摘要:

A FORTRAN computer program was written to select the norms and coefficients of variation (CV) for DRIS. The program splits the population into a high and low yielding subpopulation and then calculates the mean, variance and standard deviation for each element and form of expression (ratio and product of each element to all others). Based on the significance of the variance ratio (low yield/high yield), one then selects the form of expression which has the highest variance ratio and uses the corresponding high yield means and CV's as the norms from which DRIS indices are calculated.

ISSN:0010-3624    

DOI:10.1080/00103628509367609

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Previous research suggests that calcium (Ca) can increase monovalent cation uptake and that Ca added to calcareous soils may improve plant growth irrespective of ammonia volatilization suppression. A greenhouse study was conducted to determine the influence of added Ca on growth and ammonium uptake by corn (Zea maysL.). Soils used were an acidic Bowie fine sandy loam (Fragic Paleudult) and a calcareous Weswood silt loam (Fluventic Ustochrept). Nitrogen (N) (0,56, 112 mg N/kg soil) and calcium (0, 42, 84 mg Ca/kg soil) were applied in factorial design, with the total amount applied split into 9 weekly applications. Corn was grown for 9 weeks following emergence. Growth parameters measured were plant height, leaf area, dry matter yields of roots and shoots, and shoot nitrogen and calcium concentrations. Total shoot content of these elements was computed by multiplying shoot concentration by shoot dry weight.

ISSN:0010-3624    

DOI:10.1080/00103628509367610

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A greenhouse experiment was conducted on clay loam soil of pH 7.8 to evaluate the effect of P, N fertilization and foliar applied Mn on yield and nutrient concentration in leaves and seeds of soybean. A significant yield increase was obtained for each added increment of P fertilizer up to 30 kg P2O5/acre. At application rates of 0, 15, 30 & 45 kg P2O5/acre, the seed yield was subsequently 27.8, 65.8, 82.8 & 83.6% of the maximum yield obtained at the maximum calculated P level. The yield increase accounted 14.2 and 10.2% for N and Mn applications. In all treatments, in which P was combined with N, the seed yield was relatively higher than with P or N applied alone.

ISSN:0010-3624    

DOI:10.1080/00103628509367611

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The effect of varying cutting frequencies on the yield of hardy and nonhardy alfalfa (Medicago sativaL. ) and red clover (Trifolium pratenseL.) cultivars and subsequent oat (Avena sativaL. ) production was studied. Analysis for nitrogen (N) in the oat crop provided an indirect measurement of residual N fixed by the preceding legume crop. Red clover produced the greatest yield and supported the greatest oat yield. Red clover and nonhardy alfalfa growth resulted in the greatest residual N (oat yield x N concentration). Highly significant linear responses between cutting frequency and residual N were found for hardy alfalfa and red clover, while no relationship was evident for nonhardy alfalfa. The data suggest that nonhardy alfalfa and new cultivars of red clover have the capacity to supply more N than hardy alfalfa.

ISSN:0010-3624    

DOI:10.1080/00103628509367612

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

This study was undertaken to determine the effect of previous water and acid‐washing soil treatment on soil pH, Delta pH and Zero Point of Charge of soil surface samples of three Hawaii soils, Molokai (Typic Torrox), Wahiawa (Tropeptic Eutrustox), and Hilo (Typic Hydrandept).

ISSN:0010-3624    

DOI:10.1080/00103628509367613

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Urea fertilisers are often applied to soil with cereal residues on the surface. Although the urease properties of soils have been investigated, the urease activities associated with cereal residues have not been thoroughly studied. Two experiments were performed to develop an acceptable urease assay for cereal residues, and to determine the effect of field exposure and concomitant saprophytic colonization on urease levels.

ISSN:0010-3624    

DOI:10.1080/00103628509367614

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Sulfur, zinc, iron, copper, manganese, and boron application did not affect the seed yield or oil percentage of sunflower (Hilianthus annuusL.) on both dryland and irrigated soils in North Dakota in 1981. Field averages indicated significant Zn, Mn, and B uptake by sunflower at the 12‐leaf stage as a result of fertilization with these elements. Increased Zn uptake was also observed in the uppermost mature leaf at anthesis from zinc fertilization.

ISSN:0010-3624    

DOI:10.1080/00103628509367615

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Surface applied lime and fertilizer normally move slowly through soils and are only beneficial in the immediate zone of application. One means for correcting subsurface acidity and potentially enhancing deeper root development is plowsole application of lime, but limited information is available on movement of lime and fertilizer placed in the plowsole. In 1980 dolomitic limestone in combination with varying levels of P and K were applied in the plowsole at a depth of 30 cm, to a Tatum clay loam (Typic Hapludult, clayey, mixed, thermic). In 1982 soil samples were collected from the Ap (0 to 5 cm), the plowsole depth (30 cm), 5 and 10 cm above and below the plowsole and at the 45 and 100 cm depths and analyzed for pH, exchangeable Al, Ca, Mg, K, and extractable P. Soils that did not receive lime had lower pH and increased Al concentrations compared to lime treated plots. Plowsole placement of lime increased pH and decreased Al, particularly at the 25 to 35 cm depth. Calcium and Mg applied in the plowsole from dolomitic limestone were present in high concentrations in the plowsole layer with little indication of leaching through the soil. Elevated levels of exchangeable Ca and Mg were present in the top 10 cm of the soil profile as a result of surface application of lime. The plowsole‐applied K movement was discernible throughout the 20 to 50 cm soil zone. Part of the surface‐applied P had moved to the 30 cm depth, while the plowsole‐applied P remained in place. The data reported in this paper shows that plowsole application of lime does alleviate subsoil acidity and that there is little movement of fertilizer constituents from the zone of application.

ISSN:0010-3624    

DOI:10.1080/00103628509367616

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628509367608

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor