摘要:

A two‐year fertilizer study on a mature vineyard of grapes (Vitis viniferaL., cv. ‘Cabernet Sauvignon’ and ‘Sauvignon blanc') was conducted on a White House sandy loam (fine, mixed, thermic Ustollic Haplargid) soil at the University of Arizona Oracle Agricultural Center. Two cultivars were grown and treated with different levels of N and P fertilizer and tested for total P and NO3‐N content of plant tissues.

ISSN:0010-3624    

DOI:10.1080/00103629009368262

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Transformation of native P and changes in water pH and cation exchange capacity (CEC‐pH 7) were investigated in acid (I) and neutral (IV) soil incubated with 0, 50 and 100 mg Cr/kg for 3 months. Phosphorus was sequentially obtained as P‐resin, P‐NaHCO3, P‐NaOH and P‐HCl, with the P‐NaHCO3and P‐NaOH being separated into organic and inorganic fractions. The low Cr level had little impact on the parameters. The high level increased the pH from 5.1 to 7.3 and from 6.8 to 7.5 in soils I and IV, respectively, while also significantly (P=5%) increasing CEC and decreasing P‐resin content. Subsequent to the Cr treatment, total P‐NaHCO3significantly declined in Soil I, but did not change markedly in Soil IV. Although total P‐NaOH was not affected by the Cr applications, its inorganic form doubled in Soil IV. Most of the total P‐NaHCO3and P‐NaOH was in organic form. Whereas P‐HCl was stable in Soil IV, the P nearly doubled in Soil I at the expense of P‐NaHCO3(r = ‐0.94**). pH was correlated with CEC (0.62*), total P‐NaHCO3(‐0.83**) and P‐HCl (0.76**), while CEC was correlated with P‐resin (‐0.70**), total NaHCO3(‐0.88**) and P‐HCl (0.94**).

ISSN:0010-3624    

DOI:10.1080/00103629009368263

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A mathematical equation predicting cation exchange capacity (CEC) of pine bark‐sand container media from CEC of the individual components was formulated. The equation is the weighted sum of milliequivalents contributed by each component and is corrected for shrinkage due to mixing of components. Both measured and predicted CEC increased linearly with increasing percent volumetric bark in pine bark‐sand media. Regression equations describing measured and predicted CEC were not statistically different. The predictive equation was also tested on 6 non‐synthesized 2‐component media prepared from peat moss, perlite, pine bark, vermiculite, and sand. No statistical differences between measured and predicted CEC were obtained.

ISSN:0010-3624    

DOI:10.1080/00103629009368264

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Onion (Allium cepa) and fenugreek (Trigonella poenum‐graceum) growth was measured in glasshouse on a slightly alkaline clay‐loam soil from Northern India. Cadmium, Ni, Pb and Zn were applied at the rate of 0, 50, 100, 200 and 400 mg/kg of soil. The fresh and dry weights of onion and fenugreek were drastically reduced even at the 50 mg/kg soil addition of Cd and decreased further at higher applied levels. There was a slight decrease in the yield of both of the vegetables at 50 mg Ni/kg soil but at 100 mg Ni/kg soil and above yield decrease was significant. No growth was observed at 400 mg Ni/kg soil. The application of 50 mg Zn/kg soil slightly increased the yield of both of the vegetables, but the yield decreased at higher levels of applied Zn and more so for fenugreek. The threshold concentration, toxicity index and loading rate to produce ten percent yield reduction were also calculated. These values suggested that the toxicity of heavy metals varied with crop species. The concentrations of the elements in onion bulb and fenugreek root and leaves increased linearally with increasing levels of applied elements. The uptake of Zn was highest, followed by Cd, Ni and then Pb. The roots accumulated higher amounts of these elements than the leaves. Tissue concentrations of Cd, Ni, Pb and Zn associated with ten percent yield reduction for onion were 6, 3.2, 8 and 75 ppm, respectively, and for fenugreek, the concentrations were 1.5, 7.8, 11.5 and 54.5 ppm, respectively. In general, phytotoxicities were found to be in the order: Cd > Ni > Pb > Zn. The DTPA extractable elements in soil, after the harvest of crops, increased with increasing levels of applied elements in soil.

ISSN:0010-3624    

DOI:10.1080/00103629009368265

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

In order to quantify the uptake by lettuce plants (Lactuca sativa L.)of heavy metals contained in the phosphate fertilizers and to evaluate their residual bioavailability in the growth substrate a greenhouse experiment was carried out. The superphosphate added to the soil contained varying amounts of heavy metals, particularly Cd, Cr and Zn which accumulated in the soil and increased the amounts available for plant uptake. The accumulation of metals observed in the plant tissues did not have physiological effects on lettuce and did not affect negatively the growth of the plants. The heavy metal speciation in soil indicated that metals extractable by EDTA increased by increasing the phosphorus added. These amounts of metals, adsorbed or complexed in the soil after harvest, represent in protected environments a potentially bioavailable species for the following cultivations.

ISSN:0010-3624    

DOI:10.1080/00103629009368266

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Coastal bermudagrass yields were increased by 3.1 Mg ha‐1with K applications of 300 kg ha‐1yr‐1in a 7‐year study on Olivier silt loam at Baton Rouge, but available soil K depletion occurred even though K applications exceeded K removal in the forage. At lower rates of K application, K removal exceeded K applications, causing severe depletion of available soil K. Applying 600 kg of K ha‐1exceeded both the crop K requirement and K removal in the forage, resulting in increased levels of available soil K. Ninety percent of the maximum yield was obtained at about 100 kg of K ha‐1. Potassium concentrations in the forage averaged 9.2 and 13.4 g kg‐1at K rates of 100 and 300 kg ha‐1, respectively. Apparent recovery of fertilizer K decreased from 53 to 47% as K applications increased from 37 to 300 kg ha‐1. The Olivier silt loam supplied 105 kg of K ha‐1annually where no K was applied. The study indicates that K applications must be sufficient to produce yields very near the maximum yield in order to avoid depletion of available soil K by high‐yielding Coastal bermudagrass.

ISSN:0010-3624    

DOI:10.1080/00103629009368267

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A field trial showed that strawberries do not need large quantities of N and that N applied in spring had the biggest influence on yield. Plants receiving spring N yielded 43.1 t ha‐1compared with 26.0 t ha‐1by plants not receiving spring N. Although N applied in autumn did not influence yield to a marked extent, it caused a shift in production peaks. Plants that had received autumn N produced an early crop, while plants receiving no autumn N showed a delayed production peak. Highest yields were obtained with 36.5 kg N ha‐1in the spring, and 36.5 kg N ha‐1in autumn in split applications. For optimum yields, N should be applied from mid‐winter in small, regular amounts. Although yield was not greatly affected by K applications, it is essential to keep the soil K content at about 40 ppm Bray II extractable K in order to obtain better fruit size.

ISSN:0010-3624    

DOI:10.1080/00103629009368268

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Soil analyses indicated that strawberries did not take up large quantities of N during the autumn, causing a build‐up of soil N even with the small, regular applications used. Spring applied N was the most important factor determining yield. This was supported by the higher soil N values in plots receiving N during the spring. Although soil N levels were very low in the spring, differences can be ascribed to leaching and plant uptake during the interval between application and sampling. The highly significantly higher soil N levels in treatments that received spring N indicated that sufficient N was available in the period between applications to ensure a large yield. Soil K levels were influenced by both spring and autumn N applications. The differences in soil K can be ascribed to difference in plant size and to competition between K+and NH4+for sites on the cation exchange complex. Although yield was not influenced by the different K treatments, application of N in both spring and summer influenced soil K level. K in commercial plantings should be supplemented only if Bray II extractable K levels drop lower than 35 ppm.

ISSN:0010-3624    

DOI:10.1080/00103629009368269

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The youngest fully expanded mature leaf of each plant was sampled from a factorial N and K fertilization field trial on July 4, August 22, October 27 and December 4. Nutrient uptake was not very active during the late autumn and winter. On the first sampling date no differences in leaf N content were observed among the different fertilization treatments, probably because of a dilution effect. During the remainder of the growing season, N fertilization generally affected leaf nutrient values. The levels of all the nutrients tested decreased during the harvesting period, but, with the exception of N, remained within the Californian standards. Nitrogen content decreased during the harvesting season to levels of about 1 %, for both fertilized plants and unfertilized controls, indicating that either no uptake was taking place during the late harvesting period, or that all N was being transported to fruit. Leaf K levels should not be higher than about 1.65% at the beginning of the harvesting season, as leaf levels of 1.80% were associated with soil K levels of 80 ppm, which resulted in decreased yield and fruit size. There is no single time at which leaves should be sampled for diagnostic purposes, and different standards for leave analyses should be developed for different periods during the growing season.

ISSN:0010-3624    

DOI:10.1080/00103629009368270

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A survey was conducted of 55 state and 371 commercial laboratories throughout the United States in order to document the current applications of plant analyses and the extent of application of the diagnosis and recommendation integrated system (DRIS) and to identify factors that have hindered or facilitated the implementation of the DRIS. State labs listed “research”; and commercial labs listed “diagnosis of nutrient deficiencies”; as the most common uses for plant analyses. Plant analysis results were widely used in combination with soil tests when diagnosing nutrient deficiencies and recommending corrective action (96% of state labs and 92% of commercial labs diagnosing nutrient deficiencies). Nationwide, the sufficiency range was the most commonly identified method of interpreting plant analyses (61% of the state and 58% of the commercial labs). The DRIS was used more extensively in the North Central region (14 labs) than in any other region. The two most commonly identified factors hindering the implementation of the DRIS were 1) lack of field verification and/or calibration and correlation data and, 2) unfamiliarity with the system. Computer availability appears to be the most important factor facilitating the implementation of the DRIS.

ISSN:0010-3624    

DOI:10.1080/00103629009368271

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor