Sorption–desorption of phenolic acids as affected by soil properties

Phenolic acids have been implicated in the process of allelopathy and are, therefore, of interest in plant management as a basis for new herbicide structures. The potential bioavailability of phenolic acids is controlled by sorption–desorption processes in soil. Sorption–desorption of p-coumaric acid (4-hydroxycinnamic acid), ferulic acid (3-methoxy-4-hydroxycinnamic acid), veratric acid (3,4-dimethoxybenzoic acid), vanillic acid (3-methoxy-4-hydroxybenzoic acid), and p-hydroxybenzoic acid (4-hydroxybenzoic acid) was characterized on soils with varying physicochemical properties. The phenolic acids sorbed quickly (<8 h) and in high proportions to the amount applied (average 84% of applied was sorbed). Sorption was irreversible with the batch desorption method used (0.01 N CaCl₂ extraction). Pretreatment of soils to remove organic matter and free metal oxides from the soils decreased sorption, particularly in soils with free oxides removed. Statistical analysis suggested that sorption of p-coumaric and ferulic acids was correlated with soil clay content and veratric acid sorption was correlated with several soil factors. In contrast, no consistent relationship between soil characteristics and vanillic and p-hydroxybenzoic acid sorption was found. Based on the results of these experiments, i.e. the high reactivity of the phenolic acids, it is unlikely that these chemicals would be transported far from their point of origin, limiting their range of influence. It appears that, for phenolic acids to have allelopathic effects on plants, they would have to persist in the soil for long periods, resulting in a buildup of the chemical to high enough levels so that sufficient chemical would be in solution to cause the allelopathic effects, even though they may be strongly sorbed at lower concentrations.     

Critical soil phosphorus of a low‐P loess‐derived soil as affected by storage temperature

Abstract

Overwintering soil temperature may influence crop response to phosphorus (P) and indices of P availability in the humid, temperate, transitional climate of Tennessee. The effects of P fertilization and soil incubation temperature on sorghumsudangrass (Sorghum bicolor x S. Sudanese) grown on a Typic Hapludalf was investigated in a greenhouse study. In order to determine the effect of temperature on P availability, soils were incubated prior to cropping, at a constant temperature of 6°C or an average diurnal temperature of 24 and 36°C. Reagent grade Ca(H₂PO₄)₂.H₂O was used as the fertilizer source and applied at rates of 0, 10, 20, and 30 mg P kg^‐1 for the first test and 0, 20, 40, 60, and 80 mg P kg_‐ ¹ for the second test. Critical P concentration in the shoots for optimum yield was found to be 1.3 mg g‐¹, corresponding to soil solution and labile P concentrations of 5.5 μmol L^‐1 and 167 μg g^‐1, respectively. Optimum yield occurred for applications of >65 mg P kg^‐1 and was unaffected by soil incubation temperature. Applied P rates affected extractable P by five chemical extractants (Bray I, Bray II, Mehlich I, Mehlich III, and Mississippi), but soil incubation temperature had no affect. The extractants, however, were poorly correlated to plant P uptake and no one extractant appeared preferable to the others as an indicator of P availability.     

Rice yield and water use as affected by soil management practices

A field experiment was conducted at the Shenyang Experimental Station of Ecology, Chinese Academy of Sciences,to study the effects of soil management practices on water use and rice (Oryza sativa L.) yield in an axtuic brown soil during 2001 and 2002. A completely random experimental design with three replications was employed, having four soil management practices as treatments, namely: an undisturbed plow layer (CK), a thin plastic film (TN), a thick plastic film (TI) and subsoil compacting (CP). Results indicated no significant differences among all treatments for rice biomass and grain yields. Also, water consumption was about the same for treatments TN and CK, however the treatments TI and CP were much lower with more than 45% and 40% of the irrigation water in the treatments TI and CP, respectively,saved each year compared to CK. Therefore, water use efficiency was higher in the treatments TI and CP. These results will provide a scientific basis for the water-saving rice cultivation.     

Effects of concentrated application of soil conditioners on soil–air permeability and absorption of nitrogen by young peach trees

ABSTRACT

To study the effects of concentrated application of two soil conditioners, two-year-old peach trees (Prunus persica L.‘Chunmei’) were selected to test the soil air permeability, ¹⁵N absorption and the growth of trees. The experiment comprised three treatments involved concentrated applying either polyacrylamide (treatment I) or Agri-SC (a proprietary soil conditioner, treatment II) at the bottom of each pit or neither of the two (treatment III). And then the whole pit was back-filled with soil. Neither digging a hole nor use of soil conditioners as the control (CK). The results showed that volumetric oxygen content in gases in 5–10 cm soil layer upon concentrated application layer was significantly higher in treatments I and II than that in CK. Soil volumetric water content upon concentrated application layer was higher in treatments I and II than that in CK. Compared with CK, no matter root activity, leaf area, leaf chlorophyll content, or leaf net photosynthesis rate in treatments I and II increased in August and October, which promoted the growth of new shoots and the stem. Compared with CK, the leaf superoxide dismutase activity increased 31.24%, 22.66% and 4.74%, Guaiacol peroxidase increased 21.88%, 13.25% and 3.39%, Catalase increased 11.80%, 7.92% and 1.24% respectively in treatments I, II and III in October. As a result, values of the total roots surface area, total root volume, number of root tips, dry matter accumulation, and organ nitrogen content were markedly higher in treatments I and II than that in CK. And the ¹⁵N utilization rate significantly increased 24.22% and 10.40% respectively in treatments I and II. The result suggested that concentrated application of soil conditioners formed a rhizosphere water storage and breathable layer that not only stores moisture but is also permeable to air. That, in turn, promotes plant growth, increases the nitrogen use efficiency.     

Dynamics of zinc under long-term application of chemical fertilizers and amendments by maize–wheat cropping sequence in Typic Hapludalfs

This present investigation took place on a continuing long-term fertilizer experiment, initiated in 1972 at the experimental farm of the College of Agriculture CSK HPKV, Palampur, aimed at studying nutrient dynamics of micronutrients, especially Zn, after continuous use of chemical fertilizers and amendments over the previous 36 years in an acid Alfisol under a maize–wheat system. Treatments investigated were as follows: T₁: Control; 100% N; 100% NP; 100% NPK (optimal application - 120:26:33(maize)/25(wheat)); 100% NPK + FYM (10 t ha⁻¹ to the maize crop); T₆: 100% NPK + lime (900 kg ha⁻¹); T₇: 100% NPK + Zn (25 kg ha⁻¹ as ZnSO₄); T₈: 100% NPK + Hand weeding; T₉: 100% NPK (-S); T₁₀: 150% NPK (super-optimal application); and T₁₁: 50% NPK (sub-optimal application). Different forms of zinc in soil were determined through a sequential extraction method. Results revealed that previous applications of high-analysis fertilizers and amendments caused a marked depletion in the pools of Zn as compared to buffer plots. All pools of Zn as well as crop productivity and Zn uptake were noticeably greater in farmyard manure (FYM)-amended plots compared with plots not receiving fertilizer. The residual fraction was the dominant form but organically bound and exchangeable forms were found to play major role in nutrient supply, crop productivity and nutrient uptake. Correlation and regression analysis studies showed that organic forms constituted the most important pool contributing towards variation in yield and uptake by maize and wheat crops. Exchangeable and organically bound forms contributed significantly towards the availability of DTPA-extractable Zn in soil.     

Topsoil and subsoil potassium as affected by long‐term potassium fertilization of corn‐soybean rotations

Abstract

Long‐term potassium (K) fertilization practices are likely to affect the K content of soils. This study assessed the effect of long‐term K fertilization strategies for corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] rotations on extractable K in the soil profile of a major Iowa soil type at two locations. The soil type was a Webster fine‐loamy, mixed, mesic, Typic Haplaquoll at both sites. Soil samples were collected from the 0–15, 15–30, 30–60, and 60–90 cm depths after 17 years (Site 1) or 19 years (Site 2) of K fertilization with combinations of two initial rates and four annual rates. The initial rates were 0 and 1,344 or 1,120 kg K ha^‐1 at Site 1 and 2, respectively, and the annual rates ranged from 0 to 100 kg K ha^‐1. Samples were analyzed for ammonium acetate‐extractable K (STK) and nitric acid (HNO₃)‐extractable nonexchangeable K (HNO₃‐K). Concentrations of STK and HNO₃‐K in the top 0–15 cm soil layer at the two sites were higher for the high initial K rates and were linearly related with the annual K rate. Results for the subsoil layers varied between sites and extractants. At Site 1, annual rates of 30 kg K ha^‐1 or higher resulted in a relative accumulation of HNO₃‐K in the 15–30 cm layer. At Site 2, these rates resulted in relative accumulations of STK in the 30–60 cm layer and of HNO₃‐K in the 60–90 cm layer, but with relative depletions of STK in the 15–30 and 60–90 cm layers. Thus, use of one extractant may not always be sufficient to evaluate cropping and fertilization effects on subsoil K. Long‐term K fertilization of corn and soybean rotations affected extractable K of both the topsoil and subsoil. The effects on subsoil K, however, were smaller compared with effects on the topsoil and varied markedly between sites, subsoil layers, and extractants.     

Response of phosphorus fractions to land-use change followed by long-term fertilization in a sub-alpine humid soil of Qinghai–Tibet plateau

Purpose

Identification of phosphorus (P) species is essential to understand the transformation and availability of P in soil. However, P species as affected by land use change along with fertilization has received little attention in a sub-alpine humid soil of Tibet plateau.

Materials and methods

In this study, we investigated the changes in P species using Hedley sequential fractionation and liquid-state ³¹P-NMR spectroscopy in soils under meadow (M) and under cropland with (CF) or without (CNF) long-term fertilization for 26 years in a sub-alpine cold-humid region in Qinghai–Tibet plateau.

Results and discussion

Land-use change and long-term fertilization affected the status and fractions of P. A strong mineralization of organic P (OP) was induced by losing protection of soil organic matter (SOM) and Fe and Al oxides during land-use change and resulted in an increase of orthophosphate (from 56.49 mg kg^?1 in M soils to 130.07 mg kg^?1 in CNF soils) and great decreases of orthophosphate diesters (diester-P, from 23.35 mg kg^?1 in M soils to 10.68 mg kg^?1 in CNF soils) and monoesters (from 336.04 mg kg^?1 in M soils to 73.26 mg kg^?1 in CNF soils). Long-term fertilization boosted P supply but failed to reclaim soil diester-P (from 10.68 mg kg^?1 in CNF soils to 7.79 mg kg^?1 in CF soils). This may be due to the fragile protection from the combination of SOM with diester-P when long-term fertilization had only improved SOM in a slight extent.

Conclusions

These results suggest that SOM plays an important role in the soil P cycling and prevents OP mineralization and losses from soil. It is recommended that optimization of soil nutrient management integrated with SOM was required to improve the P use efficiency for the development of sustainable agriculture.

     

The effects of straw return on potassium fertilization rate and time in the rice–wheat rotation

In order to investigate the effects of straw return on potassium (K) fertilizer application rate and time in the rice–wheat rotation, field experiments were conducted at three sites. The results showed that when the K rate was decreased to 70% of the recommended K dosage, crop yields showed no significant decrease. With K fertilization only at rice phase, crop yields showed no marked difference compared with that provided K fertilizer both at wheat and rice seasons. Though the NH₄OAc-extracted K and HNO₃-extracted K differed slightly among the treatments, the soil apparent K balance was negative without K fertilization. With crop straw fully incorporated, the recommended K dosage could be at least reduced by 30% at the experimental sites and the K fertilizer could be applied only at rice phase. A further hypothesis can be made that the best K rate was the amount of K took away by crop grain. In the long run, straw return combined with K fertilization would be an effective method to maintain soil K fertility and productivity.     

Evaluation of the growth and quality of the “Ife Plum” tomato as affected by boron and calcium fertilization

A local variety of tomato (Lycopersicon esculentum, Ife plum cv. 51691) was grown in soil culture for 5 months and treated with B at concentrations of 0, 1, 2, 4, 8, and 16 ppm as H₃BO₃, and Ca at 0, 40, 80, and 160 ppm as Ca(OH)₂. A significantly positive correlation was established between organic matter and water ‐ soluble B (r = 0.970), while the relationship between pH and B was negative (r = ‐0.490). Application of B at 2 ppm improved all growth parameters studied. Boron application higher than 2 ppm, induced leaf chlorosis and later necrosis of nodes and roots. Fruit yield correlated positively with soil ‐ B, stem diameter and floral number (r = 0.597, r = 0.650 and r = 0.812, respectively). Soil‐ and plant‐B were positively correlated (r = 0.790). Calcium when applied singly at higher levels increased total chlorophyll content of the leaf. Tomato fruit yield was optimum at B:Ca treatment concentration of 2 ppm B (4.48 kg/ha B) and 160 ppm Ca (358.4 kg/ha Ca), corresponding to a B:Ca fertilizer ratio of 1.80.     

