摘要:

In a greenhouse study on Morrison Sandy Loam an increase in yield, protein, percent lysine and methionine was observed in soybeans when 10 ppm and 20 ppm of sulfur were applied.

ISSN:0010-3624    

DOI:10.1080/00103627309366421

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Phosphorus sorption isotherms were constructed for two Idaho soils with widely different chemical properties. The soils were equilibrated with various amounts of Ca(H2PO4)2in 0.01 M CaCl2for 1, 3, 7, and 11 days at temperatures of 5°C and 20°C. The two soils which had been equilibrated previously for 11 days at 20°C with various amounts of Ca(H2PO4)2in 0.01 M CaCl2were desorbed at 5°C and 20°C.

ISSN:0010-3624    

DOI:10.1080/00103627309366422

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The iron content of tropical leaf vegetables was moderately increased by adding 1 ppm Fe to the nutrient solution for sand culture which corrected moderate Fe deficiencies and enhanced leaf yield. Substantial amounts of Fe accumulated in leaves of plants supplied with 3 ppm Fe in the nutrient solution. The Cu and Mn content of the leaves was slightly influenced by the Fe supply but varied greatly with species of plant. Species differences in Fe content were most apparent with 3 ppm Fe in the nutrient solution.

ISSN:0010-3624    

DOI:10.1080/00103627309366423

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Zinc of index corn leaves samples from 91 Minnesota sites on numerous soil types was correlated with soil Zn extracted by four routine procedures. The EDTA•(NH4)2CO3‐ extractable soil Zn was more closely correlated with leaf Zn than soil zinc extracted by 0.1N HCl, EDTA‐NH4OAc, or by NH4OAc ‐ dithizone. Soil pH, CaCO3equivalent, extractable P, and organic matter of both acid and calcareous soils were negatively correlated with leaf Zn. When EDTA • (NH4)2CO3‐ extractable Zn was included with routine soil tests, a prediction equation for corn leaf Zn was formulated and compared with analytical values. However, the use of 1.4 ppm EDTA • (NH3)2CO3, ‐ extractable soil Zn alone as a critical value was equally effective in predicting leaf Zn.

ISSN:0010-3624    

DOI:10.1080/00103627309366424

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Experiments were conducted to evaluate DTPA as an extractant of available soil Fe and to establish interpretive guides. A critical level of 6 ppm DTPA‐extractable soil Fe correctly predicted Fe deficiency of field grown plants at 11 of 13 locations. In a greenhouse experiment increased yields of sorghum from treatments that increased soil Fe availability were correctly predicted on 13 of 14 soils by a critical level of 5 ppm.

ISSN:0010-3624    

DOI:10.1080/00103627309366425

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Inherent complexity and instability of enzyme preparations make deceptively‐simple enzymic methods more vulnerable to error than methods using pure stable chemicals. Hence, four D‐amino acid oxidase (DAAO) preparations from three commercial sources were compared for enzymatic effectiveness. Per unit of claimed activity, the four DAAO enzyme preparations differed by <2 to >100 fold in apparent ability to oxidize “reactive”;14C‐D‐methionine and “unreactive”;14C‐D‐lysine in pure solution. The data illustrate how use of such differing preparations on less‐pure soil or plant extracts, which may contain unknown amounts of enzyme‐inhibiting or ‐inactivating components, would produce confounding results and permit erroneous conclusions. Implications are that users of commercially available DAAO preparations must acquire large enough lots of homogenous enzyme to establish effectiveness on the most resistant substrates of interest and still have enough for all experimental assays where direct relative comparisons are required.

ISSN:0010-3624    

DOI:10.1080/00103627309366426

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

A fertility index as used by the Auburn University Soil Testing Laboratory for P, K, Ca, and Mg is described. It is reported as percentage sufficiency and is the amount extracted by soil test expressed as a percentage of the amount shown by research to be adequate for maximum yield of cotton or legumes on the soil sampled. It is calculated and reported by the computer in multiples of 10 from 0 to 9990. The index below 100 follows the curvilinear relationship between soil‐test values and yield without addition of the element. The primary objectives of the index are to report all nutrients determined on a common basis that can be understood by growers, and to provide a quantitative result that can be used in keeping records of soil fertility build‐up or depletion.

ISSN:0010-3624    

DOI:10.1080/00103627309366427

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The relative growth rate of tops (RT) of Nandi setaria (Setaria ancepscv. Nandi), kikuyu (Pennisetum clandestinum). pangola (Digitaria decumbens) and Biloela buffel grass (Cenchrus ciliariscv. Biloela) in pot experiments was a curvilinear function of the % N in the blades of the youngest fully‐expanded leaves on vegetative tillers (leaf N). The mean RT's differed significantly between grasses, but the response curves did not deviate significantly from being parallel. The mean quadratic curve for vegetative growth of Nandi setaria predicted increasing RT as leaf 11 rises from below 1 to about 3%, and near‐maximum RT between 3 and 6% N.

ISSN:0010-3624    

DOI:10.1080/00103627309366428

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Variation in leaf nitrogen (N) concentration was studied in pot and field experiments with the tropical grasses Nandi setaria (Setaria ancepscv. Nandi) and Biloela buffel (Cenchrus ciliariscv. Biloela). The % N of samples of 20 leaf blades from grazed fields up to 2.7 ha in area had a relative standard deviation of less than 10%. The variation in leaf N (%) between different‐sized tillers on the same plants (tussocks) was statistically significant but relatively small. The results showed that accidental selection of the blade from the leaf one older or younger than the usual index leaf (the youngest with the ligule exposed) is unlikely to bias leaf N seriously.

ISSN:0010-3624    

DOI:10.1080/00103627309366429

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Lateral variation in soil N content was studied in five pastures to find the best method of sampling for precise estimates of changes in soil N content with time. Variation increased with sampling area up to, but not beyond, 1.2 ‐ 2.4 ha. Consequently, the most efficient method of sampling for changes in N content was to repeatedly sample a fixed set of small sites. An allocation of 1–3 cores per site was shown to be optimum. The number of cores needed to measure a change in N content in a field with a probability of 0.8 that the 0.95 confidence limits of the mean change would be within ± 50 kg N ha‐1ranged from 150 to 1000.

ISSN:0010-3624    

DOI:10.1080/00103627309366430

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor