The persistence of 2‐chloro‐6‐(trichloromethyl)‐pyridine in soil

Abstract

The half‐life of 2‐chloro‐6‐(trichloromethyl)‐pyridine in three soils varied from 43 to 77 days at 10 C and from 9 to 16 days at 20 C. The Q₁₀ values were highest in coarse textured soils.     

Ammonium,nitrite, and nitrate nitrogen levels in the soil under blight‐affected and healthy citrus trees

Abstract

Ammonium, nitrite, and nitrate nitrogen levels in the root zone of blight‐affected and healthy trees in a 35‐year‐old commercial orange grove were monitored at 30‐day intervals for 2 years. There was essentially no difference in NH₄‐N and NO₂‐N; however, at four sampling dates and overall, the NO₃‐N level was slightly higher under healthy trees.     

Effects of insecticides on populations of microflora,nitrification and respiration in soil

Abstract

Tests were conducted to determine the effects of leptophos, phorate, terbufos, and WL 24073 {0‐ [2‐chloro‐1‐(2,5‐dichloro‐phenyl) vinyl] 0‐methylethylphosphonothioate} on microbial populations and activities in a sandy loam. A stimulatory effect on bacterial numbers was observed with some insecticide treatments in the early stages of incubation. WL 24073 increased the nitrification of the incorporated (NH₄)₂SO₄‐N. Phorate stimulated soil microbial respiration.     

Evaluation of nitrification inhibitors for use under tropical conditions

Abstract

Six simple chemical compounds were evaluated for inhibition of nitrification. The compounds of o‐nitroaniline, m‐nitroaniline, o‐nitrophenol, benzotriazole, and 2,4,6‐trinitrophenol were compared with dicyandiamide by adding 10 μg inhibitor/g of a sandy loam soil, incubating for 30 days at 30°C and analyzing for NH⁺ ₄, NO^‐ ₂, and NO^‐ ₃ formation. The results indicated that benzotriazole, o‐nitrophenol, and m‐nitroaniline were very effective nitrification inhibitors.     

The application of fluorescence detection to the determination and speciation of aluminium in soil solutions by ion chromatography

Abstract

The determination and speciation of aluminium in soil solutions and extracts by ion chromatography with post‐column reaction and fluorescence detection is described. The fluorogenic post‐column reagent consists of 4 x 10^‐3 M 8‐hydroxyquinoline‐5‐sulfonic acid and 2 x 10^‐3 M cetyltrimethylammonium bromide in a 1 M acetate buffer at pH 4.4. The method is applicable to soil solutions and extracts and is more sensitive than existing colorimetric methods. Aluminium species could be detected at concentrations of 35 nM. Nine metals were checked for interference; only Zn²+ and Cd²+ were found to give responses, which were however well separated from the Al³⁺ peak.     

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.     

Buchbesprechung

Erich Rübensam

“70 jahre forschung müncheberg/mark vom kaiser‐wilhelm‐institut für züchtungsforschung zum institut für acker‐ und planzenbau 1928–1968”;

ISBN 3–930842–49–1 Buchverlag GmBH Frankfurt Oder Editionen.

200 Seiten. 15518 Eggersdorf—10405 Berlin—1998     

Iron oxide as an iron source in potting‐soil mixtures

Abstract

A commercial product of Fe oxide‐metallic Fe at rates of 2 and 10 pounds per cubic yard (1.2 and 6 kg per cubic meter) in soil‐sawdust and soil‐bark mixtures was useful when Fe‐inefficient plants were grown in containers. A high Zn level in the Ys₁/Ys₁ Fe inefficient corn inbred (Zea mays L.) was associated with low Fe status. High Fe levels seemed to suppress Cd uptake.     

An evaluation of some manual colorimetric methods for the determination of inorganic nitrogen in soil extracts

Abstract

A number of manual colorimetric methods for the determination of inorganic nitrogen in 1 M KCl soil extracts were investigated to find techniques that were inexpensive, rapid, versatile and suitable for laboratories with limited analytical equipment. Three colorimetric methods for No^? ₃‐N determination were evaluated and only the copperised/cadmium reduction technique suffered no significant interference from the Cl^? present in the extracting solution. A phenol‐hypo‐chlorite (Berthelot) procedure for NH⁺ ₄‐N determination and the Griess‐Ilosvay method for NO^? ₂‐N determination were both found suitable for N determination in 1M KC1 soil extracts. The reliability and accuracy obtainable with the manual colorimetric methods described was shown to be comparable with that obtained from colorimetric analyses performed using an AutoAnalyser.     

Concentrations of total nitrogen in squash,cucumber and melon in relation to growth,and to a piper‐steenbjerg effect

Abstract

Squash (Cucurbita pepo), cucumber (Cucranis sativus), and sweet melon (Cucumis dudain) were grown in sand cultures with N supply concentrations as the variable. For several reasons, total‐N values were found to be less satisfactory than NO ‐N for the purpose of determining the critical nitrogen concentration for maximum growth. Concentrations of total‐N in mature petioles were higher in plants severely deficient in N than in less deficient plants, characteristic of a Piper‐Steenbjerg effect.     

Boron toxicity of strawberry

Abstract

Radlands Crimson strawberries were grown in a glasshouse with 7 rates of applied boron. Wood shavings mulches with different boron concentrations were also applied as separate treatments. Boron toxicity symptoms were produced in leaves by boron rates of 0.32 kg ha^‐1 and greater on a soil containing 1.6 ug B g^‐1 of hot water extractable boron. Concentrations greater than 123 μg B g^‐1 in old leaves were associated with boron toxicity symptoms.

In the B rate experiment, soil boron concentrations greater than 1.9 μg B g^‐1 soil were associated with leaf toxicity symptoms which increased in severity with increasing soil boron concentrations up to 4.1 μg B g^‐1 soil. Wood shavings mulch containing 17 μg B g^‐1 caused boron toxicity symptoms in older leaves whereas mulches containing less than 6 μg B g^‐1 did not produce toxicity symptoms.     

Estimating total Pb,Cd, and Zn in contaminated soils from NH4HCO3‐DTPA‐extractable levels

Abstract

Twenty‐six garden soils from Aspen, Colorado, contaminated with old silver mine dumps, were extracted with diethylenetriamine pentaacetic acid (DTPA) and NH₄HCO₃‐DTPA (AB‐DTPA). Total soil digests (HNO₃‐HClO₄‐HF) were carried out on 21 highly contaminated soils. All soil extracts and digests were analyzed for Pb, Cd, and Zn using inductively‐coupled plasma atomic emission spectrometry (ICPS). Linear regression equations for DTPA versus AB‐DTPA values gave 0.96, 0.99 and 0.99 “r”; values for Pb, Cd, and Zn, respectively. Linear regression equations for total Pb, Cd, and Zn levels versus their respective AB‐DTPA extractable levels were developed with “r”; values of 0.92, 0.93, and 0.89, respectively. It was concluded that AB‐DTPA test can be used to screen soils contaminated with the above‐mentioned elements.     

The effect of soil ph on the activity of oryzalin and metribuzin on five common weeds in no‐till crop production

Abstract

Metribuzin [4‐amino‐6‐tert‐buty1–3‐(methylthio)‐as‐triazine‐5(4H)‐one] and oryzalin (3,5‐dinitro‐N ⁴ N ⁴‐dipropylsufanilamide) at two rates each were applied to pots of Cecil sandy loam soil adjusted to pH levels of 5.8, 6.2, 6.8, and 7.2 containing five weed species. Redroot pigweed (Amaranthus retroflexus L.) and large crabgrass [Digitaria sanguinalis (L.) Scop.] were completely controlled by both herbicides at all rates and all pH levels. Sicklepod (Cassia obtusifolia L.) was controlled by metribuzin, but not completely, by oryzalin. Jimsonweed (Datura stramonium L.) and tall morningglory [Ipomoea purpurea (L.) Roth] were not controlled by either herbicide. Soil pH had no effect on jimsonweed control with either herbicide. Morningglory was best controlled by both herbicides at higher soil pH.     

Improved SMP buffer method for determining lime requirements of acid soils

Abstract

Single buffer‐two pH and two‐buffer adaptations were compared as double buffer features of the SMP method using a group of 54 soils of wide range in lime requirement (LR). Data from both methods were highly correlated both with each other and with Ca(OH)₂‐titrated acidity.

Formulas for LR based on the schematics of similar triangles relating differences in measured pH vs corresponding acidities for the double buffer system were developed. A regression equation relating buffer‐indicated LR and Ca(OH)₂ titrated acidity was used to adjust the quick‐test double buffer‐indicated values to levels nearer the actual ones. A recommended SMP double buffer procedure, and a formula for computing LR from soil‐buffer pH's measured by the double buffer, quick‐test method are presented.     

Clay fraction determinations with a beta‐ray gauge

Abstract

Comparative measurements of the clay fraction of soils were made with a beta‐ray gauge system, a density meter, and a hydrometer. Reliable clay fraction determinations could be made by a beta‐ray gauge, and a density meter in less than 25 minutes of sedimentation. The beta‐ray gauge measured clay fractions were not affected by surface tension which was the possible cause for variable results obtained with the gamma‐ray attenuation technique.     

The growth of tagestes erecta,petunia hybrida nana compacta and myosotis alpestris in a range of peat‐based container media

Abstract

The dry matter yield and nitrogen content of marigold (Tagestes erecta), petunia (Petunia hybrida nana compacta) and forget‐me‐not (Myosotis alpestris) plants growing in a range of peat‐based container media amended with different proportions of either sand, perlite, pumice, sawdust, bark chips or soil were studied under glasshouse nursery conditions.

Plant responses differed between species as manifested by their different correlations with measured moisture and aeration characteristics of the media. Marigold and petunia were adversely affected by excessive moisture content as demonstrated by their negative correlation with micropore water and container capacity. However, forget‐me‐not, being adapted to relatively high moisture regimes, responded adversely to increased aeration.     

Evaluation of soil sulfate extractants and methods of analysis for plant available sulfur

Abstract

A steady decline in sulfur additions to Atlantic Canadian soils has prompted the need for an accurate method of determining their plant available sulfur status. Three soils were extracted with five soil extractants ‐ 0.01M Ca(H2PO₄)₂‐H₂O in 2M HOAc, 0.1M CaCl₂, Bray‐1 and de‐ionized water. The soil extracts were analyzed for sulfur or sulfate using inductively coupled argon plasma emission spectrometry (ICAP), AutoAnalyzer (AAN), anion exchange‐high performance liquid chromatography (HPLC‐CD) or atomic absorption spectroscopy (AAS). Results were compared with plant response of sulfur treatments to red clover, ryegrass, canola and wheat in a growth room. Instrument reproducibility and crop response indicated the ideal method of determining plant available soil sulfur was HPLC‐CD using the extractant Ca(H2PO₄)₂‐H₂O.     

Sulphur fertilizer effect on cotton: I. Nitrogen and sulphur status and petiole nitrate‐nitrogen

Abstract

The effect of S fertilization on S and N status and petiole NO₃ ^?‐N in cotton was observed during the growing seasons of 1980 and 1981. Four sites representing 2 soil subgroups were studied using a randomized complete block design with 4 replications. Leaf and petiole sampling began one week prior to bloom initiation and continued weekly for eight weeks. Leaf samples were analyzed for S and N and the petioles for NO₃ ^?‐N. Levels of leaf‐S varied directly with amounts of applied S. Leaf‐N and petiole NO₃ ^?‐N varied directly with amounts of applied N. Though not always significant, petiole NO₃ ^?‐N and leaf‐N showed negative correlations with leaf‐S. These results suggest that knowledge of the cotton plant S status may be necessary to interpret petiole NO₃ ^?‐N for N fertilization of cotton.     

Activity,Adsorption, and Lixiviation of Acetochlor in Soil under No Tillage and Conventional Tillage: Influence of Straw Coverage

Abstract

The activity of residual herbicides employed for weed control varies with adsorption, lixiviation, degradation, and biological transformation of these compounds in the soil. The purpose of this study was to evaluate the activity of the herbicide acetochlor (2‐chloro‐N‐ethoxymethyl‐6′‐ethylacet‐o‐toluidine) in Typic Paleodult under no tillage and conventional tillage. Field and laboratory experiments were carried out at the Universidade Federal do Rio Grande do Sul. Weed control with and without straw coverage, and adsorption and lixiviation of acetochlor, in soil with both tillage systems were evaluated. Adsorption and lixiviation processes were determined by high‐performance liquid chromatography (HPLC) with UV detector. The coefficients K _d and K _oc were higher in no‐tillage soil, indicating a more effective acetochlor adsorption. The maximum concentration of acetochlor was found in a depth of 15–20 cm, indicating a higher lixiviation in this soil. The acetochlor was more effective in weed control using conventional tillage when compared to no tillage. The straw coverage reduced the control efficiency of the herbicide.     

The rapid determination of nitrate at low concentrations in soil extracts: Comparison of ion‐selective electrode with continuous‐flow analysis

Abstract

The efficiency of extraction of nitrate with saturated CaSCO₄ solution and with IM KCl was compared for a range of field‐moist and air‐dried soils. Saturated CaSO₄ was as effective for moist soils and slightly more effective for dried ones, and removed 95% of the nitrate after shaking for 5 min. Three methods of nitrate analysis using an ion‐selective electrode were compared with continuous‐flow analysis (CFA). All gave good correlations with CFA but only one, a “known addition” method, gave results which agreed quantitatively. This method could be applied at nitrate‐N concentrations at least as low as 0.5 mg kg^‐1.