摘要:

An experiment was conducted to help understand the contributions of different soil layers to soil fertility, plant growth, and response to fertilization. Douglas‐fir (Pseudotsuga menziesii) seedlings were used in a pot bioassay to delimit the effects of volcanic ash soils, urea fertilization at 100 and 200 ppm, and the technique of using undisturbed soil as a growth medium. Volcanic ash horizons contained more available phosphorus and mineralized more nitrogen than underlying horizons. Best seedling growth occurred in ash horizons fertilized with 200 ppm of urea‐N. Fertilization decreased soil pH, mycorrhizae formation and foliar‐P levels but increased foliar‐N. The technique of using undisturbed soil had little effect on seedling growth in the weak structured ash horizons but did decrease root weights in the moderate structured sub‐ash layers.

ISSN:0010-3624    

DOI:10.1080/00103628309367346

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The relationship between Bray P1extractable phosphate and labile phosphate was studied for some recently published data from soils of northern New South Wales. The relationship between extractable phosphate and labile phosphate is more complex than might be assumed, and depends upon the sorption characteristics of the soil. It is therefore not possible to accurately estimate labile phosphate simply from Bray P1extractable phosphate.

ISSN:0010-3624    

DOI:10.1080/00103628309367347

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A two‐year experiment was conducted on Edwards muck (Limnic Medisaprist) on the Pinney‐Purdue Agricultural Center at Wanatah, Indiana to study the effect of NPK fertilization on Ca and Mg concentrations in Kentucky bluegrass (Poa pratensisL.). Eight combinations of N‐P‐K fertilizer (0–0–0, 0–99–0, 0–0–372, 0–99–372, 168–0–0, 168–99–0, 168–0–372, 168–99–372 kg/ha), were applied each spring. Four cuttings were taken annually during the 1979 and 1980 growing seasons from a 1.5 m2caged area.

ISSN:0010-3624    

DOI:10.1080/00103628309367348

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

From 1976 through 1979 blueberry (Vaccinium corymbosum, cv. Bluecrop) plots received five rates of ammonium sulfate [(NH4)2SO4] supplying 28, 84, 140, 196 and 252 kg nitrogen (N)/hectare/ year. Response was measured by fruit yield and mineral element analysis of leaves and soil. The highest average yield was produced from plots receiving 140 kg N/hectare, from plants with a leaf N of 1.96 to 2.06 percent dry weight, and from soil with a pH of about 4.6.

ISSN:0010-3624    

DOI:10.1080/00103628309367349

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Five commercially available penetrating agents and sulfuric acid were tested for their ability to facilitate water penetration in soil using soil column and/or field experiments. Only one of these, “Charge”;, increased water penetration in soil column tests; all five compounds were ineffective under field conditions. While initial treatment with sulfuric acid resulted in slower penetration, periodic rewetting of treated soil indicated that water penetration was significantly enhanced.

ISSN:0010-3624    

DOI:10.1080/00103628309367350

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A comparison was made between dry combustion in a Leco NP‐28 nitrogen and protein determinator, and acid digestion by the Kjeldahl procedure in the analyses of soil and plant material for total nitrogen. A statistical functional relationship demonstrated that the methods gave results similar in size and reproducibility. Thus the traditional Kjeldahl procedure can be replaced by a simpler and quicker method.

ISSN:0010-3624    

DOI:10.1080/00103628309367351

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A method for the determination of carbonates in soils and minerals is described. It consists of the digestion of a sample, containing between 0.5 and 15 mg C as carbonate, in 5N HCl under a stream of nitrogen gas, followed by the determination of the evolved carbon dioxide in a sodium hydroxide trap. The carbon dioxide is titrated directly as carbonic acid in a two‐endpoint titration between pH 8.3 and 3.7.

ISSN:0010-3624    

DOI:10.1080/00103628309367352

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Factorial experiments with the treatments N, P, K, and a minor and trace element treatment (T) were carried out with African mahogany (Khaya senegalensis) on two soils in the glasshouse. The best growth was on the N+P+T treatments; if any one element was omitted growth was greatly reduced. A second experiment showed that of the elements in the T treatment, S gave a growth response while Ca, Mg, and B did not. (Zn, Cu and Mo were not tested but tip die‐back and chlorotic leaves suggested that Zn was required.) Applications of N, P, K, and S increased the corresponding foliar levels but in the treatments which showed the best growth response the foliar levels were lower than those when one of the elements was omitted. It is suggested that foliar nutrient levels higher than those occurring in healthy trees may indicate that another nutrient is limiting growth. For instance foliar levels greater than about 0.12% P, 0.7% K and 0.13% S may indicate that the supply of P, K and S respectively is adequate but another element (such as one of the trace elements) is deficient.

ISSN:0010-3624    

DOI:10.1080/00103628309367353

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628309367345

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor