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31.
Tile drainage is a common water management practice in many agricultural landscapes in the Midwestern United States. Drainage ditches regularly receive water from agricultural fields through these tile drains. This field-scale study was conducted to determine the impact of tile discharge on ambient nutrient concentration, nutrient retention and transport in drainage ditches. Grab water samples were collected during three flow regimes for the determination of soluble phosphorus (SP), ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3-N) concentrations and their retention in three drainage ditches. Measured nutrient concentration indicated lower SP and NH4+-N, and greater NO3-N concentrations in tile effluents compared to the ditch water. Net uptake lengths were relatively long, especially for NO3-N, indicating that nutrients were generally not assimilated efficiently in these drainage systems. Results also indicated that the study reaches were very dynamic showing alternating increases or decreases in nutrient concentration across the flow regimes. The drainage ditches appeared to be nutrient-rich streams that could potentially influence the quality of downstream waters. 相似文献
32.
《Communications in Soil Science and Plant Analysis》2012,43(6):663-672
Abstract A comparison was made of automated procedures and steam distillation for analysis of NH4 + and NO3 ‐ in KCl extracts of soils. Automated analysis of NH4 + utilized the phenate‐hypochlorite reaction. Nitrate was analyzed by E. coli reduction of NO3 ‐ to NO2‐which was then determined colorimetrically by reaction with sulfanilamide and napthylethylenediamine diHCl. Soil extracts were made with 1 M and 2 M KCl. Extracting with 1 M KCl was as effective as 2 M KCl. Extracts in 1 M KCl did not interfere with E. coli reduction of NO3‐, but 2 M KCl did. The automated procedures when compared to distillation gave similar if not better precision and reduced variation particularly at low N concentrations. The automated procedure tended to give higher values at higher NO3‐concentrations. Reduced time required for the analyses provided an additional advantage for the automated procedures. 相似文献
33.
《Communications in Soil Science and Plant Analysis》2012,43(1-2):368-376
Assessing the nutrient status of low-input, low-fertility desert soils poses some unique challenges. Commonly used soil analysis procedures and resin capsules generally assess nutrient status of fertile agricultural soils. Ion-exchange resin capsules (Unibest Company, Bozeman, Mont.) provide a viable alternative. A study was conducted to determine effectiveness of resin capsules to extract low levels of nutrients applied to native soils. Loamy sand and sandy clay loam desert soils from Utah were treated with combinations of four rates of nitrogen (N) as ammonium nitrate (34–0–0), three rates of phosphorus (P) as phosphoric acid (0–72–0), and two rates of iron sulfate (FeSO4·7H2O) and zinc sulfate (ZnSO4·7H2O) (include an untreated control). Each soil treatment was implanted with a resin capsule placed into either 250 or 1000 cm3 of soil after addition of water equivalent to 50% field capacity and incubated for either 60 or 120 days at 25 °C. After the appropriate incubation time, capsules were washed and extracted using 2 M hydrochloric acid (HCl), and the extract was used to measure iron (Fe), ammonium (NH4)-N, nitrate (NO3)-N, sulfur (S), and zinc (Zn). Conventional soil tests were completed on incubated soils (60 or 120 days). Resin capsules reflected NH4-N and P fertilizer applied at low rates in the loamy sand but not in the sandy clay loam. Neither Fe nor Zn application was reflected in resin capsules, but the accompanying S was clearly quantified. In comparison to conventional soil test procedures, resin capsule NH4-N was clearly a better indicator than KCl-extractable NH4-N; resin capsule NO3-N was effective, but not as good an indicator as water extraction; and resin capsule P was reflective of soil applied P in loamy sand but not in sandy clay loam, whereas sodium bicarbonate was effective in both soils. Resin capsules show promise for use in low-input conditions, but additional understanding of interactions in variable soils is needed. 相似文献
34.
《Journal of plant nutrition》2013,36(12):2413-2424
Abstract Tomato and watermelon plants were grown in nutrient solutions in which nitrogen (N) was supplied as NO3 ? (6 mM‐N) or NH4 + (6 mM‐N). The experiments were conducted to evaluate the effect which different N sources exert on iron (Fe) uptake and accumulation, on the enzymatic activities of aconitase (Aco), chelate reductase (FeCH‐R), peroxidase (POD), catalase (CAT), and Fe‐superoxide dismutase (FeSOD), and on biomass production. For both species of plants, fertilization with NH4 + caused the total Fe concentration to be lower, in the roots and in the leaves in relation to the concentrations recorded in plants fertilized with NO3 ?. The response of the enzymes related to Fe correlated with their concentration. The plants treated with N?NO3 ? registered the highest activities in Aco, FeCH‐R, POD, and CAT for both tomato and watermelon. On the other hand, only in the tomato plants was the superoxide dismutase (SOD) activity appreciably influenced primarily by NH4 +, due possibly to the toxic effect of this N source. Finally, in relation to biomass production, fertilization with NH4 + drastically reduced growth in the tomato plants, while in watermelon plants, no significant alteration was detected in dry‐matter production, regardless of the N form used. It was concluded that the response of the parameters analyzed to NH4 + fertilization, in tomato and watermelon, compared to fertilization with NO3 ? was similar. By contrast, tomato plants, but not watermelon plants, were negatively influenced by NH4 +. 相似文献
35.
Pepper plants were hydroponically grown in a growth chamber with two levels of light intensity (300 and 240 w/m2 ) and two N03:NH4 ratios (100:0 and 80:20). Plants supplied with both N forms (80:20) under high light conditions showed a decrease of nutrient uptake and produced low plant weight and yield compared to the all NO3 treated plants. By contrast, plants receiving both N forms (80:20) with light reduced over 25% showed a growth and yield slightly superior to plants supplied with N03 as sole source of N. This suggests a significant light intensity‐N form interaction that favors all NO3 nutrition for pepper at high light intensities. 相似文献
36.
ABSTRACT Two cultivars of pea: ‘PS210713’ (‘PS’), sensitive to iron deficiency, and ‘Marveille de Kelvedon’ (‘MK’), tolerant, were cultivated in controlled climatic conditions during one month, on a nutrient solution containing either nitrate (NO3 ?, 4 mM) or ammonium (NH4 +, 4 mM) and in the presence of bicarbonate (10 mM). The effects of these nitrogen forms on the growth and the mineral nutrition, and especially iron nutrition are analyzed. The reduction of growth by bicarbonate was approximately 30% in case of NO3 ? nutrition in the two cultivars, whereas in ammoniacal treatment the reduction is only 6% and 18% respectively in ‘PS’ and ‘MK’ cultivars. In presence of bicarbonate, the plant growth is not stimulated by NO3 ?relatively to its growth on ammoniacal medium, as often noticed when plants are cultivated on medium without bicarbonate: In presence of this compound, the biomass production of plant pea, was not influenced by the nitrogen forms. The nitric source led to a ferric chlorosis in the sensitive cultivar plants whereas any chlorosis was noted when ammoniacal source was applied. On the other hand, nitric nitrogen form decreased the nitrogen feeding of plants and increased the potassium one, while the effect of the ammoniacal nitrogen form on these nutrients was quite the inverse. In addition, the later increased the allocation of iron towards shoots. Besides, with this nitrogen source there was not accumulation of nitrate in the plant tissues. In nitric feeding case, the nitrate is mainly accumulated in the roots of the two cultivars. It is noticeable that the sensitive cultivar (‘PS’) accumulates three times more nitrate than the tolerant one (‘MK’). On the level of the whole plant, the iron and phosphorus nutrition seems unaltered by the nitrogen form. 相似文献
37.
Y. K. Soon 《Biology and Fertility of Soils》1998,27(4):425-429
There is considerable interest in determining the bio-availability of non-exchangeable NH4
+ (NEA) because it constitutes nearly 10% of the total N in the top 1 m of soil. NEA is NH4
+ present in the soil that is not extractable with neutral K salt solutions, e.g. 1M KCl. This study was conducted in 1994
and 1995 to quantify the amount of NEA released by a gray luvisolic clay loam soil in Alberta, Canada, during the growing
season. Replicated plots under: (1) continuous bromegrass, (2) continuous barley, and (3) barley since 1991 but previously
under a continuous forage legume, were sampled four times through the growing season to a depth of 80 cm. The first sampling
was done before seeding of barley. Cropping systems and their interaction with time of sampling had no effect on NEA. The
NEA-N pool in the soil decreased significantly during grain-filling and maturing of barley, and had returned to approximately
its initial level by the following spring. The maximum amount of NEA-N released was 15 g m–2 at barley grain-filling in 1994, and 10 g m–2 3 weeks after barley had matured in 1995. Approximately 24% of the released NEA accumulated as 1M-KCl-extractable NH4
+ in 1994, 20–30% was absorbed by the barley crop, and most of the remainder was probably assimilated by soil micro-organisms
and immobilized in soil organic matter. The release of significant amounts of NEA during crop growth has implications for
N cycling and measurements of mineralization/immobilization turnover rates.
Received: 21 July 1997 相似文献
38.
Incubation of soil under low partial pressures of acetylene (10 Pa) is a widely used method to specifically inhibit nitrification
due to the suicide inhibition of ammonium monooxygenase (AMO), the first enzyme in NH4
+ oxidation by nitrifying bacteria. Although the inhibition of AMO is irreversible, recovery of activity is possible if new
enzyme is synthesized. In experiments with three different soils, NH4
+ concentrations decreased and NO3
– concentrations increased soon after acetylene was removed from the atmosphere. Recovery of NO production started immediately
after the removal of acetylene. The release rates of NO and N2O were higher in soil samples which were only preincubated with 10 Pa acetylene than in those which were kept in the presence
of 10 Pa acetylene. In the permanent presence of 10 Pa acetylene, NH4
+ and NO3
– concentrations stayed constant, and the release rates of NO and N2O were low. These low release rates were apparently due to processes other than nitrification. Our experiments showed that
the blockage of nitrification by low (10 Pa) acetylene partial pressures is only reliable when the soil is kept in permanent
contact with acetylene.
Received: 17 July 1996 相似文献
39.
种植水稻和长期施用无机肥对红壤氨氧化细菌多样性和硝化作用的影响 总被引:6,自引:0,他引:6
以中国科学院红壤生态试验站发育于第四纪红黏土的植稻红壤为研究对象,研究了长期种植水稻和施用无机肥对土壤β-变形杆菌纲中氨氧化细菌多样性和硝化作用的影响。原始红壤改种水稻13年后,氨氧化细菌16SrDNA的DGGE条带数量增加,条带谱与原始红壤的差异较大,相似性为61%,说明种植水稻后土壤氨氧化细菌群落结构发生了变化。PCR-DGGE方法研究结果也显示,长期施用无机氮肥的处理(NP、NPK和NK),DGGE带谱相似性较高,达到73%,硝化率和硝化势均高于未施用氮肥的处理。逐步回归分析显示硝化率和硝化势均随着土壤脲酶活性的提高而显著增加。推测尿素可提高土壤水解氮含量,使土壤脲酶活性提高,促进硝化细菌的生长,进而提高硝化率和硝化势。 相似文献
40.
《Communications in Soil Science and Plant Analysis》2012,43(6):691-706
Abstract Cowpea nodules (Vigna unguiculata [L.] Walp. cv. CB5) were pierced with two opposing optical fibers (280 μm diameter), and absorbance spectra of 0.1 mm of nodule tissue were recorded from 415 to 600 nm using a modified spectrophotometer with a nodule sampling stage. The nodule spectra exhibited two absorbance bands, a major band in the near‐UV (415–450 nm) and a lesser one in the green‐yellow region (510–585 nm); the latter exhibited a prominent peak at 550 nm. Nodule spectra were consistent with the superposition of the spectra of ferroleghemoglobin (Lb2+), oxyleghemoglobin (Lb2+‐ O2), and cytochrome c (550 nm). The detection of leghemoglobin in vivo was confirmed by demonstrating the reversibility of binding of CO to Lb, and by comparing the spectra of live nodules with those obtained from anaerobic leghemoglobin preparations. The effects on the nodule spectra of two successive applications (36 and 39 days after planting) of 5 and 10 mM NO3 ‐ or NH4 + to the nutrient solution bathing the nodulated roots were determined. The spectra of NO3 ‐‐ and NH4 +‐treated nodules were indistinguishable; in each case the height of both the near‐UV and green‐yellow absorbance bands decreased with treatment. Treatment with N caused a significant reduction in the area of the green‐yellow absorbance band. The spectra of green leghemoglobin pigments were obtained from senescent nodules; these exhibited a reduction in the height of the near‐UV absorbance band and a flattening of the green‐yellow band similar to that of nodules treated with N, but the broadening of the near‐UV band was greater in green nodules. 相似文献