-0.1, 0.1-0.2, and 0.2-0.3 m) as to: particle size, particle and bulk density, organic matter content, intrinsic permeability to air, and water retention curve. Total porosity, index for pore continuity (defined by the ratio between soil intrinsic permeability to air and aeration porosity), volume of blocked pores, and the S and Srelative indices were determined. The Srelative index was calculated as the ratio between S-index values from undisturbed and disturbed samples of the same soil (Sundisturbed/Sdisturbed). Under the studied conditions, the Srelative index is a good quantifier of the changes imposed by soil use and management. Soil cultivation maintains or improves the quality of the evaluated attributes, except for blocked porosity, when compared with the soil under native secondary forest with ten years of regeneration after agricultural use.

Soil physical quality on conilon coffee intercropping and monoculture

The objective of this study was to evaluate the effects of conilon coffee the unshaded and shaded with tree species on soil physical quality. Six treatments were studied: T1- coffee monoculture; T2, T3, T4 and T5- intercropping coffee with peach palm, gliricidia, banana and inga, respectively; T6- native vegetation in natural regeneration. Soil samples were collected at a depth of 0-0.10 m for determination of soil attributes. Similar values of soil bulk density, total porosity, organic matter and carbon stocks occurred in the coffee monoculture and intercropping managements. T2 and T3 showed a greater plant-available water capacity, with 142 and 135 L m-3, which resulted in higher soil moisture. Lower aeration porosity occurred in T2 and T3. The treatments presented non-limiting S index (S>0.035), with the exception of T4. The treatments presented critical bulk density of 1.32 Mg m-3. The increase in soil organic matter resulted in an increase of the S index. The managements of the conilon coffee plantation with peach palm and gliricidia presented improvements in soil physical quality. The choice of species used in intercropping with conilon coffee must be adjusted to the characteristics of the region and the farmer.

The coupling interaction of soil water and organic carbon storage in the long vegetation restoration on the Loess Plateau

Secondary succession can recover the properties of degraded soil. The moisture stored in different soil layers is recognized as an important driver of the productivity and sustainability of semi-arid terrestrial ecosystems, and land-use change has a significant effect on the global carbon (C) cycle through changing soil C accumulation rates. To evaluate the response of soil water storage (SWS) and soil organic carbon storage (SOCS) to long-term natural vegetation succession (∼150a) and the coupling interaction between them, we examined the soil moisture and soil organic carbon content in the land for different restoration ages in the Ziwuling Forest region located in the central part of the Loess Plateau, China. Our results showed that the SWS decreased and the SOCS increased with long-term natural vegetation restoration. The SOCS decreased along with the increase in the soil depth, and it was highest in the topsoil (0–20cm). In addition, the soil depth at which the SWS intensely varied and at which the SOCS tended to be stable moved downward and upward, respectively, with the vegetation succession. Furthermore, the correlation between SWS and SOCS was significant (P<0.05) in the long-term restoration and gradually weakened with the increase in the soil depth and the vegetation restoration stages. Clay, silt, sand, total porosity (TP), inactive porosity (IP), aeration porosity (AP) and capillary porosity (CP) were important factors that influenced the coupling interaction of SWS and SOCS at the grass restoration stages (<50a), and BD influenced this interaction in the shrub and early forest restoration stages (<130a). The effect of soil physical factors on the interaction of SWS and SOCS gradually weakened during the vegetation restoration succession. These results are expected to help improve the understanding of the response of deep soil water and soil organic carbon to long-term natural vegetation restoration and to provide insights into the coupling interaction between soil water and soil organic carbon influenced by vegetation.

Soil physical quality response to sugarcane expansion in Brazil

Globally, the rate of land-use change (LUC) is increasing rapidly to support biofuel feedstock production. In Brazil, sugarcane (Saccharum officinarum) expansion to produce ethanol is displacing degraded pastures. Intensive mechanization for sugarcane production, could impact soil physical quality in these areas. We evaluated a typical LUC sequence (i.e., native vegetation–pasture–sugarcane) on soil physical quality at three sites in the central-southern region of Brazil. The soil physical properties evaluated through on-farm and laboratory soil analyses were: bulk density, degree of compactness, macroporosity, microporosity and total porosity, water-filled pore space, indexes of soil water storage and aeration capacity, soil resistance to penetration, field-saturated hydraulic conductivity and stability structural index. Calculations of mean weight diameter for the soil aggregates and soil physical quality ratings from a visual evaluation of soil structure (VESS) were also included in this study. From those data we defined a minimum dataset for calculating an additive soil physical quality index (SPQI). Long-term conversion from native ecosystems to pasture increased soil compaction (i.e., higher bulk density, degree of compactness and resistance to penetration values), decreased aeration porosity and water hydraulic conductivity, and consequently, created an unbalanced ratio between water- and air-filled pore space in the soil. Based on our SPQI, the soil's capacity to perform its physical functions decreased from 90% under native vegetation to 73% under pasture. Land-use change from pasture to sugarcane induced slight soil physical quality degradation, in which soil function was 68 and 56% of capacity. Overall, soil physical quality decreased under sugarcane fields, due to decreases in soil porosity, aeration and water hydraulic conductivity as well as increases in soil penetration resistance, structural degradation and erosion risk. Tillage operations performed during the sugarcane replanting (~5years) had a short-term positive effect on soil physical quality, although over time it further decreased the resistance to erosion and structural degradation. Therefore, to convert degraded pasture to sugarcane in a sustainable manner, the soils should be managed in ways that increase the soil organic matter and minimize compaction. These actions are needed to prevent further soil physical quality degradation and to improve both economic and environmental sustainability of sugarcane ethanol production.

Interaction of soil water storage dynamics and long-term natural vegetation succession on the Loess Plateau, China

Soil water is a key terrestrial water resource, particularly in arid and semi-arid regions of the world such as the Loess Plateau of China. Information on the dynamics of soil moisture following vegetation restoration is essential for managing water resources and can be helpful for adjusting relevant government policies. To evaluate the response of soil water storage (SWS) to long-term natural vegetation succession (~160a), we examined the soil moisture for different restoration ages in the Ziwuling forest region, which is located in the central part of the Loess Plateau. Our results showed that the SWS decreased with long-term natural vegetation restoration. The bulk density (BD), soil water content (SWC), and clay and silt content presented similar trends to those of the SWS throughout the entire vegetation succession. The SWS was significantly and positively correlated with the SWC and aeration porosity (P<0.05). The SWC was lower in the upper soils (0–50cm) than in the deeper soils (>50cm) at every restoration stage, as was the SWS; however, the SWS in the 200–300cm soil layer was the highest (164.61–212.80mm) compared to other layers in all restoration stages. These results are expected to help improve the understanding of the response of deep soil water to long-term natural vegetation restoration and to provide insights into the dynamics of deep soil water influenced by vegetation.