Reduced Bulk Density Research Articles

The adoption of annual subsoiling as conservation tillage in dryland maize and wheat cultivation in northern China

Soil compaction caused by random traffic or repetitive tillage has been shown to reduce water use efficiency, and thus crop yield due to reduced porosity, decreased water infiltration and availability of nutrients. Conservation tillage coupled with subsoiling in northern China is widely believed to reduce soil compaction, which was created after many years of no-till. However, limited research has been conducted on the most effective time interval for subsoiling, under conservation tillage. Data from conservation tillage demonstration sites operating for 10 years in northern China were used to conduct a comparative study of subsoiling interval under conservation tillage. Three modes of traditional tillage, subsoiling with soil cover and no-till with soil cover were compared using 10 years of soil bulk density, water content, yield and water use efficiency data. Cost benefit analysis was conducted on subsoiling time interval under conservation tillage. Yield and power consumption were assessed by based on the use of a single pass combine subsoiler and planter. Annual subsoiling was effective in reducing bulk density by only 4.9% compared with no-till treatments on the silty loam soils of the Loess plateau, but provided no extra benefit in terms of soil water loss, yield increase or water utilization. With the exception of bulk density, no-till and subsoiling with cover were vastly superior in increasing water use (+10.5%) efficiency and yield (+12.9%) compared to traditional tillage methods. Four years of no-till followed by one subsoiling reduced mechanical inputs by 62%, providing an economic benefit of 49% for maize and 209% for wheat production compared to traditional tillage. Annual subsoiling reduced inputs by 25% with an increased economic benefit of 23% for maize and 135% for wheat production. Yield and power consumption was improved by 5% and 20%, respectively, by combining subsoiling with the planting operation in one pass compared with multipass operations of subsoiling and planting. A key conclusion from this is that annual subsoiling in dryland areas of northern China is uneconomical and unwarranted. Four years of no-till operations followed by 1 year subsoiling provided some relief from accumulated soil compaction. However, minimum soil disturbance and maximum soil cover are key elements of no-till for saving water and improving yields. Improved yields and reduced farm power consumption could provide a significant base on which to promote combined planter and subsoiling operations throughout northern China. Further research is required to develop a better understanding of the linkages between conservation tillage, soil quality and yield, aimed at designing most appropriate conservation tillage schemes.

Topdressing Turf with Composted Manure Improves Soil Quality and Protects Water Quality

Compost can improve soil properties when incorporated into soil; however, little information is available regarding impacts of compost topdressing. Objectives of this study were to evaluate the effects that topdressing composted dairy manure onto Kentucky bluegrass (Poa pratensis L.) has on: (i) soil physical properties, (ii) soil chemical properties, (iii) soil nitrate (NO3–N) and P concentrations below the rootzone, (iv) total runoff and sediment losses, and (v) N and P concentrations in runoff. Plots were topdressed with compost at 0, 33, 66, and 99 m3 ha−1 Saturated hydraulic conductivity, bulk density, water retention, and soil nutrient levels were measured. A rainfall simulation was conducted, and runoff was collected and analyzed for total nitrogen (TN), nitrate nitrogen (NO3–N), ammonium nitrogen (NH4–N), total phosphorus (TP), total dissolved P (TDP), and ortho‐phosphate (OP). Compost application of 99 m3 ha−1 reduced bulk density, and increased water retention and P, K, Fe, and Mn concentrations in the surface soil. Compost applications of 66 m3 ha−1 or greater raised soil electrical conductivity (EC); however, this increase in soil EC did not negatively impact turf quality. Rates of runoff and erosion and concentrations of TN, NO3–N, TP, TDP, and OP in runoff were not different among treatments. However, all compost treatments did increase NH4–N concentrations in runoff. There were no differences in soil NO3–N or available P levels below the root zone. Topdressing composted manure onto established turf improved soil physical properties and nutrient concentrations without increasing nutrient runoff, with the exception of increased NH4–N levels in runoff.

The causes of piping in a set of abandoned agricultural terraces in southeast Spain

This study aims to identify some of the factors contributing to the piping process in abandoned terraces in seven sites located in the Murcia Region (southeast Spain). The local landscape has the appearance of badland geomorphology, possessing deep valleys which until the 1970s were terraced and cultivated. The terraces have now been abandoned to the piping process. The research focuses on the relationship between the size and position of pipes and the physical and geochemistry properties of the local highly dispersive marl lithology; and the extent to which the reworking of the materials for terrace cultivation has exacerbated piping erosion. Morphologically, the terracing in the stream beds has resulted in a series of gentle benches separated by steeper risers with variable ‘drop’, (riser height). A series of flat infiltration surfaces result, and because the resculpting produces a reduced bulk density infill with enhanced throughflow, infiltrating water is forced along steep hydraulic gradients to a low outfall at the base of the riser. Paralleling studies of land levelling and terrace abandonment in similar materials elsewhere, piping in the study area is shown to be closely related to the physical and chemical characteristics of the materials its sodicity and dispersive character. Considerable differences in structure, texture, mineralogical composition and material's surface crust and subsoil geochemical properties emerged from ‘site signature’ plots, and these results suggest that agricultural processes affect the dispersive character of the crust materials, presumably because agricultural activity increases the buffering effect of organic acids on the dispersed clay. This is supported by the observation that on the one site that was levelled but not used for agriculture, a stable organically-distinct crust like the abandoned agricultural sites has not formed. The changes to the material's aggregate stability and bulk density properties when terracing occurs is examined, but insufficient evidence is available from the data collected to unpick the causes of aggregate stability changes in the study plots. The way in which differences between crust and subsoil enhance infiltration is discussed, and the role of the terrace ‘drop’ in influencing hydraulic gradients and pipe development is illustrated. A possible index to describe the relationship between evacuated material volumes and the controlling parameters discussed above is tested. It is concluded that terracing which is intended as a conservation practice has, in dispersive materials, actually enhanced piping, leading to the abandonment of farming.

Dairy manure and tillage effects on soil fertility and corn yields

Organic amendments have received renewed attention to improve soil fertility for crop production. A randomized complete block split plot experiment was conducted to evaluate the dairy manure (DM) amendments of soil for corn ( Zea mays L. cv. Monsanto 919) production under different tillage systems. Main plot treatments were no-till (NT), conventional tillage (CT), and deep tillage (DT), and subplot treatments were chemical fertilization (DM 0), and DM at 10 Mg ha −1 yr −1 (DM 10) and 20 Mg ha −1 yr −1 (DM 20) with supplemental chemical fertilization. Results show that tillage and DM had significantly reduced bulk density ( ρ b) with greater porosity ( f t) and hydraulic conductivity ( K fs) than soils under NT and DM 0. Manuring was effective to improve soil physical properties in all tillage treatments. While manure significantly increased C sequestration, the N concentration was influenced by both tillage and manure with significant interaction. The CT significantly increased P as did the addition of manure. However, with manure, K was significantly increased in all tillage treatments. While tilled soils produced taller plants with higher grain yields, and water-use efficiency than NT soils, manuring, in contrast, increased corn harvest index. Manure exerted significant quadratic effect on corn biomass N and K uptake. The variable effects of tillage and dairy manuring on soil properties and corn growth are most probably related to “transitional period” in which soil ecosystems may have adjusting to a new equilibrium.

Effects of different organic amendments on seed germination and soil physical properties

A screen house study was carried out to assess the effects of three organic amendments (poultry droppings – pd, brewer's spent grain – bsg and wood shavings-ws) on the germination of four crops (Maize: Zea mays , Cowpea: Vigna sinensis , Okro: Abelmoschus esculentum and pepper: Capsicum annum ), and on some properties; of an ultisol in Port – Harcourt, southeastern Nigeria. The four treatments, made up of the organic amendments were laid out in a completely randomized design replicated thrice, for each of the crops. Wood shavings were best suited for pepper and maize with 77.7 and 43.3 percents germination, respectively as against their controls of 59.9 and 33.3 percents. Brewer's spent grain gave a germination rate of 60% for cowpea while the poultry droppings treatment gave 100% germination for okra. Generally, the wood shavings enhanced germination for all the crops. Organic amendments reduced bulk density by 8.2,4.5 and 38.1% and increased porosity by 10.2, 6.1 and 40% for poultry droppings brewer's spent grain and wood shavings respectively. Wood shavings and poultry droppings significantly increased volumetric moisture contents from 0.37 to 0.50 and 0.43 respectively. There were inverse linear relationships between percentage germination and volumetric moisture contents for all treatments, with r-values of -0.06, -0.54, and -046 for PD, BSG and WS respectively. There were also the same relationship between percentage germination and bulk density for only PD and WS respectively. There were also the same relationship between percentage germination and bulk density for only PD and WS with r-values of -0.31 and -0.83 respectively. International Journal of Agriculture and Rural Development Vol. 7(2) 2006: 134-140

Influence of organic amendments on soil structure and soil loss under simulated rain

The influence on soil properties and soil loss under simulated rain, of four organic by-products (cotton gin crushed compost (CCGC), by-product obtained after the two-step olive oil extraction process (BOO), sewage sludge (SS) and organic municipal solid by-product (MSW) applied annually at 10,000 kg organic matter ha −1, was studied over 4 years on a Typic Xerofluvent under dryland conditions near Sevilla (Spain). All organic by-product treatments reduce bulk density, aggregate instability and soil loss. The CCGC and BOO treatments had similar effects and were more effective than SS and MSW treatments. Compared with the control (no organic amendment) treatment, CCGC and BOO treatments reduced bulk density by 20% and 19%, respectively, aggregate instability by 33% and 28%, respectively, and soil loss under simulated rain at 140 mm h −1 by 32% and 30%, respectively. Compared with the control treatment, the SS and MSW treatments reduced bulk density by 12% and 9%, respectively, aggregate instability by 16% and 14%, respectively, and soil loss under simulated rain at 140 mm h −1 by 23% and 19%, respectively. The stronger effects of CCGC and BOO might have been because they had humic acid contents than SS and MSW.

Effect of Tillage on Physical Properties of Young Alluviam and Residual Root Volume after Winter Maize (Zea Mays L.)

A series of experiments were conducted for two consecutive winter seasons at Rajendra Agricultural University, Pusa, India on loamy sand soil having pH 8.8, O.C.- 0.38%, E.C. - 0.26 dsm-1, bulk density 1.45 Mgm-3, available N 225.7 kg ha-1, available Pps 12.1 kg ha-1 and available Kp 87.71 kg ha-1• The experiment was designed in splitsplit plot with the treatments of tillage (main), irrigation (sub) and nitrogen (sub-sub plot) having three levels each with three replication under late (28th November) and timely (06th November) sown conditions. Among the treatments only tillage caused significant variation in physical properties manifested through reduction in bulk density from 1.41 to 1.30 Mgm-3, penetration resistance from 2.94 to 2.11 Mpa, mean weight diameter from 6.97 to 5.68 mm with subsequent increase in water stable aggregate from 6.76 to 10.37 per cent and infiltration rate from 0.218 to 0.512 cmh-1 .The Mould Board plough caused higher root volume (35.30 and 40.38 cc) under late and timely sown, respectively.

Long-term continuous cropping, fertilisation, and manuring effects on physical properties and organic carbon content of a sandy loam soil

Effects of continuous cropping, fertilisation, and manuring on soil organic carbon content and physical properties such as particle size distribution, bulk density, aggregation, porosity, and water retention characteristics of a Typic Ustochrept were examined after 31 cycles of maize–wheat–cowpea (fodder) crop rotation. Five contrasting nutrient treatments from a long-term fertiliser experiment were chosen for this study: control (no fertiliser or manure); 100% (optimum dose) nitrogen (N) fertiliser; 100% nitrogen and phosphorus (NP); 100% nitrogen, phosphorus, and potassium (NPK); 100% NPK + farmyard manure (NPK+FYM). The NPK+FYM treatment significantly improved soil organic carbon (SOC) content in 0–0.15 m soil compared with the other 4 treatments; the NPK treatment resulted in significantly more SOC than the control and N treatments (P < 0.05). The SOC in NPK and NPK+FYM treatments was 38.6 and 63.6%, respectively, more than the initial level of SOC (4.4 g/kg) after 31 cycles of cropping. The control and N treatments maintained the SOC status of the soil at the initial value. NPK+FYM significantly improved soil aggregation, soil water retention, microporosity, and available water capacity and reduced bulk density of the soil at 0–0.30 m depth. Greater crop growth under the NPK treatment resulted in increased organic matter content of soil, which improved aggregate stability, water retention capacity, and microporosity compared with the control. The effects were more conspicuous with the NPK+FYM treatment and at the surface soil (0–0.15 m). Application of imbalanced inorganic fertiliser (N and NP treatments) did not have a deleterious effect on the physical properties of the soil compared with the control. SOC content showed a highly significant and positive correlation with mean weight diameter (0.60), % water-stable macro-aggregates (0.61), and soil water retention at –0.033 MPa (0.75) and –1.5 MPa (0.72), and negative correlation with bulk density (–0.70) for the surface 0–0.15 m soil. The study thus suggests that application of balanced mineral fertilisers in combination with organic manure sustains a better soil physical environment and higher crop productivity under intensive cultivation.

Effect Of Depth Of Tillage On Soil Physical Conditions, Growth And Yield Of Sweet Potato In An Ultisol At Abakaliki, Southeastern Nigeria

A study was conducted at Abakaliki, southeastern Nigerian during the raining seasons of 2000 – 2001. The experiment evaluated the changes in some soil physical properties owing to depth of tillage, and the effect on growth and yield of sweet potato. The tillage depth treatments included zero tillage, 10cm, 20cm, 30cm and 40cm tillage depths. The soil physical properties measured were bulk density, penetrometer resistance and soil moisture content. Tilling the soil to depths of 20, 30 and 40cm significantly (P = 0.05) reduced soil bulk density by 13, 15 and 22 % respectively when compared with zero tillage. Penetrometer values were 54, 66, 74 and 78 % significantly higher on 10, 20, 30 and 40cm tillage depth plots than the untilled plots. The gravimetric moisture content was 20, 33, and 43 % significantly higher in the zero than the 20, 30, and 40 cm tillage depths respectively. Tilling the soil significantly increased crop growth and yield compared to untilled soil. Plants on the 40cm tillage depth produced the highest fresh potato tuber yield of 14.5 t ha-1. The study shows that improving soil physical properties, such as reduced bulk density, increased penetration and good drainage, promotes high crop yield. Key words: Tillage depth, soil properties; Potato yield Journal Of Agriculture And Social Research Vol. 5 (1) 2005: 41-47

Use of Flyash and Biogas Slurry for Improving Wheat Yield and Physical Properties of Soil

This study explores the potential use of by-products of energy production, i.e., (i) flyash from coal-powered electricity generation and (ii) biogas slurry from agricultural waste treatment, as nutrient sources in agriculture. These residues are available in large amounts and their disposal is a major concern for the environment. As both residues contain considerable amounts of plant nutrients, their use as soil amendment may offer a promising win-win opportunity to improve crop production and, at the same time, preventing adverse environmental impacts of waste disposal. Effect of flyash and biogas slurry on soil physical properties and growth and yield of wheat (Triticum aestivum) was studied in a field experiment. Leaf area index, root length density and grain yield of wheat were higher in plots amended with flyash or biogas slurry compared to unamended plots. Both types of amendments reduced bulk density, and increased saturated hydraulic conductivity and moisture retention capacity of soil. The study showed that flyash and biogas slurry should be used as soil amendments for obtaining short-term and long-term benefits in terms of production increments and soil amelioration.

Impact of incorporated hay mulch on selected physical, chemical and microbiological properties of a loam soil in Atlantic Canada after five years of continuous potato production

Maintenance of soil quality and crop productivity is a major concern under intensive potato (Solanum tuberosum L.) production. The effects of four consecutive annual applications of 0.00, 2.25, 4.50 and 9.00 t ha-1 wet hay on growing season soil moisture and thermal regimes, soil quality and yield were evaluated on a loamy Orthic Humo-Ferric Podzol between 1995 and 1999. Hay mulching increased soil moisture at the beginning of the growing season by 6.5 to 12.7%, with increases significant until June 24, September 07 and September 20 for the 2.25, 4.50 and 9.00 t ha-1 treatments, respectively. Growing season soil temperature of the 4.50 and 9.00 t ha-1 treatments were lower than control, but only by −0.2 and −0.8°C, respectively. Hay mulching increased soil organic carbon (SOC) of the plow layer (0–25 cm), which increased biological activity resulting in better soil aggregation with more macropores, faster saturated hydraulic conductivity and reduced bulk density. Soil air CO2 concentration was significantly correlated to SOC content, aggregation, porosity and saturated hydraulic conductivity. Hay mulching at 2.25 and 4.50 t ha-1 increased total potato yield over that of the unmulched control by 11–14%, but was insufficient to maintain soil productivity. Hay mulching at 9.00 t ha-1 may have been excessive in terms of crop yield as it showed no total yield benefits. Key words: Organic carbon, CO2 concentration, aggregates, porosity

Comparative effects of plant residues and NPK fertilizer on soil properties in a humid ultisol

Field experiments were conducted at two locations in 2001 and 2002 on acidic Ultisol of Southeast Nigeria to assess the effects of amending soil with plant residues on soil physical and chemical properties. The soil amendment treatments compared were natural fallow, wood ash at 6 tha -1 , peanut residue at 12 tha -1 , combination of wood ash and peanut residue at 6 tha -1 and 12 tha -1 respectively, and NPK fertilizer (300 kg ha -1 ). Incorporated wood ash, peanut residue, their combination, and fertilizer increased cation exchange capacity (CEC) compared with fallow, peanut residue increased soil N but not P. Ash increased soil P and not N, NPK fertilizer increased soil N, P and CEC. Ash and peanut residue, alone or combined, reduced soil bulk density and increased aggregate stability and porosity. Nigerian Journal of Soil Science Vol. 15 2005: 9-13

EFFECT OF ANNUAL, BIENNIAL, AND TRIENNIAL IN-ROW SUBSOILING ON SOIL COMPACTION AND COTTON YIELD IN SOUTHEASTERN U.S. SILT LOAM SOILS

For those soils that require deep tillage to alleviate soil compaction, subsoiling can be an expensive andtime-consuming tillage event. Alternative tillage methods are needed which conserve natural resources without sacrificingcotton yields. An experiment was conducted in the Tennessee Valley region of north Alabama to determine how frequentlydeep tillage is needed to alleviate soil compaction problems in these soils. Three different subsoilers (an in-row subsoiler andtwo bentleg subsoilers) were tested against a no-till treatment to determine if differences in crop productivity or soil conditioncould be detected. Annual subsoiling resulted in reduced bulk density compared to biennial subsoiling, triennial subsoiling,or no subsoiling. Reductions in draft force were also found for annual subsoiling. However, cotton yield results over a two-yearperiod from tillage three-years previous, two-years previous, and one year previous found no differences.

Amelioration of a highly alkaline soil by trees in northern India

Abstract. A study was carried out to compare the impact of 6‐year‐old plantations of Prosopis juliflora (Swartz) D.C., Dalbergia sissoo Roxb. Ex. D.C. and Eucalyptus tereticornis Sm. on the physical and chemical properties of sodic soil in the Indo‐Gangetic alluvial plains of Uttar Pradesh, India. Soil properties under the three tree species showed significant improvement through a reduction in the pH, electrical conductivity, exchangeable sodium percentage, CaCO3 and gypsum requirement, and by increase in organic C, total N, and available P and K. The six years of reclamation had achieved a marked reduction in exchangeable sodium (from 11.5 to 4.5 cmolc kg−1) to a depth of 1.5 m in the soil profile, whereas the levels of exchangeable calcium, magnesium and potassium had increased. There was also a significant reduction in soil bulk density (from 1.66 to 1.24 g cm−3) and increases in porosity, water holding capacity, field capacity, permeability and infiltration rate. The equilibrium infiltration rate after 455 min increased from 0.03 cm h−1 in the control to 0.13 cm h−1 under P juliflora and D. sissoo and 0.10 cm h−1 under E. tereticornis. It is concluded that salt‐tolerant tree species have a significant impact on soil properties, which could help to rehabilitate the sodic wastelands in the region.

Generation of microcellular biodegradable polycaprolactone foams in supercritical carbon dioxide

AbstractMicrocellular foaming of low‐Tg biodegradable and biocompatible polycaprolactone (PCL) in supercritical CO2 has been studied. The purpose is to apply microcellular materials to drug containers and medical materials for artificial skin or bone. Effects of a series of variable factors on the foam structures, such as saturation temperature, saturation pressure, saturation time, and depressurization time were studied. The experimental results indicate that, while keeping other variables unchanged, higher saturation temperature leads to reduced bulk densities and different saturation pressures result in different nucleation processes. In addition, saturation time has a profound effect on the structure of the product. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 593–597, 2004

A Note on Particle Segregation by Size in Liquid−Solid Fluidized Beds

Piecemeal derivations of a model in the literature for predicting the degree of particle segregation by size of a binary particle mixture in a liquid−solid fluidized bed are unified and simplified. It is shown that the degree of particle segregation at a given liquid velocity can be represented quantitatively by the reduced bulk density difference of the two particle species each fluidized separately at the same liquid velocity and that for equal-density particles the reduced bulk density difference is given by the corresponding voidage difference of the two species. This criterion indicates an increase of particle segregation as the particle size ratio (large/small) increases, as the fluid velocity and, hence, the voidage level increase, and as the Archimedes number Ar decreases from the Newton regime (Ar > 85 000) to the Stokes regime (Ar < 4).

On-farm assessment of organic matter and tillage management on vegetable yield, soil, weeds, pests, and economics in California

In intensive vegetable production, low organic matter (OM) inputs and leaching of nitrate (NO3 − -N) decrease soil quality with time. Four management regimes were compared for their effects on soils and on production issues in a cooperative research project with a commercial vegetable grower in the Salinas Valley, California, USA, on an 8.3 ha field: minimum tillage with OM (+OM) inputs; minimum tillage with no OM (−OM) inputs; conventional tillage +OM inputs; and conventional tillage −OM inputs. Minimum tillage retained the same raised beds for the 2-year study (four crop cycles), and tilled to approximately 20 cm depth. Conventional tillage used many passes for surface and subsoil tillage, and disturbed the soil to approximately 50 cm depth. In +OM, compost was added two times per year, with a rye (Secale cereale) cover crop in the fall or winter, whereas −OM treatments followed the typical practice of only incorporating crop residues. Addition of cover crops and compost increased microbial biomass C (MBC) and N (MBN), reduced bulk density, and decreased the NO3 − -N pools in the 0–90 cm profile, so that leaching potential was lower compared to −OM treatments. Tillage practices had generally similar effects on soils except that surface soil moisture and NO3 − -N in the deep profile were consistently lower with minimum tillage. Minimum tillage tended to decrease lettuce (Lactuca sativa) and broccoli (Brassica oleracea) yields, but was not associated with increased pest problems. Weed density of shepherd’s purse (Capsella bursa-pastoris) and burning nettle (Urtica urens) were occasionally lower in the +OM treatments. Disease and pest severity on lettuce was slight in all treatments, but for one date, corky root disease (caused by Rhizomonas suberifaciens) was lower in the +OM treatments. The Pea Leafminer, Liriomyza huidobrensis, was unaffected by management treatments. Economic analysis of the three lettuce crops showed that net financial returns were highest with minimum tillage −OM inputs, despite lower yields. Various tradeoffs suggest that farmers should alternate between conventional and minimum tillage, with frequent additions of OM, to enhance several aspects of soil quality, and reduce disease and yield problems that can occur with continuous minimum tillage. © 2004 Elsevier B.V. All rights reserved.

Sod establishment and turfgrass growth as affected by urea–formaldehyde resin foam soil amendment

Urea–formaldehyde resin foam (UFRF) has recently been introduced as a soil amendment for turfgrass culture. A field study was performed to evaluate the impact of UFRF on soil physical and chemical properties, sod establishment and turfgrass shoot and root growth. Treatments included a non-amended, sandy loam soil and the same soil amended with UFRF at a rate of 20% (v/v) incorporated into the upper 0.1 m of the substrate. Physical and chemical analyses of the two substrates involved the determination of bulk density, total porosity, air-filled porosity at 0.4 m, moisture release curve, pH and electrical conductivity. Turfgrass growth was determined through several measurements that included shoot growth rate, root growth rate and monitoring of three root architecture parameters namely, total root length, total root area and mean root diameter. Turfgrass establishment was evaluated by measuring the vertical force applied to detach the sod from the substrate. UFRF amendment did not influence pH and EC and provided minimal alterations (non-significant) in soil physical properties by slightly increasing total porosity, easily available water and air-filled porosity, and by reducing bulk density. The impact of UFRF amendment improved cumulative clipping yield in five sampling dates but root growth and sod establishment rate were better than the control only on one sampling date. There appears to be limited benefit in amending soil with UFRF.

Effect of cultural practices on soil properties, moisture conservation and grain yield of winter sorghum ( Sorghum bicolar L. Moench) in semi-arid tropics of India

A field experiment was laid out during winter seasons of 1994–1995 and 1995–1996 on deep black clayey soils (Vertisols) at Regional Research Station, Bijapur, in the northern dry zone of Karnataka State (Zone 3) of south India to evaluate the effect of cultural practices on soil moisture conservation, soil properties, root growth and yield of sorghum ( Sorghum bicolar L. Moench). Lay out of plots with in situ moisture conservation practices reduced bulk density, increased infiltration rate, porosity, improved root growth and grain yield of winter sorghum. Conservation and availability of higher amount of moisture and nutrients during various stages of crop growth with moisture conservation practices resulted in better crop growth with higher amount of dry matter production and its translocation to ear in winter sorghum. Compartmental bunding and ridges and furrows increased the grain yield by 22.8 and 25.6% (mean of 1994–1995 and 1995–1996), respectively, over flat bed with similar trend observed during 1994–1995 and 1995–1996. Among organic sources, incorporation of Leucaena loppings improved soil physico-chemical properties, conserved higher amount of moisture and increased winter sorghum yield to a greater extent than farmyard manure and vermicompost. Average grain yield (1994–1995 and 1995–1996) of winter sorghum increased by 11.7% with Leucaena application as compared to vermicompost. Grain yield increased significantly by 20% with application of 25 kg N ha −1 and further increase in nitrogen dose up to 50 kg ha −1, increased the grain yield by 30.5% in the pooled data.

Density functional study of the adsorption and separation of hydrogen in single-walled carbon nanotube

In this work, we report an investigation by means of density functional theory (DFT) of the adsorption of hydrogen and the separation of hydrogen–carbon monoxide mixture in an isolated single-walled carbon nanotube. The theory is based on a perturbative construction of free energy functional for inhomogeneous pure fluid and binary fluid mixture. The reformulated Rosenfeld's fundamental-measure theory using the excess Helmholtz energy density from the Boublik–Mansoori–Carnahan–Starling–Leland equation of state proposed by Yu and Wu (J. Chem. Phys. 117 (2002) 10156) is applied to represent the pure and binary hard-sphere repulsive interaction, and Weeks–Chandler–Andersen perturbation theory is used to build the attractive contribution. The density profiles in three sizes of tubes at 300 K and reduced bulk density from 0.2 to 0.7 for pure hydrogen and hydrogen–carbon monoxide mixture are obtained. The theoretical calculations are in good agreement with the simulation results in this work and other data available in literature. The adsorption of hydrogen and the selectivity of hydrogen–carbon monoxide mixture are predicted from DFT and the adsorption characteristics of the isolated cylindrical wall is discussed.