L. Vittori Antisari

Characterization of humified compounds by extraction and fractionation on solid polyvinylpyrrolidone.

Abstract New humification parameters are proposed for characterizing soils and organic fertilizers or amendments. They include an index, a degree and a rate of humification, all devised to assess the ratio between humified and non-humified materials. The separation of the two types of materials is essentially performed by extraction and fractionation on solid polyvinylpyrrolidone.

Determination of organic carbon in soils and fertilizers

Abstract Many methods have been proposed to determine the total amount of organic carbon in soil; some of them determine only a percentage of the actual carbon content and therefore the results need the application of a correction factor. Methods for the determination of organic carbon in soil have been rarely extended to organic fertilizers and amendments. We propose a rapid method based on a modification of the original Springer and Klee10procedure. Samples are oxidized for exactly 10 minutes with a mixture of 20 ml 2N K2Cr2O7and 26 ml conc. H2SO4at 160±2°C; the excess dichromate is titrated either potentiometrically or manually with FeSO4. The method is fast, accurate, and more reliable than other commonly used procedures. The procedure can be easily adopted for serial determination of carbon in both soils and organic fertilizers or amendments

Effects of the urease inhibitor N-(n-butyl)phosphorothioic triamide in low concentrations on ammonia volatilization and evolution of mineral nitrogen

Laboratory incubation experiments were conducted to study the influence of increasing concentrations of N-(n-butyl)phosphorothioic triamide (NBPT) on NH3 volatilization and rate of urea hydrolysis and evolution of mineral N in Ozzano, Rimini and Carpi soils with different physicochemical characteristics. Low concentrations of NBPT reduced NH3 losses due to volatilization after urea fertilization and the effectiveness of the inhibitor was related to the soil characteristics (e.g. high concentrations of organic C and sand). After 15 days of incubation, no significant reductions of losses were found for any of the NBPT concentrations employed in Rimini soil. The application of NBPT led to a considerable reduction of the formation of nitrite. This process was completely annulled with the highest dose of NBPT (0.5% w/wurea) in the Carpi soil after 15 days. In Rimini soil, however, the use of NBPT was less effective in influencing nitrite formation. The use of NBPT favoured accumulation of nitrate proportional to the NBPT concentration employed while it had no influence on the NHinf4sup+fixation by 2:1 layer silicates. The data obtained support previous evidence that NBPT is effective in reducing the problems encountered in using urea as fertilizer. However, environmental conditions and soil physicochemical characteristics may have an important influence on the effectiveness of NBPT.

An enzymatic approach to the determination of the degree of stabilization of organic carbon in fertilizers.

An enzymatic approach to assess the stability of organic matter extracted from organic fertilizers and amendments is proposed. The use of 0.1M NaOH plus 0.1M Na4P2O7 previously suggested as a suitable extractant solution for soil organic matter was also found satisfactory for the extraction of organic matter from organic fertilizers and amendments, especially when the temperature was raised to 65°C. The presence of nonhumified compounds in the extracts from organic fertilizers may interfere considerably during fractionation of organic carbon. An enzymatic hydrolysis with lipase, lysozyme and pronase, added sequentially to the extracts, led to an appreciable reduction in the interference. The interference was further reduced by carrying out a successive acid hydrolysis with 3N H2SO4; in this case the DH values (percentage of humified fractions with respect to total extractable carbon) were reduced to less than 10% in all organic fertilizers, but remained higher than about 70% in organic amendments.

Seasonal pattern of nitrate losses from cultivated soil with subsurface drainage

Subsurface drainage systems have been installed in about 10000 ha of agricultural land in the flat part of the Emilia-Romagna Region in northern Italy. Nitrate loss in drainage water from a representative farm in this area was measured for three consecutive years (1986, 1987, 1988). During this period a total of 369 water samples were collected, filtered at 0.45 µm and analyzed. The nitrate concentration exceeded the limits for surface water set by Italian law regarding water pollution (90 mg NO3−L−1 = 20 mg N L−1) in 84% of the samples. The greatest nitrate loss was recorded during the winter and early spring when drainage was high. After this period loss of nitrate, via drainage water, progressively decreased. This was attributed to a decrease in the amount of drainage water and increase in crop uptake of N. The average annual nitrate loss via drainage water was around 200 kg of NOinf3sup− ha−1. Annual nitrate losses of this order of magnitude (≊ 50 kg N ha−1) indicate an urgent need for implementation of management practices directed towards achieving considerable reductions in these losses.

Bioavailability and biological effect of engineered silver nanoparticles in a forest soil

The extensive use of silver nanoparticles (SNPs) as antimicrobial in food, clothing and medicine, leads inevitably to a loss of such nanomaterial in soil and water. Little is known about the effects of soil contamination, in particular, on microbial cells, which play a fundamental ecological role. In this work, the impact of SNPs on forest soil has been studied, investigating eco-physiological indicators of microbial biomass and microbial diversity with culture-dependent and independent techniques. Moreover, SNPs bioavailability and uptake were assessed. Soil samples were spiked with SNPs at two different concentrations (10 and 100 μg g(-1)dw) and incubated with the relative controls for 30, 60 and 90 days. The overall parameters showed a significant influence of the SNPs on the soil microbial community, revealing a marked shift after 60 days of incubation.

Characterization of humified substances in organic fertilizers by means of analytical electrofocusing (EF): A first approach

The objectives of the study were to test the electrofocusing technique to determine its suitability as a method for the characterization of organic fertilizers from a qualitative point of view and identification of the organic matrix in an unknown fertilizer; no laboratory methods for this purpose are presently available.Analytical electrofocusing (EF) is shown to fulfill these objectives and may be easily adopted as a routine manual procedure. A solution of sodium hydroxide was chosen as the extractant because it allows comparisons between various types of humified materials and permits the evolution of organic matter to be followed during “maturation” of the fertilizer itself. The organic fertilizers considered included many nitrogen-rich waste materials, mostly of animal origin. They are divided into different groups according to origin and EF profiles.

Geochemistry and stable isotope composition of surface waters from the Ravenna plain (Italy): implications for the management of water resources in agricultural lands

This paper examines the issues related to salinization and water quality in the complex drainage system of the historical land reclamation of Lamone basin (Ravenna coastal plain, northern Italy), with the aim of guiding ongoing agricultural-related decisions. Major and trace element concentration and O–H–B–Sr isotope-ratios were measured on surface water from a network of canals and ditches. Sampling was carried out during the winter period and in summer, to assess the effects of agricultural water management on the aquatic system. Results show widespread salinization of waters over the entire crop, due to both the direct saltwater inland flushing through the canals in proximity of the mouths, and sea salt leaching from soils. During winter, salinization is partly mitigated by rainfalls, while in summer dilution processes are due to freshwater input from outside the watershed, planned to assist the agricultural water demand. In the winter season, the concentration of some elements such as Fe, Mn, Al, and Cu in waters exceeds the maximum permissible limits imposed by the Italian regulations, while during summer the concentration of these elements is significantly reduced. A seasonal cycling is established, where the bottom sediments of canals and ditches act as sinks of harmful elements, mostly through adsorption by Fe–Mn–Al oxy-hydroxide solid phases. The irrigation practice, although improving the water quality, increases water turbidity by re-mobilization of sediments which act as transport agents of contaminants, with detrimental effects that may become significant over the years.

Turnover of interlayer ammonium in soil cropped with sugar beet

We studied the turnover of interlayer NHinf4sup+in three soils cropped with sugar beet. The three soils chosen for this study (Carpi, Cadriano, and Ozzano) are typical of the soils in the Po Valley where sugar beet is grown. The variation in interlayer NHinf4sup+content during the growing season was significant and very similar for the Carpi and Cadriano soils, while there was no significant variation in the NHinf4sup+content in the Ozzano soil during the same period. The turnover of interlayer NHinf4sup+in the Carpi and Cadriano soils was high, and appeared to cover a substantial amount of the N requirement of the crop. The turnover in these two soils showed a significant decrease during the initial phase followed by a period during which the pool of interlayer NHinf4sup+was replenished and reached the initial levels again. The spatial distribution of the root system, the pattern of N uptake by the sugar beet crop, and the processes of immobilization-mineralization of organic N all have an influence on the mechanisms of adsorption and release of interlayer NHinf4sup+. The release of interlayer NHinf4sup+, and thus its availability for plant uptake, was greater at the beginning of the growing season. The physicochemical characteristics of the soils, the K concentration, and the types of clay minerals present were found to be important in determining the dynamics of interlayer NHinf4sup+turnover of soils.

Influence of cultivation on soil nitrogen pools

Abstract Exchangeable NH4, organic N, and fixed NH4, were followed in three soil layers (0–25, 25–50, and 50–75 cm) of plots under conventional and minimum tillage in a 10—year field experiment. The main effect of both tillage treatments was a marked increase of fixed NH4 during the first two years which was attributed to the heavy application of N fertilizers because soils were not fertilized prior to the experiment. Due to spatial variability of soil composition, a statistically significant increase over the 10—year was observed for total and fixed NH4 only in the surface layer of conventionally tilled soils, probably due to thorough mixing caused by intense cultivation. In this layer the organic N pool did not appear to vary with the years, while the fixed NH4 pool was influenced by N fertilization. A general trend was a uniform increase of the ratio between fixed NH4 and total N. Under conventional tillage, the trend was similar for the three soil layers while the reduced amount of fixed NH4 present i...