The impact of earthworms on the abundance of Collembola: improvement of food resources or of habitat?

I assessed the direct influence of earthworm excretions, and the impact of earthworms through their action on the soil structure (increased macroporosity), on the population dynamics of the collembolan species Heteromurus nitidus. The intestinal content of Collembola arising from cultures on different soil types was observed, and two experimental cultures of H. nitidus were run: (1) a culture performed on an inert substrate supplied either with earthworm casts or with soil as food resource, (2) an experiment using microcosms with cores of two humus forms (moder and calcic mull), in the presence or absence of earthworms. The observation of gut contents revealed that H. nitidus feeds on excrements, the composition of which (ratio organic matter/mineral matter) varies according to the humus form where it lived. Slightly aged (10–15 days) organo-mineral casts of earthworms appeared to be a better food than calcic mull aggregates or organic material from moder. Densities of H. nitidus cultured in cores of calcic mull were higher than in moder, except when cores of moder were inhabited by an anecic earthworm for 2 months. The humus form strongly influenced populations of H. nitidus, firstly because densities of predators were higher in moder than in calcic mull, and probably also because of soil macroporosity. It was concluded that earthworms would affect predation on H. nitidus by creating a network of interconnected macropores in which Collembola can move and find shelter.     

Pressure-induced denaturation of β-lactoglobulin in skim milk: effect of milk concentration

The effect of milk concentration (10-40% TS) on the kinetics of the pressure-induced denaturation of β-lactoglobulin (β-LG) was studied. The denaturation was found to be a second-order process at all milk concentrations and pressures. There was a change in pressure dependence of the rate constants for denaturation at about 300 MPa, and this effect became more pronounced as the milk concentration increased. At pressures ≥300 MPa, a small effect of milk concentration was observed, with small decreases in the rate of denaturation as the milk concentration was increased above 20% TS. This was attributed to the lower pH as the milk concentration was increased. In contrast, at 200 MPa, β-LG denaturation was markedly retarded as the milk solids concentration was increased. This was attributed to the increased lactose concentration at higher milk concentrations. This would promote β-LG dimerization at this pressure and this would stabilize the β-LG to denaturation.     

Environmental degradation in karst areas of Cambodia: A legacy of war?

Karst areas in Kampot Province, southwest Cambodia, have suffered relatively recent soil erosion and partial infilling of caves by the eroded sediment. This soil loss is most pronounced in localities that have been a focus of human activity, such as along pedestrian and vehicular access routes and in areas subject to vegetation clearing and agricultural activity, but it also occurs more widely across the hillslopes. In comparable karst environments elsewhere in Cambodia and neighbouring countries erosion is similarly evident in areas that have been subject to intensive human use, but in contrast to Kampot it is absent from the broader landscape. The soil degradation in the Kampot karst seems to require disturbance of the natural vegetation cover which stabilizes the soil cover in the other karsts, probably during the latter half of the 20th century. No major changes in deliberate land‐use at the study sites that might have triggered this erosion have been identified. However, this part of Cambodia was subject to heavy aerial bombardment between 1965 and 1973, and the karst hills and their caves were a particular focus of military activity. This bombing in turn facilitated ascent of the genocidal Khmer Rouge regime which drove virtually the entire population into a subsistence rural existence, and then further armed conflict prior to that regime's overthrow, both of which are likely to have generated additional environmental damage. Copyright © 2010 John Wiley & Sons, Ltd.     

Respiration Rate – Reheating Potential: A Comparison of Measures of Compost Stability

In this study, respiration rate was found to be a useful tool for assessing the relative stability of compostable materials. Internal windrow temperature and/or reheating potential were compared to respiration rate, and therefore, to the degree of compost stability. Parameters that evaluate biological activity, such as respiration rate and reheating potential, exhibited an ability to indicate compost stability.

There are no federal regulations and only a limited number of state regulations regarding compost stability or end use. Minnesota, New York, Florida and a few other states have developed classifications for maturity or end use. These regulations generally define mature or stable compost as having achieved 60 percent decomposition or having been in active decomposition for at least 180 days. Reheating potential or declining windrow temperatures have been used as qualitative measures of maturity.     

Biofortification of soybean meal: immunological properties of the 27 kDa γ-zein

Legumes, including soybeans ( Glycine max ), are deficient in sulfur-containing amino acids, which are required for the optimal growth of monogastric animals. This deficiency can be overcome by expressing heterologous proteins rich in sulfur-containing amino acids in soybean seeds. A maize 27 kDa γ-zein, a cysteine-rich protein, has been successfully expressed in several crops including soybean, barley, and alfalfa with the intent to biofortify these crops for animal feed. Previous work has shown that the maize 27 kDa zein can withstand digestion by pepsin and elicit an immunogenic response in young pigs. By use of sera from patients who tested positive by ImmunoCAP assay for elevated IgE to maize proteins, specific IgE binding to the 27 kDa γ-zein is demonstrated. Bioinformatic analysis using the full-length and 80 amino acid sliding window FASTA searches identified significant sequence homology of the 27 kDa γ-zein with several known allergens. Immunoblot analysis using human serum that cross-reacts with maize seed proteins also revealed specific IgE-binding to the 27 kDa γ-zein in soybean seed protein extracts containing the 27 kDa zein. This study demonstrates for the first time the allergenicity potential of the 27 kDa γ-zein and the potential that this protein has to limit livestock performance when used in soybeans that serve as a biofortified feed supplement.     

Effects of fermented cow‐manure on rooting of mung bean cuttings: The role of nutrients and of abscisic acid

The effects of cabutz, an end product of anaerobic fermentation of cow manure, and the effects of its components, on rooting of cuttings were investigated. Cuttings of mung bean (Vigna radiata L. Wilcz.) plants have rooted better in cabutz than in other rooting media. Cabutz extract increased the number of roots of mung bean cuttings as well as their roots length. Similar effects were obtained with a solution containing only the inorganic constituents of cabutz extracts. The complete cabutz extract, but not its mineral components, caused three pronounced effects: (a) it changed the distribution pattern of adventitious roots along the cuttings; (b) it delayed the initiation of roots at the base of the cuttings in the presence of high concentrations of cabutz extract; and (c) it reduced the water loss by cabutz‐treated cuttings. Similar effects were obtained when external abscisic acid was applied in concentrations similar to what was found in cabutz extracts. It is suggested that the effects of cabutz, on the rooting capability of cuttings, are mostly due to two of its components, nitrate and abscisic acid.     

SW—Soil and Water: Construction of an Artificial Perched Watertable,Part 1: Air Permeability of Soils and Aspects of Soil Failure

The annual precipitation in the Three-river Plain of the People's Republic of China is only 500–600 mm and, besides, the rainfall is uneven; 60–70% of the annual precipitation occurs in July and August and there is almost no rainfall in the winter and spring seasons. Experiments were conducted to form the artificial perched watertable where the runoff caused in summer could preferably be held, by injecting high-pressure air into the soil. A horizontal soil cavity is required, so this paper deals with the determination of the air permeability of soils and the difference in the soil failure mechanisms due to the different air permeabilities.The results show that the air permeability k of 10 m² s⁻¹ MPa⁻¹ defined the situation between the fluidization and the V-shaped soil failure. When the value of k was from 10 to 0·1 m² s⁻¹ MPa⁻¹, the V-shaped soil failure took place and when it was less than 0·1 m² s⁻¹ MPa⁻¹, the soil cavity production took place. In order to produce the soil cavity in the B horizon of the planosol or Cg1 horizon of the meadow soil by air injection, the value of k for these soils should be less than 0·1 m² s⁻¹ MPa⁻¹ and the soil water content of these soils should be more than 30% d.b.     

PH—Postharvest Technology: The First Period of Convection Drying of Vegetables and the Effect of Shape-dependent Shrinkage

Research on the kinetics of convection drying of vegetables has shown that the first period of drying exists, and non-linear changes in water content of the vegetables occur. The non-linear changes in the water content result from shrinkage of the drying materials. A mathematical, non-linear theoretical model for the first period of drying contains a coefficient N, the value of which depends on the surface shrinkage of the dried material. Up to now, the value ofN has been determined by a process of trial and error. In this paper, a method is presented for determining the value of the coefficient N analytically for cut vegetables. Models for the coefficient N for bodies having the shape of either a cuboid or a circular cylinder are formulated. For cut vegetables, the value of the coefficient N can also be determined by the Monte-Carlo method, using a reversed distribution function of the coefficient N treated as a random variable, and established on the basis of its empirical distribution. This method can be useful in practical applications. The proposed models were verified empirically for cut vegetables, such as garden beet and carrots.     

Forms of Rare Earth Elements in Soils: Ⅱ. Differentiation of Rare Earth Elements

The present paper deals mainly with the relationships between the distribution of rare earth elements (REE) in different forms in soils and the atomic number and with the odd-even phenomenon in the distribution of ionic lanthanides in soils.The enrichment tendency of light REE relative to heavy REE in soils was pointed out on the experimental results about the proportions of Ce-group and Y-group elements in different REE forms in soils.Meanwhile,the differentiation of Tm in different soil REE forms was compared and the reasons why Tm is enriched in soils were preliminarily discussed.     

Release of emamectin from sediment: effects of oil,organic material or infauna?

Purpose

The aim of this study was to quantify the release of the hydrophobic contaminant emamectin (EMA) from marine sediments in response to inputs of organic material (OM) and/or oil, in the presence or absence of two different bioturbating species. Specifically, it was designed to test whether oil would decrease the release of EMA and whether OM and/or the presence of bioturbating macrofauna would increase the release of EMA from sediment.

Materials and methods

Experimental sediments were spiked with EMA (5 μg kg^?1 wet sediment). The different treatments were prepared by the addition of OM (310 g algae m^?2) and/or an aliphatic oil (29.6 g oil m^?2). In addition, two bioturbating species, Brissopsis lyrifera or Ennucula tenuis, were added in some aquaria, resulting in a total of 12 treatments with four replicates each. Water samples for analyses of silicate and EMA and sediment samples for analyses of total organic carbon (TOC) were taken at the start and end of the experimental exposure. In addition, oxygen was measured during the experimental period of 8 days. Fluxes were calculated and compared between treatments using generalised linear models (GLMs).

Results and discussion

The EMA release flux was significantly increased in treatments with added OM, possibly reflecting the presence of soluble complexes formed between EMA and dissolved OM. The presence of B. lyrifera caused a small, but statistically significant, increase in EMA release from sediment. This species would be expected to have a stronger effect on bioirrigation and particle mixing than E. tenuis, particularly when the population density of the latter species is low (as in the present experiment). There were no consistent effects of oil in this experiment, but the presence of oil decreased the EMA release flux when co-occurring with added OM and/or B. lyrifera. Increased retention of hydrophobic contaminants in the presence of oil is consistent with the existing literature on contaminant fate.

Conclusions

The results from this study highlight the need to consider both the infauna present in polluted areas and the level of organic enrichment of the sediment when modelling the environmental fate of hydrophobic contaminants. It also highlights that labile OM and refractory oil appear to differ in their effects on the remobilisation of hydrophobic organic contaminants, by reducing and increasing release, respectively.     

Sulphur nutrition of clover: Effects of plant age on the composition‐yield relationship

Abstract

Five levels of S (as gypsum) were topdressed on to a pasture containing subterranean clover. Yield responses by the clover fraction of the pasture were measured, together with the total S concentration, the sulphate S concentration and the N:S ratio in young clover plants collected in autumn prior to the fertilizer application, and in plants from the control plots collected in winter and in spring.

As there were irregular changes in analytical values from autumn through winter to spring, a more detailed series of samples was taken in the second year. Therein, values for total S and sulphate S in clover plants from each treatment rose during the winter and fell during the spring, so that the critical concentration of sulphur or sulphate varied during the growing period. However, the critical N:S ratio was relatively stable, and in view of previously demonstrated correlations with response to added S, appears to be the more useful index for both diagnosis and prognosis.     

Formation of volatile organic products in soils under anaerobiosis—I: Metabolism of glucose

A simple trapping procedure for concentration of volatile organic compounds present in a head space and the subsequent analysis of the retained compounds by combined gas chromatographymass spectrometry is described. The procedure was used to study the organic metabolites evolved from various soils when they were amended with glucose and incubated under argon. A number of organic acids, alcohols, aldehydes and esters were evolved during a 4 week period. Less than 10 per cent of the added carbon was recovered as organic compounds, which was largely due to poor recovery of volatile organic acids from soil. Some implications of the observations to microbial ecology are discussed.     

Enzymatic hydrolysis of chestnut purée: process optimization using mixtures of alpha-amylase and glucoamylase

The enzymatic hydrolysis of starch present in chestnut purée was performed through a one-step treatment with a mixture of a commercial thermostable alpha-amylase (Termamyl 120 L, type S) and glucoamylase (AMG 300 L) at 70 degrees C. The effect of the enzyme concentration and the ratio of both amylases in the reaction mixture was studied by means of a factorial second-order rotatable design, which allowed conditions to be set leading to the total conversion of starch to glucose after 15 min of incubation (60 total enzymatic units g(-1) of chestnut; ratio of alpha-amylase/glucoamylase enzymatic units, 0.35:0.65). At lower enzyme concentration, the delay in the addition of the glucoamylase with regard to the addition of the alpha-amylase allowed a slightly higher hydrolysis percentage to be reached when compared to the simultaneous addition of both amylases at the same low enzyme concentration. The kinetics of liberation of glucose supports the existence of a synergistic effect between these two enzymes only in the first moments of the reaction. Finally, a sequential one-step hydrolysis was assayed, and more concentrated glucose syrups were thus obtained.     

Interaction of NPK fertilizers during their transformation in soils: Ⅲ. Transformations of monocalcium phosphate

Interactions of N, P and K fertilizers in soil-plant systems are widely recognized. This study focused on the transformations of monocalcium phosphate (Ca(H2PO4)2) (MCP) with co-application of ammonium and potassium fertilizers in three different soils. The results showed that after 1 d incubation a large portion of the MCP applied in the paddy,calcareous and red soils became the water-insoluble form and the recoveries of P applied as Olsen P varied greatly in these three soils. Application of ammonium sulfate ((NH4)2SO4) (AS) or potassium chloride (KC1) reduced WSP significantly in the soils with AS more effective than KC1 in the calcareous soil, while the reverse occurred in the red soil. Meanwhile, in the paddy soil, co-application of the two fertilizers reduced WSP more than when the fertilizers were applied individually. The co-application of AS with MCP in the paddy and calcareous soils significantly reduced Olsen P, but the opposite occurred in the red soil. The experiment on the effect of different accompanying anions showed that the ammonium fertilizers (PNC1 and PNS) reduced WSP more effectively than the corresponding potassium fertilizers (PKC1 and PKS) in the calcareous soil due to the difference of the cations, whereas in the red soil, the chlorides reduced WSP more effectively than the sulfates. Overall, co-application of ammonium or potassium fertilizers with MCP significantly decreased availability of P from MCP during its transformation in soils, especially when MCP was applied in combination with ammonium in the calcareous soil.     

Potential effect of conservation tillage on sustainable land use: A review of global long-term studies

Although understood differently in different parts of the world, conservation tillage usually includes leaving crop residues on the soil surface to reduce tillage. Through a global review of long-term conservation tillage research, this paper discusses the long-term effect of conservation tillage on sustainable land use, nutrient availability and crop yield response. Research has shown several potential benefits associated with conservation tillage, such as potential carbon sequestration, nutrient availability, and yield response. This research would provide a better perspective of the role of soil conservation tillage and hold promise in promoting application of practical technologies for dryland farming systems in China.     

Formation of volatile organic products in soils under anaerobiosis—II: Metabolism of amino acids

Volatile organic compounds generated microbiologically under anaerobic conditions from various soils amended with glucose and amino acids were identified by combined gas chromatographymass spectrometry. Volatile compounds were usually found up to 4 weeks and sometimes longer. Acetaldehyde, acetone, methyl ethyl ketone, methyl propyl ketone, diacetyl, ethanol, n- and iso-propanol, n-, 2- and iso-butanol, acetic acid, butyric acid, ethyl acetate, ethyl butyrate, butyl acetate, butyl butyrate, methane thiol, dimethysulfide, dimethyldisulfide and methyl thioacetate were detected at various time intervals. Volatile organic sulfur compounds were evolved from soils amended with glucose and methionine but not with glucose and cysteine. Volatile nitrogen containing organic compounds were not detected with any of the amended soils.     

Depletion of plant‐available silicon in soils: A possible cause of declining rice yields

Abstract

The phenomenon of yield decline in different rice ecosystems from many parts of the world has been reported to be associated with decreases in the effective nitrogen (N) supply from soil. However, many reports in the literature suggest that silicon (Si) is an agronomically essential element for sustainable rice production. Depletion of plant‐available Si in soils where rice is grown could be a possible limiting factor contributing to declining yields. In order to address this problem of yield decline or stagnation, it seems necessary to survey Si status of soils and rice grown in different ecosystems throughout the world and develop region‐specific integrated nutrient management systems that include the element Si.     

Fermentation of β-glucans derived from different sources by bifidobacteria: evaluation of their bifidogenic effect

β-Glucans obtained from barley, seaweed, bacteria, and mushroom sclerotia were incubated with pure cultures of Bifidobacterium infantis, Bifidobacterium longum, and Bifidobacterium adolescentis for a 24 h batch fermentation to evaluate their bifidogenic effect with inulin as the positive control. The pH value in all culture media was decreased by 0.5-1.5 units. All β-glucans supported the growth of the three bifidobacteria with B. infantis, having a relatively larger increase in populations (3-4 log(10) colony forming units). B. infantis produced almost double the amount of total short-chain fatty acids (SCFAs) than the other two bifidobacteria. The SCFA profile of B. infantis had a relatively higher proportion of propionic and butyric acid but less acetic acid than the other bifidobacteria. The utilization of all the β-glucans isolated from different sources regardless of their differences in glycosidic linkages and molecular weight by all three bifidobacteria was comparable to that of inulin.