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1.
The feasibility of producing biodiesel from Idesia polycarpa var. vestita fruit oil was studied. A methyl ester biodiesel was prepared from refined I. polycarpa fruit oil using methanol and potassium hydroxide (KOH) in an alkali-catalyzed transesterification process. The experimental variables investigated in this study were catalyst concentration (0.5–2.0 wt.% of oil), methanol/oil molar ratio (4.5:1 to 6.5:1), temperature (20–60 °C) and reaction time (20–60 min). A maximum yield of over 99% of methyl esters in I. polycarpa fruit oil biodiesel was achieved using a 6:1 molar ratio of methanol to oil, 1.0% KOH (% oil) and reaction time for 40 min at 30 °C. The properties of I. polycarpa fruit oil methyl esters produced under optimum conditions were also analyzed for specifications for biodiesel as fuel in diesel engines according to China Biofuel Systems Standards. The fuel properties of the I. polycarpa fruit oil biodiesel obtained are similar to the No. 0 light diesel fuel and most of the parameters comply with the limits established by specifications for biodiesel.  相似文献   

2.
Saturated mono-estolide methyl esters and enriched saturated mono-estolide 2-EH esters were synthesized from oleic and different saturated fatty acids under three different synthetic routes. Estolide numbers (EN), the average number of fatty acid units added to a base fatty acid, varied with synthetic conditions. The attempts at obtaining saturated mono-estolide 2-EH esters, EN = 1, via distillation proved to be challenging, which lead to estolide samples with EN > 1 and the pour point values followed the same trend as the high EN estolides. The other synthetic routes provided saturated mono-estolide methyl esters with EN = 1. The resulting pour point values showed a linear relationship between the saturated capping chain length and pour point. As the saturated capping chain length increased the pour points also increased (higher temperatures): C-2 capped ?30 °C, C-10 capped ?12 °C, and C-18 capped 3 °C.The saturated mono-estolide methyl ester viscosities also showed an increase in viscosity at 40 and 100 °C as the saturated chain lengths increased. The viscosities for the C-4 saturated mono-estolide methyl ester was 9.5 cSt at 40 °C and 2.6 cSt at 100 °C, while medium chain length derivations (C-10 saturated mono-estolide methyl ester) were 19.7 cSt at 40 °C and 4.2 cSt at 100 °C, and at the longer chain length derivations (C-18 mono-estolide methyl esters) were 27.6 cSt at 40 °C and 10.7 cSt at 100 °C. In general, a new series of saturated oleic mono-estolide methyl esters were synthesized and physical properties were collected. The physical property data indicated that both chain length and EN affect low temperature properties.  相似文献   

3.
Vegetable oils are biodegradable and therefore good candidates for environmentally friendly base stocks. They have excellent lubricity, but poor oxidation and low temperature stabilities. For this study, synthetic lubricant basestocks with oxidative stabilities and pour points comparable with commercial synthetic lubricant basestocks have been prepared by reacting epoxidized soybean oil with Guerbet alcohols. Four different Guerbet alcohols, C12-, C14-, C16-, and C18-Guerbet alcohols were used. Reaction of epoxidized soybean oil with a Guerbet alcohol in the presence of a catalytic amount of sulfuric acid provided open-ringed products. 1H NMR has shown that transesterification follows after ring-opening reaction under the given reaction conditions. Two types of ring-opened products, 0%- and 100%-transesterified products, could be obtained under controlled reaction conditions. Pour points of the ring-opened products ranged from −18 to −36 °C without pour point depressant (PPD) and from −21 to −42 °C with 1% of PPD. Acetylation of hydroxy groups in the ring-opened products further lowered pour points that ranged from −27 to −42 °C without PPD and from −30 to −48 °C with 1% of PPD. Oxidative stability was examined using a modified Penn State microoxidation test and compared with those of synthetic lubricant basestocks and mineral oil. Oxidative evaporations of two selected products in the microoxidation test were similar to mineral oil and less than synthetic lubricant-based oils, polyalphaolefin (PAO4) and diisododecyl adipate. Deposits of these products were similar to synthetic lubricant-based oils and less than mineral oil.  相似文献   

4.
Biodegradable, vegetable oil-based lubricants must have better low temperature properties as well as comparable cost to petroleum oils before they can become widely acceptable in the marketplace. The low temperature property usually measured is the pour point (pp), the minimum temperature at which the material will still pour. Viscosity and viscosity index also provide information about a fluid's properties where a high viscosity index denotes that a fluid has little viscosity change over a wide temperature range. Lesquerella oil is a good candidate for its development into a biodegradable lubricant as it is being developed as an alternative crop for the southwestern U.S. The hydroxy site on the fatty acid (FA) makes it a suitable site for esterification to yield estolides. Castor and lesquerella FA esters were combined with different types of saturated, unsaturated, and branched FAs to produce estolides. Castor and lesquerella estolide esters had the best cold temperature properties when capped with oleic (pp = −54 °C for castor and pp = −48 °C for lesquerella) or capped with a branched material, 2-ethylhexanoic acid (pp = −51 °C for castor and pp = −54 °C for lesquerella). As the saturation was increased in the estolide, pour and cloud points also increased. The increased saturation such as in stearic capped estolides allowed for sufficient alkyl stacking of these long saturated chains producing higher pour points. Oxidative stability of the estolides was compared between the oleic-castor estolide 2-ethylhexyl ester and the coco-castor estolide 2-ethylhexyl ester by the rotating bomb oxidation test (RBOT). The RBOT times for both estolides were low with a similar time of about 15 min. However, when the antioxidant package (3.5 wt.%) was added, the RBOT times increased to 403 min for the coco-castor estolide 2-ethylhexyl ester while still retaining its outstanding cold temperature properties, (pp = −36 °C and cp = −30 °C). The viscosity index ranged from 164 to 200 for these new hydroxy FA derived estolide 2-ethylhexyl esters. These oleic-castor and lesquerella estolide esters have displayed far superior low temperature properties (pp = −54 °C) than any other estolides reported to date. Due to the lack of solvent and catalysts, the cost of these estolides should be reasonable and more suitable as a base stock for biodegradable lubricants and functional fluids than current commercial materials.  相似文献   

5.
This report presents a method for synthesizing base-stock for green industrial product from a vegetable oil with a high composition of unsaturated fatty acids. Epoxy methyl ester of palm kernel oil was synthesized from laboratory purified palm kernel oil using a two-step reaction and the products were used as a base-stock for green electrical insulation fluid. Epoxidized palm kernel oil was first prepared through epoxidation reaction involving purified palm kernel oil, acetic acid and hydrogen peroxide in the presence of amberlite as catalyst which lasted for 4 h. It was then followed by transesterification reaction involving the epoxidized product and methanol in the presence of sodium hydroxide as catalyst to synthesize the corresponding epoxy methyl ester. The thermal and electrical breakdown properties of the epoxy methyl ester demonstrated significantly improved properties for its use as raw material for bio-based industrial products such as electrical insulation fluids.  相似文献   

6.
The corn dry-grind process is the most widely used method in the U.S. for generating fuel ethanol by fermentation of grain. Increasing demand for domestically produced fuel and changes in the regulations on fuel oxygenates have led to increased production of ethanol mainly by the dry-grind process. Fuel ethanol plants are being commissioned and constructed at an unprecedented rate based on this demand, though a need for a more efficient and cost-effective plant still exists.A process and cost model for a conventional corn dry-grind processing facility producing 119 million kg/year (40 million gal/year) of ethanol was developed as a research tool for use in evaluating new processing technologies and products from starch-based commodities. The models were developed using SuperPro Designer® software and they handle the composition of raw materials and products, sizing of unit operations, utility consumptions, estimation of capital and operating costs, and the revenues from products and coproducts. The model is based on data gathered from ethanol producers, technology suppliers, equipment manufacturers, and engineers working in the industry. Intended applications of this model include: evaluating existing and new grain conversion technologies, determining the impact of alternate feedstocks, and sensitivity analysis of key economic factors. In one sensitivity analysis, the cost of producing ethanol increased from US$ 0.235 l−1 to US$ 0.365 l−1 (US$ 0.89 gal−1 to US$ 1.38 gal−1) as the price of corn increased from US$ 0.071 kg−1 to US$ 0.125 kg−1 (US$ 1.80 bu−1 to US$ 3.20 bu−1). Another example gave a reduction from 151 to 140 million l/year as the amount of starch in the feed was lowered from 59.5% to 55% (w/w).This model is available on request from the authors for non-commercial research and educational uses to show the impact on ethanol production costs of changes in the process and coproducts of the ethanol from starch process.  相似文献   

7.
The demand for diesel fuel far exceeds the current and future biodiesel production capabilities of the vegetable oil and animal fat industries. New oilseed crops that do not compete with traditional food crop are needed to meet existing energy demands. Hybrid hazelnut oil is just such an attractive raw material for production of biodiesel. Hazelnut oil was extracted from hybrid hazelnuts and the crude oil was refined. Hazelnut oil-based biodiesel was prepared via the transesterification of the refined hazelnut oil with excess methanol using an alkaline catalyst. The effects of reaction temperature, time and catalyst concentration on the yield of diesel were examined, and selected physical and chemical properties of the biodiesel were evaluated. The biodiesel yield increased with increasing temperature from 25 to 65 °C and with increasing catalyst concentration from 0.1 to 0.7 wt%. The increase in yield with reaction time was nonlinear and characterized by an initial faster rate, followed by a slow rate. Hazelnut oil-based biodiesel had an average viscosity of 8.82 cP at 25 °C, which was slightly higher than that of the commercial soy-based diesel (7.92 cP at 25 °C). An approximate 12 °C higher onset oxidative temperature and a 10 °C lower cloud point of hazelnut oil biodiesel than those of its commercial soy counterpart indicated a better oxidative stability and flowability at low temperature. The average heat of combustion of hazelnut oil biodiesel was 40.23 kJ/g, and accounted for approximately 88% of energy content of diesel fuel. The fatty acid composition of hazelnut oil-based biodiesel was the same as the nature oil.  相似文献   

8.
Palm esters were synthesized through enzymatic transesterification of various palm oil fractions with oleyl alcohol using Lipozyme RM IM as the catalyst. At the optimized alcoholysis reaction condition, after 5 h reaction time all palm oil fractions exhibited a high percentage yields of esters (>80%). Simultaneous differential scanning calorimeter-thermal gravity analysis showed a high thermal stability profile of palm esters. Other physicochemical properties of palm esters such as refractive index, density, surface tension, slip melting point, saponification value, iodine value and acid value were analyzed following standard test methods modified from the American Oil Chemists’ Society standards. The dermal irritation assay of palm oil esters shows the non-irritancy of the esters with a Human Irritancy Equivalent (HIE) score below 0.9. Furthermore, an increase in skin hydration of 40.7% after 90 min after application in an acute moisturizing test, has proven the suitably of palm oil esters to be used in the cosmetics formulation.  相似文献   

9.
Evening primrose (Oenothera biennis) is increasingly cultivated for medicinal use of the γ-linolenic acid rich oil. The seed cake (EPSC) – the remaining industrial residue from cold pressing – was extracted with polar solvents in order to investigate a profitable polyphenolic recovery. The extractable matter and the total phenolic content (Folin-Ciocalteu) have been compared to a black currant residue from juice production (Ribes nigrum) and seed cakes from sesame, woad (Isatis tinctoria) and burdock (Arctium lappa). The EPSC crude extracts yielded the high total phenolic content (min 228.2 ± 11.6 to max 696.4 ± 29.0 mg GAE g−1 dry extract) within the range of already commercialized antioxidant extracts from rosemary (RO, 142.1 ± 1.9 mg g−1), green tea (GT, 446.8 ± 27.4 mg g−1) and grape seed (GS 790.0 ± 53.1 mg g−1). All extracts exhibited free radical scavenging activity (DPPH assay) with the order of potency: EPSC > GS > GT ≫ burdock = black currant > RO > butylated hydroxytoluene (BHT) ≫ woad > sesame. Accordingly EPSC extracts where very effective in scavenging superoxide anion radicals (neotetrazolium assay: GS > EPSC > GT ≫ BHT > burdock > woad > sesame) and inhibition of lipid oxidation (Rancimat assay: BHT ≫ GT > EPSC ≫ burdock > woad > RO > sesame > GS). Decreasing Rancimat activity from 80 °C upwards might indicate heat sensitiveness and limited usability. However, an efficient exploitation of polyphenols from evening primrose seed cakes in terms of an uncomplicated extraction procedure, the yield and the competitive profile as a strong radical scavenger can be concluded.  相似文献   

10.
A 20-year field experiment was employed with the aim of evaluating the effect of tillage systems on biological, chemical and physical aspects of the soil, and to establish whether there was a correlation of these parameters with the incidence of charcoal rot (Macrophomina phaseolina) of soybean and crop yield. The tillage systems evaluated were direct seeding (DS), DS + scarifier (DS + S), minimum tillage (MT) and conventional tillage (CT). DS presented higher values than CT in culturable total fungi (26.33 × 105 vs. 2.33 × 105 CFU g−1 dry soil), total bacteria (182 × 107 vs. 64 × 107 CFU g−1 dry soil), microbial respiration (0.77 mg CO2 g−1 week−1 vs. 0.45 mg CO2 g−1 week−1) and fluorescein diacetate (FDA) hydrolysis (4.17 ug fluorescein g−1 h−1 vs. 1.70 ug fluorescein g−1 h−1 in CT. Fungal and bacterial community fingerprints, by terminal restriction fragment length polymorphism (T-RFLP) analysis, of Intergenic spacer regions of rRNA and 16S rRNA genes, respectively, were influenced by the tillage system. Also FAME (fatty acid methyl ester) profiles showed that microbial community structure in DS and CT was clearly different. DS samples contained significantly higher total microbial biomass than the other tillage treatments, but there were no significant differences in fungal biomass or any consistent trend with respect to stress index. Our results showed that microbial communities were more abundant and active in DS than in CT in response to high nutrient content in soil. Indeed, DS systems presented higher soil OM, total N, K and Ca than CT. Electrical conductivity and aggregate stability (AS) were also improved by DS. Soybean grown in high-quality soil was not affected by charcoal rot, however, under CT, disease incidence in soybean was 54%. These differences were correlated to the higher microbial abundance and activity under DS, the biological component being a key factor determining soil capacity to suppress the soilborne pathogen.  相似文献   

11.
《Field Crops Research》2006,95(2-3):412-419
Jasmonic acid (JA) is a plant hormone produced via the octadecanoid pathway from its precursor, linolenic acid. Jasmonates are involved in plant wound responses and defense against insects and fungal elicitors. They can also act as signal molecules in the Bradyrhizobium-soybean symbiosis. Pre-incubation of Bradyrhizobium japonicum inocula with gensitein (Ge), an effective inducer of nodulation genes in this species enhances soybean nodulation, nitrogen fixation and yield under low spring soil temperature field conditions. Since jasmonates are also able to induce nodulation genes and cause the production of lipo-chitooligosaccharides (LCOs) by B. japonicum, we conducted two field experiments, in southwestern Quebec, Canada, to determine whether pre-incubation of B. japonicum with methyl jasmonate (MeJA) alone or in combination with genistein (Ge), prior to inoculation, increased soybean plant dry matter production and grain yield. Experiments at each site used a two factor randomized complete block design (RCBD) with four replicates. Two B. japonicum strains (USDA3 and 532C) and four inducer molecule treatments [control, Ge (20 μM), MeJA (50 μM), and Ge + MeJA (20 μM + 50 μM)] were used in the study. The bacterial cultures were induced for 24 h with the inducer molecules and then applied into the furrows at the time of planting. Both Ge and MeJA, alone or in combination, increased plant growth, dry matter accumulation, and grain yield. This study showed that MeJA, alone or in combination with Ge, can be used to promote soybean plant growth and grain yield under short season field conditions.  相似文献   

12.
This study identified the role of milling and parboiling on arsenic (As) content and its species in large numbers of rice samples. Total As contents were 108 ± 33 μg/kg in polished rice grains (PR), 159 ± 46 μg/kg in unpolished rice grains (UR), 145 ± 42 μg/kg in parboiled polished rice grains (PPR) and 145 ± 44 μg/kg in parboiled unpolished rice grains (PUR). The percentages of inorganic As (iAs) were 66% ± 8% in PR and from 72% to 77% in other grain categories. The polishing process reduced the As content in the rice grains, removing outer part of the UR with high amount of As, whereas the parboiling technique transferred the semimetal content within the grain. Total As and iAs contents were not significantly different in UR, PPR and PUR, homogenizing its distribution inside the grains. The results allowed to understand how different operations affect As fate and its chemical forms in grains.  相似文献   

13.
Rice husk is a by-product of rice milling process, and a great resource as a raw biomass material for manufacturing value-added composite products. One of the potential applications is to use rice husk as filler for manufacturing gypsum–rice husk boards for wall and ceiling materials for construction. We investigated the effect of rice husk, addition on selected physico-mechanical properties, total volatile organic compound (TVOC), and incombustibility, on the gypsum board. With increasing rice husk contents, water and moisture absorption was decreased. Because of the replacement of pore between gypsum particles by rice husk, the moisture absorption was decreased as rice husk adding contents. By rice husk adding, MOR of the gypsum–rice husk boards were increased up to 9.8 MPa at 30 wt%. However, MOR was decreased more than 40 wt% of adding contents. The modulus of elasticity (MOE) showed similar behavior with MOR. However, internal bonding strength (IB) was slightly increased as rice husk adding contents up to 20 wt%, 0.5 MPa and decreased over 20 wt%. The incombustibility of the gypsum–rice husk boards decreased on increasing the rice husk adding content. However, up to 30 wt% of rice husk adding contents board samples was of incombustibility first class. Gypsum particle can be replaced up to 30 wt% by rice husk with incombustibility first class for housing materials. In all cases, TVOC emission factor and formaldehyde emission remained under the ‘Excellent’ grade as defined by Korean Air Clean Association (KACA).  相似文献   

14.
Integrated use of organic and inorganic fertilizers can improve crop productivity and sustain soil health and fertility. The present research was conducted to study the effects of application of green manures [sesbania (Sesbania aculeate Poiret) and crotalaria (Crotalaria juncea L.)] and farmyard manure on productivity of rice (Oryza sativa L.) and its residual effects on subsequent groundnut (Arachis hypogaea L.) crop. Rice and groundnut crops were grown in sequence during rainy and post-rainy seasons with and without green manure in combination with different fertilizer and spacing treatments under irrigated conditions. The results showed that application of green manures sesbania and crotalaria at 10 t ha−1 to rice compared to no green manure application significantly increased grain yield of rice by 1.6 and 1.1 t ha−1, and pod yields of groundnut crop succeeding rice by 0.25 and 0.16 t ha−1, respectively. There was no significant difference between the application of crotalaria or farmyard manure at 10 t ha−1 on grain yields of rice, but pod yields of subsequent groundnut crop were greater with application of green manure. There was no significant effect of different spacing 20×15,15×15,15×10 cm2 (333 000; 444 000; 666 000 plant ha−1, respectively) on grain yield of rice. Pod yields of groundnut were significantly greater with closer spacing 15×15 cm2 (444 000 plants ha−1) as compared to spacing of 30×10 cm2 (333 000 plants ha−1). Maximum grain of rice was obtained by application of 120:26:37 kg NPK ha−1 in combination with green manures, whereas maximum pod yield of groundnut was obtained by residual effect of green manure applied to rice and application of 30:26:33 kg NPK ha−1 in combination with gypsum applied to groundnut crop.  相似文献   

15.
The objectives of this study were to investigate the mechanisms of action and to evaluate the potential application of Desmos chinensis extracts for controlling rice sheath blight. The dichloromethane extract from D. chinensis demonstrated high antifungal activity against Rhizoctonia solani. The extract was shown to have anti-R. solani activity with minimum inhibitory concentration (MIC) and minimum fungicidal concentration values ranging from 31.2 to 62.5 μg mL−1 and from 62.5 to 500 μg mL−1, respectively. Bioautography on thin-layer chromatography plates demonstrated antifungal activity of the extract with an Rf value of 0.33. A total of 7 compounds, 2 benzoate esters (benzyl benzoate and benzyl 2-hydroxybenzoate), 2 sesquiterpenoids (α-eudesmol and β-eudesmol), 1 aromatic alcohol (benzyl alcohol), 1 aromatic ketone (acetophenone) and 1 diterpenoid (phytol), were detected and identified using gas chromatography–mass spectrometry analysis. Electron micrographs confirmed the effects of the extract on morphological and ultrastructural alterations in the treated fungal cells. The micrographs of the mycelia treated with the extract at 4MIC illustrated aberrant morphology such as shrinkage, partial distortion and globular structures of different sizes along the surface of the mycelia. Damaging membranous structures including disruption of the cell membrane, partial loss of nuclear membranes, and depletion of hyphal cytoplasm and membranous organelles were observed. Foliar application of D. chinensis extract at a concentration of 2 mg mL−1 on rice markedly decreased sheath blight severity. It was concluded that the application of D. chinensis extract can be used as a botanical fungicide to control rice sheath blight.  相似文献   

