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1.
Abstract

Samples of seven controlled‐release fertilizers, Nutricote Total 13–13–13, Nutricote Total 18–6–8, Osmocote Plus 15–9–12, Osmocote 13–13–13, Polyon 18–6–12, Polyon 14–14–14, and Plantacote 14–8–15, were placed in leaching columns containing acid‐washed sand. Samples of all leachates were analyzed weekly to determine release rates of ammonium‐nitrogen (N), nitrate‐N, phosphorus (P), potassium (K), magnesium (Mg), manganese (Mn), and iron (Fe). Release rates for P from all products were slower than those for NH4‐N, NO3‐N, and K. Release of Mg, Mn, and Fe was very poor, with less than 50% of the total amount of each of these elements ever being released from the prills for some products. Nutricote products released Fe and Mn more effectively than did Osmocote or Plantacote.  相似文献   

2.
An experiment was conducted with Phalaris aquatica L. cv. Sirolan under hydroponic conditions in the glasshouse at constant temperature of 25°C and natural sunlight. Plants were grown in double pot system with four sulfur and three molybdenum levels along with all the major‐ and micro‐nutrient elements. There was increase in growth, nitrate‐reductase activity and contents of most of the nutrient elements at all levels of sulfur and 1.68 μ/L molybdenum. Molybdenum at 3.36 μg/L level inhibited growth and nitrate‐reductase activity and decreased concentration of nutrient elements in plant. The inhibitory effect of higher level of molybdenum is perhaps mediated through its role in the nitrate‐reductase.  相似文献   

3.
Abstract

To examine the distribution of DTPA‐extractable Fe, Zn, and Cu in clay, silt, and sand fractions; surface soils were collected from cultivated fields of North Dakota, South Dakota, West Virginia, Iowa, Ohio, and Illinois. Clay, silt, and sand fractions were separated after sonic dispersion of soil water suspension and analyzed for DTPA‐extractable Fe, Zn, and Cu. In general, clay had the highest and sand the lowest amount of DTPA‐extractable metals. Consequently, clay had the highest and sand the lowest intensity and capacity factors for these metals since DTPA micronutrient test measures both these factors.  相似文献   

4.
Abstract

Pearl millet and annual ryegrass were continually doubled‐cropped on Olivier silt loam soil for seven years at six levels of N, applied as ammonium nitrate in three applications to millet and in two applications to ryegrass. Forage yields increased as N application rates increased. During seven years at the 0 and 448 kg/ha N rate, millet produced 35% and 95%, respectively, as much yield as it produced at the 800 kg/ha N rate, while comparable values for ryegrass were 19% and 83%. At 448 kg/ha of N the two grasses produced a combined yield of over 20 Mg/ha of dry forage per year. Ryegrass yields following millet were consistently lower than yields previously obtained at this site.

Nitrogen applications consistently increased concentrations of N, Ca, and Mg in both forage grasses, while effects on P and K were variable and S concentrations were unaffected. The amounts of all nutrients removed in the forages were increased as yields increased with N application rates. Nitrate‐N levels considered to be toxic to ruminant animals occurred only where N applications exceeded 170 kg/ha at any one time. In vitro digestibility of each grass was consistently increased by N applications.

The percentage of fertilizer N that was removed in the crops ranged from 66% to 68% for millet and from 35 to 52% for ryegrass as N applications increased up to 448 kg/ha. Residual ammonium and nitrate levels in the top 1.2 m of soil were not increased by N rates of 448 kg/ha or lower. At the 800 kg/ha N‐rate, the apparent N recovery rate decreased and residual ammonium and nitrate levels increased throughout the soil profile.  相似文献   

5.
Abstract

Phosphorus (P) deficiency is one of the most yield‐limiting factors in lowland acid soils of Brazil. A field experiment was conducted during two consecutive years to determine dry‐matter and grain yield, nutrient uptake, and P‐use efficiency of lowland rice (Oryza sativa L.) grown on an acidic Inceptisol. Phosphorus rates used in the experiment were 0, 131, 262, 393, 524, and 655 kg P ha?1 applied as broadcast through termophosphate yoorin. Dry‐matter yield of shoot and grain yield were significantly (P<0.01) and quadratically increased with P fertilization. Concentrations (content per unit dry‐weight leaves) of nitrogen (N), P, and magnesium (Mg) were significantly increased in a quadratic fashion with the increasing P rates. However, concentrations of potassium (K), calcium (Ca), zinc (Zn), copper (Cu), and iron (Fe) were not influenced significantly with P fertilization, and Mn concentration was significantly decreased with increasing P rates. Phosphorus use efficiencies (agronomic, physiological, agrophysiological, recovery, and utilization) were decreased with increasing P rates. However, magnitude of decrease varied from efficiency to efficiency.  相似文献   

6.
Abstract

Most Brazilian soils do not possess sufficient concentrations of available potassium (K) to produce maximum apple yield. Potassium distribution was evaluated with a depth profile of a Humic Xanthic Hapludox receiving K fertilization in an apple orchard, cv. Gala/MM106, at Vacaria, Rio Grande do Sul, Brazil. Treatments consisted of four rates of annual maintenance K fertilization. After 12 years of cultivation, soil was sampled in eight depth increments. Potassium, calcium (Ca), and magnesium (Mg) contents were extracted by Mehlich I, ion‐exchange resin, and ammonium acetate pH 7.0. Long‐term application of K fertilizer resulted in K accumulation mainly in the 0‐ to 30‐cm surface layer, with low K mobilization to deeper layers. Increasing rates of K fertilizer did not affect soil Mg concentration but induced a lower Ca concentration extracted by Mehlich I, especially in the 0‐ to 20‐cm layer. The estimated K2O rate for maximum apple yield was 86.5 kg/ha/year.  相似文献   

7.
Abstract

Spatial variation of bicarbonate soil test phosphorus (P) and bicarbonate soil test potassium (K) was studied by measuring soil test values for 40 individual soil samples collected from random locations within eight uniform 100 m by 100 m field sites in south‐western Australia. In addition, for five of the sites, spatial variation of the three P sorption indices (ammonium oxalate extractable iron, ammonium oxalate extractable aluminum, and the P retention index) and of organic carbon (C) was measured for 20 individual soils samples. Spatial variation was found to be large, with coefficient of variation (CV) exceeding 20% in most cases, and 50% in some cases. It is therefore essential to collect an adequate number of soil samples from uniform areas in paddocks in order to provide a representative composite sample to measure the soil properties.  相似文献   

8.
Abstract

This study evaluated the performance of photo‐acoustic infra‐red spectroscopy (PAIRS) for measuring nitrous oxide (N2O) fluxes in the field, in comparison with long‐path infra‐red spectroscopy ('Hawk'), gas chromatography (GC), and continuous flow isotope‐ratio mass spectrometry (CF‐IRMS). The N2O flux measurements from fertilized and grazed grassland were made simultaneously by the different methods, before and after water application. Before irrigation, mean N2O fluxes ranged from 3 to 20 g N ha1 day1 for the PAIRS and GC measurements, but were undetectable with the Hawk. Within 2 hours of irrigation, mean fluxes increased to 740, 640, and 270 g N ha‘1day1, based on GC, PAIRS, and Hawk measurements, respectively. After about 24 hours, irrigation had reached its full effect and N2O fluxes had increased to 1,050,710, and 410 g N ha1 day1. The GC measurements were consistently higher than the PAIRS measurements. However, a second experiment, comparing the PAIRS analyzer with continuous flow isotope‐ratio mass spectrometry (CF‐IRMS), suggested that the former was negatively biased; the PAIRS response was about 33% lower than CF‐IRMS. When the resulting correction factor was applied to the results of the first experiment, there was very good agreement between the PAIRS and GC measurements. The Hawk measurements were lower than PAIRS and GC, but a statistical comparison was not possible, due to the limited number of Hawk measurements that could be made in the windy weather conditions. Windy conditions also resulted in an underestimation of the N2O flux by PAIRS compared to GC and CF‐IRMS analysis, which could not solely be attributed to a change in the analyzer sensitivity. There was no obvious explanation for this discrepancy and further investigations are needed to resolve this issue.  相似文献   

9.
Abstract

The study reported herein was intended to determine the effect of (i) wet‐incubation and subsequent air‐drying, and (ii) oven‐drying on DTPA‐Fe, Zn, Mn, and Cu.

Analysis of wet‐incubated soils showed significant decreases in DTPA‐Fe, Mn, and Cu at the 1% and Zn at the 10% level of probability. Air‐drying of these moist‐incubated soils increased the levels of Fe, Zn, and Cu to values close to their original levels. Levels of Mn sharply deviated from their original values after air‐drying of incubated soils. Correlation coefficients (r) between the amounts of extractable nutrients in original air‐dry soils and wet‐incubated soils were 0.54, 0.87, 0.91, and 0.13 for Fe, Zn, Cu, and Mn, respectively. Oven‐drying increased the levels of DTPA‐extractable micronutrients from 2 to 6 fold.  相似文献   

10.
Abstract

Tests were made to determine the effects of grinding, type of extraction vessel, type of shaker, speed of shaking, time of shaking, time of filtering, soil to solution ratio and other variables on DTPA‐extractable Zn, Fe, Mn, and Cu from soils.

Time of grinding, force of grinding, and the quantity of soil being ground greatly affected the amount of extractable Fe. At the lower grinding force, the quantity of soil being ground only slightly affected extractable Fe, but at the higher grinding force, more Fe was extracted from the smaller sized samples especially at the longer grinding period. Extractable Zn was also increased by longer grinding time and greater grinding force, but increases were much less than increases for Fe. Increasing grinding time tended to increase extractable Mn. The effects of grinding on Cu was inconclusive. Increasing the ratio of extractant to soil increased the amount of extractable Fe from soils and tended to increase Zn, Mn, and Cu but to a lesser extent. Both shaker speed and type of extracting vessel affected the ex‐tractability of all nutrients except Cu. Greatest differences between extracting vessels occurred at the lowest shaker speed, while these differences were smaller or disappeared at the higher shaker speeds. The more thorough the mixing of soil and extracting solution, the higher were the levels of extractable Fe and Mn. A reciprocal shaker extracted more Fe and Mn from soils than a rotary shaker. The rate of dissolution of all four nutrients by DTPA was greatest during the first 5 minutes of extraction. There were large and significant correlation coefficients between levels of nutrients extracted after 15 or 30 minutes of shaking and those extracted after 120 minutes. The findings indicate that the levels of micronutrients extracted under one set of conditions can be related to levels extracted under other conditions by use of a simple linear regression equation for each nutrient.

The results of this study demonstrate the importance of standardizing the methods of preparation and extraction of soils used in the DTPA micronutrient soil test. A standard method for soil grinding and extraction is proposed for DTPA soil test.  相似文献   

11.
Abstract

Vertisols of India are developed over isohyets of 600 to 1500 mm, and their chemical cycles are set by drainage, landforms, and particle size, which results in variable pedogenic development within the otherwise homogeneous soils. The purpose of this study was to identify pedogenic processes in the distribution of total and DTPA‐extractable zinc (Zn), copper (Cu), manganese (Mn), and iron (Fe). The soils are developed over basaltic parent material of Cretaceous age. Soil samples were drawn from genetic horizons of the 13 benchmark profiles and analyzed by using HF–HClO4 acid for total and DTPA extraction. Correlation coefficients were calculated taking all samples together. The total concentration varied from 24 to 102 mg kg?1 for Zn, 21 to 148 mg kg?1 for Cu, 387 to 1396 mg kg?1 for Mn, and 2.36 to 9.50% for Fe. Their variability was proisotropic and haplodized, and their concentrations increased with advancing isohyets. Within the isohyets, hindrance in drainage caused retention of Zn and Cu but loss of Fe. The piedmont soils had more Fe than alluvium soils. The spatial distribution of total contents of Zn, Cu, and Fe was influenced by the pedogenic processes associated with Haplusterts but not with provenance materials. Surface concentrations of the elements by biotic lifting and/or harvest removal were negated by the pedoturbation that further contributed to the irregular distribution of the elements in the profiles. Total Zn and total Cu had positive coefficients of correlations with coarse clay, whereas total Mn and total Fe were positively correlated with fine clay. The DTPA‐extractable forms were functions of isohyets and drainage and showed association with organic carbon content and coarse clay.  相似文献   

12.
Nitrate levels and nitrate reductase activity (NRA) of the widely cultivated prickly‐pear Opuntia ficus‐indica were measured for 5‐year‐old orchard plants in the field between flowering and fruit ripening (May‐August) and for rooted cladodes (stem segments) in a glasshouse in pots that were supplied with 0.8,4, or 16 mM nitrate during the early growth of new cladodes (6 weeks). Nitrate levels were much higher in the cladodes than in the fruit peels or the roots; in both cladodes and fruit peels, nitrate levels were higher in the inner water‐storing layer (parenchyma) than in the outer green photosynthetic layer (chlorenchyma). NRA was confined to the cladode chlorenchyma and was higher in new cladodes than in the underlying cladodes. The orchard study suggested that the nitrate accumulated in 2‐ and 3‐year‐old cladodes served as a reserve for the growth of new organs. At the beginning of the reproductive season, such older cladodes had high nitrate levels of 7 mg/g DW in the chlorenchyma and 45 mg/g DW in the parenchyma, which decreased by 72% and 43%, respectively, by the end of the season. The glasshouse experiments indicated that the cladodes were more important for nitrate reduction than the roots, particularly under high external nitrate concentrations.  相似文献   

13.
Abstract

Tomato and melon plants were grown in a greenhouse and irrigated with nutrient solution having an EC of 2 dS m?1 (control treatment) and 4, 6, and 8 dS m?1, produced by adding NaCl to the control nutrient solution. After 84 days, leaf water relations, gas exchange parameters, and ion concentrations, as well as plant growth, were measured. Melon plants showed a greater reduction in shoot weight and leaf area than tomato at the two highest salinity levels used (6 and 8 dS m?1). Net photosynthesis (Pn) in melon plants tended to be lower than in tomato, for all saline treatments tested. Pn was reduced by 32% in melon plants grown in nutrient solution having an EC of 4 dS m?1, relative to control plants, and no further decline occurred at higher EC levels. In tomato plants, the Pn decline occurred at EC of 6 dS m?1, and no further reduction was detected at EC of 8 dS m?1. The significant reductions in Pn corresponded to similar leaf Cl? concentrations (around 409 mmol kg?1 dry weight) in both plant species. Net Pn and stomatal conductance were linearly correlated in both tomato and melon plants, Pn being more sensitive to changes in stomatal conductance (gs) in melon than in tomato leaves. The decline in the growth parameters caused by salinity in melon and tomato plants was influenced by other factors in addition to reduction in Pn rates. Melon leaves accumulated larger amounts of Cl? than tomato, which caused a greater reduction in growth and a reduction in Pn at lower salinity levels than in tomato plants. These facts indicate that tomato is more salt‐tolerant than melon.  相似文献   

14.
Pre‐ and post‐transplant growth of bedding plants is affected by seedling nutrition. However, there is little information available on how seedling nutrition affects the growth of ornamental bedding plants. In this study, we quantified the effects of nitrogen (N) (8 to 32 mM) and phosphorus (P) and potassium (K) concentration (0.25 to 1 mM) of the seedling fertilizer on pre‐ and post‐transplant growth and nutrient element content of salvia (Salvia splendens F. Sellow ex Roem. & Schult.) and vinca (Catharanthus roseus L.) seedlings. Shoot growth of salvia and vinca increased with increasing concentrations of N in the pre‐transplant fertilizer and these differences lasted until the end of the study at 15 days after transplanting. Pre‐transplant root dry mass of these species was not affected by the N concentration of the fertilizer, but root dry mass at 12 days after transplanting was positively correlated with the N concentration of the pre‐transplant fertilizer. Increasing N concentrations in the seedling fertilizer increased tissue N levels of salvia and decreased tissue K level of vinca at transplanting. Increasing P and K concentrations in the pre‐transplant fertilizer increased tissue P level of salvia and P and K levels of vinca, but had little effect on seedling growth. Leaf area and root dry mass at transplanting decreased slightly with increasing P and K concentration in the fertilizer. There were no lasting effects of pre‐transplant P and K concentration of the fertilizer. These results indicate that salvia and vinca seedlings can benefit from high concentrations of N (up to 32 mM) in the fertilizer, while only low concentrations of P and K (0.25 mM) are needed.  相似文献   

15.
Soybean plants [Glycine max (L.) Merr.] were grown in pots and inoculated with Rhizobium japonicum and/or Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe, either at planting or 20 days later. Nitrogen was supplied in the nutrient solution to plants without nitrogen‐fixing bacteria, and P was added to those without the mycorrhizal fungus. At harvest, 50 days after planting, all plants had leaves of similar dry mass. Each root symbiont grew best in the absence of the other. Growth of Glomus reflected the duration of its growing time and the presence and duration of competition from Rhizobium. Nodule weight in the tripartite associations, on the other hand, was inhibited only by the earlier introduction of Glomus.

Dipartite associations and the plants inoculated with both root symbionts at planting had the highest concentration of leaf N, and the lowest was in those inoculated with both organisms at d 20. Leaf P was highest in plants inoculated only with Rhizobium, and lowest in those tripartite associations involving any inoculation at day 20. The low values were presumably a result of the short duration of endophyte‐mediated P uptake before the plants were harvested.

Although there was almost no difference in leaf sugar concentrations, starch concentrations reflected the duration of Glomus growth, and were greatest in those plants that had supported it for the least time. Uninoculated plants contained the least starch, but produced a greater fresh mass of leaf tissue than any of the tripartite symbionts.  相似文献   


16.
Two rates of broiler litter (20 and 40 mt/ha) were compared to recommended rates of inorganic nitrogen (N), phosphorus (P), and potassium (K) in a double cropping system of spring sweet corn (Zea mays L. ‘Silverqueen') and fall broccoli (Brassica oleracea L, ‘Southern Comet')‐ Sweet corn matured one week earlier both years when fertilized with 40 mt/ha of broiler litter compared to commercial fertilizer. The early maturity may be due to improved P nutrition. Similar or higher yields of fall broccoli were produced with broiler litter following sweet corn than with commercial fertilizer.  相似文献   

17.
In this work, the relationship among accumulation of selenium, auxin, and some nutrient elements [magnesium (Mg2+), iron (Fe3+), manganese (Mn2+), copper (Cu2+), zinc (Zn2+)] in tissues of roots, mesocotyls, and leaves of Zea mays L. plants was studied. Seeds of maize were cultivated for 4 days in the darkness at 27 °C on moist filter paper, then the individual seedlings were transferred into an aerated solution containing the macro‐ and microelements and were cultivated in a greenhouse for 12 h in the light and 12 h (12‐h photoperiod) in the dark at 25 °C. The seedlings were exposed to the solution containing sodium hydrogen selenite (NaHSeO3), indole‐3 acetic acid (IAA), or IAA+NaHSeO3 for approximately 96 h before chemical analysis. The concentration of IAA in the external medium was 10?4 mol dm?3, concentration of selenite (NaHSeO3) was 10?6 mol dm?3, and the pH of the medium was 6.5.

The accumulation of the probed elements in seedlings of maize was measured by inductively coupled plasma optical emission spectroscopy (ICP‐OES). It was determined that the selenite and IAA, present in the external medium of growing plants, changed the uptake and accumulation of some cations in tissues of leaves, mesocotyls, and roots. The change of transport conditions of these nutrient elements is probably one of the first observed symptoms of selenium effects on plants.  相似文献   

18.
A field study was made of the seasonal changes in dry‐matter production, and the uptake, distribution, and redistribution of 12 mineral nutrients in the semi‐dwarf spring wheat, Egret, grown under typical irrigation farming conditions. Most of the dry‐matter production and nutrient uptake had occurred by anthesis, with 75–100% of the final content of magnesium (Mg), copper (Cu), chloride (Cl), sulfur (S), phosphorus (P), nitrogen (N), and potassium (K) being taken up in the pre‐anthesis period. The above‐ground dry‐matter harvest index was 37%, and grain made up 76% of the head dry matter. Redistributed dry matter from stems and leaves could have provided 29% of the grain dry matter. Concentrations of phloemmobile nutrients, such as N and P, decreased in the leaves and stems throughout the season, whereas concentrations of phloem‐immobile nutrients, such as calcium (Ca) and iron (Fe), generally increased. The decline in the N concentration in stems and leaves was not prevented by N fertilizer applied just before anthesis. Leaves had the major proportion of most nutrients in young plants, but stems had the major proportion of these nutrients at anthesis. Grain had over 70% of the N and P, and 31–64% of the Mg, manganese (Mn), S, and zinc (Zn), but less than 20% of the K, Ca, sodium (Na), Cl, and Fe in the plant. Over 70% of the N and P, and from 15 to 51% of the Mg, K, Cu, S, and Zn was apparently redistributed from stems and leaves to developing grain. There was negligible redistribution of Ca, Na, Cl, Fe, and Mn from vegetative organs. Redistribution from stems and leaves could have provided 100% of the K, 68–72% of the N and P, and 33–48% of the Zn, Cu, Mg, and S accumulated by grain. It was concluded that the distribution patterns of some key nutrients such as N, P, and K have not changed much in the transition from tall to semi‐dwarf wheats, and that the capacity of wheat to redistribute dry matter and nutrients to grain is a valuable trait when nutrient uptake is severely restricted in the post‐anthesis period.  相似文献   

19.
Growth and N‐P‐K uptake in pumpkin (Curcubita moschata Poir.) cv ‘Libby‐Select’ were studied in dryland and irrigated culture. In both moisture regimes, maximum rates of dry matter accumulation occurred between the early and mid‐fruiting developmental stages. Higher total dry matter production with irrigated than dryland culture was primarily associated with increased shoot growth. Concentrations of N, P, and K in foliage generally decreased as pumpkin age increased. Irrigated pumpkins in conjunction with higher total vegetative dry matter accumulated more N, P, and K than dryland pumpkins. Up through early fruit development, N, P, and K accumulation was primarily in leaves and vines and by the late growth stages was almost entirely in the fruit. Total N, P, and K uptake at late fruiting was estimated at 219, 32, and 228 kg/ha in irrigated pumpkins and 180, 21, and 177 kg/ha in dryland pumpkins. Approximately 58% of the N, 52% of the K, and 68% of the P accumulated by late‐fruiting was absorbed by the plant after the early‐fruiting stage in both moisture regimes. Potassium redistribution from vegetative tissues during late fruit development decreased foliar K contents 32% in dryland pumpkins and 21% in irrigated pumpkins.  相似文献   

20.
Abstract

This study evaluated the effect of variety and nitrogen (N) fertilization on sucrose, dry‐matter, and cation concentrations in sugarbeet (Beta vulgaris L.) root tissue. A field experiment was conducted on a non‐saline, calcareous Nunn clay loam soil (Aridic argiustoll) using a factorial experimental design with three N‐rates, two varieties, and four replications. Beets were harvested nine times during the growing season. The first and final harvests were on June 25 and October 11, respectively. In addition to the above measurements, purity and extractable sucrose also were measured at the final harvest. Dry‐matter content, sucrose, sums of monovalent and divalent cations, and the monovalent:divalent cation ratios all were influenced significantly by variety, N‐fertilization, and date of harvest. Sucrose concentration was negatively correlated to the sum of monovalent and divalent cations. Root drymatter content was negatively correlated to the monovalent:divalent cation ratio. A relationship of cation concentration to the organic‐ and inorganic‐ anions that influence purity is discussed.  相似文献   

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