摘要:

The Langmuir parameters of orthophosphate (OP) and pyrophosphate (PP) sorption for the ammoniated tropical soils were determined. Positive linear relationships between OP and PP sorption maxima and amounts of anhydrous NH3added were noticed. Indexes of bonding energy of OP and PP increased exponentially as ammoniation level of the soils increased from 33 to 100% of ammonia retention capacity.

ISSN:0010-3624    

DOI:10.1080/00103627909366913

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Quantitative distribution of15N in artificially and naturally enriched field‐growing legume‐based pastures are presented and compared. The results are discussed in terms of the assumption of the15N‐dilution technique as a means of measuring symbiotic nitrogen fixation under field conditions.

ISSN:0010-3624    

DOI:10.1080/00103627909366914

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Nitrate (20 mg N03‐ N l−1) was leached through 180 cm columns of oxisol subsoil until the leachate attained the initial nitrate concentration. Leaching was continued with water until no nitrate was detectable in the leachate.

ISSN:0010-3624    

DOI:10.1080/00103627909366915

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

This study was conducted to ascertain further the need for P and K fertilizers to obtain maximum herbage yields from alfalfa (Medicago sativaL.). Vernal alfalfa was established on a low K Piano silt loam (Typic Argiudoll) soil and topdressed with zero, 22.4, and 44.8 kg/ha of P in autumn of seeding year and with zero, 224, and 672 kg/ha of K as KC1 each autumn. The harvest schedule was three cuts annually at first flower; a schedule widely recommended in the North Lake states. No statistical significance was found for P levels nor for the P x K interaction; significance was found only for K levels. Maximum herbage yield was obtained with 224 kg/ha of K in the first harvest year, but with the 672 kg/ha of K rate in the second harvest year. Herbage K and Cl percentages and amounts removed from the soil increased significantly each year with each increase in K applied. Herbage P and N percentages were decreased significantly with the first increment of K. Residual herbage yields showed dramatically the influence of K fertilization on winter survival. All alfalfa stands with no K fertilization were killed completely. Residual yields and stands increased with each increase in K applied. Yield increase over the control was significant only with the second increment of K, while stands increased significantly with each increase in K applied. These data continue to confirm that high levels of soil K are needed for stand survival as well as for high herbage yields.

ISSN:0010-3624    

DOI:10.1080/00103627909366916

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Wet soil conditions prompted improper drying of soil samples prior to shipment for analyses. Various methods and temperatures were involved in field drying such samples. We accepted that changes in analysis could occur as drying temperatures were elevated. An experiment was run to determine the changes and the magnitude of the changes. An acid Brookston silty clay loam soil was used. P, SO4‐S, Mn and soluble salts can be greatly effected by drying temperatures. Buffer pH, pH, Ca, Mg, Cu and K are slightly effected. OM, Zn, and B are little effected. If samples need drying before shipping, only partial air drying should be employed. Reiteration of basic sample handling methods is needed.

ISSN:0010-3624    

DOI:10.1080/00103627909366917

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Nitrogen applications affected plant growth characteristics, color, nutrient content of leaves and yield of chili peppers as shown by results in this two‐year study. Moderate rates of N (100–150 kg/ha) tended to produce a more desirable type of plant and highest yields. Phosphorus treatments did not affect yields under these conditions.

ISSN:0010-3624    

DOI:10.1080/00103627909366918

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Legumes and grasses are widely grown in mixtures throughout the United States and Canada. This study was conducted to determine the changes in chemical composition of herbage that occur as proportion of legume and grass change in the mixture. Composition of mixtures of alfalfa (Medicago sativaL.) and orchardgrass (Dactylis glomerataL.) were studied after their herbage had been mixed by weight into seven different proportions: 100% alfalfa ‐ 0% orchardgrass, 80% ‐ 20%, 65% ‐ 35%, 50% ‐ 50%, 35% ‐ 65%, 20% ‐ 80%, and 0% ‐ 100%, respectively. The forages were grown in rows of pure alfalfa or pure orchardgrass spaced 45 cm apart on fertilized Dodge silt loam (Typic Hapludalf). Alfalfa was at late bud and orchardgrass was a few days from the appearance of the first anthers when harvested on May 29, 1975. Four replications of each of the mixtures were prepared, and the mixtures were made after tissues had been ground to 40‐mesh size.

ISSN:0010-3624    

DOI:10.1080/00103627909366919

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

One to two foliar applications of NPKS solutions enhanced yields from 10–40% when applied to pot grown bean plants (Phaseolus vulgaris, var. Bulgarian) during the seed filling period. Further spray applications had progressively more negative effects on yields. Addition of calcium ions or cytokinin to the spray treatments did not give further yield increases. Addition of an organo‐silicone surfactant (L77) to the spray solution gave higher yield increases than those obtained by adding a carbohydrate based surfactant (Tween 80). Percent N P and K contents of the bean seeds were inversely related to yields suggesting that the rate of supply of these minerals to the seeds was not limiting production; the results support the idea that leaf integrity was one of the main factors affected by late season N P K S sprays, and that this in turn affected yields.

ISSN:0010-3624    

DOI:10.1080/00103627909366920

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Certain concepts regarding the simultaneous transport of surface ‐salts and water under transient unsaturated flow conditions vere verified for three soils using laboratory soil columns. Treatments included different water application rates (i.e., continuous ponding and controlled rates) and different initial soil water contents. Calcium chloride, spread on the soil surface to simulate a salt‐affected soil or broadcasting of a fertilizer (or other additive), was leached with chloride free water (0.01 N CaSO4). Salt and water profiles were determined by destructive sampling at 2 cm depth intervals at two stages: (i) immediately following infiltration and (ii) after Batching infiltration plus redistribution time.

ISSN:0010-3624    

DOI:10.1080/00103627909366921

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

To determine the effect of incubation on DTPA‐extractable Fe, Zn, and Cu in soils with a wide pH range (4.2 ‐ 9.4) and to determine the nature of this effect, soils were incubated at field moisture capacity for 1 week with and without a sterilant (toluene). After incubation these soils as well as their air‐dry counterparts were analyzed for DTPA‐extractable Fe, Zn, and Cu.

ISSN:0010-3624    

DOI:10.1080/00103627909366922

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor