Reduced Bulk Density Research Articles

Effect of Tillage Practices and Cropping Pattern on Soil Properties and Crop Yield in the Humid Lowlands of Beles Sub-Basin, Ethiopia

Tillage is a land management practice where a sequence of manipulating the soil for crop production. To investigate the response of land management and cropping pattern on soil properties and crop yield, a field experiment was conducted under natural environment on Nitisol of Pawi area. Nine treatments combining two tillage methods (Zero and conventional), four crop covers (continuous maize, continuous soya bean, rotated maize, and maize soya bean intercrop) were laid out in RCBD with three replications. The result showed that land management and crop cover significantly affect bulk density, porosity, soil moisture, nitrogen, organic carbon, available phosphorus, and yield of a crop. Relative to conventionally tilled continuous maize, maize soya bean intercropping managed under zero tillage improve capillary porosity, non-capillary porosity, organic carbon, available phosphorus, and total nitrogen with a response ratio of 1.7, 2.7, 1.3, 2, and 1.3, respectively while reducing bulk density by 10%. Conversion of tillage system from conventional to zero tillage improves grain yield, biomass yield, and soil moisture by 6%, 10%, and 6%, respectively. Generally, zero tillage with greater cover is an appropriate approach to improve soil properties without negatively affecting grain yield. To understand and quantify the long-term impact of tillage and crop cover on soil health and productivity in Ethiopia long-term study is needed as this study was based on one-year data from four years permanent plots.

Effect of Land Use and Slope Position on Infiltration Characteristics on Sandstone-Derived Soils of Southern Nigeria

A study of some soil properties that influence infiltration under different land use types and slope positions in sandstone-derived soils was carried out in Akwa Ibom State, Southern Nigeria. Soil samples were collected in triplicate for laboratory analyses and infiltration tests were conducted using the double ring infiltrometer method. Analysis of variance, correlation and regression analyses were used to assess the data Oil Palm Plantation and Fallow Land increased the organic matter content of the soil, reduced bulk density, increased the soil porosity and aggregate stability over Continuously Cultivated Land. Downslope soil movement caused the upper slopes to lose their clay and organic matter to the middle and lower slope soils. Initial infiltration rate, final infiltration rate, cumulative infiltration, sorptivity and transmissivity varied highly across the studied locations but were not significantly (P ≤ 0.05) affected by land use, slope position and their interactions. Apparently higher infiltration rates were observed in all slope positions under Oil Palm Plantation and Fallow Land as a result of their apparently higher clay contents, total porosity, mean weight diameter, saturated hydraulic conductivity and organic matter contents over those of Continuously Cultivated Land. Heavier organic matter input will help to modify the upper slope soils for increased infiltration rates. Plantation agriculture should be adopted and continuous cultivation discouraged to increase water infiltration on sloppy terrains of the study area.

Modeling Cotton Module Builder and Loader to Enhance Biomass Testing

HighlightsPhysical models of module builder and module loader were developed to enhance biomass testing with reduced mass and volume of biomass.Models used dimensional analysis, Pi Terms, and engineering factors and emphasis on reduced module upsetting and disturbance.Some engineering terms such as tamping face pressure and velocity, and particle size were not scaled to reduce biological-material distortions.Switchgrass bulk density at 8% wet basis for prototype and model were 115 and 80 kg m-3, respectively.Abstract. The objective was to design and implement separate models of a first-generation cotton module builder and a module loader that facilitated tamping quasi-confined biomass and the minimal disturbances of modules during emptying from the builder and during loader operations including unloading. The 122-cm long model, compared to 978-cm long prototype, reduced the mass of module contents required for testing from 6188 to 44 kg, or by a factor of 141:1. The tamping process was emphasized with constant tamper pressure of 76.6 kPa applied to module contents for prototype and model. Consistent properties such as SG characteristic length were also held constant among module sizes to reduce the complications of introducing un-anticipated biological-material distortions. Similarities in design aspects beyond dimensional analysis were emphasized to reduce inadvertent module upset and disturbance. Hydraulics ensured uniform tamping and lifting. An efficient module box for the model resembled the prototype-scale commercial unit with z-shaped ribs and upward-tapered module sides. Seed cotton [8% moisture wet basis (w.b.)] bulk densities for prototype and model were 166 and 107 kg m-3, respectively. Bulk densities for switchgrass (8% w.b.) prototype and model were 115 and 81 kg m-3, respectively. Reduced bulk density of models was attributed to essentially no external confinement stresses being applied to modules at rest resulting in only self-imposed confinement stresses due to module content over-burden. However, unconfined modules may have a role in handling biomass for reduced distances. Also related to minimizing module upsetting, module loading emphasized the counter-motions of advancing the loader versus the conveyor motion in the opposite direction, all driven with an electric motor. Module stability during loading was attributed to a self-imposed normal stress of module weight acting downward onto a horizontal plane of the module. The fixed loading angle of 15° and material bulk properties were held constant between prototype and model. Dependent variable for the module loader was normal stress for module stability. Normal stresses resulting from seed cotton at 8% moisture content (wet basis) were 4.754 and 0.637 kPa, respectively. Normal stresses for chopped SG at 8% moisture content (wet basis) were 3.302 and 0.484 kPa, respectively. Biomass modules would not be as stable as cotton modules based on normal stress, and due to lack of intermeshing cotton fibers. Results of loading and unloading a dozen SG model modules resulted in one module failure due to upset, and that was attributed to a 2-layer fill versus 3-layer fill for that one module. Keywords:

Convective Baking Characteristics and Effective Moisture Diffusivities of Yellow Mealworms

Yellow mealworm is an alternative protein source studied by researchers to provide an alternative supply of protein to meet the growing demands of human consumption. In this research, convective baking of yellow mealworms at 80°C, 100°C, and 120°C was carried out to study the baking kinetics and product quality. Studies showed the typical falling trend of the moisture ratio curves, which are typical for most bioproducts that undergo hot air treatment. Mathematical modelling showed that the Page model gave a good prediction on the baking kinetics with high fitting accuracy (R2>0.99). Effective diffusivities were determined from 1.66 x 10-11 to 2.88 x 10-11 m2/s within the temperatures tested. The activation energy was estimated at 15.7 kJ/mol based on the Arrhenius equation. The final baked samples appeared darker in color because the browning reaction and reduction in bulk density and product length were observed in the range of 48-54% and 3.0-16.3%, respectively.

Biochar Effects on Soil Physiochemical Properties in Degraded Managed Ecosystems in Northeastern Bangladesh

A body of emerging research shows the promise of charcoal soil amendments (“biochars”) in restoring fertility in degraded agricultural and forest soils. “Sustainable biochars” derived from locally produced waste biomass and produced near the application site are of particular interest. We tested the effects of surface applications of wood-derived biochars (applied at 7.5 t·ha−1) on soil physiochemical properties (N, P, K, pH, soil moisture content, organic matter content, and bulk density) in three land-use types: agriculture (Camellia sinensis monoculture), agroforestry (C. sinensis with shade trees), and secondary forest (Dipterocarpus dominated) assessed over seven months. We found significant positive effects of biochar on soil physiochemical properties in all land-use types, with the strongest responses in the most degraded tea monoculture sites. Although biochar had no significant effect on soil N and K, it improved soil P—the primary nutrient most commonly limiting in tropical soils. Biochar also enhanced soil moisture and organic matter content, reduced bulk density, and increased soil pH in monoculture sites. Our results support the general hypothesis that biochar can improve the fertility of degraded soils in agricultural and forest systems in Bangladesh and suggest that biochar additions may be of great benefit to the most degraded soils.

Effect of biochar particle size on water retention and availability in a sandy loam soil

The ability of biochar to enhance the physical and hydrological properties of light textured soils is highly dependent on the characteristics of biochar including its particle size. To investigate the effect of biochar particle size on water characteristics and soil structure of a sandy loam soil, date palm biochar prepared at a pyrolysis temperature of 450–500 °C was fractioned by dry sieving into four sizes: 2–1, 1–0.5, 0.5–0.1, and <0.1 mm, and mixed in soil pots with a sandy loam soil at an application rate of 4%. The soil pots were incubated in a greenhouse for 120 days, and water content was kept at field capacity throughout the experiment. Water retention, hydraulic conductivity, and soil structure parameters were measured. Results showed that the largest increase in both water content at field capacity and available water content was observed with the smallest biochar particle size due to increased microporosity as a result to the larger internal surfaces and the porous structure of the biochar particles. Condense particle packing and increased tortuosity due to increased microporosity resulted in a reduction in saturated hydraulic conductivity and bulk density of the soil and biochar mixtures. Soil structure was improved in the soil and biochar mixtures at all biochar particle sizes, nevertheless, no significant increase in soil structures was observed among biochar particle sizes < 1 mm. The application of biochar with particle sizes < 1 mm can enhance the physical and hydrological properties of light textured soils and increase water conservation in the soil, which will help to reduce the amount of water required for irrigation. However, assessment under field conditions is required to assess the long-term effect of biochar on water characteristics and soil structure.

Grazing Systems to Retain and Redistribute Soil Phosphorus and to Reduce Phosphorus Losses in Runoff

A study of phosphorus accumulation and mobility was conducted in eight pastures in the Georgia piedmont, USA. We compared two potential grazing treatments: strategic-grazing (STR) and continuous-grazing-with-hay-distribution (CHD) from 2015 (Baseline) to 2018 (Post-Treatment) for (1) distribution of Mehlich-1 Phosphorus (M1P) in soil and (2) dissolved reactive phosphorus (DRP) and total Kjeldahl phosphorus (TKP) in runoff water. STR included rotational grazing, excluding erosion vulnerable areas, and cattle-lure management using movable equipment (hay-rings, shades, and waterers). After three years of treatment, M1P had significantly accrued 6- and 5-fold in the 0–5 cm soil layer and by 2- and 1.6-fold in the 5–10 cm layer for CHD and STR, respectively, compared to Baseline M1P. In STR exclusions, M1P also increased to 10 cm depth post-treatment compared to Baseline. During Post-Treatment, TKP runoff concentrations were 21% and 29% lower, for CHD and STR, respectively, in 2018 compared to 2015. Hot Spot Analysis, a spatial clustering tool that utilizes Getis-Ord Gi* statistic, revealed no change in Post-Treatment CHD pastures, while hotspots in STR pastures had moved from low-lying to high-lying areas. Exclusion vegetation retained P and reduced bulk density facilitating vertical transportation of P deeper into the soil, ergo, soil P was less vulnerable to export in runoff, retained in the soil for forage utilization and reduced export of P to aquatic systems

Influence of Biochar on Soil Physicochemical Properties, Erosion Potential, and Maize (Zea mays L.) Grain Yield under Sandy Soil Condition

ABSTRACT Degraded soils in humid tropics are characterized by low fertility and high soil erosion potential. Hence, field experiments were conducted during 2018 and 2019 cropping seasons on an Alfisol at Owo in the forest–savanna transition zone of southwest Nigeria to evaluate the effects of the application of biochar (B) produced from waste wood of trees on physicochemical characteristics, erosion potential, and maize yield. Four treatments considered were control (no biochar application, 10 t ha−1 B, 20 t ha−1 B and 30 t ha−1 B). The treatments were laid out in a randomized complete block design with three replications. Results in both years indicated that B application significantly improved grain yield of maize and soil chemical properties, and reduced bulk density (BD) and penetration resistance (PR), and increased porosity (PO), moisture content (MC), and the mean weight diameter (MWD) of soil aggregates. Pooled over 2 years, B applied at 10, 20 and 30 t ha−1 increased grain yield of maize by 44.4%, 66.7%, and 88.9%, respectively, compared with the control. Averaged over 2 years, incorporating B into the soil significantly reduced soil loss (SL) by 32.3%, 56.9%, and 69.7% at 10, 20, and 30 t ha−1 application rates, respectively, compared with the control. The formation of macroaggregates in the B-amended soils is the critical factor to improve soil erosion potential. Therefore, the application rate of 30 t ha−1 B is considered as suitable for severely degraded soil because this application rate efficiently improves maize yield and soil properties and reduces SL.

Detecting near-surface Urochloa ruziziensis (Braquiaria grass) effects on soil physical quality through capacity and intensity indicators

In Brazil, no-tillage is the most widely used soil conservation system (on more than 32 million hectares). However, intensification of the mechanisation of agricultural operations with larger and heavier machines increases the pressure on the soil, which, together with the reduced diversity of crops, results in compaction and physical degradation of soils under no-tillage systems. In this context, strategies to reduce soil compaction have been employed and the use of Braquiaria grass (Urochloa ruziziensis) (hereafter urochloa) as a cover plant is one promising strategy. The objectives of this study were to quantify, using physical indicators of capacity and intensity processes, the effects of cultivating urochloa sown in the interrow between corn (Zea mays L.) on storage and transmission of air and water in the surface layer of the soil and to evaluate the sensitivity of these indicators at detecting such effects. The results indicated that urochloa cultivation in the interrow produced an increase in storage capacity of air and water, and transmission of air and water, compared with the treatment in which the interrow was without urochloa. Cultivation of urochloa also alleviated compaction through an 18% reduction in soil bulk density and an increase of up to 490% in pore system continuity, in addition to improving the relationship between water and air storage, creating an environment that facilitates access to water and air. These results suggest that the use of urochloa as an interrow cover plant in corn improves the physical functions of the topsoil, producing a physical environment more favourable to development of crops. The use of intensity process indicators of physical properties was ~10 times more sensitive at detecting the effects of urochloa than the properties indicating capacity processes.

Physicochemical and emulsifying properties of orange fibers stabilized oil-in-water emulsions

The present work aimed to evaluate the physical and techno-functional property and microstructure of freeze-dried orange pulp and peel powders modified by high-pressure homogenization (HPH) treatment, and their emulsifying properties of oil-in-water emulsions treated with HPH. For orange pulp and peel powders, HPH pre-treatment was found to significantly reduce bulk density and increase the water and oil holding capacity (P < 0.05) of orange pulp and peel powders, and the particles appeared to have flake-like shape. When orange-pulp and peel dispersions were subjected to HPH treatment, all samples showed significant decreases in particle size and increases in ζ-potential (P < 0.05), and could maintain higher stability with extended storage time. Furthermore, Confocal Laser Scanning Microscopy (CLSM) also revealed that emulsion destabilization occurred with increased storage time due to oil-droplet aggregation and coalescence. The results indicated that emulsion stability was improved by HPH treatments, probably due to a steric or electrostatic repulsion against flocculation or coalescence of oil droplets, and orange fibers, particularly orange pulp are suitable feedstock as natural emulsifiers.

Production Potential and Economic Feasibility of Planting Pattern and Nutrient Management in Pigeonpea (Cajanus cajan) Based Intercropping System under Rainfed Condition

Background: Pigeonpea grown as sole crop is not economically viable because of its slow initial growth rate, low productivity and longer duration. The initial slow growth rate, widely spaced, deep root system and longer duration of pigeonpea offers a good scope for intercropping with fast growing and early maturing compatible crops. Proper row arrangement of main as well as intercrops in appropriate proportion is the promising way to exploit the natural resources such as space, nutrient, sunlight, soil moisture to greater extent and boost up the system productivity.Methods: The study was carried out for four consecutive years during kharif 2013-14 to 2016-17 at Tirhut College of Agriculture, Dholi, RPCAU, Pusa, Bihar. The treatment comprised 3 intercropping systems with two method of planting viz, pigeonpea (60 cm)+ urdbean (1:1), pigeonpea (60 cm) + sesame (1:1), pigeonpea (60 cm) + sorghum (1:1), pigeonpea paired (45 cm) + urdbean (2:2), pigeonpea paired (45 cm) + sesame (2:2), pigeonpea paired (45 cm) + sorghum (2:2) and 3 fertilizer levels of intercrop viz, 75% recommended dose of fertilizer (RDF), 100% RDF and 125% RDF along with sole crop of pigeonpea, urdbean, sesame and sorghum. Result: Intercropping of urd bean [Vignamungo (L.) Hepper], sesame (sesamumindicum (L.) and sorghum (sorghum bicolor (L.) Moench] paired row planting of pigeonpea (45 cm) in 2:2 row ratio recorded significantly higher pigeonpea – equivalent yield, LER, water-use efficiency, production efficiency and net return than their intercropping with pigeonpea in normal planting pattern (60 cm) in 1:1 row ratio and sole pigeonpea. However, only pigeonpea + urdbean and pigeonpea + sesame in paired row planting recorded significantly higher B:C ratio than sole pigeonpea. Pigeonpea + urdbean in paired row planting recorded significantly higher pigeonpea equivalent yield (3.57 t/ha), LER (1.81), water-use efficiency (4.96 kg ha/mm), production efficiency (12.01 kg/ha/day), NPK-uptake by pigeonpea, net return (148.63 x 103 ¹ /ha) and B:C ratio (4.84) than their intercropping in normal planting pattern, pigeonpea + sesame and pigeonpea + sorghum in both planting pattern. Pigeonpea + urdbean and pigeonpea + sesame in paired row recorded significantly higher number and dry weight of nodules/plant than sole pigeonpea. Pigeonpea equivalent yield in pigeonpea + urdbean intercropping system did not increased significantly with increasing levels of fertilizer. However, it increased significantly upto RDF and 125% RDF of sesame and sorghum in pigeonpea + sesame and pigeonpea + sorghum intercropping systems respectively in both the planting pattern. Pigeonpea + urdbean in both the planting pattern reduced bulk density of the soil and increased organic carbon, available N,P,K content of the soil than other intercropping systems and initial soil value but magnitude of improvement in physico-chemical properties of soil was higher in paired row planting.

Effect of Biochar Application and Re-Application on Soil Bulk Density, Porosity, Saturated Hydraulic Conductivity, Water Content and Soil Water Availability in a Silty Loam Haplic Luvisol

Due to climate change the productive agricultural sectors have started to face various challenges, such as soil drought. Biochar is studied as a promising soil amendment. We studied the effect of a former biochar application (in 2014) and re-application (in 2018) on bulk density, porosity, saturated hydraulic conductivity, soil water content and selected soil water constants at the experimental site in Dolná Malanta (Slovakia) in 2019. Biochar was applied and re-applied at the rates of 0, 10 and 20 t ha−1. Nitrogen fertilizer was applied annually at application levels N0, N1 and N2. In 2019, these levels were represented by the doses of 0, 108 and 162 kg N ha−1, respectively. We found that biochar applied at 20 t ha−1 without fertilizer significantly reduced bulk density by 12% and increased porosity by 12%. During the dry period, a relative increase in soil water content was observed at all biochar treatments—the largest after re-application of biochar at a dose of 20 t ha−1 at all fertilization levels. The biochar application also significantly increased plant available water. We suppose that change in the soil structure following a biochar amendment was one of the main reasons of our observations.

Optimization of process parameters using a hybrid intelligent system model and evaluation of physicochemical properties of microwave roasted Chironji (Buchanania lanzan) kernels

Microwave (MW) roasting of Chironji kernels was carried out at different combinations of microwave power and roasting time. The impact of MW roasting on bulk density, hardness, water absorption capacity (WAC), water activity (WA), browning index (BI), total phenolic content (TPC) and antioxidant activity (AA) were evaluated. Significant reduction in bulk density, hardness, and WA was noticed upon roasting, while a substantial increase in WAC, BI, TPC, and AA was found. A hybrid intelligent system model was used for achieving the optimal conditions of MW roasting parameters. The model comprised of several steps such as a general full factorial experimental design, computation of Taguchi’s quality loss function, principal component analysis, grey relational analysis, and process optimization using combined artificial neural network—genetic algorithm technique. Under optimal condition of 700 W power and 5.5 min of roasting time, decrease in bulk density of 8.02 ± 0.15%, hardness of 16.63 ± 0.17 N, WAC of 1.02 ± 0.06 g/g, WA of 0.0541 ± 0.0009, BI of 76.79 ± 1.23, TPC of 26.74 ± 0.32 mg GAE/g, and AA of 73.23 ± 0.86%, were recorded for roasted Chironji kernels. Further, the SEM analysis confirmed microstructural changes in the kernels roasted at optimal conditions.

Thirty-one Years Study of Integrated Nutrient Management on Physico-Chemical Properties of Soil Under Rice–Wheat Cropping System

ABSTRACT Long-term sustainability is the concern of today’s agriculture. A long-term field experiment (since 1983) comprising of 14 treatments with different combinations of inorganic (NPK) and organic fertilizers (such as farmyard manure, wheat cut straw and Sesbania aculeate as green manure) was conducted to evaluate their effect on soil physico-chemical properties under a rice–wheat system. There was significant (P < .05) reduction in bulk density and soil strength but significant (P < .05) increase in infiltration rate and water retention with the use of organic manures along with chemical fertilizers. Organic C, nitrate-N, ammonical-N, and nutrient content were significantly (P < .05) higher in integrated nutrient management treated plots as compared to control. The highest carbon sequestration rate over the 3 decades was recorded in T6, i.e., 50% recommended NPK dose through fertilizers + 50% N through FYM in kharif and 100% recommended NPK dose through fertilizers in rabi (0.29 Mg C ha−1 year−1) as compared to chemically fertilized plots T5, i.e., 100% recommended NPK dose through fertilizers (0.13 Mg C ha−1 year−1). A positive and significant correlation was observed between organic carbon and soil physico-chemical properties barring bulk density, soil strength, pH, and electrical conductivity. The results clearly suggest that integrated use of balanced chemical fertilizers in combination with organic manures on long-term basis improves soil physico-chemical properties and soil carbon sequestration thereby having the potential to enhance soil sustainability.

X‐ray computed tomography–measured soil pore parameters as influenced by crop rotations and cover crops

AbstractThis study examined the effect of crop rotations and winter cover crops (CCs) on near‐surface pore characteristics of a silty clay loam soil in a 27‐yr no‐till field experiment. The crop rotation treatments included a 2‐yr corn (Zea mays L.)–soybean [Glycine max L. (Merr.)] (CS) rotation and a 4‐yr corn–soybean–oat (Avena sativa L.)–winter wheat (Triticum aestivum L.) (CSOW) rotation. The subplot treatment was CC and no‐CC (fallow). Intact soil cores (7.62 by 7.62 cm) were extracted from each treatment in July 2018 from soybean plots and examined for X‐ray computed tomography (CT)‐measured pore parameters and other soil physical and hydrological properties. Data showed that, compared with fallow, the CC reduced bulk density (ρb) by 6% and increased saturated hydraulic conductivity (Ksat) and water infiltration rate (qs) by 1.5 times. Soils under CSOW rotation had 16, 14, and 4% higher values of soil organic carbon (SOC), total nitrogen (TN), and wet aggregate stability (WAS) compared with those under CS rotation, respectively. The CSOW rotation significantly (P &lt; .05) increased number of CT‐measured pores, number of macropores (&gt;1,000 μm diameter), coarse mesopores (226–1,000 μm diameter), macroporosity, and mesoporosity compared with the CS system. The CT‐measured total porosity, number of macropores, and macroporosity were 43, 34, and 60%, respectively, higher with CC as compared to the fallow plots. The CT‐measured pore parameters were well correlated with soil ρb, Ksat, qs, SOC, TN, and WAS. This study emphasizes that cropping systems that include diverse crop rotations (CSOW) and CC has potential to enhance SOC, pore characteristics, and associated physical and hydrological properties.

The effects of weathering on limestone used for building the cemetery wall in Tel Kaif-North Iraq

The purpose of this study is to evaluate the impact of weathering on rocks used in construction during a defined period of these rocks. The field study involves weathering and rock strength measurements using a geological hammer. Laboratory testing for both wall limestone and fresh quarry limestone was performed to determine the bulk density, the porosity and absorption of water, and the durability test was performed for fresh quarry limestone. A polarized microscope and scan electron microscope, petrographic analysis has been conducted for various weathering rates. Field notes explain the moderate and high degree of weathering and low strength in the bottom of the wall, whilst the top is slightly weathered and high strength. Laboratory notes through stone crushing show a change from white to beige for slightly weathered samples to moderately and highly weathered samples in powder color. Increasing weathering reduces bulk density and insoluble residues, from 13% in non-weathered rocks to 25% in high-weathered rocks the level of insoluble residue increases. Water absorption in non-weathered rocks and high weathering rocks rises from 6% to 14% and porosity from 14% to 27% respectively. Durability tests show that calcarenite exceeds very high durability, high durability calcirudite and calcilutite, and moderately durable calcisiltite. Four types of porosity, intergranular, intragranular, mold and microfracture appear in the petrographic study using a polarized microscope. Clay minerals and iron oxides surrounding the pores appear in weathered specimens, not in fresh, calcite crystal oxidation and secondary calcite growth on the inner surface of voids have also been shown in the scanning of electron microscopes.

Evaluation of three new insecticide formulations based on inert dusts and botanicals against four stored-grain beetles

Three new insecticide formulations were developed that combine diatomaceous earth (Celatom MN 23) with compounds with low mammalian toxicity. Sitophilus oryzae, Sitophilus granarius, Rhyzopertha dominica and Tribolium castaneum were held on wheat (13.5% moisture content) treated with different doses of the formulations at 28 ± 1 °C and 60 ± 5% RH for 2–7 days, and then held for progeny emergence. The three formulations were made up of: dill essential oil, bait, silica gel and DE (Dill-DE); pyrethrin, PBO, dill essential oil, silica gel and DE (Py-Dill-DE); and disodium octaborate tetrahydrate (DOT), pyrethrin, PBO, dill essential oil, silica gel and DE (DOT-PY-Dill-DE). They were applied either as powders or as slurries. Applying the formulations as powders over a range of concentrations showed that pure DE is the least effective insecticide, with 50% mortality ranging from 430 to 1000 ppm depending on the species after 2–3 days. Dill-DE formulation was the next least effective formulation. The Py-Dill-DE and DOT-Py-Dill-DE formulations had similar activity and being the most effective formulations with 50% mortality from 40 to 260 ppm depending on the species. Bioassays were also run at single doses. Dill-DE was applied at 300 ppm, Py-Dill-DE at 150 ppm and DOT-PY-Dill-DE at 200 ppm. After 3 days, Py-Dill-DE and DOT-PY-Dill-DE formulations there was 100% mortality for S. oryzae, S. granarius and R. dominica. After 7 days the mortality of T. castaneum was from 96 to 100%. Both formulations reduced the progeny almost by 100%. There was survival for all insects with Dill-DE formulation. The concentrations of 150 ppm of Py-Dill-DE, 200 ppm of DOT-PY-Dill-DE and 300 ppm of Dill-DE reduced bulk densities by 0.7, 0.8 and 5.7 kg/hL, respectively.

Rice (Oryza sativa L.) Establishment Techniques and Their Implications for Soil Properties, Global Warming Potential Mitigation and Crop Yields

Rice-based intensive cropping systems require high input levels making them less profitable and vulnerable to the reduced availability of labor and water in Asia. With continuous conventional puddled rice transplanting, the situation is exacerbated by damaged soil structure, declining underground water and decreasing land and water productivity. To minimize these negative effects a range of new crop establishment practices have been developed (zero tillage, dry direct seeding, wet direct seeding, water seeding, strip planting, bed planting, non-puddled transplanting of rice, mechanical transplanting of rice crop and combinations thereof) with varying effects on soil health, crop productivity, resource saving and global warming mitigation potential. Some of these allow Conservation Agriculture (CA) to be practiced in the rice-based mono-, double- and triple cropping systems. Innovations in machinery especially for smallholder farms have supported the adoption of the new establishment techniques. Non-puddling establishment of rice together with increased crop residue retention increased soil organic carbon by 79% and total N (TN) in soil by 62% relative to conventional puddling practice. Rice establishment methods (direct seeding of rice, system of rice intensification and non-puddled transplanting of rice) improve soil health by improving the physical (reduced bulk density, increased porosity, available water content), chemical (increased phosphorus, potassium and sulphur in their available forms) and biological properties (microbiome structure, microbial biomass C and N) of the soil. Even in the first year of its practice, the non-puddled transplanting method of rice establishment and CA practices for other crops increase the productivity of the rice-based cropping systems. Estimates suggest global warming potential (GWP) (the overall net effect) can be reduced by a quarter by replacing conventional puddling of rice by direct-seeded rice in the Indo-Gangetic Plains for the rice-based cropping system. Moreover, non-puddled transplanting of rice saves 35% of the net life cycle greenhouse gases (GHGs) compared with the conventional practice by a combination of decreasing greenhouse gases emissions from soil and increasing soil organic carbon (SOC). Though the system of rice intensification decreases net GHG emission, the practice releases 1.5 times greater N2O due to the increased soil aeration. There is no single rice establishment technology that is superior to others in all circumstances, rather a range of effective technologies that can be applied to different agro-climates, demography and farm typologies.

PHYSICAL ATTRIBUTES, TOTAL CARBON AND 13C NATURAL ABUNDANCE IN FERRALSOL UNDER DIFFERENT AGRICULTURAL SYSTEMS

The objective of this study was to evaluate the bulk density, total pore volume, carbon stock and natural abundance of 13C in Rhodic Ferralsol in no-tillage system (NTS) areas under different succession and rotation of cultures in the Cerrado of Goiás State, Brazil. In order to do so, NTS areas were selected in Montividiu, Goiás, under the same soil and climatic conditions as the following rotations: soybean-corn succession, soybean-millet succession, soybean-corn-millet-beans-cotton rotation, soybean-corn-brachiaria succession and a pasture area (PA), used as a control. In each area, samples were collected at depths of 0.0–0.05, 0.05–0.10, 0.10–0.20, and 0.20–0.40 m. The lowest levels of carbon content and stocks were verified in PA in comparison to the other areas evaluated. The NTS with soybean-corn-millet-beans-cotton crop rotation followed by NTS with soybean-corn-brachiaria succession were those that presented greater potential for carbon stock increase and total soil pore volume, as well as bulk density reduction. The origin of the soil organic matter in the NTS areas is related to plants employing the C4 photosynthetic cycle; however, for mixed C3 and C4 plant systems, the isotopic signature of 13C is reduced, mainly in areas with crop rotation.

Production of a lightweight masonry block using alkaline activated natural pozzolana and natural fibers

Lightweight geopolymers are alternative low-carbon footprint building materials with high potential to produce value added products for the construction industry such as low-density masonry units. This work focuses on presenting the development of a new lightweight masonry block using natural pozzolana-based geopolymer mortar, hydrogen peroxide as a foaming agent and jute fibers as reinforcement additive. The experimental plan allowed the optimization of the production process and the definition of the optimum quantities of hydrogen peroxide content, pozzolana: fine aggregate ratios and the appropriate amount of fibers to be incorporated. The experimental results demonstrate the feasibility of the production of new masonry units, which can achieve up to 8.1 MPa of compressive strength after 28 days of fabrication with reduced bulk densities of 1269 kg/m3.