摘要:

Arsenic (III) in soil digests can be quantitatively extracted with pyrrolidinedithiocarbamate into chloroform at pH 1. The organic bound arsenic in chloroform can be back‐extracted into a 25% nitric acid solution for instrumental analysis. For total arsenic determination, arsenic (V) in soil digests must be reduced to arsenic (III) by sodium thiosulfate prior to the extraction. The proposed extraction eliminates matrix interferences so that reliable data of arsenic in soil digests can be obtained using ICP‐AES (Inductively Coupled Plasma‐Atomic Emission Spectroscopy). The accuracy of the method has been tested by analyzing arsenic in two different standard reference materials.

ISSN:0010-3624    

DOI:10.1080/00103628609367702

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A long‐term P experiment is currently being conducted on a Typic Tropudult in Panama to study plant growth and yield response of a sequence of crops, with differential external P requirements, to initial applications of fertilizer P at rates of 0, 25, 50, 100 and 200 kg P/ha. The response of field beans (Phaseolus vulgarisL.). the first crop in this sequence, to P fertilization is reported in this paper.

ISSN:0010-3624    

DOI:10.1080/00103628609367703

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Limited information is available for the S requirements of higher yielding winter wheat (Triticum aestivumL.) crops grown in the eastern United States. Three experiments were conducted in the Coastal Plain region of Virginia on Kenansville loamy sand (loamy, siliceous, thermic Arenic Hapludult), Dothan loamy sand (fine‐loamy, siliceous, thermic Plinthic Paleudult), and Pactolus loamy sand (thermic, coated Aquic Quartzipsamment) soils. These three soils have low monocalcium phosphate‐acetic acid extractable SO4‐S (<3.1 kg/ha) and would be expected to be S deficient With respect to corn (Zea maysL). Winter wheat response to S application was investigated on the Kenansville and Dothan soils, while the N x S interaction was studied on the Pactolus soil. In the two studies where S was the dependent variable there was no significant change in concentration of the flag leaf at Feekes growth stage 10 for N, S, P, K, Ca, Mg, and N/S ratio. Also yields were not significantly influenced by S application and averaged 5.6 Mg/ha for the Kenansville and 4.3 Mg/ha for the Dothan soils. In the N x S interaction study, yield increased linearly with increased N application, and N and P tissue concentrations were increased with N application. These data indicate that S concentrations of 0.20% and a N/S ratio of 18 in the flag leaf at Feekes growth stage 10 is sufficient for high yields. The absence of S deficiency in these relatively high‐yielding experiments on coarse textured soils with low levels of extractable SO4‐S may be related to atmospheric accretions during much of the wheat growing season.

ISSN:0010-3624    

DOI:10.1080/00103628609367704

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A 2‐year nutrition experiment was conducted to determine the effects of sludge, bed, and genotype on lettuce growth and leaf elemental concentration levels. Three leaf lettuce cultivars (Lactuca sativacvs. Grand Rapids, Ruby, Salad Bowl) were grown in field plots of silt loam amended with 90 MT/ha/year of industrial or municipal sludge and a control with no sludge application. The 3 bed types used were a level or flat bed, a 15‐cm raised bed, and a 15‐cm raised bed of unamended topsoil over prepared flat bed (overcover bed). Sludge and bed type did influence yield and leaf elemental concentrations for all 3 cultivars. When significant differences occurred, the highest yields were with municipal sludge and raised beds and the highest leaf nutrient concentrations with the industrial sludge. Bed effects on leaf elemental concentrations were variable. ‘Grand Rapids’ had significantly lower leaf concentration levels for all elements (except P in 1982) when compared to either ‘Grand Rapids’ or ‘Salad Bowl’.

ISSN:0010-3624    

DOI:10.1080/00103628609367705

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Greenhouse‐grownLigustrum sinense‘Variegatum’ plants pruned after 4, 5, 6, or 7 weeks of growth had similar dry weights 4 weeks after each pruning time. The mg of N, P, and K removed in pruned shoot tips was minimized by pruning at the 4‐week pruning treatment. Delaying pruning each week resulted in an increase in the amount of N, P, and K removed and the ratio of mg of N, P, and K removed in shoot tips to N, P, and K accumulated by shoots for each pruning time.

ISSN:0010-3624    

DOI:10.1080/00103628609367706

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A method was developed for the simultaneous analysis of P, K, Cu, Cd, Zn, Fe, Mn and Pb in soils and sediments by inductively coupled plasma spectrometry (ICP) after digestion in nitric acid. The procedure extracted 82 to 94% of the totals of the heavy metals, 78% of total P and 34% of total K. Inter‐element interference correction data are given for the ICP method. The method gave results similar to those obtained by other analytical procedures. The precision of the method was satisfactory but was lowest for Cd which had the lowest concentrations (<2.7 mg/kg) of the elements determined.

ISSN:0010-3624    

DOI:10.1080/00103628609367707

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A simple chemical method of assessing potentially available organic N in soil is described. It involves determination of the ammonium‐N produced by treatment of the soil sample with 2MKCl at 100°C for 4 hours in a block digester. The method is rapid and precise, and its results are not significantly affected by air‐drying or air‐dry storage of the soil sample before analysis. It is well suited for routine use in soil testing laboratories because it does not require filtration or transfer steps. Studies using 33 Brazilian soils showed that the results obtained by this method were highly correlated with those obtained by aerobic and anaerobic incubation methods of assessing potentially available organic N in soil.

ISSN:0010-3624    

DOI:10.1080/00103628609367708

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

We recently developed two rapid and precise chemical methods of assessing potentially available organic N in soils. One method involves determination of the ammonia‐N produced by steam distillation of the soil sample with pH 11.2 phosphate‐borate buffer solution for 8 min. The other involves determination of the ammonium‐N produced by treatment of the soil sample with 2MKCl solution at 100°C for 4 hours. Studies using 33 Brazilian soils showed that the results obtained by these methods were highly correlated with those obtained by anaerobic and aerobic incubation methods of assessing potentially available organic N in soil.

ISSN:0010-3624    

DOI:10.1080/00103628609367709

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628609367701

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor