摘要:

In an attempt to develop an improved extractant for the soil test evaluation of plant available nutrients the influence of fluoride, sulfate and acidity on extractable P and Ca was investigated with 12 taxonomically different soils, (sequentially fractionated for Ca, Al, and Fe forms of phosphorus). The soils were extracted with 0.025, 0.05, 0.075 and 0.1N HCl alone and in combination with 0.0, 0.005, 0.01, 0.02 and 0.03N NH4F and in part in the presence of 0.025N (NH4)2SO4or 0.025N H2SO4. A 1:10 soil: solution ratio with 5 minutes shaking at 200 reciprocations per minute was used for extraction. In Ultisols where Fe‐P was predominant, extractable P increased with increasing concentrations of NH4F and increased further in the presence of sulfate, while in one Ultisol and one Terric Medisaprist where Al‐P was predominant, extractable P increased with increasing concentrations of NH4F but with no further increases due to sulfate. Where Ca‐P was predominant (Alfisol, Inceptisol, Mollisols, Typic Medisaprist) extractable P increased greatly with increasing concentrations of acid, whereas NH4F had either little influence or decreased ex‐tractable P above 0.01N NH4F, particularly above 0.05N HCl. Extractable Ca, Mg and K increased with increasing concentrations of acid while NH4F had little influence on extractable K, decreased Mg slightly and greatly reduced extractable Ca due to precipitation as CaF2. Soil factors influencing formation of CaF2were largely related to pH and concentration of Ca in solution.

ISSN:0010-3624    

DOI:10.1080/00103627809366823

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The objective of this investigation was to evaluate a new soil test extractant which would allow simultaneous extraction of several plant nutrients over a wide range of soil properties and eliminate the present need for grouping of soils. The new extractant is composed of 0.2N NH4Cl‐0.2N HOAc‐0.015N NH4F‐0.012N HCl at approximately pH 2.5. It was compared to Bray 1 (0.025N HCl‐0.03N NH4F), Olsen (0.5M NaHCO3, pH 8.5), DA (0.05N HC1–0.025N H2SO4), 0.075N HCl and DAP (DA + 0.008N NH4F) for extractable P. The uptake of P by millet grown in the greenhouse on six taxonomically different Ultisols at two rates of lime and six levels of P was correlated with the chemically extractable P. In addition, K, Mg, Ca, Na, Mn and Zn extracted by the new method from 122 acid to calcareous soils from the U.S. and Jamaica were compared to those extracted by DA, while K, Mg, Ca and Na extracted by the new method were also compared to those extracted by neutral, normal ammonium acetate. The ratio of extractable P by 0.075N HCl/DAF was used to classify soils into groups of < 0.34, 0.34 ‐ 0.66 and > 0.66.

ISSN:0010-3624    

DOI:10.1080/00103627809366824

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The initial effectiveness of two rock phosphate samples from Morocco (MRP) and North Carolina (NCRP) was compared with concentrated superhposphate (CSP) in greenhouse using two Alfisols and one Ultisol from southern Nigeria.

ISSN:0010-3624    

DOI:10.1080/00103627809366825

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Two cultivars of cotton (Gossypiumspp) were grown in solution culture in a glasshouse to determine phytotoxicity effects of excesses of Cu, Zn, Co and Mn. Leaf yields of Acala SJ‐2 were depressed 76% by 10‐4MCuSO4, 86% by 5×10‐4MZnSO4, 82% by 10‐4MCoSO4, and 20% by 10‐3MMnSO4. Leaf concentrations associated with these depressions were (μg/g) 110 Cu, 198 Zn, 180 Co, and 5470 Mn respectively. Plants were tolerant of inμg/g of about 15 Cu, 106 Zn, 69 Co, and 1830 Mn. Leaf yields of Giza 70 were depressed 91% by 10‐4MCuSO4, 88% by 5×10‐4MZnSO4, 87% by 10‐4MCoSO4, and 68% by 10‐3MMnSO4. This cv. was less tolerant of Mn than was Acala SJ‐2. Leaf metal concentrations at these application rates were (μg/g) 65 Cu, 243 Zn, 255 Co, and 6550 Mn respectively. In general roots were higher in these four metals than stems and leaves. There was no strong gradient from stems to leaves. Many nutrient interactions were observed as result of excesses of the four trace metals.

ISSN:0010-3624    

DOI:10.1080/00103627809366826

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Two cultivars of cotton (Gossypiumspp.) were grown in Yolo loam soil (soil pH about 6) in pots in a glasshouse to determine phytotoxic effects of excesses of Cu, Zn, Co, and Mn. Leaf yields of cv. Acala SJ‐2 were depressed 35% by 400μg Cu/g soil, 54% by 400μgZn/g soil, 98% by 400μg Co/g soil, and 84% by 2000μg Mn/g soil. Leaf metal concentrations at these application levels inμg/gleaf were 12.0 Cu, 520 Zn, 243 Co, and 14780 Ma, respectively. Plants were tolerant of in / dry leaves of 10 Cu, 157 Zn and 444 Mn. The concentration for Co could not be ascertained. Leaf yields of cv. Giza 70 were depressed 53% by 400μg Cu/g soil, 25% by 400μg Zn/g soil, 92% by 400μg Co/g soil and 90% by 2000μg Mn/g soil. This cv. was more tolerant of Zn than Acala SJ‐2. Leaf metal concentrations at these application levels inμg/g leaf were 11.8 Cu, 312 Zn, 224 Co, and 18300 Mn respectively. Gradients of these four elements existed from leaves to stems. Many interactions with other elements were observed.

ISSN:0010-3624    

DOI:10.1080/00103627809366827

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The mineralization potential of forest soils is a useful tool in predicting nitrogen fertilizer response in unthinned stands of Douglas‐fir. As the mineralization potential of the soil increased, diameter growth for 200 lbs/A of added N decreased. Significant growth response could not be detected when mineralizable nitrogen level was above 46 ppm.

ISSN:0010-3624    

DOI:10.1080/00103627809366828

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Soil solution P level is believed to be important in determining P uptake rates from soil. The objective of this research was to investigate the relation between initial P concentration in the soil solution and P flux into the root. Millet (Panicum milaceum) was grown on five soils each of which was adjusted to six Clilevels by addition of P. Millet was also grown in solution culture and P influx vs. P concentration in solution measured. There was a curvilinear relation between P influx and relative yield of the Clilevels on each soil (R2=0.74). A P influx of at least 16 pmoles cm‐1sec‐1was needed to obtain 90% of maximum yield. However, yield response was not correlated with Cli, indicating Cliwas not a suitable indicator of P availability on these soils. Influx of P on soils with Cliless than 6 μMwas greater than occurred at similar P concentrations in solution culture indicating P influx was increased by the effect of the root on the soil.

ISSN:0010-3624    

DOI:10.1080/00103627809366829

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103627809366822

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor