摘要:

Extraction efficiency for metribuzin [4‐amino‐6‐(1,1‐dimethyl‐ethy 1)‐3‐(methylthio)‐l,2,4‐triazin‐5(4H)‐one] from soil was evaluated using four solutions of methanol:water at ratios of 1:1, 7:3, 4:1, and 1:0 v/v. Two concentrations of metribuzin (O.216 and 2.44 ug/ g soil, unlabeled andI4C‐metribuzin, respectively) were added to surface and subsurface samples of a Dundee silt loam soil. Although the differences in extraction efficiencies were slight due to differences in methanol:water ratios, the metribuzin recovery varied with soil depth. Less metribuzin was recovered from surface soil extracted with 1:1 and 1:0 methanol:water solutions when compared to 7:3 and 4:1 solutions (80 and 81% vs 89 and 88% recoveries, respectively). About equal quantities, 81 to 85%, were recovered from the subsurface soil. Three extraction shaking times (0.5 h followed by another 0.5 h; 4 h:4 h; and 24 h:24 h) were also evaluated using the 4:1 extractant. No recovery differences were observed between the 0.5 h and 4 h shaking times. However, significantly higher recoveries occurred in both the surface and subsurface soil with 24 h shaking. The efficiency of this method was also determined on Eustis loamy sand, Sharkey clay, and Dorovan muck soils of diverse physical and chemical properties. The 4:1 extracting solution consistently yielded among the highest metribuzin recovery (74 to 97%) from the four soil types, and two soil depths of a Dundee soil.

ISSN:0010-3624    

DOI:10.1080/00103629009368365

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Incubation studies were conducted to evaluate the effectiveness of Dwell (5‐ethoxy‐3‐trichloromethy 1–1–2–4‐thiadiazole), as a nitrification inhibitor of urea and ammonium sulfate (AS) in three Arizona surface soils. In the first experiment, 50 g soil samples were treated with urea to provide ? equivalent to 224 kg/ha. Half of these samples were treated with Dwell solution equivalent to 1.27 kg/ha active ingredient. These samples were incubated at 33 ± 2C and the pH was measured at intervals of 0, 1, 2, 3, 4, 6, 8 and 16 days. In the second experiment one set of 25 g soil was treated with 39 ppm ? as urea solution, and another set received an equal amount amount of ? as AS solution. Half of the urea and AS treated soils received 0.55 mL of 9.68 mg active ingredient Dwell solution which is equivalent to 1.27 kg/ha. Moisture was adjusted to 3/4 field capacity in each soil sample. The samples were incubated at a constant 30C temperature for 0, 5, 10, 15, 20 and 25 days. Total inorganic ? (NO2‐, NO3‐and NH4+)‐N were determined after extraction with 2 M KC1. Nitrate plus NO2‐N was determined by subtraction of NH4‐N values from total inorganic‐N values. As indicated by pH and inorganic ? fractions, Dwell retarded nitrification of both urea and AS for 10 days in Laveen and Vinton soils and for 15 days in Anthony soil. A high nitrification rate was observed in the light textured soil (Vinton) and in the soil with high CaCO3content (Laveen). Obviously, Dwell was more effective with soils with normally high nitrification rates. A small loss of NH3by volatilization was observed in Dwell‐urea treatments of Laveen and Vinton soils as a result of retardation of nitrification. Dwell had no effect on urea hydrolysis, since all urea treatments showed an increase in pH during the first 5 days after urea application.

ISSN:0010-3624    

DOI:10.1080/00103629009368366

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The effectiveness of Dwell, a nitrification inhibitor, was tested in a greenhouse with two fertilizers and three Arizona soils. Tomato plants(Lycopersicum esculentumMill., cv. Row Pak) were grown in ABS plastic columns 10 cm diameter and 50 cm long containing 4500 g soil. Urea and ammonium sulfate (AS) were applied at 112 and 224 kg N/ha and Dwell (5‐ethoxy‐3‐trichloromethyl‐l,2,4‐thiadiazole) was applied at rates of 0 and 1.27 kg/ha of active ingredient. Both fertilizers and Dwell were added by mixing uniformly or in a band. Dwell increased ? uptake by 41%. The highest ? uptake was with Dwell with the highest urea rate, but Dwell was effective with both fertilizers in all soils. The lowest response to Dwell was with AS‐Laveen loam treatment, whereas the highest response, but the lowest ? uptake, was with urea ‐ Vinton loamy sand treatment. Dwell did not affect the inorganic‐N contents of the soils.

ISSN:0010-3624    

DOI:10.1080/00103629009368367

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

An apparatus for grinding plant and soil samples to <250um for15N analysis is described. This inexpensive and easily constructed roller grinder uses bottles for grinding individual samples, thus eliminating the potential for cross contamination. The unit running over‐night is capable of grinding 70 samples. In addition a method is described for diffusing NH4+and NO3onto filter paper for subsequent15N analysis. This method utilizes disposable test tubes and an incubator‐shaker to help speed the diffusion process. At low A%I5N (2–3%) a diffusion period of 7 days is sufficient for total15? recovery. At an A%15N of 8% the diffusion period needed to be extended to 10 days for total recovery.

ISSN:0010-3624    

DOI:10.1080/00103629009368368

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Phosphorus (P) and potassium (K) requirements of snap bean(Phaseolus vulgarisL.) in North Florida are not well defined in the literature. Response of a bush type snap bean to P and K was determined in a 2‐year test at NFREC, Quincy. The resulting data were used in site specific soil‐test interpretations. Residual soil‐P levels were 7, 11, 29, and 66 mg/kg the first yr and 7, 12, 21, and 42 mg/kg the second yr, no fertilizer K was added either yr. Residual soil‐K was 26, 60, and 73 mg/kg the first yr. Fertilizer K was added the second yr at 0,95, and 190 kg/ha. Soil samples were collected from each plot near the beginning of each growing season for determination of soil‐test P and K levels. Soil type was Norfolk loamy fine sand (fine loamy, siliceous, thermic, Typic Kandiudult). Maximum nutrient levels required for snap bean were: soil‐test P 30 mg/kg and soil‐test K 80 mg/kg. Soil‐test interpretations for P were: low <15 mg/kg, medium 15 to 30 mg/kg, and high >30 mg/kg. Potassium soil‐test interpretations were low <40 mg/kg, medium 40 to 80 mg/kg, and high >80 mg/kg.

ISSN:0010-3624    

DOI:10.1080/00103629009368369

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

In 100 different soils,hot(100C) water extractable boron was determined and the results were compared with boron data after extraction of the same soil samples withcold(20C) 0.01 M CaCl2. Since the boron concentrations in cold soil extracts are too low for direct determination, the extracted boron was converted into BF4‐ and subsequently extracted with a liquid anion exchanger, Aliquat 336, into xylene, and measured by ICP‐AES. A linear relation with R2= 0.74 was found between the two tested procedures. It is, therefore, concluded that with a cold 0.01 M CaCl2extraction equally valuable soil boron values can be obtained as with the more difficult to standardize hot water extraction procedure.

ISSN:0010-3624    

DOI:10.1080/00103629009368370

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Soil test values from three laboratories using the Mehlich‐3 extradant on Coastal Plain soils with a wide range in soil test levels were compared. Soil samples were collected over a four year period from four Southeastern/Mid‐Atlantic states (SC, NC, VA and DL). The results among labs were highly correlated (r > 0.9) for all elements analyzed (P, K, Ca, Mg, Mn, Zn, and Cu). Regression equations were developed to predict the soil test values among laboratories for each element. Comparisons of extractable levels for the elements shown above among the three laboratories are given.

ISSN:0010-3624    

DOI:10.1080/00103629009368371

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103629009368354

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor