Influence of different long-term mineral–organic fertilization on yield,nutrient balance and soil C and N contents of a sandy loess (Haplic Phaeozem) in middle Germany

In a long-term field trial (Halle, Germany, founded in 1949 by K. Schmalfuß, soil type Haplic Phaeozem), the effects of different mineral and organic fertilization on dry matter yields, soil C and N contents and N balances were investigated. Over a period of 60 years, yields increased on average in all cultivated crops (winter and spring cereals, potatoes, sugar beets, silage maize), even without any fertilization. Nitrogen deficiency in unfertilized and PK treatments caused strong decreases in yield (up to 48%) in comparison with the N2PK standard treatment. The effect of omitting K or P supply was smaller (up to 18% and 7% yield reduction, respectively). The highest yields were obtained with high mineral N + PK application and (except winter wheat) with farmyard manure in combination with mineral fertilization. The N balances were negative in all treatments. However, if N immission from the air (40 kg ha^?1 a^?1) was included in the calculation, N balances were negative only in low N treatments. The soil C and N contents increased up to 1975. A considerable decrease has been seen since about 1985. The highest soil C and N contents were observed in the farmyard manure treatments. In addition to fertilization effects, this development of soil properties reflects changes in environmental pollution, climatic changes, as well as shifts in cultivation methods like tillage depths, over recent decades.     

‘Non-exchangeable’ ammonium in soils from Swedish long-term agricultural experiments: Mobilization and effects of fertilizer application

Abstract

In intensive agricultural systems, efficient nutrient use is necessary for high crop yields as well as for sustainable environmental management. Recent studies in temperate regions indicate that non-exchangeable NH₄ ⁺-N (NEA), which is fixed in clay minerals, may affect crop productivity and soil N dynamics more than previously thought. To estimate the quantity and plant availability of NEA in Swedish soils, ryegrass (Lolium perenne) was grown in a pot experiment using 18 soils that were collected (0–20?cm depth) from two long-term agricultural experiment series at five locations. Initial NEA, total N and soil K contents were measured, as well as NEA content 56, 112 and 168?days after planting of ryegrass. The results show that the soils (0–20?cm) contained 21–217?mg?NEA?kg^?1 sieved soil (5–300?kg?NEA?ha^?1) estimated as corresponding to 0.1–5.1% of the total soil N. Long-term application of farmyard manure (FYM) did not increase contents of soil NEA. Long-term application of K fertilizer increased soil contents of AL-extractable K, but there was no significant correlation with NEA content. Concurrent with ryegrass growth, NEA content decreased on average by 16% between day 0 and day 112, indicating that NEA was released from the soil and taken up by the plants.     

Photochemical oxidation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in soils — a tool to assess their degradability?

To determine the degradability of PAHs and PCBs for soil remediation or ecotoxicological risk assessment, a simple method is needed. We tested the suitability of photocatalytic oxidation for this purpose. We determined the concentrations of 20 PAHs and 12 PCBs in four mineral topsoil horizons, six organic horizons, and four particle‐size fractions of each of three soils before and after UV irradiation with TiO₂ as a catalyst in suspension. Preliminary experiments showed that in dry soil no photooxidation occurred, but after 48 h of irradiation in suspension the PCB concentrations decreased by up to 40—50 %, while the PAH concentrations did not change significantly. In contrast to this, 95—100 % of PAH and PCB standards spiked on quartz sand were degraded within 8 h, indicating that sorption to organic matter limited degradation of PAHs and PCBs in soil suspensions. There was no difference in the degradation among different individual PAHs and PCBs, respectively, indicating that the degradation did not occur in dissolved state, but in association with soil organic matter. In all samples except one, the degradation of PCBs (10—80 % loss of initial concentrations) was higher than those of the PAHs (0—40 % loss). This suggests that the accessibility of PCBs for OH· radicals generated during irradiation was higher, or the oxidation of PAHs was limited by the properties of the sorbing organic matter. Thus, the tested method was not suitable to predict biodegradability, because it did not reflect the differences in degradability of individual compounds.     

Potential nitrification, nitrate reductase, and β-galactosidase activities as indicators of restoration of ecological functions in a Zn-contaminated soil

The present study was conducted to assess the possible restoration of different ecological functions in a Zn-contaminated soil. Experiments were conducted in a soil microcosm contaminated with 350?mg?kg^?1 of Zn and in an uncontaminated control microcosm, both incubated for 4?months. At regular intervals, potential nitrification, nitrate reductase, and β-galactosidase activity were determined. All these activities were significantly reduced just after Zn contamination in contaminated microcosms compared to the activities of the control, but then increased. In order to confirm that the restoration of ecological functions was not due to an aging phenomenon, a reinoculation protocol was also applied. A significant restoration was found for β-galactosidase activity, while for nitrate reductase activity and potential nitrification, there was a clear shift of dose–response curves but with partial overlap of the EC₅₀ ranges estimation, thus indicating that different ecological functions are restored over time in Zn-contaminated soils.     

Effect of incubation and microbial inhibition at field moisture capacity on changes in DTPA‐extractable Fe,Zn, and Cu in soils of varying pH

Abstract

To determine the effect of incubation on DTPA‐extractable Fe, Zn, and Cu in soils with a wide pH range (4.2 ‐ 9.4) and to determine the nature of this effect, soils were incubated at field moisture capacity for 1 week with and without a sterilant (toluene). After incubation these soils as well as their air‐dry counterparts were analyzed for DTPA‐extractable Fe, Zn, and Cu.

Incubated soils were significantly lower in DTPA‐extractable Fe, Zn, and Cu than air‐dry soils over all soil pH values tested but there was no significant difference in mean values for incubated soils due to the addition of toluene. The results suggest that, upon incubation at field moisture capacity, the decrease in DTPA‐extractable Fe, Zn, and Cu observed was noa‐microbial in nature.     

Entwicklung der organischen bodensubstanz (obs) auf löss in abhängigkeit von unterschiedlicher düngung am beispiel des bodenbildungsversuches in Halle/Saale: Development of soil organic matter (som) on loess in dependence of different fertilization e.g. of the soil formation trial at Halle/Saale

In 1948, a model trial to study soil formation was arranged at Halle/Saale by K. Schmalfuß. Loess with very low content of soil organic matter was used as substrate. The aim was to investigate the soil formation processes influenced by the P and N mineral fertilization. After 30 years, crop yields reached a characteristic, approximately constant level corresponding to the different fertilization treatments and cultivated plants. Recent comparisons of the highest N with the no-N fertilizer treatment show that the mean shoot dry weight per year has a 2.5-fold higher but the C_org content in the topsoil only a 1.2-fold higher value. An accumulation of alkaline-soluble organic soil substances and a decrease of hot water soluble carbon compounds were observed in the highest fertilizer treatment as well as in the treatments without N or P fertilization. Carbon compounds were apparently enriched in the inert carbon pool of the topsoil. During soil formation, the cation exchange capacity and the content of easily soluble P compounds increased, lime content decreased and the C/N ratio became narrower. The results suggest that these parameters are continuing to change and the steady state of the level of organic soil substances and of the transformation processes between C pools in the topsoil has not yet been reached.     

Emission rates of N<Subscript>2</Subscript>O and CO<Subscript>2</Subscript> from soils with different organic matter content from three long-term fertilization experiments—a laboratory study

Increasing organic matter stocks in soils reduce atmospheric carbon dioxide (CO₂), but they may also promote emissions of nitrous oxide (N₂O) by providing substrates for nitrification and denitrification and by increasing microbial O₂ consumption. The objectives of this study were to determine the effects of fertilization history, which had resulted in different soil organic matter stocks on (1) the emission rates of N₂O and CO₂ at a constant soil moisture content of 60% water-holding capacity, (2) the short-term fluxes of N₂O and CO₂ following the application of different fertilizers (KNO₃ vs. farmyard manure from cattle) and (3) the response to a simulated heavy rainfall event, which increased soil moisture to field capacity. Soil samples from different treatments of three long-term fertilization experiments in Germany (Methau, Spröda and Bad Lauchstädt) were incubated in a laboratory experiment with continuous determination of N₂O and CO₂ emissions and a monitoring of soil mineral N. The long-term fertilization treatments included application of mineral N (Methau and Spröda), farmyard manure + mineral N (Methau and Spröda), farmyard manure deposition in excess (Bad Lauchstädt) and nil fertilization (Bad Lauchstädt). Long-term addition of farmyard manure increased the soil organic C (SOC) content by 55% at Methau (silt loam), by 17% at Spröda (sandy loam) and by 88% at Bad Lauchstädt (silt loam; extreme treatment which does not represent common agricultural management). Increased soil organic matter stocks induced by long-term application of farmyard manure at Methau and Spröda resulted in slightly increased N₂O emissions at a soil moisture content of 60% water-holding capacity. However, the effect of fertilization history and SOC content on N₂O emissions was small compared to the short-term effects induced by the current fertilizer application. At Bad Lauchstädt, high N₂O emissions from the treatment without fertilization for 25 years indicate the importance of a sustainable soil organic matter management to maintain soil structure and soil aeration. Emissions of N₂O following the application of nitrate and farmyard manure differed because of their specific effects on soil nitrate availability and microbial oxygen consumption. At a soil moisture content of 60% water-holding capacity, fertilizer-induced emissions were higher for farmyard manure than for nitrate. At field capacity, nitrate application induced the highest emissions. Our results indicate that feedback mechanisms of soil C sequestration on N₂O emissions have to be considered when discussing options to increase soil C stocks.     

Kinetics of K Desorption from Soils in a Constant Electric Field (Electro-Ultrafiltration) and Its Application

Kdesorption from soils in a constant electric field (field strength:44.5Vcm^-1) by means of electro-ultrafil-tration (EUF) followed second-order kinetics and could be described by the equation dd/dt=k(D-d)2. From theequation, such kinetic parameters relating to K desorption from soils as the maximum desorbable quantity D, quantity of K desorbed within 40 minutes d40, initial desorption rate Vo, desorption rate constant k and half-time t1/2 could be calculated. An expression which describes the relationships between the kinetic parameters on the one hand and the responses of barley to fertilizer-K in the field experiments in different sites and the potassium-supplying power of soils on the other was established. Vo, D and d40 were significantly correlated with barley relative yield, K uptake by barley and the content of soil available potassium. The rate constants of K desorption varied between 4.42×10^-4-1.80×10^-3kg mg^-1 min^-1 and highly correlated with the relative yield of barley.     

Genesis of soils developed from red-brown clays and loesslike loams in the southwest of the Central Russian plain (the Belogor’e reserve)

Soils developed from the red-brown Neogene clay and the Quaternary loesslike loams have been studied in the south of the forest-steppe zone on the Central Russian Upland. A polygenetic nature of the soil profile on the loesslike loams is shown. The modern pedogenetic processes in this soil ensure its eluvial-illuvial differentiation with the development of multilayered coatings in the illuvial horizon. The soil developed from the Neogene clay has a lower degree of differentiation despite the more acid reaction. The micromorphological study of the coatings and the mineralogical analysis of the clay fraction separated from the coatings and from the intraped mass disclose differences in the geneses of B horizons of the two soils. In the soil developed from the loesslike loam, hydromica predominates among clay minerals of the coatings; in the soil developed from the red-brown clay, smectitic minerals predominate in the clay fraction. Differences in the properties of these two parent materials predetermined differences in the major directions of soil formation: the metamorphic pedogenesis predominates on the red-brown clay, whereas the textural differentiation develops in the soil on the loesslike loam. The middle horizons in the studied soil profiles are referred to as the structural-metamorphic and textural (clay-illuvial) horizons, respectively.     

Irrigation of steppe soils in the south of Russia: Problems and solutions (Analysis of Irrigation Practices in 1950–1990)

Experience in irrigation of chernozems in the steppe zone of Russia for a period from 1950 to 1990 is analyzed. By the end of this period and in the subsequent years, the areas under irrigation reduced considerably, and the soil productivity worsened. This was caused by the improper design of irrigation systems, on the one hand, and by the low tolerance of chernozems toward increased moistening upon irrigation, on the other hand. The analysis of the factors and regimes of soil formation under irrigation conditions shows that irrigation-induced changes in the soil hydrology also lead to changes in the soil physicochemical, biochemical, and other properties. In particular, changes in the composition of exchangeable cations lead to the development of solonetzic process. In many areas, irrigation of chernozems was accompanied by the appearance of solonetzic, vertic, saline, and eroded soils. The development of soil degradation processes is described. In general, the deterioration of irrigated chernozems was related to the absence of adequate experience in irrigation of steppe soils, unskilled personnel, improper regime of irrigation, and excessively high rates of watering. In some cases, the poor quality of irrigation water resulted in the development of soil salinization and alkalization. To improve the situation, the training of personnel is necessary; the strategy of continuous irrigation should be replaced by the strategy of supplementary irrigation in the critical periods of crop development.     

Sequential cold and hot water extract of boron from soils and re‐extraction after adsorption by bentonite,kaolinite, iron,and aluminum hydrous oxides over a range of pH values

Abstract

The relative amounts of boron re‐extracted by cold and hot water sequentially after adsorption, over a range of pH values, onto bentonite, kaolinite, precipitated iron, and aluminum (AI) hydrous oxides have been examined, in an attempt to understand why hot water especially is successful as an extractant to indicate plant availability of boron (B). The relative ability of cold and hot water to extract boron was also tested on some Scottish soils. The recovery of boron adsorbed by bentonite, by extraction with cold water compared with that extracted by hot water, was related to pH, but this was not the case for kaolinite. Comparison of the results for the minerals and soil systems indicates that mineral composition and pH in combination probably regulate the relative extraction power of cold and hot water for soil B. It may be assumed, therefore, that hot water better reflects the capability of plant roots to access B from different adsorption sites than cold water does.     

Anthropogenic transformation of soils in the northern Ergeni Upland (studies at the first experimental plot of the Arshan’-Zelmen Research Station)

The results of soil studies performed in 2005–2009 at the first experimental plot of the Arshan’-Zelmen Research Station of the Institute of Forest Science of the Russian Academy of Sciences are discussed. The post-reclamation state (about 55 years after reclamation) of the soils under forest shelterbelts and adjacent croplands in the rainfed agriculture was studied. The long-term efficiency of forest reclamation and crop-growing technologies developed in the 1950s by the Dokuchaev Soil Science Institute and the Institute of Forest to reclaim strongly saline solonetzic soils was proved. In 55 years, strongly saline sodic solonetzes with sulfate-chloride and chloride-sulfate composition of salts were replaced by agrogenic soils with new properties. Under forest shelterbelts, where deep (40–60 cm) plowing was performed, the soils were transformed into slightly saline solonetzic agrozems with slight soda salinization in the upper meter and with dealkalized plowed and turbated horizons (0–20(40) cm). Under the adjacent cropland subjected to the influence of the shelterbelts on the soil water regime, strongly saline solonetzes were transformed into solonchakous agrosolonetzes with slight soda salinization in the upper 50 cm. In the plow layer, the content of exchangeable sodium decreased to 4–12% of the sum of exchangeable cations. An increased alkalinity and the presence of soda were found in the middle-profile horizons of the anthropogenically transformed soils.     

Triacylglycerols, glycerophospholipids, tocopherols, and tocotrienols in berries and seeds of two subspecies (ssp. sinensis and mongolica) of Sea Buckthorn (Hippophaë rhamnoides)

Berries and seeds of two subspecies (ssp. sinensis and mongolica) of sea buckthorn (Hippopha? rhamnoides L.) were compared in terms of triacylglycerols, glycerophospholipids, tocopherols, and tocotrienols. The berries of ssp. mongolica contained less oleic acid (4.6 vs 20.2%, p < 0.001) and more palmitic (33.9 vs 27.4%, p < 0.01) and palmitoleic (32.8 vs 21.9%, p < 0.05) acids in triacylglycerols than those of ssp. sinensis. The proportions of linoleic acid (32.1 vs 22.2%, p < 0.01, in berries; 47.7 vs 42.7%, p < 0.05, in seeds) and palmitic acid (21.1 vs 16.4%, p < 0.001, in berries; 17.0 vs 14.1%, p < 0.05, in seeds) in glycerolphospholipids were higher in ssp. mongolica than in ssp. sinensis, and vice versa with oleic acid (4.3 vs 18.5% in berries, 10.0 vs 22.2% in seeds, p < 0.001). A higher proportion of alpha-linolenic acid was also found in the glycerophospholipids of ssp. sinensis berries (16.2 vs 10.1%, p < 0.001). alpha-, beta-, gamma-, and delta-tocopherols constituted 93-98% of total tocopherols and tocotrienols in seeds, and alpha-tocopherol alone constituted 76-89% in berries. The total contents of tocopherols and tocotrienols varied within the ranges of 84-318 and 56-140 mg kg(-1) in seeds and whole berries, respectively. The seeds of ssp. mongolica were a better source of tocopherols and tocotrienols than those of ssp. sinensis (287 vs 122 mg kg(-1), p < 0.001). The compositional differences between the two subspecies should be considered when the berries are bred and exploited for nutritional purposes.     

Isotopic Model (NISOTOP) used to Investigate 15N-Urea Transformations in the Presence of Phenanthrene,Chrysene and Benzo(a)pyrene in a Soil–Plant System

An isotopic model (NISOTOP) has been developed to investigate the effect of the addition to soil of xenobiotics on urea hydrolysis, N mineralization and immobilization, nitrification and plant uptake of nitrogen in a soil-plant system, after addition of ¹⁵N enriched compounds. Therationale of the model follows from the errors in %¹⁵N abundance (^15N _D) and N concentration (C_N) determinations which cause high variability coefficients in the calculation of the amount of nitrogen present in the different compounds derived from the added ¹⁵N enriched urea. The extent of these errors, besides depending on C_N and ^15N _D errors, will also depend on natural ¹⁵N and ¹⁵N of the added compound, and therefore on the experimental conditions. The model is described by 18 first-order differential equations and is numerically solved by Euler's method with a time increment of 0.01 day. As an illustration, the model is applied to the effect of phenanthrene, chrysene and benzo(a)pyrene to a soil-plant system, following the addition of ¹⁵N-urea. These compounds have been chosen as examples of molecules having 3, 4 and 5 fused aromatic rings and are hereafter collectively referred to as PAHs. PAHs at the rate of 2 mg kg^-1 soiland ¹⁵N-urea at the rate of 166.7 mg N kg^-1 soil were added to wheat pots. At harvesting (after 14 days from plantation) the dry matter yield, the total N content and the N concentration of the wheat seedlings were not statistically affected by addition of the PAHs (P = 0.05). The efficiency of N uptake, that is the percentage of fertilizer taken up by the plants at harvesting in the absence of PAHs was 47.3%, while it was 11.7, 15.2 and 14.8% in the presence of phenanthrene, chrysene and benzo(a)pyrene,respectively. The computation of the first-order rate constants of the N transformations showed that N mineralization, nitrification and N-uptake were affected by the addition of phenanthrene, chrysene and benzo(a)pyrene, whilst benzo(a)pyrene inhibited urea hydrolysis more than phenanthrene and chrysene.     

Potential use of karanjin (3-methoxy furano-2′,3′,7,8-flavone) as a nitrification inhibitor in different soil types

Karanjin, a furanoflavonoid (3-methoxy furano –?2 ′ , 3 ′ , 7, 8-flavone), is obtained from the seeds of karanja tree (Pongamia glabra Vent.), which is reported to have nitrification inhibitory properties but has been tested in few soil types. Efficiency of karanjin as a nitrification inhibitor in seven different soils of India was tested in a laboratory incubation study. The soils (800?g) were adjusted to field capacity moisture content, fertilized with urea and urea combined with karanjin at a rate of 20% of applied urea-N (100?mg?kg^???1 soil) and incubated at 35°C for a period of 7 weeks, during which urea [CO(NH₂)₂], ammonium (NH₄ ^?+?), nitrite (NO₂ ^???) and nitrate (NO₃ ^???) content in the soils was measured periodically and nitrification inhibition at different stages was calculated. Urea hydrolysis was almost complete within 72?h of application in all the soils and was not affected by karanjin. Karanjin had conserved ammonium in all the soils at all stages and nitrate formation was effectively minimized. Nitrite in soils was short-lived and low. Nitrification inhibition by karanjin remained high for a period of approximately 6 weeks, decreased with time and ranged from 9?–?76% for all the soils. The study shows that this plant product can be an effective nitrification inhibitor in several types of soil.     

The effect of concentrations and properties of phenanthrene, pyrene, and benzo(a)pyrene on desorption in contaminated soil aged for 1 year

Purpose

The choice and timing of microorganisms added to soils for bioremediation is affected by the dominant bioavailable contaminants in the soil. However, changes to the concentration of bioavailable PAHs in soil are not clear, especially when several PAHs coexist. This study investigated the effects of PAH concentration and chemical properties on desorption in meadow brown soil after a 1-year aging period, which could reflect changes of PAH bioavailability during bioremediation.

Materials and methods

Based on the percentage of different molecular weights in a field investigation, high-level contaminated soil (HCS) and low-level contaminated soil (LCS) were prepared by adding phenanthrene (PHE), pyrene (PYR) and benzo(a)pyrene (BaP) to uncontaminated meadow brown soil. The concentrations of HCS and LCS were 250 mg?kg^?1 (PHE, PYR, and BaP: 100, 100, and 50 mg?kg^?1) and 50 mg?kg^?1 (PHE, PYR, and BaP: 20, 20, and 10 mg?kg^?1) respectively. The soils were aged for 1 year, after which desorption was induced by means of a XAD-2 adsorption technique over a 96-h period.

Results and discussion

The range of the rapidly desorbing fraction (F _rap) for PHE, PYR, and BaP in HCS and LCS was from 1.9 to 27.8 %. In HCS, desorption of PYR was most difficult, and the rate constant of very slow desorption (K _vs) of PYR was 8 orders of magnitude lower than that of BaP, which had similar very slow desorbing fractions (49.8 and 50.5 %, respectively). However, in LCS, desorption of PYR was the easiest; the K_vs of PYR was 8–10 orders of magnitude higher than those of PHE and BaP. In HCS, the time scale for release of 50 % of the PAHs was ranked as BaP?>?PYR?>?PHE, while in LCS this was BaP?>?PHE?>?PYR.

Conclusions

The combined effect of PAH concentrations and properties should be taken into account during desorption. The desorption of PAH did not always decrease with increasing molecular weight, and the desorption of four-ring PAHs might be special. These results are useful for screening biodegrading microbes and determining when they should be added to soils based on the dominant contaminants present during different periods, thus improving the efficiency of soil bioremediation.