NO3‐N Soil Test—approaches to use and interpretation

Abstract

Nitrate‐nitrogen (NO₃‐N) soil tests have been instituted by several Great Plains States to aid in making nitrogen fertilizer recommendations. The NO₃‐N soil test is useful in the Great Plains because climatic conditions are such that NO₃‐N leaching is low and soil rooting depths are great.

Essentially four basic approaches to the use and interpretation of the NO₃‐N soil test have been developed and are discussed. They are: (1) total amount of NO₃‐N extracted from a two foot soil profile is available to the growing crop; (2) only a portion of the extractable NO₃‐N is available to the growing crop; (3) other mineral nitrogen, such as NH₄‐N, is just as available to the growing crop and (4) some nitrogen becomes available from the soil organic matter. The NO₃‐N soil test requires that deep samples (two feet or more) be taken and that they are air‐dried as rapidly as possible. Late fall or early spring soil samples are necessary for interpretation of the NO₃‐N soil test.     

Deep‐freezing pretreatment and time of extraction of soil samples for inorganic nitrogen determination

Abstract

Soil samples for inorganic nitrogen (N) determination are usually deep‐frozen to prevent microbial transformations of N between sampling and analysis. For analysis, frozen soils are thawed, which may also lead to transformations of N. A specially manufactured mill for grinding frozen soil was tested to minimize these transformations. Whether the time of extraction of the samples could be extended to 20 hr to better accomondate routine work and to make the clay aggregates to disperse better during extraction was also investigated. Freezing of the samples did not produce different results to fresh soils from ammonium nitrogen (NH₄ ⁺‐N) or nitrate nitrogen (NO₃ ^‐‐N) determination. Thawing of the samples increased the concentration of NO₃ ^‐‐N in the extracts and grinding increased that of NH₄ ⁺‐N. When either thawing or grinding was applied, the total inorganic nitrogen concentration was about the same. Thawing of the ground samples increased concentrations of NO₃’‐N and NH₄ ⁺‐N in the extracts. Extending the time of extraction from 0.5 or 1 hr to 20 hr increased the concentration of NH₄ ⁺‐N in the extracts, while NO₃ ^‐‐N content was also increased slightly. It was concluded that sample pretreatment may cause serious errors in the determination of inorganic N even by methods which have proven most successful to prevent microbial transformations of nitrogen, unless the soils are extracted immediately after sampling. The period of extraction should not exceed two hours.     

Presidedress soil nitrogen test for corn in Virginia

Abstract

The presidedress soil nitrate test (PSNT) and the presidedress tissue nitrogen test (PTNT) have been developed to assess residual soil nitrogen (N) sufficiency for corn (Zea mays L.) in the humid eastern U.S. We conducted field studies at 47 sites during 1990 and 1991 to evaluate the use of the PSNT and PTNT for corn in Coastal Plain, Piedmont, and Appalachian Ridge and Valley regions of Virginia. Seven rates of fertilizer N (0, 45, 90, 135, 180, 225, and 270 kg/ha) were applied at corn height of 0.40 to 0.50 m and replicated four times in a randomized complete block design. Whole corn plants and soil to a depth of 0.30 m were sampled when corn height was 0.15 to 0.30 m to estimate available soil N prior to the application of fertilizer N treatments. Corn grain yield response to fertilizer N was used to assess residual soil N availability. Nitrogen concentration of whole corn plants at 0.15 to 0.30 m height was not an accurate indicator of plant‐available soil N. Corn yields were maximized without sidedress N at the 19 sites where soil NO₃‐N was at least 18 mg‐kg^‐1 and at the 17 sites where soil (NO₃+NH₄)‐N was at least 22 mg‐kg^‐1. The PSNT predicted corn N sufficiency regardless of soil physiographic region or surface texture; however, the critical values for NO₃‐N and (NO₃+NH₄)‐N were 3 to 5 mg‐kg^‐1 lower than those established in Pennsylvania and Maryland, where cooler soil temperatures may permit greater residence time of inorganic N.     

Development of a New Soil Extractant for Simultaneous Phosphorus,Ammonium, and Nitrate Analysis

Abstract

A new soil extractant (H³A) with the ability to extract NH₄, NO₃, and P from soil was developed and tested against 32 soils, which varied greatly in clay content, organic carbon (C), and soil pH. The extractant (H³A) eliminates the need for separate phosphorus (P) extractants for acid and calcareous soils and maintains the extract pH, on average, within one unit of the soil pH. The extractant is composed of organic root exudates, lithium citrate, and two synthetic chelators (DTPA, EDTA). The new soil extractant was tested against Mehlich 3, Olsen, and water for extractable P, and 1 M KCl and water‐extractable NH₄ and NO₂/NO₃. The pH of the extractant after adding soil, shaking, and filtration was measured for each soil sample (5 extractants×2 reps×32 soils=320 samples) and was shown to be highly influential on extractable P but has no effect on extractable NH₄ or NO₂/NO₃. H³A was highly correlated with soil‐extractable inorganic N (NH₄, NO₂/NO₃) from both water (r=0.98) and 1 M KCl (r=0.97), as well as being significantly correlated with water (r=0.71), Mehlich 3 (r=0.83), and Olsen (r=0.84) for extractable P.     

Influence of two “nitrogen regulators”; on soil n transformations and movement

Abstract

Experiments were conducted to assess the potential influence of a commercial product, EXTEND, on nitrogen transformations and movement in a sandy soil. Neither nitrapyrin (a commercially‐available nitrification inhibitor) nor EXTEND significantly affected the rate of NH₄ ⁺‐N or NO₃ ^‐‐N movement through a column of soil treated with urea‐ammonium nitrate liquid fertilizer. Nitrapyrin effectively inhibited nitrification, but the nitrification rate in the EXTEND treated systems were the same as control.     

不同轮作模式对黄淮平原潮土区土壤养分及作物产量的影响

通过大田试验,研究黄淮平原潮土区不同轮作方式对不同土层土壤速效养分和小麦产量构成因素及产量的影响.采用随机区组设置连续的小麦-玉米(WM-WM-WM)、1周期小麦-玉米+1周期小麦-大豆(WM-WS-WM)、1周期小麦-玉米+1周期小麦-夏花生(WM-WP-WM)、连续的小麦-夏花生(WP-WP-WP)和连续的小麦-大...     

Dicyandiamide effects on nitrification and total inorganic soil nitrogen in sandy soils

Abstract

Inhibition of nitrification in soil results in a decreased ratio of nitrate‐nitrogen (NO₃‐N) to ammonium‐nitrogen (NH₄‐N). If the conditions for NO₃‐N loss by leaching or denitrification exist, nitrification inhibitors should increase concentrations of total inorganic soil nitrogen (N) (TISN) (NH₄‐N + NO₃‐N). This can then result in plants taking up more N and developing more crop yield or biomass. This study examined whether inhibition of nitrification by dicyandiamide (DCD) would result in increased concentrations of TISN under field conditions. The effects of DCD on soil N were evaluated in hyperthermic sandy soils planted to potato (Solanum tuberosum L., cv. Atlantic). Treatments were factorial combinations of N as ammonium nitrate (NH₄NO₃) at 67, 134, and 202 kg N ha^‐1 and DCD at 0, 5.6, and 11.2 kg DCD ha^‐1. Soil NH₄‐N, NO₃‐N, and TISN concentrations were determined for up to five potato growth stages at two locations for two years for a total of 16 determinations (cases), i.e., four were not determined. The N form ratio [NO₃‐N/(NH₄‐N + NO₃‐N] x 100 was decreased in 10 of 16 cases, indicating that nitrification was inhibited by DCD. With two of these 10 cases, TISN concentration increased, but with four others, TISN concentration decreased with at least one N rate. With four of these 10 cases, inhibition of nitrification had no effect on TISN concentration. Under the conditions of these field studies, DCD inhibited nitrification more often than not. Inhibition of nitrification was, however, more likely to reduce TISN concentration than to increase it. This may have been due to DCD effects on immobization of applied NH₄‐N.     

Soil nitrate and ammonium variation with area and date sampled

Abstract

Soil nitrate test reports are being used more widely for making nitrogen fertilizer recommendations. Seldom does the literature refer to the ammonium concentration in the soil. Seemingly, an assumption is made that the level is insignificant or a constant. Selected soils upon which both NO₃‐N and NH₄‐Nwere analyzed were surveyed to determine the degree of variation that is found in routine soil samples from different situations. Our 134 sets of data were divided into groups by area (state) and date (month sampled). Group means and standard deviations, medians, coefficient of variations (C.V.), and ranges were determined for soil nitrate nitrogen (NO₃‐N), ammonium‐nitrogen (NH4‐N), sum of NO₃‐N + NH₄‐N (Sum N), % of N found as NO₃‐N, and ratio of NH₄‐N/ NO₃‐N.

Values varied widely with date of sampling within areas as well as among areas. Observed values ranged as follows: NO₃‐N from 2 to 83 ppm, NH₄‐N from 4 to 30 ppm, sum of N from 9 to 91 ppm, % of N as NO₃‐N from 15 to 91% and NH₄‐N/NO₃‐N ratio from 0.1 to 5.5. C.V.’s ranged from 10 to 133% and were highest for NO₃‐N and NH₄‐N/NO₃‐N ratios and lowest for NH₄‐N and % NO₃‐N data.

The survey data suggests that nitrogen fertilizer recommendations could be improved if the NH₄‐N were considered along with the NO₃‐N levels for predicting response to nitrogen fertilization. A method for determining both soil NO₃‐N and NH₄‐N from a single extract is described.     

Simultaneous determination of soil aluminum,ammonium‐ and nitrate‐nitrogen using 1 M potassium chloride extraction

Abstract

Determination of soil aluminum (Al), ammonium‐nitrogen (NH₄‐N), and nitrate‐nitrogen (NO₃‐N) is often needed from the same soil samples for lime and fertilizer recommendations, but Al has to be extracted and quantified separately from NH₄‐N and NO₃‐N according to present methods. The objective of this study was to develop a reliable method for simultaneous analyses of soil Al, NH₄‐N and NO₃‐N using a Flow Injection Autoanalyzer. Thirty‐five soil samples from different locations with wide ranges of extractable Al, NH₄‐N and NO₃‐N were selected for this study. Aluminum, NH₄‐N and NO₃‐N were extracted by both 1 M and 2 M potassium chloride (KCl), and quantified using a LACHAT Flow Injection Autoanalyzer simultaneously and separately. One molar KCl was found to be a suitable extractant for all three compounds when compared to 2 M KCl. The 1 M KCl extract proposed could aid in decreasing the costs associated with simultaneous NH₄‐N, NO₃‐N, and Al analyses. Results of those three compounds analyzed simultaneously were not statistically different from those analyzed separately in 1 M KCl solution. This new procedure of simultaneous determination of NH₄‐N, NO₃‐N, and Al increases efficiency and reduces cost for soil test laboratories and laboratory users.     

Does the potential ammonium fixation of soils have an impact on the optimum nitrogen fertilizer rate?

Field experiments were conducted to determine the effect of nitrogen (N) fertilizer forms and doses on wheat (Triticum aestivum L.) on three soils differing in their ammonium (NH₄) fixation capacity [high = 161 mg fixed NH₄-N kg^?1 soil, medium = 31.5 mg fixed NH₄-N kg^?1 soil and no = nearly no fixed NH₄-N kg^?1 soil]. On high NH₄⁺ fixing soil, 80 kg N ha^?1 Urea+ ammonium nitrate [NH₄NO₃] or 240 kg N ha^?1 ammonium sulfate [(NH₄)₂SO₄]+(NH₄)₂SO₄, was required to obtain the maximum yield. Urea + NH₄NO₃ generally showed the highest significance in respect to the agronomic efficiency of N fertilizers. In the non NH₄⁺ fixing soil, 80 kg N ha^?1 urea+NH₄NO₃ was enough to obtain high grain yield. The agronomic efficiency of N fertilizers was generally higher in the non NH₄⁺ fixing soil than in the others. Grain protein was highly affected by NH₄⁺ fixation capacities and N doses. Harvest index was affected by the NH₄⁺ fixation capacity at the 1% significance level.     

Extractable nitrogen using hot potassium chloride as a mineralization potential index

Inorganic nitrogen (N) in soils is a primary component of soil‐plant N buffering. This study was conducted to determine if non‐exchangeable ammonium‐nitrogen (NH₄‐N) could serve as an index of potentially mineralizable organic N which is an important sink in N buffering. Four long‐term winter wheat (Triticum aestivum L.) experiments that had received annual fertilizer N at 0 to 272 kg N ha^‐1 were used. Soils from these experiments were extracted by four 10 mL portions of 2M potassium chloride (KC1) at room temperature followed by extraction with 20 mL of 2M hot KC1. Extraction at 100°C for four hours using 3 g soil and 20 mL 2M KC1 was found to be the most effective. Hot KC1‐extractable NH₄‐N minus room temperature KCl‐extractable NH₄‐N was considered non‐exchangeable NH₄‐N. Non‐exchangeable NH₄‐N was correlated with the long‐term N rates, and believed to be a reliable index of potentially mineralizable organic N. The relationship was linear for NH₄‐N where the lowest N rate had the lowest extractable N. The mean non‐exchangeable NH₄‐N concentration ranged from 8.42 to 16.34 mg kg^‐1; whereas, nitrate‐nitrogen (NO₃‐N) ranged from 0.07 to 1.87 mg kg¹. Total inorganic N extracted was similar to that mineralized in a 42‐day aerobic water saturated incubation. In addition, using a linear‐plateau model, extractable NH₄‐N was highly correlated with long‐term average yield (R²=0.92). For the soils evaluated, this method provided a rapid measure of potentially mineralizable N.     

Effects of substituting chemical fertilizers with manure on rice yield and soil labile nitrogen in paddy fields of China: A meta-analysis

Substituting chemical fertilizers with manure is an important method for efficient nutrient management in rice cropping systems of China.Labile nitrogen(N) is the most active component of the soil N pool and plays an essential role in soil fertility.However,the effects of manure substitution on soil labile N in rice cropping systems and their relationships with soil properties,fertilization practices,and climatic conditions remain unclear and should be systematically quantified.Here,we investiga...     

Evaluation of methods for soil inorganic nitrogen analysis

Abstract

This study determined the effects of soil preservation methods on inorganic nitrogen (N) analysis and evaluated methods of soil inorganic N analysis. Soils were preserved by oven‐drying at 55'C, air‐drying at 27°C, and freezing at ‐ 7°C. Inorganic N results were compared with initial N levels prior to imposing preservation treatments. Soil preservation effects on ammonium‐nitrogen (NH₄ ⁺‐N) were not consistent across soil types. Soil nitrate‐nitrogen (NO₃ ^‐‐N) levels after air‐drying and freezing compared most favorably with initial levels indicating that both are acceptable methods of soil inorganic‐N preservation. Levels of NH₄ ⁺‐N averaged across soils were 3.9 mg/kg for steam distillation, 4.2 mg/kg for sodium salicylate‐hypochlorite, and 3.7 mg/kg for indophenol blue. When compared with steam distillation averaged across soils, NO₃ ^‐‐N for cadmium‐copper (Cd‐Cu) reduction was 4 mg/kg greater, followed by nitrate electrode at 3 mg/kg, and salicylic acid at 2 mg/kg. Recovery of added N ranged from 83.3 to 94.8% for the NH4+‐N methods and from 74.8 to 112.4% for the NO₃ ^‐‐N methods with the nitrate electrode averaging 98.3%.     

DEVELOPMENT OF A SOIL N TEST FOR FERTILIZER REQUIREMENTS FOR WHEAT

Optimal fertilizer nitrogen (N) rates result in economic yield levels and reduced pollution. A soil test for determining optimal fertilizer N rates for wheat has not been developed for Quebec, Canada, or many other parts of the world. Therefore, the objectives were to determine: 1) the relationship among soil nitrate (NO^? ₃)- N, soil ammonium (NH ⁺ ₄)- N and N fertilizer on wheat yields; and 2) the soil sampling times and depths most highly correlated with yield response to soil NO^? ₃-N and NH ⁺ ₄-N. In a three year research work, wet and dried soil samples of 0- to 30- and 30- to 60-cm depths from 20 wheat fields that received four rates of N fertilizer at seeding and postseeding (plants 15 cm tall) were analyzed for NH ⁺ ₄-N and NO^? ₃ -N using a quick-test (N-Trak) and a standard laboratory method. Wheat yield response to N fertilizer was limited, but strong to soil NO^? ₃-N.     

模拟氮沉降对湿性常绿阔叶次生林土壤碳氮组分和酶活性的影响

为了研究氮沉降对次生林土壤碳氮组分和酶活性的影响,以华西雨屏区湿性常绿阔叶次生林为对象,从2014年1月起进行野外定位模拟氮沉降试验,分别设置对照(CK,+0 g/(m^2·a))、低氮(LN,+5 g/(m^2·a))和高氮(HN,+15 g/(m^2·a))3个氮添加水平。在氮沉降进行27个月后,按照腐殖质层和淋溶层表层进行取样,测定不同土层土壤总有机碳(TOC)、可浸提溶解性有机碳(EDOC)、易氧化碳(ROC)、全氮(TN)、硝态氮(NO_3^-—N)和铵态氮(NH_4^+—N)含量以及蔗糖酶、脲酶、酸性磷酸酶和多酚氧化酶活性。结果表明:模拟氮沉降显著增加该次生林腐殖质层土壤的TOC和NH_4^+—N含量,显著增加腐殖质层和淋溶层表层土壤的NO_3^-—N含量,腐殖质层土壤C/N显著升高。淋溶层表层土壤TOC、NH_4^+—N、C/N以及2层土壤的EDOC、ROC、TN和NH_4^+—N/NO_3^-—N均无显著影响。2层土壤的多酚氧化酶活性均随着氮添加量的升高而降低,其中淋溶层表层达到显著差异。模拟氮沉降对蔗糖酶、脲酶和酸性磷酸酶活性均无显著影响。腐殖质层中,NH_4^+—N和NO_3^-—N含量与TOC含量存在极显著正相关关系。2层土壤的多酚氧化酶活性均与NO_3^-—N含量呈极显著负相关。结果说明,模拟氮沉降使该次生林中原本较高的腐殖质层土壤TOC含量进一步显著增加,并且促进土壤无机氮的积累,而模拟氮沉降对多酚氧化酶的抑制作用更加有利于土壤有机质的积累。     

Diagnosis of the nitrogen status of wheat at tillering and prognosis for maximal grain yield

Abstract

From a field experiment in which wheat was supplied with nitrogen fertilizer at 0, 20, 40, 60, 80, 100, 150, 200, or 400 kg ha^‐1N, a correlation existed between nitrate concentration in wheat stems at tillering and subsequent grain yield. At early tillering, NO₃‐N concentrations around 8,000 μg g^‐1 were indicative of sufficient nitrogen in the crop‐soil system for maximum grain yield.

Averaging the results of this experiment with those from another seven field experiments, it was concluded that at tillering, the prognostic levels of NO₃‐N concentration in stems were: below 4000 μg g^‐1 deficient, between 4000 and 6000 μg g^‐1 intermediate, between 6000 and 10000 μg g^‐1 sufficient and above 10000 excessive for maximum grain yield. These values are applicable in a wide range of water supply conditions and to a number of cereal genotypes.     

Corn (Zea mays L.) Grain and Stover Yield as Affected by Soil Residual Mineral Nitrogen

Evaluation of nitrogen (N) dynamic in soil using regression equations is important for proper determination of N fertilization. A 3-year field experiment was conducted to (1) develop the best-fitted regression model relating corn grain and stover yield to soil residual ammonium (NH₄)-N and nitrate (NO₃)-N for corn yield prediction and (2) evaluate how such a model can be beneficial to the health of ecosystem by predicting the appropriate rates of N fertilization for corn production. Soil NH₄-N and NO₃-N were determined at corn harvest at the depths of 0–30 and 30–60 cm. Nitrogen fertilizer rates and soil mineral N accounted for a maximum of 93% variation in corn grain yield. Soil mineral N enhanced corn yield more than N fertilizer. Totals of 63.1 and 14.1 kg/ha of soil residual NO₃-N and NH₄-N were found in the 0- to 60-cm depth, indicating the importance of performing soil N tests.     

Yield of take‐all infested winter wheat as influenced by inhibiting nitrification with dicyandiamide

Abstract

The potential for using dicyandiamide (DCD) to enhance yield of take‐all‐infested winter wheat (Triticum aestivum L.) was evaluated in six field experiments on four acid soils (pH 5.7–6.2). Ammonium and NO₃ ^‐ concentrations and NH₄ ⁺: NO₃ ^‐ ratios in 0–10 and 10–20 cm soil depths were measured for ten weeks after spring topdressing 180 kg N/ha as urea with 0, 13, or 27 kg DCD/ha. Nitrification was strongly inhibited for 6 to 10 weeks by either 13 or 27 kg DCD/ha. Averaged over the ten‐week sampling period, NH₄ ⁺: N0₃ ^‐ ratios in the 0–10 cm depth of soil were 36: 1 for DCD‐treated plots as compared to 2: 1 for plots receiving only urea. Ratios in DCD‐treated plots were considerably wider than ratios associated with take‐all suppression (10: 1 to 3: 1) in earlier studies. Extractable NH₄ ⁺ + NO₃ ^‐ concentrations in soil were high in DCD‐treated plots after 30 to 40 days, suggested that DCD had reduced crop uptake of N because of the lower mobility of NH₄ ⁺ as compared to NO₃ ^‐. In four of the six studies, grain yields tended to be reduced by DCD. Results suggest that lower rates of DCD and/or application of some NO₃ ^‐ will be necessary if DCD is to be used as a tool for suppressing take‐all.     

Effect of nitrate addition on efficient use of ammonium sulfate fertilizer on corn under saline conditions. I. Pot experiment

Abstract

Plant growth in saline soils is regulated by the availability of nitrogen (N). High soil nitrate (NO₃)‐N can lead to poor water quality. Many workers think that NO₃‐N as a source for N can contribute to better plant growth in saline soils. The purpose of this work was to determine the necessity of NO₃‐N and the ratio of NO₃/ammonium (NH₄) in the N fertilizer which gives higher productivity of the biomass yield of corn. Corn (Zea mays L.) plants (Var. LG11) were grown under saline soil conditions (8.5 dS m^‐1), soils taken from the Euphrates valley (ACSAO Research Station) at Deir‐Ez‐Zor, east of Syria, from the surface layer of soil (0–25 cm). Five levels of N were applied in two forms, ammonium sulfate [¹⁵(NH₄)₂SO₄] with enrichment (1.5% a) as the NH₄‐N form and calcium nitrate [Ca(NO₃)₂] as the NO₃‐N form, besides fixed amounts of phosphorus (P) and potassium (K) for all N treatments. The corn plants were harvested at the flowering stage (56 days old), oven dried, weighed, and analyzed for total N and ¹⁵N recovery. The results indicated that the dry matter weight for treatments which received a combination of NH₄‐N and NO₃‐N gave higher dry matter yield than a single treatment of one source of N. But, NO₃‐N was more effective in improving yield than NH₄‐N. Nitrogen recoveries on the basis of added and absorbed N derived from fertilizer were significantly more affected by NO₃‐N than NH₄‐N.     

Effects of the application of wastevater from olive processing on soil nitrogen transformation

Abstract

An incubation experiment was performed to study the effects of wastewater from olive processing on nitrogen transformation in a calcareous soil. The application of this wastewater was shown to decrease NO₃ ^‐ formation in comparison with control assays during approximately the first half of the experimental period (6 weeks). Results were similar although more marked when vegetation water plus ammoniacal nitrogen was applied as opposed to ammoniacal nitrogen alone. The incorporation of vegetation water during the initial phases of study also reduced soil N‐NH₄ ⁺ levels both when residue only treatments were compared with controls and when vegetation water plus ammoniacal nitrogen treatments were compared with ammoniacal nitrogen only.