摘要:

High soluble‐sulfate (SO4) concentrations affect water quality, soil chemistry, plant sulfur (S) levels, and possibly ruminant‐animal health. The objective of this greenhouse pot study was to determine the potential for accumulating high levels of S by tansy mustard (Descurainia pinnata(Walt.) Britton), kochia (Kochia scopariaL. Schrad.), yellow sweet clover (Melilotus officinalisL.), slender wheatgrass (Elymus trachycaulus(Link) Gould ex Shinners), and sunflower (Helianthus annuusL.). Plants were grown on both a Brinegar (fine‐loamy Ultic Argixeroll) and Portneuf (coarse silty Durixerollic Calciorthid) soil. Each species received five‐SO4levels. The saturation extract electrical conductivity (EC) of the cropped soils ranged from 6 to 16 dS/m, while the soluble SO4varied from 16 to 200 mmolc/kg soil. Soil solutions were saturated or very nearly saturated with respect to gypsum at the conclusion of each study. Plant dry matter yield, except of grass growing on the non‐calcareous soil, was not reduced by SO4treatment nor by the sulfate‐induced decrease in mole fraction of calcium (Ca)/(sum cations) to values less than 0.10 for kochia and grass. Sulfur concentration in the plants ranged from 2.5 mg/g in grass to 10 mg/g in mustard and for each species was linearly related to the SO4treatment and soil‐SO4activity. Plant SO4‐S values ranged from 70 μg/g in the grass to nearly 900 μg/g in mustard. Total nitrogen (N): organic S was 4.4, 7.5, 11.4, 16.5, and 5.8 for mustard, kochia, clover, grass, and sunflower, respectively. It was concluded that these species could accumulate high levels of S in the above ground tissue.

ISSN:0010-3624    

DOI:10.1080/00103629409369205

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Sodium bicarbonate (NaHCO3) and calcium chloride (CaCl2) are proposed as simultaneous extractants of available nitrate‐nitrogen (NO3‐‐N), phosphorus (P), potassium (K) in soils. Flow Injection methods were used for the determination of NO3‐and P, and atomic emission spectroscopy for K. Parameters, such as reproducibility, precision, and recovery of the different extraction processes were studied. The usefulness of the proposed extractants was tested by applying them to different samples from the Spanish Soil Collection. The results obtained were compared with those provided after using the extractants recommended by the official methods. Sodium bicarbonate turned out to be suitable for the simultaneous extraction of NO3‐, P, and K in alkaline soils, whereas CaCl2was only advisable for NO3‐.

ISSN:0010-3624    

DOI:10.1080/00103629409369206

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Nitrate nitrogen (NO3‐N), which is an essential source of nitrogen (N) for plant growth, is now also considered a potential pollutant by the Environmental Protection Agency (EPA). This is because excess applied amounts of NO3‐N can move into streams by run‐off and into ground water by leaching, thereby becoming an environmental hazard. Soils have varied retentive properties depending on their texture, organic matter content, and cation exchange capacity (CEC). The purpose of this study was to determine the effect of soil texture on NO3‐N retention to reduce NO3‐N contamination in the environment. A sand, 85:15 sand:peat Greensmix, a loamy sand, and sandy clay loam soils were placed in 2×3 inch metal cylinders and soaked in a 240 ppm solution of NO3‐N for seven days to saturate the soil with NO3ions. The columns were leached with water to collect 10 soil percolate samples of 50 mL each until a total volume of 500 mL was collected. Nitrate‐N was measured in each 50‐mL aliquot by automated colorimetry. The results showed that soil texture affected the retention of N03‐N in the sand, which adsorbed the least amount of NO3‐N at 119 ppm, followed by the Greensmix at 125 ppm, loamy sand at 149 ppm, and sandy clay loam at 173 ppm. More NO3‐N was released in the first 50 mL of the sand percolate at 63% followed by the Greensmix, loamy sand, and sandy clay loam at 58,46, and 37% NO3‐N released, respectively. Soils with more silt, clay, and organic matter retained more NO3‐N than the straight sand. Therefore, a straight sand would be the poorest of soil types since NO3‐N retention was low.

ISSN:0010-3624    

DOI:10.1080/00103629409369207

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The objective of this experiment was to measure the impact of molybdenum (Mo) addition to the soil on changes in rate of photosynthesis (PN), specific root nodule nitrogenase activity (SNA), chlorophyll ‐ (Chl‐a) and (Chl‐b) and biomass of soybean (Glycine maxL. Merrill), exposed to carbon dioxide (CO2) (350, 400, or 450 μL/L) for 5 d during its sensitive growth stage (R2). Plants grown in soil with Mo (0, 0.5, or 1.0 mg/kg soil dry weight) were exposed to carbon dioxide (CO2) in open‐top field chambers for 12 h/d for 5 d with a nitrogen (N)‐free fertilizer. Increasing CO2levels reduced SNA and increased both Chl‐a and Chl‐b. Addition of 1 mg/kg Mo significantiy reduced SNA for plants grown with 350 μL/L CO2with no change in PN.

ISSN:0010-3624    

DOI:10.1080/00103629409369208

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103629409369184

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor