Reduced Bulk Density Research Articles

Utilization of Non-Traditional Fibers for Light Weight Concrete Production

Along with energy savings for heating and cooling, the demand for thermal insulation materials is increasing and is an attempt to achieve good thermal insulation properties for some of the construction materials. In the field of porous and lightweight concrete, this is e.g. concrete for foundations, concrete for floor constructions or flat roofs. The problem with these concrete is a relatively rapid drop in mechanical properties in reducing bulk density, with using conventional silicate binders, especially in the area below 1000 kg/m3. The paper describes the possibility of using recycled organic fibers in combination with lightweight aggregates based on foam glass for the production of porous and lightweight concrete with a good ratio of mechanical and thermal insulation properties.

Effect of Germination on Nutritional Composition and Functional Properties of Fenugreek (Trigonellafoenum-graecum Linn) Seed Flour

This study evaluated the effect of germination on the chemical composition and functional properties of fenugreek seed flour. The study was conducted at Addis Ababa Institute of Technology in Food Engineering laboratory. Fenugreek seed was germinated for 0, 24, 48 and 72 hrs. Germinated fenugreek flour had higher crude protein 29.89% in fenugreek flour germinated for 72 hrs followed by 29.36% in fenugreek flour germinated for 48 hrs and 27.42% in raw fenugreek flour. The crude fiber ranged from 11.349 to 14.70%. But as the time of germination increased the crude fiber content slightly decreased. Fenugreek flour germinated for 48 hrs proved to be more beneficial in most mineral content than the rest of the germination periods (p<0.05). Germinated fenugreek flour for 72 hrs had significantly lower contents of anti-nutritional factors. The phytate content decreased significantly (p<0.05) from 64.22 to 18.99 with 53.96% reduction. The study showed that fenugreek flour germinated for 72h proved to be the best for highest nutrient content. The reduction of bulk density further increased as germination time increased. The control fenugreek flour have higher amount of water absorption capacity (401.86%). On germination the water absorption capacity decreased to 250.07, 248.13, and 245.15% at 24, 48, 72 hrs germination, respectively. The processed fenugreek flour had a higher oil absorption capacity in the range of 346.13-398.40 ml/g, which was significantly (p<0.05) higher than that of control flour. Therefore, the use of processed fenugreek seed flour can be exploited in functional foods as well as a therapeutic agent on a regular basis.

Effect of Germination on Nutritional Composition and Functional Propertiesof Fenugreek (&amp;lt;i&amp;gt;Trigonellafoenum-graecumLinn&amp;lt;/i&amp;gt;) Seed Flour

This study evaluated the effect of germination on the chemical compositionand functional propertiesof fenugreek seed flour. Germinated fenugreek flour had higher crude protein 29.89% in fenugreek flour germinated for 72h followed by 29.36% in fenugreek flour germinated for 48h and 27.42% in raw fenugreek flour. The crude fiber ranged from 11.349 to 14.70%. But as the time of germination increased the crude fiber content slightly decreased. Fenugreek flour germinated for 48h proved to be more beneficial in most mineral content than the rest of the germination periods (p<0.05). Germinated fenugreek flour for 72 hrhad significantly lower contents of anti-nutritional factors. The phytate content decreased significantly (p<0.05) from 64.22 to 18.99 with 53.96% reduction. The study showed that fenugreek flour germinated for 72h proved to be the best for highest nutrient content. The reduction of bulk density further increased as germination time increased. The control fenugreek flour have higher amount of water absorption capacity (401.86%). On germination the WAC decreased to 250.07, 248.13, and 245.15% at 24, 48,72h germination, respectively. The processed fenugreek flour had a higher oil absorption capacity in the range of 346.13-398.40 ml/g, which was significantly (p<0.05) higher than that of control flour.

Development of Saw Band Cylinder-type Single Locking Cotton Feeder for Double Roller Gin

Low capacities of double roller (DR) gins provides an economic barrier to its widespread application. Feeding mechanism to DR gin plays a significant role in enhancing ginning efficiency. Saw band cylinder-type single-locking feeder was developed with an aim to unlock the cotton bolls and maintain constant feeding rate of individual locules. It comprised of twin regulator, reservoir box, saw band cylinders and feeding apron. It regulated feed rate to about 220-240 kg.h-1. The performance was evaluated in comparison to conventional feeding system. Saw band cylinder speed and cotton moisture content were optimized by using RSM. Quadratic equations for prediction of ginning output and specific energy were generated by using RSM. The ginning output and reduction in bulk density increased by 6.47 % and 22.57 %, respectively, whereas the specific energy decreased by 3.25 per cent. Multiple response analysis showed the optimum levels of moisture content of 7.32 % (w.b.) and saw cylinder speed of 200 rpm with desirability of 0.936 by maximazing output and minimizing specific energy. Cotton quality was found to improve in terms of colour grade due to increase in degree of reflectance and reduction in yellowness.

Biochar in the Agroecosystem-Climate-Change-Sustainability Nexus.

Interest in the use of biochar in agriculture has increased exponentially during the past decade. Biochar, when applied to soils is reported to enhance soil carbon sequestration and provide other soil productivity benefits such as reduction of bulk density, enhancement of water-holding capacity and nutrient retention, stabilization of soil organic matter, improvement of microbial activities, and heavy-metal sequestration. Furthermore, biochar application could enhance phosphorus availability in highly weathered tropical soils. Converting the locally available feedstocks and farm wastes to biochar could be important under smallholder farming systems as well, and biochar use may have applications in tree nursery production and specialty-crop management. Thus, biochar can contribute substantially to sustainable agriculture. While these benefits and opportunities look attractive, several problems, and bottlenecks remain to be addressed before widespread production and use of biochar becomes popular. The current state of knowledge is based largely on limited small-scale studies under laboratory and greenhouse conditions. Properties of biochar vary with both the feedstock from which it is produced and the method of production. The availability of feedstock as well as the economic merits, energy needs, and environmental risks—if any—of its large-scale production and use remain to be investigated. Nevertheless, available indications suggest that biochar could play a significant role in facing the challenges posed by climate change and threats to agroecosystem sustainability.

Insecticidal efficacy of beauveria bassiana, diatomaceous earth and fenitrothion against rhyzopertha dominica and tribolium castaneum on stored wheat

ABSTRACTBioassays were conducted in stored grains to evaluate the combined use of the entomopathogenic fungus Beauveria bassiana, diatomaceous earth (DE) and fenitrothion against adults of Rhyzopertha dominica and Tribolium castaneum. The insecticide agents were applied to wheat as follows: the fungus at 1 × 108 conidia/kg of wheat, DE at 3 g/kg of wheat and fenitrothion at a rate of 0.15 ml/kg of wheat (25% of field dose rate). Surviving insects and progeny production were monitored at thirty-day intervals until four months. For both insect species, significantly less progeny was produced on wheat treated with fenitrothion and DE + B. bassiana formulations in comparison with controls. The effect of insecticides on the grain damage, germination power of wheat and bulk density was also evaluated. After four months, B. bassiana mixed with DE reduced the damaged insect grains by 50% in comparison with both fenitrothion and control treatments. Trials using DE caused a reduction in bulk density while there were no significant differences for germination testing between treatments.

EFFICACY OF NINE CROATIAN INERT DUSTS AGAINST RICE WEEVIL SITOPHILUS ORYZAE L. (COLEOPTERA: CURCULIONIDAE) ON WHEAT

Laboratory bioassay was carried out to study the insecticidal effect of 9 Croatian inert dusts against Sitophilus oryzae (L.) and to test their influence on bulk density of treated wheat. In order to compare effectiveness of Croatian inert dust samples, a standard USA diatomaceous earth (DE) Celatom® Mn 51, registered as an insecticide for stored-products protection, was used. Wheat kernels with approximately 13% moisture content were treated with inert dusts at doses 300, 400, 500 and 600 ppm and mortality of S. oryzae adults was assessed after 7 and 14 days and progeny after 49 days. The most effective Croatian inert dust samples were D-02B, D-01 and MA-4 with the LD90 values of 359.6, 447.2 and 458.7 ppm, respectively. In addition, effective dose that reduced F1 progeny in half was lower in regard to the other tested samples including the standard DE Mn 51, with the ED50 values 71.9, 54.6 and 137.6 ppm, respectively. According to the XRF analytical results, the highest amount of biogenic silica (BSi) was found in samples D-02B, D-01 and MA-4 (45.98, 35.09 and 21.28%, respectively). Paleontological data analysis confirmed diatoms species in only 5 samples of Croatian inert dusts (D-01, D-02B, PD-1, MA-4 and JU-1). All tested inert dusts affected reduction in bulk density of treated wheat at the LD90 concentrations, from 4.4 (D-02B) to 5.6 (JU-1) kg hL-1. More effective inert dusts at lower doses equally reduced bulk density as less effective inert dusts at much higher doses.

The in vitro biological assessment of a novel hybrid tobacco product and comparison with a cigarette smoke

Discarded cigarette butts (CBs) are among the most common types of litter found around the world. As a possible solution to this problem, this study investigated the possibility of encapsulating CBs with different classes of bitumen and paraffin wax, and incorporating them into asphalt concrete (AC) for pavement construction. The idea behind encapsulation involves restricting the interaction of CBs with fluids and thus preventing chemical translocation. This paper presents and discusses the results of two investigations. The first involved assessing the effects of incorporating different amounts of CBs (10 kg/m3, 15 kg/m3 and 25 kg/m3) encapsulated with different classes of bitumen (C170, C320, C600) into an AC mix manufactured with Class 170 bitumen. The second involved assessing the effects of incorporating 10 kg/m3 of CBs encapsulated with paraffin wax into AC mixes that were manufactured with different classes of bitumen (C170, and C320). All samples, including the control AC samples (no CBs), were tested for mechanical and volumetric properties, including stability, flow, resilient modulus, bulk density, maximum density, air voids, and voids in mineral aggregates. For the first investigation, involving encapsulation of CBs with bitumen, using 10 kg/m3 and 15 kg/m3 of CBs in an asphalt mix gave results that satisfied the requirements for light, medium and heavy traffic conditions. For the second investigation, involving encapsulation of CBs with paraffin wax, the changes in mechanical and volumetric properties for 10 kg/m3 CBs only satisfied the light traffic conditions for road pavements. The reduction in bulk density of AC caused by incorporating encapsulated CBs, increases the porosity, particularly when encapsulating in higher grade bitumen, which, in turn, lowers its thermal conductivity. This helps reduce the Urban Heat Island effect in urban environments.

A multi-year study of tillage and amendment effects on compacted soils

Constructing roads and buildings often involves removal of topsoil, grading, and traffic from heavy machinery. The result is exposed, compacted subsoil with low infiltration rate (IR), which hinders post-construction vegetation establishment and generates significant runoff, similar to impervious surfaces. Our goal was to assess tillage and adding amendments for improving density and maintaining perviousness of subsoils compacted during construction. The effects of tillage with and without amendments on (1) soil compaction, (2) IR, and (3) vegetative growth at five sites in North Carolina, USA were evaluated over a period of up to 32 months. The sites, representing a range of soil conditions, were located at three geographic regions; one in the Sandhills (located in Coastal Plain), one in the mountains, and three in the Piedmont. Amendments varied by site and included: (1) compost, (2) cross-linked polyacrylamide (xPAM), and (3) gypsum. Bulk density (BD) and soil penetration resistance (PR) tests were used to characterize soil physical condition. The IR was measured using a Cornell Sprinkle Infiltrometer. Vegetative growth was evaluated by measuring shoot mass and vegetative cover at all sites and root density at the Piedmont sites. Tillage decreased BD and PR compared to the compacted soil at four out of five sites for observations ranging from 24 to 32 months. Compost was applied to four sites prior to tillage and reduced BD in two of them compared to tillage alone. The IR in the tilled plots was maintained at about 3–10 times that of the compacted soil among the five sites over the monitoring periods. Adding amendments did not increase IR relative to tillage alone except at one Piedmont site, where compost and xPAM increased IR at 12 months and compost at 24 months after site establishment. Vegetative responses to tillage and amendments were inconsistent across sites. Results suggest that tillage is a viable option to reduce bulk density and increase infiltration for areas with compacted soils where vegetation is to be established, and that the effect is maintained for at least several years.

Biogas digestates based on lignin-rich feedstock – potential as fertilizer and soil amendment

ABSTRACTWith advances in biogas technology, lignocellulosic material may be increasingly included in feedstock due to the abundance of raw materials. The main goal of this study was to evaluate fertilizing and soil amendment effects of digestates based on lignin-rich feedstock. The digestates originated from reactors fed with manure co-digested with Salix, wheat straw or sugarcane bagasse, respectively. In pot experiments with three different soils, Italian ryegrass and reed canary grass were grown with 120 kg ha−1 total nitrogen or 150 kg ha−1 available nitrogen, respectively, given as either mineral fertilizer or digestate. Soil chemical and physical characteristics were determined after ended experiments. Additionally, an incubation study was carried out to estimate N mineralization from one digestate over time. Digestate addition resulted in similar yields compared to mineral fertilizer, varying from 0.5 (loam) to 1 kg dry matter m−2 (silt) for Italian ryegrass and 1.2 (loam) to 2.3 kg m−2 (silt) for reed canary grass. Digestates contributed to a favourable pH for plant growth, reduced bulk density in the loam and improved water retention characteristics in the sand. Biogas digestates based on lignin-rich feedstock appear promising as fertilizers and for soil amelioration but results have to be verified in field experiments.

Physico-mechanical properties of asphalt concrete incorporated with encapsulated cigarette butts

Discarded cigarette butts (CBs) are among the most common types of litter found around the world. As a possible solution to this problem, this study investigated the possibility of encapsulating CBs with different classes of bitumen and paraffin wax, and incorporating them into asphalt concrete (AC) for pavement construction. The idea behind encapsulation involves restricting the interaction of CBs with fluids and thus preventing chemical translocation. This paper presents and discusses the results of two investigations. The first involved assessing the effects of incorporating different amounts of CBs (10kg/m3, 15kg/m3 and 25kg/m3) encapsulated with different classes of bitumen (C170, C320, C600) into an AC mix manufactured with Class 170 bitumen. The second involved assessing the effects of incorporating 10kg/m3 of CBs encapsulated with paraffin wax into AC mixes that were manufactured with different classes of bitumen (C170, and C320). All samples, including the control AC samples (no CBs), were tested for mechanical and volumetric properties, including stability, flow, resilient modulus, bulk density, maximum density, air voids, and voids in mineral aggregates. For the first investigation, involving encapsulation of CBs with bitumen, using 10kg/m3 and 15kg/m3 of CBs in an asphalt mix gave results that satisfied the requirements for light, medium and heavy traffic conditions. For the second investigation, involving encapsulation of CBs with paraffin wax, the changes in mechanical and volumetric properties for 10kg/m3 CBs only satisfied the light traffic conditions for road pavements. The reduction in bulk density of AC caused by incorporating encapsulated CBs, increases the porosity, particularly when encapsulating in higher grade bitumen, which, in turn, lowers its thermal conductivity. This helps reduce the Urban Heat Island effect in urban environments.

Root competition, not soil compaction, restricts access to soil resources for aspen on a reclaimed mine soil

Restricted rooting space in response to soil compaction and belowground competition with herbaceous plants are two main limiting factors for successful reforestation after surface mining. Fine-textured, nutrient-rich soils with adequate soil moisture are particularly susceptible to both of these concerns and while there are recognized ways to manage competition, attempts to alleviate soil compaction through mechanical means have produced varying results. While roots of some herbaceous plants may penetrate compacted soil layers, possibly offering an alternative means to overcome physical restrictions, these potential benefits need to be weighed against negative effects from competition with planted trees. We examined the individual and combined impact of soil decompaction (deep tillage) and management of competing vegetation (herbicide) on soil properties, resource availability, and above- and below-ground growth of aspen (Populus tremuloides Michx.) seedlings on a reconstructed mine soil affected by severe subsoil compaction. Our findings suggest that although deep tillage reduced bulk density, this did not increase resource availability and had limited effect on seedling growth. In contrast, competition with smooth brome grass (Bromus inermis Leyss.) drastically reduced aspen belowground growth because the grass rapidly occupied available rooting space, while simultaneously lowering the availability of water and nutrients, in particular nitrogen.

Vermicompost and Gypsum Amendments Improve Aggregate Formation in Bauxite Residue

AbstractImproving aggregate formation and stability of bauxite residue is essential for the development of a soil on the residue. Effects of gypsum and vermicompost on related chemical and physical conditions of bauxite residue were studied in a laboratory incubation experiment. The addition of gypsum at 2% and 4% w/w reduced pH and exchangeable sodium percentage while increasing exchangeable calcium content. The addition of vermicompost reduced bulk density while significantly increasing porosity and total organic carbon. Vermicompost had a positive effect on the formation and stabilization of water‐stable aggregates in the residue, while gypsum was more beneficial to silt‐sized microaggregate flocculation. Amendments also enhanced the erosion resistance of bauxite residue. Furthermore, wet sieving using the modified Le Bissonnais' method revealed that in comparison with differential clay swelling and mechanical breakdown, slaking was the major disaggregation mechanism of residue aggregates. The combination of gypsum and vermicompost converted the residue from a sheet‐like structure to a granular macroaggregated structure while converting microaggregates from a grain to a granular or prismatic structure. The findings of this work suggest that application of gypsum and vermicompost to bauxite residue may directly influence aggregate size distribution and its micromorphology, resulting in the improvement of both aggregate stability and structure. Copyright © 2017 John Wiley &amp; Sons, Ltd.

FIELD EVALUATION OF SOIL AND WHEAT RESPONSES TO COMBINED APPLICATION OF HARDWOOD BIOCHAR AND INORGANIC FERTILIZERS IN ACIDIC SANDY LOAM SOIL

SUMMARYBiochar application appears to be a promising method to improve soil physicochemical and biological properties by increasing soil carbon. Along with the influence of hardwood biochar on wheat growth, yield and soil quality for a period of two years, this study also evaluates the major soil parameters to be taken as minimum data set while assessing the impact of hardwood biochar in an acidic sandy loam soil. Five fertilizer treatments combining inorganic fertilizers and biochar were applied: unfertilized control (T1); 100% NPK (T2); 5 Mg ha−1 biochar (T3); 100% NPK + 5 Mg ha−1 biochar (T4); and 50% N + 100% PK + 5 Mg ha−1 biochar (T5). Biochar application (T3 vs. T1; T4 and T5 vs. T2) significantly increased leaf chlorophyll content, net photosynthesis rate, leaf N concentration and above and below-ground biomass, with improved wheat yield and grain quality (total grain protein and carbohydrate). Soil pH, water-holding capacity, available nutrients (N, P and K), organic carbon and its fractions also enhanced in biochar applied plots with reduced bulk density. Increased activities of soil enzymes urease, phosphatase, dehydrogenase, fluorescein di-acetate and arylsulphatase were recorded in biochar treatment along with significant increase in N recovery index (22%) and agronomic efficiency (40%). Multivariate analysis identified activity of phosphatase, pH and humic acid to fulvic acid ratio as the indicators to explain the total variance from biochar addition in acidic sandy loam soil under wheat cultivation. Soil quality index showed a significant improvement when biochar was added with reduced N doses (T5). This study confirms the efficacy of biochar as a soil conditioner when applied with reduced N fertilizer and would be a sustainable option to improve wheat production and soil quality in acidic sandy loam soils of northeast India.

Effect of dung beetle species richness and chemical perturbation on multiple ecosystem functions

1. The relationship between biodiversity and ecosystem functioning is typically positive but saturating, suggesting widespread functional redundancy within ecological communities. However, theory predicts that apparent redundancy can be reduced or removed when systems are perturbed, or when multifunctionality (the simultaneous delivery of multiple functions) is considered.2. Manipulative experiments were used to test whether higher levels of dung beetle species richness enhanced individual functions and multifunctionality, and whether these relationships were influenced by perturbation (in this case, non‐target exposure to the veterinary anthelmintic ivermectin). The four ecosystem functions tested were dung removal, primary productivity, soil faunal feeding activity and reduction in soil bulk density.3. For individual functions, perturbation had limited effects on functioning, with only dung removal significantly (negatively) affected. Species richness did not, on its own, explain significant variation in the delivery of individual functions. In the case of primary productivity, an interaction between richness and perturbation was found: species‐rich dung beetle assemblages enhanced forage growth in the unperturbed treatment, relative to the perturbed treatment.4. Using a composite ‘multifunctionality index’ it was found that species‐rich dung beetle assemblages delivered marginally higher levels of multifunctionality in unperturbed conditions; however, this benefit was lost under perturbation. Using a relatively new and robust method of assessing diversity–multifunctionality relationships across a range of thresholds, no significant effect of species richness on multifunctionality was found.

Soil hydro-physical characteristics and water retention function of typical shrubbery stands in the Yellow River Delta of China

The shell ridge worldwide that presents a combination of old and new shell ridges is located in the Yellow River Delta of China. The water storage and retention capacities of the shell sand soil are key factors for the growth and development of vegetation and act as important indicators in evaluations of vegetation-related soil and water conservation. We investigated the hydrological and physical characteristics of the soil and the interactions of these characteristics for the following dominant shrubbery stands on the shell ridge: Tamarix chinensis Lour, Periploca sepium Bunge and Ziziphus jujuba var. Spinosa. The different shrubbery stands presented significantly different physical shell sand parameters, such as water storage capacity, permeability and water-holding capacity. Compared with the bare soil, the shrubbery-covered shell sand soils showed significantly reduced bulk densities; increased porosities, water storage capacities, infiltration rates and water-holding capacities; and reduced particle sizes. The shrubbery increased the amount of soil water-stable aggregates and reduced the amount of soil air-dried aggregates, and the fractal dimension of the soil water-stable aggregates was significantly higher than that of the air-dried aggregates. T. chinensis shrub growth yielded a better soil aggregate structure compared with that of Z. jujuba, whereas the P. sepium shrub yielded the poorest structure. The soil porosity and the mean weight diameter of the soil aggregates were the major factors that affected the water retention capability of the shell sand. The best water retention capability was observed with the T. chinensis shrub stand followed by the Z. jujuba and P. sepium stands, whereas the bare soil exhibited the poorest results. Our results indicate that T. chinensis seedlings are the best choice for planting to improve soil porosity and soil aggregates on the shell ridges of the Yellow River Delta.

Evaluation of soil health in organicvs. conventional farming of basmati rice in North India

AbstractConventional agricultural practices that use excessive chemical fertilizers and pesticides come at a great price with respect to soil health, a key component to achieve agricultural sustainability. Organic farming could serve as an alternative agricultural system and solve the problems associated with the usage of agro‐chemicals by sustainable use of soil resources. A study was carried out to evaluate the impact of organicvs. conventional cultivations of basmati rice on soil health during Kharif (rainy) season of 2011 at Kaithal district of Haryana, India, under farmers' participatory mode. Long‐term application of organic residues in certified organic farms was found to improve physical, chemical, and biological indicators of soil health. Greater organic matter buildup as indicated by higher soil organic carbon content in organic fields was critical to increase soil aggregate stability by increasing water holding capacity and reducing bulk density. Proper supplementation of nutrients (both major and micro nutrients) through organic residue addition favored biologically available nutrients in organic systems. Further, the prevalence of organic substrates stimulated soil microorganisms to produce enzymes responsible for the conversion of unavailable nutrients to plant available forms. Most importantly, a closer look at the relationship between physicochemical and biological indicators of soil health evidenced the significance of organic matter to enzyme activities suggesting enhanced nutrient cycling in systems receiving organic amendments. Enzyme activities were very sensitive to short‐term (one growing season) effects of organicvs. conventional nutrient management. Soil chemical indicators (organic matter and nutrient contents) were also changed in the short‐term, but the response was secondary to the biochemical indicators. Taken together, this study indicates that organic farming practices foster biotic and abiotic interactions in the soil which may facilitate in moving towards a sustainable food future.

Effect of gypsum and rice straw compost application on improvements of soil quality during desalination of reclaimed coastal tideland soils: Ten years of long-term experiments

The objective of this study was to investigate the effectiveness of applying gypsum and rice straw compost on improvements in soil quality during the desalination of previously reclaimed coastal tideland soils. The four treatments were control (without amendment), gypsum, rice straw compost, and gypsum+rice straw compost. The experiments were carried out in a completely randomized design with three replicates. Saturated electrical conductivity (ECe) and exchangeable sodium percentage (ESP) values of soils treated with gypsum, or gypsum+rice straw compost, reached the salinity and sodicity classification limits of 4dSm−1 and 15% (US Salinity Laboratory Staff, 1954), respectively, after eight years of leaching experiments. However, despite 10years of leaching experiments, neither the control nor the rice straw compost alone treatment reached the salinity and sodicity classification limits. The addition of gypsum and rice straw compost resulted in a reduction in soil bulk density and a corresponding increase in soil porosity in highly saline-sodic soils (p≤0.05). The results of mean weight diameter (MWD) showed that the application of soil amendments increased MWD significantly (p≤0.05); the highest MWD was observed for the gypsum+rice straw compost treatment and was twice the magnitude of the control.

Comparison of soil amendments for reforestation with a native multipurpose tree under semiarid climate: Root and root tuber response of Spondias tuberosa

The Caatinga biome, characterized by a species-rich seasonally dry tropical forest, but highly disturbed covers most of Brazil's Northeast. Endemic to this biome is the multipurpose tree Spondias tuberosa Arr., which forms numerous root tubers to resist drought stress. In order to develop improved soil management for reforestation with S. tuberosa the response of its root system to different soil amendments was studied with 52 seedlings, using goat manure, clay substrate, biochar as soil amendments, and mineral fertilizer. The default root architecture of three-year-old S. tuberosa and the relation between soil physical parameters and fine root dry matter (≤2mm), root length density, root tuber volume, root tuber fresh weight, and shoot-root ratio were analyzed.Seedlings still formed a tap root with a maximum rooting depth of 63cm and a maximum horizontal extent of 35cm, developing 2–4 root tubers per seedling. Fine root dry matter in 3000cm3 soil samples differed significantly, ranging from 0.23g in the control to 0.03g in the treatment combining manure with biochar and mineral fertilizer. According to the orthogonal contrast, manure was the pivotal soil amendment affecting fine root dry matter negatively. Simultaneously, manure application led to increased soil water content compared to treatments without . The shoot-root ratio increased by 32% compared to the control, when S. tuberosa was grown in wet soils. Root tuber growth was significantly enhanced by manure addition. This effect is attributed to a reduction of soil bulk density as root tuber volume exhibited a negative correlation with soil bulk density. There was no statistical relationship between root tuber volume and seedling survival during the field experiment. Compared with the control, neither clay, biochar nor solely mineral fertilization significantly affected root growth.Soil management focused on improving water availability is suspected of hampering fine root growth of S. tuberosa seedlings, whereas reducing soil bulk density enables better root tuber development and could, therefore, be a promising measure to increase S. tuberosa drought resistance in the long term for more successful reforestation. Disregarding its negative impact on fine root growth, we assume manure is the most promising amendment among the tested treatments, due to its positive effect on root tuber growth.

Evaluation of Expanded Black Cotton Soil as a Hydroponics Medium

The traditional system of producing crops using soil (geoponics) is currently facing major challenges resulting in food deficits. An alternative is the adoption of soil-less culture (hydroponics) which is regarded as key in increasing production of vegetables, herbs and ornamentals. The study aimed at preparing a hydroponic medium from black cotton soil and rice husks. This involved moulding, firing and size reduction. The aggregates were evaluated based on dry bulk density and saturated hydraulic conductivity. The optimal conditions for preparing the medium was found to be at 750°C, 30 minutes and 9:1 for firing temperature, time and ratio of black cotton soil to rice husk (on a weight basis). This process resulted in 33% reduction in bulk density from 1.43 g cm-3 to 0.954 g cm-3 while the saturated hydraulic conductivity improved from 0.333*10-5 cm s-1 to 0.00385 cm s-1, a value that lies between the ranges of Sandy Loam and Loamy Sand. The process improved black cotton soil into a light weight aggregate medium with reduced bulk density, loose and friable aggregates, easy to drain and having moderate permeability to permit water and nutrient movement. The medium is therefore better suited to grow potted plants under indoor or outdoor conditions.