16.
The color (L*, a*, b* parameters), the total phenols content and the global chemical composition (moisture, protein, fat, carbohydrates and ash) of four fresh varieties of olive leaves (Chemlali, Chemchali, Zarrazi and Chetoui) were determined. Fresh olive leaves are characterized by a green color (greenness parameter, a*, varying from ?5.01 ± 0.26 to ?9.14 ± 1.21), an intermediate moisture content (0.85 to 1.00 g/g dry matter, i.e. 46 to 50 g/100 g fresh matter) and a variable amount of total phenols according to the olive leaf variety (from ≈2.32 to ≈1.40 g caffeic acid/100 g dry matter).Fresh leaves were submitted to blanching and/or infrared drying at 40, 50, 60 and 70 °C in order to be stabilized by reducing their moisture contents. The impact of IR drying temperature on some quality attributes (color, total phenols and moisture rate removal) was evaluated. Nevertheless, the effect of prior blanching treatment on the quality attributes of dried leaves is less significant and it depends on the olive leaf variety. The infrared drying induces a considerable moisture removal from the fresh leaves (more than 85%) and short drying durations (varying from ≈162 at 40 °C to 15 min at 70 °C). IR drying temperature showed a significant effect of on total phenols content and the color of the leaves whatever the leaf variety. In fact, total phenols content of dried olive leaves increased if compared to fresh ones. For example, total phenols of Chemlali leaves increased from 1.38 ± 0.02 (fresh leaves) to 2.13 ± 0.29 (dried at 40 °C) and to 5.14 ± 0.60 g caffeic acid/100 g dry matter (dried at 70 °C). IR drying allows preserving the greenness color of fresh leaves and enhancing their luminosity. It could be suggested for preserving olives leaves before their use in food or cosmetic applications.  相似文献   

17.
《Field Crops Research》2006,95(2-3):367-382
For maximizing water retention and attaining high yields, transplanting into puddled soil (TPR) is often considered the optimal method of rice (Orzya sativa L.) establishment. Alternative management techniques like direct seeding (DSR) and deep tillage have been proposed as mechanisms to improve soil physical properties for subsequent dry-season crops, but the risks to rice are uncertain. In this full factorial study on a valley terrace in Nepal, the influence of tillage (shallow—T1, deep chisel—T2, deep chisel + moldboard plough—T3) and establishment practice (TPR, DSR) on the field water balance and rice performance were evaluated in two adjacent landscape settings (terrace edge “upland”, central terrace “lowland”). Although deep tillage had only modest influences on seepage and percolation (SP) rates in both years (Y1, Y2), landscape placement and establishment practice had significant implications for the water balance (e.g. Y2 SP cm day−1: TPR-lowland = 1.6, DSR-lowland = 2.3, TPR-upland = 4.1, DSR-upland = 6.1). During low rainfall periods, however, soil water potential and drought vulnerability were governed solely by landscape placement. Despite water balance differences, there was little evidence that rice rooting behavior was substantially modified by landscape or establishment method. Weed biomass was higher in DSR, but was uncorrelated with water balance and productivity trends. In Y1, lower SP rates and more days with continuous flooding were positively associated with rice productivity. DSR yields were significantly lower than TPR in both landscape positions, with the lowland outperforming the upland (Y1 mt ha−1: TPR-lowland = 6.4, DSR-lowland = 5.2, TPR-upland = 5.7, DSR-upland = 4.7). To determine if N dynamics were contributing to productivity differences, fertilizer nitrogen was increased from 120 to 150 kg N ha−1 in Y2. Results suggest that DSR performance is comparable – and landscape less important – if nitrogen is non-limiting (Y2 mt ha−1: TPR-lowland = 6.9, DSR-lowland = 6.5, TPR-upland = 7.0, DSR-upland = 6.5); no aspect of the field water balance was associated with yield variability in Y2. For direct seeding in N-deficient farming systems, landscape criteria may prove useful for minimizing production risks by identifying field areas with lower SP rates.  相似文献   

18.
《Field Crops Research》1999,63(3):237-246
Using data from large, grower-managed fields we investigated the variation in yield of dryland soybean in an area with low and variable summer rainfall, and soils that are variable in depth and poor in phosphorus (P). First, using data from unfertilised, wide-row (0.7 m) crops grown under standard management between 1989 and 1992 (Series 1), we quantified the relationship between yield and W, a rainfall-based estimate of water availability during the period of pod and grain set. Separate functions were established for deep (depth ≥ 1 m) and shallow soils (0.75 m ≥ depth ≥ 0.5 m). Second, we partially tested these functions using two independent data sets (Series 2 and 3). Third, we evaluated the effects on yield of large (18 kg P ha−1, Series 4) or moderate doses of P fertiliser (8–12 kg P ha−1) in narrow-row crops (0.35 m, Series 5). To investigate water × management interaction we (i) calculated ΔY, the difference between actual yield in Series 4 and 5 and yield calculated with the functions derived from Series 1, and (ii) tested the association between ΔY and actual W. In a set of 24 crops (Series 1), yield varied between 2.1 and 3.1 t ha−1 in deep soils and between 1.3 and 2.6 t ha−1 in shallow soils; non-linear functions described fairly well, the response of yield to W. Fertilisation with 18 kg P ha−1 increased yield by 0.6 t ha−1 irrespective of water availability. The combination of narrow rows and a moderate dose of fertiliser increased yield in 73% of crops in deep soil but only in 53% of crops in shallow soil. There was a positive association between ΔY and W in deep soil but no relationship between these variables in shallow soil. Yield responses to management were thus differentially affected by rainfall in deep and shallow soils.  相似文献   

19.
Effect of pressing time on physical and mechanical properties of phenolic-impregnated bamboo strips was evaluated. Bamboo strips (Gigantochloa scortechinii) were impregnated with low molecular weight phenol formaldehyde (LMwPF) resin. Samples were submerged in LMwPF resin using a vacuum chamber of 750 mmHg for 1 h before it was released within 1.5 h. Treated strips were dried in an oven with a temperature of 60 °C within 6–9 h. It was hot pressed at 14 kg m?2 and a temperature of 140 °C for 5, 8, 11, 14 and 17 min. The physical and mechanical properties of the test indicated that the properties of phenolic-treated strips have significantly increased as compared to control samples. Dimensional stability (water absorption, thickness swelling and linear expansion) of the phenolic-treated properties were significantly lower than control after 5-min pressing time. The antishrink efficiency (ASE) of phenolic-treated strips increased when pressing time were extended from 5 to 17 min. The mean value of modulus of rupture (MOR) for the control samples (177 N mm?2) showed a significant difference with phenolic-treated strips after 17-min pressing time (224 N mm?2). However, there is no significant difference in compression parallel to grain. The MOE of phenolic-treated strips was 21,777 N mm?2 and for control was 18,249 N mm?2, whereas the compression parallel to grain values for phenolic-treated and control samples were 94 and at 77 N mm?2, respectively.  相似文献   

20.
《Field Crops Research》2001,70(2):101-109
Field pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.) were intercropped and sole cropped to compare the effects of crop diversity on productivity and use of N sources on a soil with a high weed pressure. 15N enrichment techniques were used to determine the pea–barley–weed-N dynamics. The pea–barley intercrop yielded 4.6 t grain ha−1, which was significantly greater than the yields of pea and barley in sole cropping. Calculation of land equivalent ratios showed that plant growth factors were used from 25 to 38% more efficiently by the intercrop than by the sole crops. Barley sole crops accumulated 65 kg soil N ha−1 in aboveground plant parts, which was similar to 73 kg soil N ha−1 in the pea–barley intercrop and significantly greater than 15 kg soil N ha−1 in the pea sole crop. The weeds accumulated 57 kg soil N ha−1 in aboveground plant parts during the growing season in the pea sole crops. Intercropped barley accumulated 71 kg N ha−1. Pea relied on N2 fixation with 90–95% of aboveground N accumulation derived from N2 fixation independent of cropping system. Pea grown in intercrop with barley instead of sole crop had greater competitive ability towards weeds and soil inorganic N was consequently used for barley grain production instead of weed biomass. There was no indication of a greater inorganic N content after pea compared to barley or pea–barley. However, 46 days after emergence there was about 30 kg N ha−1 inorganic N more under the pea sole crop than under the other two crops. Such greater inorganic N levels during early growth phases was assumed to induce aggressive weed populations and interspecific competition. Pea–barley intercropping seems to be a promising practice of protein production in cropping systems with high weed pressures and low levels of available N.  相似文献   

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