Effects of the herbicide Topogard on soil respiration, nitrification, and denitrification in potato-cultivated soils differing in pH

We investigated the effects of Topogard 50 WP (3 kg ha^–1) on soil respiration, mineral N content, and number of denitrifying and total bacteria in four coarse-textured volcanic soils for 91 days. Topogard application decreased CO₂ evolution in acid soils (Tepedibi and Karaçakl) whereas soil respiration was initially increased in neutral and alkaline soils (Kaba and Balar). The herbicide application significantly stimulated ammonification in Kaba and Balar soils, while Tepedibi and Karaçakl soils showed significantly lower NH₄⁺-N contents than the control. The treatment inhibited the activity of nitrifying microorganisms and, thus it decreased the NO₃^–-N content in Tepedibi, Karaçakl, and Kaba soils, whereas the NO₃^–-N content was increased in Balar soil. The NO₂^–-N content of soils was not affected by the treatment. The activity of denitrifying bacteria was stimulated by the addition of herbicide in all soils, whereas the total number of bacteria was not influenced. It may be concluded that the effects of Topogard on the microbiological characteristics of coarse-textured soils are likely to be dependent on soil pH.     

Effects of the herbicide glyphosate on nitrogen cycling in an acid forest soil

The herbicide glyphosate was sprayed aerially on a section of conifer forest in Atlantic Canada that had been previously clearcut and reforested. Glyphosate was then tested for effects on ammonification, nitrification, and denitrification for a period of 8 months by comparing microbial activity in treated and untreated zones of the clay loam forest soil and the overlying decomposing litter, both with a pH of 3.8. With ammonification, there was generally a stimulation of activity in both the forest litter (FL) and forest soil (FS) that had been exposed to glyphosate during spraying. Nitrification rates in FL and FS were very low and glyphosate had no appreciable stimulatory or inhibitory effect on nitrification. Although glyphosate stimulated denitrification in a few instances, it generally had no significant effect on denitrification activity in FL and FS exposed during spraying. With all processes, microbial activity in FL was significantly greater than that in FS. Laboratory bioassays were also performed with FL and FS, as well as two silt loam (pH 5.8 and 6.4) and one sandy loam (pH 6.8) agricultural soils, using glyphosate concentrations up to 200 times higher than field application rates. With ammonification and denitrification, glyphosate generally stimulated activity at all levels tested and in all soil used. Glyphosate stimulated ammonification by 50% at concentrations ranging from 140 to 550 μg g^?1 for the soils and >4000 μg g^?1 for FL. With denitrification, the corresponding herbicide levels were approximately 2250 μg g^?1 for FS, > 10,000 for FL, and 450 for an agricultural soil. With nitrification, it was estimated that glyphosate concentrations greater than 1000 to 2000 μg g^?1 would be required to cause a 50% inhibition of activity. The careful use of glyphosate in forestry should have no toxic effects on N cycling in soils.     

Effects of organic manure on nitrification in arable soils

Summary The production of nitrate by the process of nitrification is highly dependent on other N-transforming processes in the soil. Hence, changes in the type of N compound applied to enrich agricultural soils may affect the production of nitrate. The size and activity of the chemolithotrophic bacterial community were studied in an integrated farming system, with increased inputs of organic manure and reduced inputs of mineral nitrogenous fertilizer, versus conventional farming. The integrated farming had a positive effect on potential nitrifying activity, but not on the numbers of chemolithotrophic nitrifying bacteria as determined by a most probable number technique or by fluorescence antibody microscopy. Cells of the recently described nitrite-oxidizing species Nitrobacter hamburgensis and Nitrobacter vulgaris were just as common as the cells of the well known species Nitrobacter winogradskyi. It was concluded that nitrification is stimulated by integrated farming, presumably by an increased mineralization of ammonium which is not immediately consumed by the crop or immobilized in the heterotrophic microflora of the soil. Since nitrifying bacteria are involved in the production of NO and N₂O, integrated farming with the application of manure may favour the production of noxious N-oxides.Communication no. 40 of the Dutch Programme on Soil Ecology of Arable Farming Systems     

Effects of nitrification inhibitors on transformations of urea nitrogen in soils

The effects of three patented nitrification inhibitors on transformations of urea N in soils were studied by determining the effects of these compounds (10 μg/g of soil) on urea hydrolysis, ammonia volatilization. and production of ammonium, nitrite, and nitrate in soils incubated under aerobic conditions (30°C, 60% WHC) after treatment with urea (400 μg of urea N/g of soil). The inhibitors used (N-Serve, ATC, and CL-1580) had little, if any, effect on urea hydrolysis, but they retarded nitrification of the ammonium formed by urea hydrolysis and increased gaseous loss of urea N as ammonia. They also decreased the amount of (urea + exchangeable ammonium + nitrite + nitrate) — N found in urea-treated soils after various times.Two of the soils used accumulated substantial amounts of nitrite(> 160 μg of nitrite N/g of soil) when incubated under aerobic conditions after treatment with urea. Addition of nitrification inhibitors to these soils eliminated or substantially reduced nitrite accumulation and greatly retarded nitrate formation, but had little, if any, effect on the recovery of urea N as (urea + exchangeable ammonium + nitrite + nitrate + ammonia) — N after various times. This finding and other observations reported indicate that the “nitrogen deficits” observed in studies of urea N transformations in soils may not largely be due to gaseous loss of urea N through chemodenitrification and are at least partly due to volatilization and fixation of the ammonium formed by urea hydrolysis in soils. The work reported also indicates that N-Serve and other nitrification inhibitors may prove useful for reduction of the nitrite toxicity problems associated with the use of urea as a fertilizer but that application of such inhibitors in conjunction with fertilizer urea, when surface applied, may promote gaseous loss of urea N as ammonia.     

Effects of biotechnology byproducts and organic acids on nitrification in soils

Summary Recent developments in biotechnology industries produce increasing amounts of byproducts with potential uses in agriculture. The present research focused on the nitrification of NH _inf4 ^sup+ -N in biotechnology byproducts added to soils, and on the effects of 29 naturally occurring organic acids (19 aliphatic and 10 aromatic) on nitrification in soils. A 10-g soil sample was incubated for 10 days at 30°C with 2.0 mg NH _inf4 ^sup+ -N in a byproduct or with 10 or 50 mol organic acid and 2.0 mg reagent-grade NH _inf4 ^sup+ -N. In condensed molasses-fermentation solubles, produced during the microbial fermentation of sugar derived from corn (Zea mays L.) and molasses derived from beets (Beta sp.), in the production of lysine as a supplement in animal food, the nitrification of NH _inf4 ^sup+ -N was similar to that of byproduct or reagent-grade (NH₄)₂SO₄. Nitrite accumulated when either of these materials was added to a calcareous Canisteo soil. The NH _inf4 ^sup+ -N in slops (produced during microbial fermentation processes occurring in the production of citric acid) was not nitrified in soils. Some organic acids inhibited, whereas others activated, nitrification in soils. Formic, acetic, and fumaric acids enhanced the production of NO _inf2 ^sup- -N in a calcareous Canisteo soil, whereas all other aliphatic and aromatic acids studied decreased the accumulation of NO _inf2 ^sup- -N. It is concluded that the addition or production of organic acids in soils affects the microbial dynamics, leading to significant changes in rates of nitrification and possibly in other N-transformation processes in soils.     

Effects of afforestation on ammonification and nitrification rates in former agricultural soils

Abstract. The effects of afforestation on potential nitrification, nitrification and ammonification rates were studied at an experimental site in NE Scotland 4½ years after afforestation of former arable land. The site had been planted with three tree species (Sitka spruce, sycamore and hybrid larch) at three different planting densities, with half the plots treated with inorganic NPK fertilizer. Laboratory measurements of potential nitrification, nitrification and ammonification rates, measured using a perfusion system, were compared between the unforested control and combinations of the various treatments. Differences in soil pH and soil moisture content were also investigated.
Potential nitrification rates measured in plantation soils were significantly lower than in the unplanted control soil. Nitrification and ammonification rates were also consistently lower, although these differences were only significant in a few of the treatments. Soils planted with a normal tree density had a tendency to show higher nitrification rates compared to soils planted with a high tree density.
The results suggest that afforestation of former agricultural soils may cause changes in important parts of the soil N cycle soon after planting. At this early stage in the life of the plantation this appears to be unrelated to changes in soil pH or moisture content, even though soils beneath the trees are drier. The apparent change may be the result of differences in the soil microbial community associated with the type of organic matter substrate present in the unplanted and planted soils.     

Effects of successive soil freeze-thaw cycles on nitrification potential of soils

Abstract

In our previous report (Yanai et al. 2004: Soil Sci. Plant Nutr., 50, 821–829), we demonstrated that soil freeze-thaw cycles caused a partial sterilization of the soil microbial communities and exerted limited effects on the potential of organic matter decomposition of soils. In the present study, the effects of soil freeze-thaw cycles on the nitrification potential of soils were examined and the impacts of the freeze-thaw cycles on the nitrifying communities were analyzed. Samples of surface soils (0 to 10 cm depth) were collected, from tropical arable land sites, temperate forest, and arable land sites~ Nitrification potential was assayed by the incubation of soils with or without the addition of 200 fig N of ammonium sulfate per g soil to reach a moisture content adjusted to 60% of maximum water-holding capacity at 27~wC following four successive soil freeze-thaw cycles (-13 and 4°C at 12 h-intervals). Nitrification potential of the soils, in which the decrease in the microbial biomass following the freeze-thaw cycles was less appreciable, was not inhibited by the soil freeze-thaw cycles. On the other hand, the nitrification potential of the soils, in which the decrease in the microbial biomass following the soil freeze-thaw cycles was relatively more appreciable, was clearly inhibited by the freeze-thaw cycles or was undetectable even in the unfrozen control. Surprisingly, nitrate production in the samples of an arable soil collected from Vietnam was inhibited by the addition of ammonium sulfate, and thus the effects of counter-anions of ammonium salts on the nitrification potential of the soils were examined. Since a much larger amount of nitrate was produced in the Vietnam soil with the addition of ammonium acetate and ammonium hydrogen carbonate than that in the soil with the addition of ammonium sulfate, it was considered that ammonium sulfate inhibited nitrification in the soil. These results indicated that ammonium sulfate may not always be a suitable substrate for estimating the nitrification potential of soils. Relationship between soil physicochemical properties and the effect of the soil freeze-thaw cycles on the nitrification potential was evaluated and it was considered that the soil pH(KCI) was likely to be responsible for the difference in the responses among soils, assuming that the pH values changed in unfrozen water under the frozen conditions of soils.     

Effect of temperature on nitrification in soils

Nitrification plays an important role in nitrogen transformation in soils. As a practical problem the fact is noteworthy that by nitrification, the loss of nitrogen from soils is caused at higher temperatures in the summer. On the contrary, it is quite slow at the lower temperatures of early spring. Recently much Work has been done on the effect of temperature on nitrification in soils. It was noticed that its effect is not the same according to the difference of soils. Soils which have high nitrifying activities at ordinary temperatures (around 25°C) show fairly good nitrification even at lower temperatures (1, 2, 5). However, in nitrification by usual experimental methods, the amount of nitrate produced can be only estimated while nitrifying organisms are increasing or decreasing in soil. As the growing Process of microbes is extremely influenced by both the properties of the soil and the cultural conditions, it is necessary to examine the effect of temperature on the growing process of microbes rather than biochemical nitrification by a unit cell. In usual methods nitrification can hardly be treated in these separate aspects. The author has succeeded in obtaining soils in which nitrifying organisms increase to the maximum limit, and no increase can be expected in number of these organisms. By using such samples, experiments were made concerning the effect of temperature on nitrification by a unit cell and its direct effect on the growth of organisms. Furthermore, the author prepared favorable cultural conditions for various kinds of soils by the “washing cultivation method” (6), and examined the effect of temperature on the increasing process of nitrifying ability.     

Leaching of N,P and glyphosate from two soils after herbicide treatment and incorporation of a ryegrass catch crop

During 2005–2007, studies were carried out in two field experiments in southwest Sweden with separately tile‐drained plots on a sandy soil (three replicates) and on a clay soil (two replicates). The overall aim was to determine the effects of different cropping systems with catch crops on losses of N, P and glyphosate. Different times of glyphosate treatment of undersown ryegrass catch crops were examined in combination with soil tillage in November or spring. Drainage water was sampled continuously in proportion to water flow and analysed for N, P and glyphosate. Catch crops were sampled in late autumn and spring and soil was analysed for mineral N content. The yields of following cereal crops were determined. The importance of keeping the catch crop growing as long as possible in the autumn is demonstrated to decrease the risk of N leaching. During a year with high drainage on the sandy soil, annual N leaching was 26 kg/ha higher for plots with a catch crop killed with glyphosate in late September than for plots with a catch crop, while the difference was very small during 1 yr with less drainage. Having the catch crop in place during October was the most important factor, whereas the time of incorporation of a dead catch crop did not influence N leaching from either of the two soils. However, incorporation of a growing catch crop in spring resulted in decreased crop yields, especially on the clay soil. Soil type affected glyphosate leaching to a larger extent than the experimental treatments. Glyphosate was not leached from the sand at all, while it was found at average concentrations of 0.25 μg/L in drainage water from the clay soil on all sampling occasions. Phosphorus leaching also varied (on average 0.2 and 0.5 kg/ha/yr from the sand and clay, respectively), but was not significantly affected by the different catch crop treatments.     

Effect of cropping systems on nitrification in soils

Abstract

Limited information is available about the effect of cropping systems and N application on nitrification potential of soils. This study was conducted to evaluate nitrification rates of soils that have been under long‐term cropping systems at three sites in Iowa. Each experiment consisted of three cropping systems (continuous corn, corn‐soybean‐corn‐soybean, and corn‐oats‐meadow‐meadow) and two fertilizer treatments: untreated (0 N) and treated (+ N) with ammonium or ammonium‐forming fertilizers (180 or 200 kg ha/yr) before corn. The rate of nitrification was studied at 30°C. Results showed that, although soil pH decreased in the plots treated with ammoniacal fertilizers before corn in the cropping system, the rate of nitrification was significantly greater in N‐treated than in untreated plots, suggesting that fertilization with ammonium or ammonium‐forming fertilizers either increased the microbial populations responsible for nitrification in soils and/or that such treatments increased the efficiency of the nitrifiers by inducing the enzymes responsible for conversion of NH⁴⁺ to NO₃‐. The results suggest that continuous application of ammonium or ammonium‐forming fertilizer could enhance the nitrification rate and increase the potential of contamination of groundwater with nitrate.     

A simple and rapid spectrophotometric method to quantify the herbicide glyphosate in aqueous media. Application to adsorption isotherms on soils and goethite

This article presents a simple, fast and low cost UV–vis spectrophotometric method to quantify glyphosate. This method can be used to perform adsorption isotherms on soils and metal oxides. It comprises a derivatization step and further measurement of the absorbance at 265 nm. The trueness of the results is validated using Ultra Performance Liquid Chromatography with tandem mass spectrometry detection (UPLC-MS/MS) as a reference method. The proposed spectrophotometric method is able to quantify glyphosate in the concentration range from 0.084 to 21.8 mg L^? 1. This range is suitable to construct reliable adsorption isotherms. Examples of adsorption isotherms on goethite at pH 4.5 and a soil sample at pH 4.5, 6.0 and 8.0 are given. Interferences caused by dissolved organic matter can be corrected at least up to an organic matter concentration of 12 mg L^? 1.     

Development of direct-drilling systems for sandy loam soils in the cool humid climate of Atlantic Canada

This study provides an overview of the adaptation of direct-drilling systems on sandy loam soils under the cool boreal, humid to perhumid soil climate of Prince Edward Island in Atlantic Canada, where the growing season is relatively short (May–October). Direct drilling can overcome the constraints of limited field workdays for seeding of spring cereals, owing to wet soil conditions in early May, or the integration of planting date with optimum soil temperatures for silage corn (Zea mays L.). However, the advantage of timeliness may be offset under sequential direct drilling for these crops, owing to a combination of reduced macroporosity at the soil surface and increased percentage of water-filled pore space, especially in soils with levels of organic carbon below 2% (w/w). In contrast, the presence of standing-crop residue, in pasture-renovation studies, allowed sequential or regular direct drilling of various forage species to occur with no adverse effect on soil structure. Use of direct drilling for spring cereals and silage corn on a rotational basis allowed intermittent soil loosening to prevent increasing surface soil compaction. Overall, direct drilling on perhumid, sandy loam soils proved successful when soil surface compaction was alleviated or circumvented.     

Effects of acetylene on nitrification and denitrification in two soils during incubation with ammonium nitrate

A loam from the Frilsham and one from the Wickham Series were incubated at 50 and 90 per cent of their water contents at saturation with 100 μg NH₄NO₃-N_g^?1 soil in the presence and absence of C₂H₂ (0.5 per cent, v/v). Acetylene inhibited nitrification in both soils, but had no effect on mineralization of N. No denitrification (measured as the production of N₂O in the presence of C₂H₂) occurred during incubation at 50 per cent saturation. At 90 per cent saturation, denitrification resulted in a loss of 28.4 and 36.7 μg N_g^?1 after 48 h from the Frilsham and Wickham soils, respectively. The concurrent inhibition of nitrification had no effect on the extent of denitrification at this time. In the Wickham soil, NO₃^? was exhausted after 168 h incubation in the presence of C₂H₂ and denitrification was underestimated by 13 μg N_g^?. The data suggested that concurrent inhibition of nitrification during measurement of denitrification using the C₂H₂ inhibition technique is most likely to affect the estimate of denitrification loss when NO₃^?supply is limited by the inhibition of nitrification.     

Effects of sorbed orthophosphate on zinc status in three soils of eastern Canada

P-Zn interactions can affect fertilizer use and produce Zn deficiencies with certain crops. Phosphorus-Zn sorption-desorption reactions were studied in topsoil and subsoil samples from three Quebec soils. Soils were equilibrated with P solutions, then with Zn solutions, and finally with solutions containing no P or Zn. The first equilibration evaluated P sorption (P_s), the second evaluated Zn sorption (Zn_s) after P sorption (P_s), and the third evaluated Zn desorption (Zn_D) as related to added P. Subsequently, Zn fractions were extracted sequentially with KNO₃ (Zn _{kno 3}), NaOH (Zn_NaOH) solutions and concentrated HN0₃+ H₂0₂(Zn_HNO,).
One mmole sorbed P resulted in increases of 0.5 to 1.0 meq (mean = 0.72) increases in cation exchange capacity (CEC). Increased Zn_s with added P was equivalent to 4 to 5% of the increase in CEC induced by P_s in the Uplands (sand) and St. Bernard (loam) soils, and 0.4 to 0.9% in the Dalhousie (clay) soils, while one meq increase in CEC resulted in 1.5-3.5% decrease in Zn_D. There existed positive correlations between P_s and extractable soil Fe materials. Phosphate sorption enhanced associations between Zn_s, Zn_D or Zn fractions and soil organic or crystalline Fe contents, confirming that P addition increased specific sorption of Zn on Fe components. Other mechanisms including precipitation, P-induced negative charge and 'bridge' effects are also discussed.     

Mineralization and nitrification in three Malaysian forest soils

Examination of three forest soils from Malaysia using the soil incubation technique suggests that nitrification was not inhibited in these oligotrophic soils. Nitrification rates were between 40 and 750 ngN produced g^?1 dry weight soil day^?1 of incubation. Addition of phenolic metabolites (tannic acid) and leaf filtrates from hill and lowland forest litter did not significantly inhibit nitrification. Addition of sucrose (1% w/w carbon source) decreased nitrification but not ammonification.     

Release of mineral N from soils: Influence of inhibitors of nitrification

Nitrification inhibitors (N-Serve, ATC, and CS₂) were added to soils without N fertilizers. While the amount of nitrification of NH₄⁺-N was reduced, so was the amount of ammonification of soil N. This effect was greater with ATC and CS₂ than with N-Serve. In three field experiments, the application in the fall of ATC at 22 kg ha^?1 mixed into the soil reduced the loss of soil mineral N in early spring. Apparently, the inhibition suppressed both ammonification and nitrification of soil N during the winter, and consequently there was less NO^?₃ in soil when the wet period occurred in the spring.     

Inhibition of nitrification in soils by volatile sulfur compounds

Carbon disulfide, dimethyl disulfide, methyl mercaptan, dimethyl sulfide, and hydrogen sulfide retard nitrification of ammonium in soils incubated in closed systems. The inhibitory effects of these volatile sulfur compounds on nitrification decrease in the order listed. Hydrogen sulfide is a relatively weak inhibitor of nitrification, but carbon disulfide is considerably more effective than patented nitrification inhibitors (N-Serve. AM, and ST) for inhibition of nitrification in closed systems.It is concluded from the work reported that the inhibitory effects of methionine, cystine, cysteine, and other nonvolatile organic sulfur compounds on nitrification in soils may be at least partly due to decomposition of these compounds by soil microorganisms with formation of volatile sulfur compounds that retard nitrification.     

两种离子液体对Cd2+在四种土壤上吸附的影响

研究了2,3-吡啶二羧酸和咪唑-4,5-二羧酸两种离子液体阳离子部分对Cd2+在四种不同性质土壤上吸附的影响。结果表明,离子液体的存在显著影响了Cd2+在土壤中的吸附,与对照相比,添加1 mmol·L-12,3-吡啶二羧酸使得Cd2+在武进漂洗型水稻土、吴县潴育型水稻土、南京黄褐土和宜兴棕红壤四种土壤上的最大吸附量分别降低209、834、667、509 mg·kg-1,而添加1 mmol·L-1咪唑-4,5-二羧酸使Cd2+最大吸附量分别降低226、54、124、81 mg·kg-1,2,3-吡啶二羧酸对Cd2+在供试土壤上吸附量的影响显著大于咪唑-4,5-二羧酸。基于离子选择电极分析了平衡液中自由态Cd2+含量,发现两种离子液体都能与Cd2+络合,从而降低平衡液中Cd2+含量,其中2,3-吡啶二羧酸与Cd2+的络合能力大于咪唑-4,5-二羧酸。两种离子液体进入环境,会使Cd2+在土壤上的吸附量减少,从而增加Cd2+的移动性和环境风险。     

Heterotrophic and autotrophic nitrification in two acid pasture soils

Laboratory incubation experiments, using ¹⁵N-labeling techniques and simple analytical models, were conducted to measure heterotrophic and autotrophic nitrification rates in two acid soils (pH 4.8-5.3; 1/5 in H₂O) with high organic carbon contents (6.2-6.8% in top 5 cm soil). The soils were from pastures located near Maindample and Ruffy in the Northeast Victoria, Australia. Gross rates of N mineralization, nitrification and immobilization were measured. The gross rates of autotrophic nitrification were 0.157 and 0.119 μg N g⁻¹ h⁻¹ and heterotrophic nitrification rates were 0.036 and 0.009 μg N g⁻¹ h⁻¹ for the Maindample and Ruffy soils, respectively. Heterotrophic nitrification accounted for 19% and 7% of the total nitrification in the Maindample and Ruffy soils, respectively. The heterotrophic nitrifiers used organic N compounds and no as the substrate for nitrification.     

Effects of nickel addition on nitrogen mineralization,nitrification, and nitrogen leaching in some boreal forest soils

The effects of Ni additions on nitrification, N mineralization, and N leaching were examined in soils from boreal jack pine (Pinus banksiana Lamb.) forests. The results of a series of incubation experiments suggested that under certain conditions, Ni at 100 μg g^?1 soil can stimulate nitrification, and at 500 μg g^?1 can stimulate N mineralization. Nitrification rates were very low overall, but were higher in soils from the vicinity of the Sudbury, Ontario Ni-Cu smelters than in uncontaminated soils. The nitrifier populations, estimated by the most probable number method, were extremely low in uncontaminated soils, but also increased following some Ni additions. Increased leaching of NO_f3 ^p was observed in soil columns treated with Ni. Since N tends to be in low supply in boreal forests, and therefore tightly cycled, the observed disruptions caused by Ni inputs could have an effect on forest productivity.