Inoculation responses of perennial forage legumes grown in fresh hill‐land ultisols as affected by soil acidity‐related factors

A growth chamber experiment was initiated with two field moist, marginal and acidic (pH 5.1–5.2) soils of the Lily series (Typic Hapludults) in order to determine the need for improved legume‐rhizobia symbioses for forage species of current, or potential, use in the renovation of Appalachian hill‐land pastures. One soil was from an abandoned pasture having broomsedge (Andropogon virginicus L.) as the predominant vegetation, whereas the other was from a minimally‐managed pasture dominated by orchardgrass (Dactylis glomerata L.). Treatments included inoculation (or no inoculation) and the addition of aluminum, nil, or lime to provide a range of soil acidities. Both soils contained effective populations of naturalized rhizobia for white clover (Trifolium repens L.) and red clover (Trifolium pratense L.), but low and/or ineffective naturalized populations of rhizobia for alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), bigflower vetch (Vicia grandiflora Scop.), and flatpea (Lathyrus sylvestris L.). Seed inoculation, by lime‐pelleting, was highly beneficial in establishing effective symbioses for all these latter species. The addition of low levels of aluminum or lime (1.5 and 2.0 cmol/kg soil, respectively) had little effect on any of the symbioses, with the exception of those for alfalfa. Thus, an improved legume rhizobia symbiosis would not seem to be a prerequisite for renovating pastures established on chemically similar ultisols with the forage legume species examined in this study, especially if the pasture has at least some history of management.     

Recent advances in the chemistry of nitrogen,phosphorus and potassium as fertilizers in soil: A review

The advent of civilization has made humans dependent on plants for food and medicine, leading to the intensification of agricultural production. The intense cultivation of crops has resulted in the depletion of available nutrients from soil, thereby demanding the application of excess nutrients to soil to improve yield. Thus, mineral fertilizer discovery and application have, in many ways, contributed greatly to meeting global food demands. However, aside from the positive effects of mineral fer...     

Deactivation of ferrylmyoglobin by vanillin as affected by vanillin binding to β-lactoglobulin

Vanillin was found to be efficient as a deactivator of ferrylmyoglobin with a second-order rate constant of k(2) = 57 ± 1 L mol(-1) s(-1) for reduction to metmyoglobin with ΔH(?) = 58.3 ± 0.3 kJ mol(-1) and ΔS(?) = -14 ± 1 J mol(-1) K(-1) in aqueous pH 7.4 solution at 25 °C. Binding to β-lactoglobulin (βLG) was found to affect the reactivity of vanillin at 25 °C only slightly to k(2) = 48 ± 2 L mol(-1) s(-1) (ΔH(?) = 68.4 ± 0.4 kJ mol(-1) and ΔS(?) = 17 ± 1 J mol(-1) K(-1)) for deactivation of ferrylmyoglobin. Binding of vanillin to βLG was found to have a binding stoichiometry vanillin/βLG > 10 with K(A) = 6 × 10(2) L mol(-1) and an apparent total ΔH° of approximately -38 kJ mol(-1) and ΔS° = -55.4 ± 4 J mol(-1) K(-1) at 25 °C and ΔC(p, obs) = -1.02 kJ mol(-1) K(-1) indicative of increasing ordering in the complex, as determined by isothermal titration microcalorimetry. From tryptophan fluorescence quenching for βLG by vanillin, approximately one vanillin was found to bind to each βLG far stronger with K(A) = 5 × 10(4) L mol(-1) and a ΔH° = -10.2 kJ mol(-1) and ΔS° = 55 J mol(-1) K(-1) at 25 °C. The kinetic entropy/enthalpy compensation effect seen for vanillin reactivity by binding to βLG is concluded to relate to the weakly bound vanillin oriented through hydrogen bonds on the βLG surface with the phenolic group pointing toward the solvent, in effect making both ΔH(?) and ΔS(?) more positive. The more strongly bound vanillin capable of tryptophan quenching in the βLG calyx seems less or nonreactive.     

Yield,fruit quality and nutrient uptake of ‘Nabbut-Ahmar’ date palm grown in sandy loam soil as affected by NPK fertigation

A field experiment was conducted in 2011 and 2012 to study the effect of fertigation on yield, fruit quality and nutrient uptake of ‘Nabbut-Ahmar’ date palm cultivar grown in sandy loam soil. Three fertigation treatments were compared with traditional application. In traditional treatment (CT), the recommended dose [2300 g nitrogen (N), 1200 g phosphorus (P) and 1400 g/tree] was applied as a soil broadcast in three equal doses. The fertigation treatments, (T2), (T3) and (T4), represent all nitrogen, phosphorus and potassium (NPK) amounts of CT, 2/3 CT and 1/3 CT, respectively that were injected in twelve equal doses. The results showed that compared to CT, the fertigation treatments increased yield/palm by 41%, 31% and 18% for T3, T2 and T4, respectively. Beside the increase in yield, 33% and 66% of the applied fertilizers were saved by T3 and T4, respectively, compared with CT. Feritgation treatments had no negative impact on the overall fruit quality characteristics and even increased total soluble solids (TSS), soluble tannins and total phenols concentrations compared to the conventional fertilization. Availability of NPK increased by fertigation but without further increase in leaves and fruit. In conclusion applying 2/3 of the recommended dose of NPK fertilizers under dry land condition through fertigation maximize yield, quality and fertilizer use efficiency.     

Stimulation of N2‐fixation in chickpea by gamma irradiation as affected by different levels of ammonium sulfate fertilizer

Abstract

A pot experiment was conducted under natural climatic conditions to study the effect of low doses of gamma irradiation (0, 5, 10, and 20 Gy) on the performance of winter chickpea (Cicer arietinum L.) in the presence of increased supply of ¹⁵N labeled ammonium sulfate (0, 20, 50, and 100 kg N ha^‐1). Presowing seed irradiation produced a significant increase in dry matter production (up to 3 6%) and total nitrogen yield (up to 45%). The stimulative effect of irradiation was more pronounced with the application of NH₄ ⁺‐N fertilizer. Seed irradiation increased the amount of N₂‐fixation by 8–61% depending on the dose and level of NH₄ ⁺‐N fertilizer rate. A 10 Gy was found to be the optimal irradiation dose for enhancing N₂‐fixation. High levels of NH₄ ⁺‐N decreased the percentage and the amount of N₂‐fixation, but did not affect nodule formation. However, the presowing 10 Gy irradiation dose reduced the negative effect of ammonia‐N fertilizer on N₂‐fixation. Therefore, we recommend irradiating chickpea seeds with a 10 Gy dose before planting in soil containing high levels of mineral nitrogen to reduce its negative effect on N₂‐fixation.     

Iron chlorosis in macadamia as affected by phosphate‐iron interactions 1

Iron (Fe) chlorosis induced by heavy phosphate (P) fertilizations is a serious problem for macadamia (Macadamia integrifolia) in Hawaii. To address this problem, a study was conducted to quantify the effects of P‐Fe interaction on macadamia leaf composition and chlorosis. The soil used was a limed Oxisol (Tropeptic Eutrustox, Wahiawa Series), pH 5.5. Phosphate was added as treble superphosphate at 0, 150 and 500 mg P/kg. The 150 mg P/kg rate was designed to yield approximately 0.04 mg P/L in the soil solution, a level considered adequate for macadamia growth. The 500 mg P/kg rate was intended to produce approximately 0.2 mg P/L, a level required by many horticultural crops but considered excessive for macadamia. Iron was added as Fe‐DTPA at 0, 5 and 10 mg Fe/kg soil, and factorially imposed on the P treatments. Color Index, a numerical rating based on hue, value and chroma from a Munsell Color Chart for Plant Tissues, was correlated with leaf chlorophyll concentration and used as an indicator of chlorosis.

Phosphate concentrations in leaves increased with increasing P application rates as expected, but decreased remarkably with increasing Fe rates (at a constant P rate). Plant Fe unexpectedly remained unchanged with increasing Fe rates but decreased with increasing P rates. The results suggest that (1) soil‐solution Fe was not a limiting factor to macadamia growth as is often incorrectly assumed for high P‐fertilized soils, (2) Fe uptake was restricted not because soil‐solution Fe was low but because plant P was excessively high, and (3) Fe translocation from roots to leaves may have been hampered by high P in the plants. Consequently, Fe chlorosis was intensified primarily by P fertilization (actually, by high plant P concentrations) and secondarily by P‐Fe interactions. Chlorosis, as measured by Color Index, can be diagnosed by a leaf Fe/P ratio < 0.06, and predicted by a soil‐solution ³√Fe/P ratio < 15.     

Characteristics of synthetic soil aggregates produced by mixing acidic “Kunigami Mahji” soil with coal fly ash and their utilization as a medium for crop growth

Abstract

This study was carried out to examine the characteristics and potential utilization of synthetic soil aggregates (SSA) produced by mixing acidic “Kunigami Mahji” soil in Okinawa, Japan, with waste materials, such as coal fly ash, used paper and starch, as media for crop growth. A series of different SSA were produced by incorporating various percentages (i.e. 0, 20, 40, 60, 80 and 100%) of coal fly ash into the “Kunigami Mahji” soil with used paper and starch. The particle density and bulk density of the original “Kunigami Mahji” soil were 2.67 and 1.23 g cm^?3, respectively. The increased percentages of added coal fly ash, used paper and starch significantly decreased the particle and bulk densities of SSA compared with the original “Kunigami Mahji” soil because of the low particle and bulk densities of the coal fly ash (2.10 and 0.96 g cm^?3, respectively). The SSA particle density varied between 2.39 and 2.14 g cm^?3, and bulk density varied between 0.72 and 0.81 g cm^?3, depending on the additional percentages of coal ash from 20–100%. Maximum water-holding capacity and saturated hydraulic conductivity were increased with the formation of SSA with coal fly ash, used paper and starch binder compared with the original “Kunigami Mahji” soil. The saturated hydraulic conductivity values of the SSA increased because of their low bulk density compared with the original soil. The addition of coal fly ash, used paper and starch to the acidic (pH = 4.62) “Kunigami Mahji” soil to form SSA increased the pH (6.70–9.96), electrical conductivity, exchangeable cation concentration and cation exchange capacity. The addition of coal fly ash up to 60% increased the aggregate strength. The growth and yield of komatsuna and soybean crops with SSA as a crop growth medium was assessed. Both crops showed the highest growth and yield when grown with SSA containing 20% of coal fly ash. Synthetic soil aggregates containing more than 20% of coal fly ash reduced plant growth and yield. Therefore, SSA produced from “Kunigami Mahji” soil with 20% of coal fly ash, used paper and starch can be successfully used as a medium for crop growth.     

Effects of freeze–thaw cycles and the soil water content on carbon and nitrogen changes in different soil types of Heilongjiang Province,China

To reveal the influence of freeze–thaw cycles (FTCs) on soil carbon and nitrogen changes, six typical soils in Northeast China were selected as the research objects to conduct a FTC simulation test in an artificial climate chamber. Three soil volumetric water contents (10%, 20%, 30%) and eight FTCs (0, 2, 4, 6, 8, 10, 15, 20) were set. The results showed that the soil organic carbon (SOC) and microbial biomass carbon (MBC) contents of different soil types under the FTCs initially exhibited a downward and then an upward trend, while the dissolved organic carbon (DOC) content exhibited an upward and then a downward trend. Otherwise, the fourth and sixth FTCs were the key points of change. The SOC, MBC and DOC contents in paddy fields were higher than those in dry fields, showing upward and then downward trends spatially from northeast to southwest. The SOC and MBC contents in each soil type were the highest at the 20% water content, and the DOC content gradually increased with increasing water content. The ammonium nitrogen (NH₄⁺-N) content in different soil types at different water contents under the FTCs showed an upward trend first, then a downward trend and finally an upward trend. The NH₄⁺-N content in paddy fields was higher than that in dry fields. The nitrate nitrogen (NO₃^‒-N) content showed a downward trend first, then an upward trend and finally a downward trend. The NO₃^‒-N content in dry fields was higher than that in paddy fields. The NH₄⁺-N contents in the three soil types on the Sanjiang Plain were significantly higher than those on the Songnen Plain. The NH₄⁺-N and NO₃^‒-N contents showed upward trends with increasing water content, but the differences were not significant. The results have implications for the study of different types of soils and provide references for research on the mechanism of soil carbon and nitrogen transformation in typical farming areas in Northeast China.