摘要:

Periods of maximum hard red spring (HRS) wheat(Triticum aestivum L.)nutrient demand need to be determined in order to develop best nutrient management practices, and to provide data for nutrient uptake modeling. Aerial (aboveground biomass) whole plant samples of irrigated HRS wheat were collected from the field at 16 growth stages and separated into leaves, stems, heads, and grain for dry matter determinations and analyzed for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), chloride (Cl), zinc (Zn), manganese (Mn), iron (Fe), and copper (Cu) concentrations. Accumulation curves were computed for each plant part for the growing season from compound cubic polynomial models based on accumulated growing degree units (GDUs). Total aerial accumulations of dry matter, N, P, K, Ca, Mg, S, Cl, Zn, Mn, Fe, and Cu were 14400, 116, 30.8, 103, 9.2, 9.3, 15.2, 32.3, 0.18, 0.58, 2.05, and 0.045 kg/ha, respectively. Grain at maturity accumulated greater than 78% of the total aerial N, P, and Zn, while it contained less than 20% of the aerial accumulated K, Ca, Cl, and Fe. Nitrogen and Fe were rapidly accumulated near 200 GDU, while P, K, Ca, Mg, S, Cl, Zn, Mn, and Cu were most rapidly accumulated near 600 GDU. Accumulation rates were 183, 2.9, 0.90, 0.72, 0.008, 1.41, 0.29, and 0.12 kg/ha/d for dry matter, N, P, K, Ca, Mg, S, and Cl, respectively, and 136, 1.7, 0.48, 0.13, 0.004, 0.78, 0.20, and 0.02 g/ha/d, respectively, during grainfill. This plant information suggests the timing of in‐season nutrient applications and, when integrated with other agronomic practices, could improve overall nutrient management for HRS wheat in the northern Great Plains.

ISSN:0010-3624    

DOI:10.1080/00103629409369162

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Swiss chard(Beta vulgaris cicla’Fordhook Giant'), bean(Phaseolus vulgaris’Hawksbury Wonder'), andAgrostis capillaris’Parys’ were grown in soilless media composed ofPinus radiatabark and 0–41% by volume of dried sewage sludge containing [in mg/kg] cadmium (Cd) [22], copper (Cu) [1,116], and zinc (Zn) [1,121]. Sublots of all mixtures were adjusted to pH 4.5, 5.5, or 6.5. Shoot weights were not reduced by sludge addition but those of Swiss chard and bean shoots declined with pH. Shoot contents of Cu, Cd, and Zn increased with decreasing pH. Shoot Cu concentrations were always sub‐toxic, and in Swiss chard toxicity symptoms were not observed until shoot Zn content reached 1,300 mg/kg. Cadmium in Swiss chard shoots reached 22 mg/kg. Metal concentrations in the shoots were well correlated with total and extractable metals in the media only if pH was included in the regression equations.

ISSN:0010-3624    

DOI:10.1080/00103629409369163

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Humus formations from forest and brushwood ecosystems on calcareous substrates in representative sites from Sierra de Gador in Southern Spain were analyzed. The humus composition, as determinated by three independent fractionation procedures, suggests that soil organic matter turnover is not related to the vegetation biotypes, but to a series of local factors among which climatic and soil characteristics predominate. Of the parameters studied, the amount of fulvic acids, and to a lesser extent, the relative proportion of soil perylenequinonic pigments (P‐type humic acids), reflected differences in altitude. The percentage of nitrogen (N) in humic acids was the parameter that was most informative of the characteristics of humus. This finding contrasts with the poorly differentiated patterns of the particulate organic matter fractions, whose evolution is probably independent of environmental factors because of physical protection by soil carbonates. The carbon dioxide (CO2) release curves reproduced under laboratory conditions showed that the intrinsic biodegradability of soil organic matter does not reflect the nature of the plant residues in the sites sampled (170–2240 m), but is weakly dependent on climatic factors. We postulate that the calcium saturation, together with the active participation of inorganic colloids, force the convergent evolution of soil humus by compensating most of the effects of the climatic and biotic factors, and the historic influence of human activity in the area studied.

ISSN:0010-3624    

DOI:10.1080/00103629409369164

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

To evaluate conventional calcium dihydrogen phospahte [Ca(H2PO4)2] solution containing 500 mg P/L as an extractant for soluble plus adsorbed sulfate (SO4), we added known amounts of SO4to 10 soil samples differed in clay mineral composition and extracted with Ca(H2PO4)2solution. The experimental results showed that the five successive extractions at a soihsolution ratio of 1:10 could quantitatively recover the added SO4, and there was little effect of air‐drying the soils after addition of SO4. Based upon these experimental results, we concluded that the Ca(H2PO4)2extraction is an excellent method for determining soluble plus adsorbed inorganic SO4in soils.

ISSN:0010-3624    

DOI:10.1080/00103629409369165

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

There has been a trend toward using sandier growing media on highly trafficked turf areas to combat the detrimental effects of compaction on soil physical properties. Use of sand to modify, or even replace, existing soil also affects the nutrient status of these turf areas and could lead to both macronutrient and micronutrient deficiencies. Greenhouse experiments were conducted to determine the effects of natural organic fertilizer (Milorganite) or micronutrient supplement (Esmigran) applied to the surface or incorporated at several rates on the nutrient concentration of ‘Pennfine’ perennial ryegrass(Lolium perenneL.) grown on quartz sand, a sand‐peat topdressing mix, and a silt loam soil. Effects of Milorganite rate were most apparent on sand and topdressing, and, with at least one soil for one harvest period, increased rates of Milorganite resulted in increased tissue concentration for phosphorus (P), potassium (K), calcium (Ca), sulfur (S), manganese (Mn), iron (Fe), copper (Cu), and zinc (Zn). With Esmigran, increases in tissue concentration due to rate were found for Mn, boron (B), and Zn. Interactions among soil, rate, and application method made it difficult to generalize concerning nutrient availability from these fertilizers. Effects tended to be most obvious with sand and were more apparent with surface applications in some cases and with incorporation in others. Tissue analysis was superior to soil testing for assessing the nutrient status of a turfgrass stand.

ISSN:0010-3624    

DOI:10.1080/00103629409369166

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The increased use of urea as a nitrogen (N) fertilizer source in northern Idaho may require precautions to prevent potential losses via volatilization. The purpose of this study was to determine the effects of urea placement, water potential and time on volatilization losses of N in two northern Idaho soils under laboratory conditions maintained at 25°C. A completely randomized block factorial design with repeated measures [2 soils x 2 urea placement treatments x 4 soil water potentials x 3 replications‐measured at 0, 2, 4, 8, and 16 d] was utilized in this study. The two soils, a DeVoignes silt loam (fine silty, mixed nonacid, frigid Histic Humaquept) and a Santa silt loam (coarse silty, mixed, frigid Ochreptic Fragixeralf), were maintained at water potentials of ‐0.8, ‐2.0, ‐3.0 or ‐6.0 bars. Urea was either surface applied or incorporated into the soils at the rate of 200 kg/ha. Data were analyzed by SAS‐GLM and Omega squared (ω2) values were used to identify the impact of each main effect and interaction. The 4‐factor interaction of urea placement (NIT) x soil (SL) x water potential (WP) x time of incubation (IT), 4–3 factor interactions, 6–2 factor interactions and 4 main effects were found to be significant in this study. Due to the number of significant sources of variation, ω2values were used to assess their relative importance. The urea placement treatment accounted for 31.8% of the variation in this study as N losses after 16 d of incubation from the surface urea applications were 28.35% compared to 6.52% where urea was incorporated into the soil. The incubation time x urea placement interaction was the second most important factor and accounted for 21.98% of the observed variability. Volatilization losses were much greater at all incubation times in the surfaceapplied urea treatment when compared to incorporated urea. The differences in N lost by volatilization increased with time. Soil water potential also affected N volatilization as losses increased with increasing soil moisture levels. When the soil water content was not limiting, substantial volatilization occurred. This may be due to an increased urea hydrolysis rate as the moisture content increases. This study demonstrated that volatilization losses may be significant for surface applications of urea on some Idaho soils. To counter these losses incorporation of urea into the soil should be considered.

ISSN:0010-3624    

DOI:10.1080/00103629409369167

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Field experiments were conducted in summer 1992 on the Central Experimental Farm, Ottawa (45°22'N, 75°43'W) to determine whether a stem infusion technique developed for maize under controlled conditions was applicable to field‐grown maize and to evaluate whether providing sucrose in solution at silking via stem infusion altered plant source‐sink relationships sufficiently to increase kernel set. The higher and more variable evaporative demand and more difficult installation under field conditions dictated modifications to the stem infusion apparatus to prevent leakage and to facilitate assembly prior to field set‐up. A range of several field parameters were tested to identify conditions that would maximize infusion of sucrose solution: raising the syringe barrel height increased the volume of solution uptake; the largest amount of sucrose was taken up using a concentration of 150 g sucrose L‐1, and consecutive multiple infusions of the same plant increased solution uptake. Solution uptake was found to be greatest in the first 24 h of infusion. Leaf soluble carbohydrate and starch concentrations and ear leaf photosynthesis were not changed by sucrose infusion. Sucrose solution infused at silking appeared to increase kernel set in one of the experimental hybrids.

ISSN:0010-3624    

DOI:10.1080/00103629409369168

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Dry matter (DM) yield,in vitroorganic matter digestibility (IVOMD), crude protein (CP) and mineral composition of eightDigitariaaccessions were compared between long‐ and short‐day seasons in the semiarid southern region of Puerto Rico and evaluated in relation to grazing ruminant requirements.Digitaria milanjiana6416 was consistently among the highest DM yielding accessions in both seasons. The mean IVOMD was similar in both seasons for most accessions. Concentrations of CP, magnesium (Mg), copper (Cu), zinc (Zn), cobalt (Co), and selenium (Se) were below the recommended levels for grazing ruminants in both seasons. This study suggests the need for livestock mineral supplementation, even under conditions of high pasture fertilization (NPK) and forage‐growing conditions in the semiarid southern region of Puerto Rico.

ISSN:0010-3624    

DOI:10.1080/00103629409369169

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Measurement of total soil cadmium (Cd) is difficult due to calcium (Ca) and other chemicals which cause high background absorbance when trace levels of Cd are to be determined. When soil Cd is low, even use of deuterium background correction with flame atomic absorption spectroscopy (AAS) cannot provide accurate Cd results. Use of furnace atomic absorption with method of standard additions can circumvent these interferences, but the cost and time required are substantial. We desired a more rapid, convenient, and reliable alternative to extraction using dithizone and back‐extraction into acid, or to ammonium pyrollidinedithiocarbamate (APDC) which does not require close pH adjustment nor have many sources of potantial contamination. We evaluated analysis of these complex soil extracts with the method of Viets (1978) which extracts metals from 1N acid solutions using Aliquat‐336 in methylisobutyl‐ketone (MIBK). We tested the use of the less toxic and less water soluble 3‐heptanone as an organic solvent alternative to MIBK which can be directly analyzed by flame atomic absorption. A series of extraction experiments were conducted to determine if Cd was extracted from standard solutions and from total metal digests of calcareous soils into an Aliquat‐336/3‐heptanone solution, and under what conditions extraction was optimum. In the optimum method, Cd was extracted from aqua regia soil digests by 10% Aliquat‐336 in 3‐heptanone without addition of ascorbic acid or potassium iodide (KI) used by Viets. Excellent recovery of Cd was obtained for both standard reference soils and low Cd highly calcareous soils from North Dakota and Minnesota. Addition of ascorbic acid and KI did not increase the efficiency of extraction indicating that the extraction system used was free of ferric‐iron [Fe(III)] interference. The ion‐association complex of Cd remained stable for at least 24 hr after extraction, providing a very convenient method to analyze low levels of total Cd in soils and other geologic materials.

ISSN:0010-3624    

DOI:10.1080/00103629409369170

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Five slopes representative of the “dehesa”; grassland communities in the semi‐arid zones of Central‐Western Spain (province of Salamanca) were studied. Above‐ground biomass production was recorded from April to June and the NDF (neutral detergent fibre), ADF (acid detergent fibre), hemicellulose, cellulose, lignin, and digestibility were determined in the dry matter. Principal component analysis was applied to the data. The changes with time along the growth period show a parallel effect on the three positions of the slope, although the effect tended to be greater on the middle and upper zones. There were decreases in the levels of protein, cellular content, and digestibility, and an increase in cell wall components. The variability in nutritive characteristics induced by the phenology and time changes in the communities was reflected in the first factor of analysis, whereas the topographic gradient was related to the second component.

ISSN:0010-3624    

DOI:10.1080/00103629409369171

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor