摘要:

Resin extractable Mo explained 72% of the variation in yield of wheat (Triticum aestivum) grown on ten acid soils as measured by the relative yield of the tops or by the uptake of Mo by the youngest emerged blade.

ISSN:0010-3624    

DOI:10.1080/00103628809367955

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Boron sorption experiments were conducted on 12 Hawaiian soils, which differed remarkably in mineralogy, pH, and organic matter content. Results indicated that soils derived from volcanic ash sorbed much more B than those from basalt or alluvium. High B sorption was attributed to great quantities of X‐ray amorphous alumino silicates and high organic matter contents that are characteristic of volcanic ash soils. Increased soil pH resulting from liming also increased B sorption.

ISSN:0010-3624    

DOI:10.1080/00103628809367956

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Nitrogen applications to dallisgrass grown on Olivier silt loam, an Aquic Fragiudalf, increased forage yield, forage digestibility, nutrient concentrations and nutrient contents as N rates increased to 896 kg ha‐1. Expressing yield as a function of N application rate resulted in quadratic prediction equations that accounted for 75 to 98% of the variability in yield during five years. Eighty‐six percent of the maximum yield was obtained during the five years at 448 kg of N ha‐1. Plant concentrations of N, Ca and Mg were increased more than concentrations of the other macronutrients as N rates increased. Plant contents of N, Ca and Mg in the forage increased 4.0, 3.2 and 3.5‐fold as N rates increased to 448 kg ha‐1, while that of P, K and S increased 2.5 to 2.8‐fold. Residual N accumulations in the soil profile were apparent at the 896 kg ha‐1rate at the end of the growing seasons but were not detected the following March, indicating N losses by leaching and/or denitrification occurred at that N rate. Phosphorus applications increased forage P concentrations but did not increase forage yield nor available P levels in the surface 15 cm of soil. Maximum yields were obtained at forage P concentrations and Bray No. 2 soil P levels as low as 2.0 g kg‐1and 17 mg kg‐1, respectively.

ISSN:0010-3624    

DOI:10.1080/00103628809367957

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Surface liming will prevent the formation of an ‘acid roof’ on the surface of soil cropped in no‐till corn (Zea mays L.). A study was begun in 1985 to determine the effectiveness of unincorporated liming in raising pH in no‐till soil which had developed significant acidity throughout the upper 15 cm. Lime was applied at 0, 3.36, 6.72 and 10.08 Mg ha‐1. All lime was applied on 26 April 1985 and was not incorporated. The pre‐liming pH at 0‐5 cm below the surface was 4.5; after two months the pH was raised to 5.6, 5.8, and 6.0 by 3.36, 6.72 and 10.08 Mg ha‐1of lime, respectively. After 19 months soil‐pH was raised to 6.0, 6.4 and 6.6 by liming at 3.36, 6.72 and 10.08 Mg ha‐1respectively. Soil‐pH below 5 cm was not affected by any rate of lime during the first 19 months after liming. Tissue analysis of corn ear leaves indicated that calcium uptake was increased significantly by lime in 1985, while manganese uptake was significantly reduced. In 1986, increases in calcium were greater than in 1985 and addtional significant reduction in manganese uptake was accompanied by significantly reduced zinc and copper uptake. In both 1985 and 1986, a trend toward lower average corn grain yield in unlimed plots than in limed plots was noted, but the yield increases due to lime were not statistically significant in either year. This study will be continued as a long term investigation of lime penetration into no‐till soil and response of corn to soil‐pH changes.

ISSN:0010-3624    

DOI:10.1080/00103628809367958

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The purpose of this study was to determine the practicality of generating plant tissue norms with analytical data from a few, extremely high‐yield observations. A set of ear leaf tissue norms for corn (Zea maysL.) were developed from a set of data consisting of 10 observations of field‐grown corn with yields greater than 18 Mg ha‐1. The norms thus generated were compared with norms generated from 8494 observations from a wide geographical area. Norms for several elements (P, K, Mg, S, Mn, and B) calculated from the two data bases were significantly different, while norms for the other nutrients (N, Ca, Fe, and Cu) were not. The norms generated from the limited data base were tested with data from an N3P3K3S3factorial greenhouse experiment. Results of this test indicate that the norms developed from the limited, high‐yield data base were slightly better at predicting yield increases than those from the broader worldwide data base. The increase in accuracy seemed to be largely due to lower S norms and higher P norms when derived from the smaller data base, resulting in less frequent determinations of S‐induced yield limitations. Using a few, extremely high‐yield observations appears to be an efficient, accurate, and relatively inexpensive means of generating plant tissue nutrient optima.

ISSN:0010-3624    

DOI:10.1080/00103628809367959

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Phosphorus extractants have not been tested extensively in the Southeast. An experiment was carried out to compare four P extractant methods using samples from a field P‐K factorial experiment with soybeans (Glycine max(L.) Merr.) at three locations in Georgia over four years. There were five P rates ranging from none to 80 kg ha‐1. Soils and plant tissue were sampled at mid‐summer and yields were recorded. The four P extractants compared were Olsen, Mehlich 1, Mehlich 2, and Bray 1. Quadratic regressions for soil P versus plant P and P rates were not significant compared to linear regressions. There were no significant yield responses to P. All extractants except Olsen were similar in their response to added fertilizer P as measured by linear r2values. Olsen P gave lower linear r2values both with P rate and with plant P. Mehlich 1 values were highly correlated with Mehlich 2 (0.94**) and Bray 1 (0.96**). Mehlich 2 and Bray 1 gave nearly the same soil P values with linear regressions of slope of 1.0 and low intercepts. Results from these experiments show that Mehlich 1, Mehlich 2, or Bray 1 could be used successfully on these soils, but that Olsen should be avoided.

ISSN:0010-3624    

DOI:10.1080/00103628809367960

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Rice grown on a recently water‐leveled Crowley silt loam that contained less than 1.8 μg g‐1of 0.1NHCl‐extractable Zn with pH levels ranging from 6.8 to 7.7, responded to Zn application. Each kg ha of applied Zn as Zn chelate, 14.2 % Zn, resulted in increases of +673, +477, and +2026 kg rice ha‐1at pH 6.8, 7.3, and 7.7, respectively. There was a critically low concentration of Zn in rice plants at the midtillering, first joint, and panicle differentiation stages of plant development when no Zn was applied. A yield response to applied Zn was obtained when the concentration of Zn in rice tissue was less than 15 μg g‐1.

ISSN:0010-3624    

DOI:10.1080/00103628809367961

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Several aqueous extractants buffered above pH 6.5 were evaluated for their ability to extract gibberellic acid from a Xerollic Calciorthid. More than 90% of the GA3added to soil was recovered with 0.01 M KH2PO4, pH 7.4. Gibberellic acid in soil extracts concentrated under vacuum was determined by reverse‐phase high‐pressure liquid chromatography (HPLC) by comparing the reproducible GA3peak areas with those of standards prepared in the same background solution.

ISSN:0010-3624    

DOI:10.1080/00103628809367962

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The effect of four consecutive years of tillage method [conventional tillage (CT) or no‐tillage (NT)] and fertilizer N rate (84, 168, 336 kg N·ha‐1·yr) on soil carbon, nitrogen and and gaseous profiles was examined in a Wharton‐Cookport (Aquic Hapludults‐Aquic Fragiudults) silt loam soil in West Virginia cropped to continuous maize (Zea maysL.). At midseason (July) of the last cropping year, soil mineral N profile differences were generally discernible only at the high N (336 kg·ha‐1) rate in the topsoil (0‐ to 30‐cm layer). Ammonium (NH4+‐N) levels at this time were significantly (p ≤ 0.05) higher under CT, while NO3‐‐N levels were the same under both tillage methods. However, after silage harvest in September NH4+‐N levels were the same under both tillage systems, while NO3‐‐N levels were significantly higher under CT. Although no significant (p ≥ 0.05) tillage effects were found for TC, the level was increased by ∼16% under NT in the surface soil (0 to 15‐cm) layer at the low N (84 kg·ha‐1) rate treatment. Total N (TN) was significantly (p ≤ 0.05) increased under NT compared to CT only in the soil surface layer at the high N rate treatment. Soils under both tillage methods after cropping appeared to be equally well aerated to the deepest layer (60 cm) as O2levels were near atmospheric concentrations, and no gases commonly associated with more anaerobic environments (CH4, C2H4) were detected. Carbon dioxide (CO2) levels increased 30‐ to 40‐times atmospheric levels in the deepest layers, and were generally higher under NT. The incidence of detectable N2O (‐0.36 × 10‐2μg·ml‐1) was two‐ to seven‐times more numerous at the high N rate, and twice as numerous under NT compared to CT. These results generally corroborate previous results for soil mineral N changes as related to tillage method, but not for organic C, N and microbial activity, as has usually been reported, especially for more arid region soils.

ISSN:0010-3624    

DOI:10.1080/00103628809367963

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628809367954

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor