摘要:

Inoculated soybeans (Glycine maxL. Merr. cv. Eragg) were grown in an intensively managed cabbage (Brassica oleraceaL. Capitata group)‐ sweetcorn (Zea maysL.) multiple‐cropping sequence on a tile‐drained Arenic Haplaquod having variable residual K levels. The study was conducted to assess the effect of residual and applied K on soybean K and N composition, nodulation, root growth, and pod formation. Sidedress treatments of 0 and 100 kg K/ha were applied at bloom to plots that received either 0 or 300 kg K/ha/acre that had been applied previously to other crops in the sequence. Treatments were arranged in a randomized complete block design witn six replications. Although leaf N conc, was uniform at bloom (R2), leaf N at pod‐fill (R6) ranged from 2.8 to 4.3% and wasquadratically related to leaf K (r2= 0.92). Without residual K fertilizer from cabbage and sweet corn applications sidedress application of K increased leaf and nodule K and N. Root K conc. was correlated with root dry wt. (r = 0.35) at bloom stage, and with root 10 dry wt. (r = 0.54), pod number (r = 0.43), and pod dry wt. (r = 0.39) at pod‐fill stage. Root K conc. was negatively correlated with nodule number (r = ‐0.34) and nodule dry wt. (r = ‐0.41). Sidedress‐applied K did not increase root growth and pod number whereas residual fertilizer K did. A curvilinear relationship between leaf K and N conc. and a linear relationship between leaf N and soybean yield indicated that K deficiency limited the capacity of the soybean plant to supply N to the developing grain during pod‐fill, and that this response was not due to inadequate nodulation.

ISSN:0010-3624    

DOI:10.1080/00103629009368137

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Pericarp, embryo and testae of mature squash fruits were analysed to determine whether or not 1) the fruits’ orientation to the ground had any influence on the concentration of minerals 2) different regions of the pericarp had an uneven distribution of minerals 3) there is a relationship between the mineral concentrations of seeds and nearby pericarp. Magnesium, K, Ca and P concentrations were determined by neutron activation analysis. Pericarp samples, taken from the stalk region or stigma region or placental region, were further divided into rind, middle, innermost and stringy or fuzzy samples. Seeds were separated into embryo, outer and inner testae samples. Results showed that the orientation of the fruit did not influence the concentration of the minerals in the samples. The stigma and stalk regions differed in their Ca and K concentrations in the middle and innermost samples. The placental mineral concentrations did not differ from the other regions. Potassium and Ca were more concentrated in pericarp samples than in embryo samples whereas P and Mg had the opposite relationship.

ISSN:0010-3624    

DOI:10.1080/00103629009368138

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A microassay for the measurement of sulfate sensitive to below 1 nmol is described. Accuracy and reproducibility were demonstrated with trichloroacetic acid clarified plant sample volumes of only 5 μl. The sensitivity of this assay enabled, for the first time, the measurement of sulfate in the medium of plant suspension cultures during its depletion down to the compensation point in a non‐disruptive manner. This was possible because very small volumes could be sampled from continuously growing cultures.

ISSN:0010-3624    

DOI:10.1080/00103629009368139

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Cox's orange Pippin apple fruit samples obtained over five years from trials in five commercial orchards on different soil types where management systems were changed from herbicide strips in grassed alleys to overall herbicide were analysed for N, P, K, Mg, Ca and, in the early years, Na. At four of the sites an additional amount of N fertiliser was applied to half of the trees. When the treatments became established they usually lowered P concentrations and these effects of overall herbicide management and additional N were additive. The years in which the maximum effects occurred and the magnitude of the effects varied with site. Calcium concentrations were lowered at only two sites in some years mainly because overall herbicide management increased mean fruit mass. Treatment effects on other constituents varied but, at one site, overall herbicide and extra N fertiliser consistently increased N concentrations.

ISSN:0010-3624    

DOI:10.1080/00103629009368140

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The measurement of NH4‐N in terrestrial and aquatic solutions by the commonly used automated indophenol‐blue method was compared to a new technique based on the conductimetric measurement of NH3. Average precision (2 times relative standard deviation) was 5.3% and 7.0% for the Ammonia‐Analyzer and Auto‐Analyzer, respectively. Average accuracy as determined from spike measurements was not statistically different between the Ammonia‐Analyzer (99.5%) and Auto‐Analyzer (96.2%). Although both methods predicted similar concentrations on the same sample set, the Ammonia‐Analyzer provides an alternative to NH4‐N measurement with fewer required reagents, and simpler instrumentation.

ISSN:0010-3624    

DOI:10.1080/00103629009368141

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Soybean (Glycine max(L.) Merrill) and fababean (Vicar faba(L.)) were grown under field conditions on six Orthic Black Chernozemic soils over three years at two levels of fertility. At flowering, full pod and maturity the yield and N, P, K and S composition of harvested plant materials were compared. Application of fertilizer (P, K and S) increased dry matter and seed yields of both crops. At all, growth stages fababeans produced more dry matter than soybean, and at maturity produced higher yields of seed, hull and stalk. However, the ratio of seed: hull: stalk for both crops was similar and constant at 3.8: 1: 4.7 on all soils and at both levels of soil fertility. At the high level of soil fertility, at the flowering and full pod stages, the concentration of N, P, and K in fababean was higher than that in soybean, but both crops had a similar concentration of S. At low fertility both crops had similar concentrations of P, K and S. At maturity, soybean seed had the higher concentrations of the four nutrients. The concentration of P in the hull and stalk of both crops was similar, but fababean hull had a higher concentration of K and soybean stalk a higher concentration of S. Soybean seed also had a higher protein content and yielded more protein per hectare than fababean seed.

ISSN:0010-3624    

DOI:10.1080/00103629009368142

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Flax plants were grown in growth chamber studies using 16 soils in two experiments to examine the effect of soil Ca, Mg, Zn, P, pH and conductance on flax yield and nutrient content and to identify which of these soil characteristics would be most useful in predicting the potential for Zn deficiencies in flax. Dry matter yield increased as Zn content of the soils increased and decreased as Mg content of the soil increased. Availability of P to flax increased with increasing Zn level in the soil and decreased with increasing soil Mg and pH. Availability of Zn to the plant increased as soil levels of Zn, P and the Zn/P ratio increased and decreased as soil Mg, pH and conductance increased. Deficiencies of Zn for flax production appear most likely to occur on soils that have a low Zn and Zn/P ratio and high levels of Mg, pH and conductance.

ISSN:0010-3624    

DOI:10.1080/00103629009368143

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Amorphous and crystalline aluminum and iron oxide minerals play a major role in stabilizing soil structure as measured by aggregate stability and clay dispersion. Aluminum and iron oxide interactions with clays are pH dependent. At low pH, where the oxides carry sufficient positive charge, they precipitate on clay surfaces. These coatings, once formed, are stable at higher pHs. Precipitation of oxides at high pH occurs as phases separate from the clays. Aluminum and iron oxides stabilize clay minerals by decreasing critical coagulation concentration, clay dispersion, water uptake, and clay swelling and by increasing microaggregation. The presence of aluminum and iron oxide minerals in soils has a favorable effect on soil physical properties, increasing aggregate stability, permeability, friability, porosity, and hydraulic conductivity, and reducing swelling, clay dispersion, bulk density, and modulus of rupture.

ISSN:0010-3624    

DOI:10.1080/00103629009368144

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Corn (Zea maysL.) grown on sandy Coastal Plain soils may be subject to sulfur (S) deficiency due to the low levels of available S in the soil. The diagnosis of S deficiency in the field is sometimes ambiguous since mineralization of soil organic matter or root growth into the subsoil may supply adequate S to the crop. Yield response to S fertilizers has been more frequent since incidental additions of S to the soil by air pollution and fertilizer applications have been reduced. This study was conducted to identify S deficiency in corn grown on sandy Coastal Plain soils and to determine the effects of S source, rate and method of application on grain yield. Irrigated corn was grown on Norfolk loamy sand and Tifton loamy sand near Leesburg and Moultrie, Georgia, respectively in 1987. Grain yields were increased with addition of 11 kg S ha‐1compared to the check treatment. Increased rates of S up to 88 kg ha‐1did not increase grain yields above the 11 kg ha‐1rate. There was no difference between banded or broadcast application of (NH4)2SO4or between elemental S and (NH4)2SO4as S sources. Earleaf S concentrations of 1.6 g kg‐1and extractable soil S concentrations of 4.0 to 8.7 mg kg‐1were associated with S deficiency. Visual symtoms of S deficiency were observed in the check treatments throughout the growing season at both experimental sites. The results indicate that visual symptoms and tissue analysis can be used to identify S deficiency. Extractable soil S may be useful in determining the possible response to S fertilizer especially if the subsoil is sampled.

ISSN:0010-3624    

DOI:10.1080/00103629009368145

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The effect of irrigation water of good quality on the salt and sodium content of some Halaquepts on the floodplain of the Platte River in Central Nebraska was determined. The study compared salts and sodium concentrations in A and B horizons of adjacent soils in 3 fields within a single delineation of a map unit. Land uses were long term irrigation, recent introduction to irrigation, and permanent pasture that had never been cultivated or irrigated. The presence of a salt crust on the surface of the field that had been irrigated for some time led the farm operator to believe that irrigation was increasing salt problems within the field. The objective of the study was to determine whether or not this was true. Salt content, sodium absorption ratio, and exchangeable sodium values were not greater in the irrigated field than in the permanent pasture. Salt contents of A horizons were the same in all fields, whereas B horizon salt content tended to be lower where both long and short term irrigation had been practiced. Sodium absorption ratios and exchangeable sodium percentages followed the same pattern as that of soluble salts. Irrigation with water of good quality appeared to be decreasing both salt and sodium content of these soils.

ISSN:0010-3624    

DOI:10.1080/00103629009368146

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor