Utilization of municipal organic wastes in agriculture: where do we stand,where will we go?

Generation of organic waste is increasing worldwide and strategies for its environmentally sound use must be developed and optimized. Regulations in European countries and the USA differ largely with respect to requirements of organic waste quality and the quantities of pollutants which can be added to the soil. Research has shown beneficial effects regarding the improvement of soil fertility. Enrichment of total metals in soil was attributed to long‐term sludge application but the effect on bioavailability of metals must be further clarified. A number of organic pollutants, such as hydrophobic persistent organic contaminants and surfactants, are known to accumulate in organic wastes. However, the former interact strongly with organic matter in the sludge‐soil‐plant system and systemic plant uptake is generally assumed to be minimal. Surfactants may cause adverse environmental impacts when they enter sewage systems in high loads and accumulate in sludge. Surfactants and some of their metabolites are not readily biodegraded in non‐aerated environments. Due to their toxicity and estrogenic activity, of nonylphenol for example, more research is needed to optimize analytical techniques and to trace their behavior in soil. Some options to cope with the risks of huge amounts of organic waste and also some benefits are presented: (1) further limitation of standards for pollutants and reduced application rates; (2) improved treatment of sewage sludge to reduce the total and bioavailable portions of both heavy metals and organic pollutants; (3) adaptation of waste application rates to soil properties such as sorption capacity for pollutants; (4) harmonization of analytical protocols for organic contaminants, i.e. surfactants and metabolites, enabling a more thorough monitoring of the wastes which are to be applied onto soils.     

Characterization of soil surface properties following disturbance of a clay soil in southern Manitoba

This research demonstrated the use of a laser profiling system (LPS) and digital imagery as useful tools in measuring soil micro-topography and crop residue cover following a soil disturbance event. The soil micro-topography was characterized in terms of surface roughness using two geostatistical approaches; semivariance analysis and the mean absolute-elevation-difference method. Univariate statistical analysis was also used. All three procedures used to describe surface roughness were successful in detecting changes in surface roughness due to soil disturbance and the addition of corn residue. There was a definite advantage in using the geostatistical approaches to characterize surface roughness as the indices they provide give insight into the characteristics of the surface roughness. Crop residue cover was measured using digital images and image analysis software to contrast the soil and the crop residues.The series of field experiments examined the roles of both soil disturbance and corn residue and their interactions on surface roughness, crop residue cover, exposed surface area, and near-surface porosity. Soil disturbance and the addition of corn residue were both found to be significant factors affecting the surface roughness, crop residue cover, exposed surface area, and near-surface porosity. Due to the interaction and added effects of crop residue, it was also demonstrated that the calculated surface area may not be a measure of exposed soil area, but rather it is a combination of soil and residue surface areas. Similarly, the roughness of a surface does not only reflect the soil clods produced during tillage but that of the residue itself. Furthermore, it was demonstrated that the information gathered by the LPS and digital imagery can be used to evaluate surface characteristics arising from different tillage practices.     

Spatial patterns of adenylate kinase,catalase, endopeptidase and fructose-1,6-diphosphatase encoding genes allelic variation in <Emphasis Type="Italic">Aegilops tauschii</Emphasis> Coss.

Investigation of spatial patterns of adenylate kinase, catalase, endopeptidase and fructose-1,6-diphosphatase encoding genes (Ak, Cat1, Cat2, Ep, Fdp) allelic variation in Aegilops tauschii was carried out. About 300 accessions, representing all the species range were taken for the study. Cat2 and Fdp loci are completely monomorphic in ssp. strangulata and in the western part of ssp. tauschii range, as well. Both Cat2 and Fdp are highly polymorphic in the eastern part of ssp. tauschii range, with the patterns of this polymorphism being discordant in these two loci. Ak ¹⁰⁸, a rare allele with sporadical spatial occurrence, was found in ssp. tauschii only. On the contrary, Ak ⁹² is absent in ssp. tauschii: it is the most common Ak allele in ssp. strangulata in Precaspian Iran, the most moist part of the area, and is very rare in other parts of ssp. strangulata area. Ep is a highly polymorphic locus with the highest level of variation in the west of Ae. tauschii area, where this species had originated. Ep allele variation patterns are rather similar in ssp. tauschii and ssp. strangulata. The data reveal the adaptive nature of Ak, Cat2, and Fdp allele variation, while Ep polymorphism seems to be mostly neutral.     

Temporal and compositional differences of arbuscular mycorrhizal fungal communities in conventional monocropping and tree-based intercropping systems

Previous research has found that conventional agricultural systems adversely affect arbuscular mycorrhizal (AM) fungi. However, there is little information on how more ecologically sustainable agricultural practices such as tree-based intercropping (TBI) influence AM fungal communities. In this study, we investigated whether TBI promotes a more abundant and diverse AM fungal community compared to conventional monocropping (CM). Abundance was estimated by measuring spore abundance and hyphal length in soil, and AM fungal colonization of corn (Zea mays) roots. Overall, AM fungal abundance was similar in both systems as corn roots from the CM and TBI systems were heavily colonized (>50%) by AM fungi throughout the growing season. Additionally, soil samples from the CM and TBI systems contained similar spore densities and hyphal length. Molecular analysis of the AM fungal community was assessed using terminal restriction fragment length polymorphism (T-RFLP) analysis of large subunit rRNA genes amplified from roots in the two cropping systems. A total of fourteen AM fungal phylotypes that belonged to the Glomeraceae were found in the two cropping systems. The TBI system had a higher AM fungal richness and contained several taxa not found in the CM system. Molecular analysis of AM fungal communities also revealed significant temporal and compositional differences between the TBI and CM systems. Within the TBI system, tree species differentially influenced the AM fungal community composition in the alley cropping regions. Future research should focus on determining whether compositional differences among AM fungal communities in CM and TBI systems have a functional effect on crop growth and productivity.     

A community-based telephone survey of work and injuries in teenage agricultural workers

In order to estimate the one-year cumulative incidence of work-related injuries in teenage agricultural workers and to characterize the patterns and types of agricultural work performed by teenagers, we performed a community-based random-digit dialing telephone survey. We used a sampling frame of farm and non-farm households to access information on teenage agricultural workers. An agricultural community in eastern Washington State was selected due to the high number of teenage youth and its agricultural economy. Teenage agricultural workers who worked for an agricultural business owned by one of their family members were more likely to work a greater number of seasons, work fewer hours per week, perform tasks involving driving, animal care, and mechanic work, and were less likely to be seasonal workers or work in the harvest than teenagers who did not work for a family member. A similar pattern of work differences was seen when comparing non-Hispanic to Hispanic agricultural workers. Teenagers working for a family member in agriculture had a higher injury rate than teenagers working for an agricultural business not owned by a family member. The injury rate among Hispanic teenage agricultural workers was also higher than that of non-Hispanics.     

Slow nitrogen release from humic substances modified with aminoorganosilanes

Purpose

The purpose of the present study is to evaluate slow-release nitrogen capabilities of soil amendments obtained by modification of humic materials from peat and lignite with alkoxyorganosilanes carrying different amine substituents.

Materials and methods

The humates from lignite and peat were modified using (3-aminopropyltriethoxy)-silane (APTES) and (1-aminohexamethylenene, 6-aminomethylene)-triethoxysilane (AHATES). The obtained derivatives were characterized using elemental analysis and Fourier transform infrared spectroscopy. Nitrogen release in the form of ammonia or nitrate was evaluated using dissolution tests under sterile aqueous conditions as well as long-term soil experiments. Ammonium and nitrate were determined using ion-selective electrodes. Activity index (AI) was calculated from the dissolution tests. For soil trials, arable Retisol was sampled from 0- to 5-cm layer in Yaroslavl region (Russia). The soil experiments were conducted over 78 days using (NH₄)₂SO₄ as an activator of nitrification and 3-amino-1,2,4-triazole as an inhibitor of autotrophic nitrifying bacteria.

Results and discussion

Modification of lignite and peat humates leads to an increase in nitrogen content up to 2 and 4.3 %, respectively, in case of APTES, and up to 3 and 6 %, respectively, in case of AHATES. All humic derivatives gradually released N upon dissolution in water over 6 days up to 51 % of the total N. The AI values ranged from 4 to 13 %. Amendment of soil with the modified humic materials induced an increase in nitrate content resulting from nitrification of released ammonia by soil microflora. This was confirmed by aminotriasole experiments. The nitrogen release occurred slowly: over the first week of incubation, it did not exceed 36–69 % of the total N content. The higher release rate of ammonium nitrogen was observed for CHS-AHATES versus CHS-APTES derivative, whereas no difference was seen between the two peat derivatives, which showed release rate on the level of CHS-AHATES derivative. Positive effect of all modified humic materials lasted over 78 days.

Conclusions

Modification of lignite and peat humates with two aminoorganosilanes carrying one and two nitrogen atoms in the amine substituent brought about twofold to threefold enrichment of the parent humic materials with nitrogen, which was capable of slow release upon incubation in soils. It was released in the form of ammonia and transformed to nitrates by autotrophic nitrifying soil microflora. There was no clear relationship established between structure of amine substituent of organosilane and slow-release properties of the corresponding humic derivatives. The conclusion was met that principal application of aminoorganosilane derivatives of humic substances (HS) is soil structuring, whereas nitrogen-fertilizing capabilities might be considered as beneficial added-value feature of these humic products.

     

Sulfate--a candidate for the missing essential factor that is required for the formation of protein haze in white wine

Protein haze formation in white wine is dependent on the presence of both wine protein and other unknown wine components, termed factor(s) X. The ability to reconstitute protein haze upon heating artificial model wine solutions (500 mg/L thaumatin, 12% ethanol, 4 g/L tartaric acid) to which candidate components were added was employed to identify factor(s) X. No protein haze was formed in the absence of additives. The individual or combined addition of caffeic acid, caftaric acid, epicatechin, epigallocatechin-O-gallate, gallic acid, or ferulic acid at typical white wine concentrations did not generate protein haze. However, PVPP fining of commercial wines resulted in a reduction in protein haze, suggesting that phenolic compounds may play a modulating role in haze formation. To elucidate the nature of the unknown factor(s) wine was fractionated and fractions were back-added to model wine and tested for their essentiality. Wine fractions were generated by ultrafiltration, reverse-phase chromatography, and mixed-mode anion-exchange and reverse-phase chromatography. The only purified fraction containing the essential component(s) was free of phenolic compounds, and analysis by mass spectrometry identified sulfate anion as the dominant component. Reconstitution with KHSO4 using either commercially available thaumatin or wine proteins confirmed the role of sulfate in wine protein haze formation. The two main wine proteins, thaumatin-like protein and chitinase, differed in their haze response in model wines containing sulfate. Other common wine anions, acetate, chloride, citrate, phosphate, and tartrate, and wine cations, Fe(2+/3+) and Cu(+/2+), when added at typical white wine concentrations were not found to be essential for protein haze formation.     

Urine flavonoids and plasma carotenoids in the validation of fruit, vegetable and tea intake during pregnancy in the Norwegian Mother and Child Cohort Study (MoBa)

OBJECTIVE: To validate a new food-frequency questionnaire (FFQ) for measuring the intake of fruit, vegetables and tea reported by women participating in the Norwegian Mother and Child Cohort Study (MoBa). DESIGN: Intake of fruits, vegetables and tea estimated by the FFQ was compared with urinary flavonoid excretion, plasma carotenoid concentration and intake measured by a 4-day weighed food diary (FD). The triangular method was applied to calculate FFQ validity coefficients using two independent biomarkers. SETTING AND SUBJECTS: One hundred and nineteen women participating in MoBa. RESULTS: The FFQ estimate of fruit intake was significantly correlated with urine phloretin (r = 0.33), citrus fruit/juice with urine hesperetin (r = 0.44), cooked vegetables with plasma alpha-carotene (r = 0.37), and tea with urine kaempferol (r = 0.41) (P < 0.01 for all). On average, 60% of the participants fell into the same or adjacent quintiles when classified by FFQ and biomarkers. Significant correlations between the FFQ and FD were found for fruit (r = 0.39), vegetables (r = 0.34), juices (r = 0.50) and tea (r = 0.53). The FFQ validity coefficient was 0.65 for citrus fruit/juice and 0.59 for cooked vegetables as calculated by the triangular method. CONCLUSIONS: The validation study shows that the MoBa FFQ can be used to estimate fruit, juice, vegetable and tea intake in pregnant Norwegian women, and to rank individuals within the distribution.     

Changes in net ecosystem production associated with forest fire in taiga ecosystems,near Yakutsk,Russia

Abstract

The effect of sucrose on the growth of rice plants under gnotobiotic conditions was studied at test tube scale in vinyl isolators under weak or strong light. Under weak light (500 lux) the growth of rice plants on agar medium containing only inorganic nutrients during the 20 days after transplanting stopped at 3rd leaf stage, whereas plants on agar medium containing inorganic nutrient plus 2% sucrose grew to 5th or 6th leaf stage. Under strong light (1.5 × 10⁴ lux) the stage of tillering was promoted by supplying sucrose. The growth of rice plants in pot-hydroculture under weak light had the same tendency as that obtained in test tube culture under weak light.

Considering the concentration of inorganic elements in rice shoots, it seems most likely that the uptake of inorganic elements. especially phosphorus and potassium, was enhanced by the supplements of 2% sucrose under weak light. An increase of calcium and manganese uptake was observed in plants grown in medium containing 2% sucrose compared with that of plants grown in inorganic medium alone under strong light. The uptake of inorganic elements from medium containing inorganic nutrients plus 2% sucrose depended chiefly on light energy under strong light in the phytotron used.