Nitrogen release dynamics of a slow release urea pellet and its effect on growth,yield, and nutrient uptake of sweet basil (Ocimum basilicum L.)

Manure urea pellets were produced and their nitrogen release rate was evaluated in soil incubation at different water contents of 90, 75, and 60% soil filed capacity (FC). In another experiment, sweet basil growth was evaluated during eight months (with three shoot harvests) under the pellet application. The nitrogen release and pellet dispersion rates were slow after two months or at lower soil water content (60% FC), but they were significant after four months of soil incubation, or at higher soil water content (75 or particularly 90% FC). Application of pelleted urea reduced plant growth and yield at first harvest than urea treatment. However, at second and particularly at third harvest (and the average of three harvests) significant improvement in growth parameters of SPAD value, leaf area, plant height, shoot fresh weight, pot yield, and` leaf N and K concentrations were achieved by application of pelleted urea fertilization.     

Translocation of bacteria from animal excrements to soil and associated habitats

The population dynamics of Salmonella enterica var. Typhimurium MAE 110 gfp, Escherichia coli O157:H7 gfp, and Pseudomonas fluorescens 32 gfp were investigated in their introduction to cattle excrements and subsequent entering the soil, plants of cress (Lepidium sativum L.), and migration through the gastroenteric tract of French snails (Helix pomatia L.). The survival of these bacteria in the excrements and soil was investigated at cyclically changing (day-night, 25–15 °C) and constant (18 °C) temperatures. The cyclically changing temperature adversely affected the survival of E. coli O157:H7 gfp, and P. fluorescens but did not influence S. enterica var. Typhimurium. All the bacteria and, especially, the analogues of enteropathogens showed high survival in the cattle and snail excrements, soil, and on the plants under the gradual decrease in their population. On the cress plants grown in a mixture of cattle excrements and soil, an increase in the number of the introduced bacteria was observed.     

Effect of urea pellet size and dicyandiamide on residual ammonium in field microplots

Abstract

Nitrification of urea can be slowed by adding a nitrification inhibitor or by fertilizer localization. The purpose of this research was to compare the effects of urea pellet size (0.01, 0.1, and 1.0 g) and level of dicyandiamide (DCD) addition (0, 1, 2, 5, and 10% of N as DCD‐N) on residual ammonium in field microplots. Trials were conducted at ten locations in North Dakota during 1988 and 1989. Adding DCD to 0.01 g urea pellets slowed nitrification at all locations and the lower rates of DCD (1–2% of N as DCD‐N) often performed as well as higher rates. Increasing urea pellet size to 1.0 g was more effective in inhibiting nitrification than adding DCD to 0.01 g pellets. Increased pellet size plus addition of DCD led to a very slow nitrification. A 1.0 g urea pellet containing 1–2% of N as DCD‐N should be a practical fertilizer formulation where a very slow nitrification is required.     

Growth of Hedera helix L. Container Plants in Compost Substrates Made with Miscanthus ogiformis Honda Straw and Various N-Sources

Ammonium sulfate or urea were added as N-source to shredded straw of Miscanthus ogiformis ‘Giganteus’ and water was included as control. The combined materials were composted for seven months, and the resulting composts were tested as growth substrates for nursery container plants and compared with fertilized and unfertilized peat substrates. The pH was below recommended level for the compost substrate made with ammonium sulfate and for the unfertilized peat substrate throughout the experiment. Electrical conductivity and concentrations of most nutrients were low and decreased throughout the experiment for all growth substrates. Shrinking of the growth substrates after 4, 12 or 17 months was larger for compost substrates than for peat substrates. Bulk density increased in compost substrates and decreased in peat substrates, while the total loss of C was greater in compost substrates than in peat. Water retention was lower and air volume greater for compost substrate made with ammonium sulfate than for fertilized peat. Algae and mosses did not occur on Miscanthus compost growth substrates in contrast to peat substrates. The shoot length and dry matter of Hedera helix, produced after four and 12 months of growth, and five months following cut back, showed that plants can grow well in compost substrates made of Miscanthus straw and ammonium sulfate or urea. However, the compost substrates could not fully substitute for fertilized or unfertilized peat substrate with respect to dry matter production.     

Effect of copper and nitrogen nutrients on diosgenin production in fenugreek

Different amounts of nitrogen (N) and copper (Cu) in the forms of urea and copper sulfate (CuSO₄·5H₂O) were applied and their effects on diosgenin production and dry matter yield in fenugreek were investigated under farm cultivation conditions. High-performance liquid chromatography (HPLC) was employed to analyze diosgenin content. Diosgenin contents were measured in 25, 45 and 65 day-old leaves and in leaves at flowering stage and in fruits. The maximum diosgenin content was obtained in 45 day-old leaves. The results showed that simultaneous addition of Cu and N and the level of supply had significant effects on diosgenin production in leaves, fruits and dry matter yield. Simultaneous use of urea (100 kg ha^?1) and copper sulfate (30 kg ha^?1) increased diosgenin production and dry matter yield in 45 day-old leaves for 7.72 and 1.32 times, respectively, compared to unfertilized control group. But, the use of higher amounts of urea and copper showed a decrease in diosgenin production.     

Critical nitrate levels for leaf lettuce,radish, and spinach plants

Abstract

Leaf lettuce (Lactuca sativa var. crispa L.), radish (Raphanus sativus L.), and spinach (Spinacea oleracea L.) plants were grown in sand culture under variable N concentrations from 0.187 to 48.0 meq/l. The plants were harvested when those grown at 12 meq N/l had attained approximate market maturity. Growth was restricted, and symptoms of N deficiency were evident at the low levels of N. Growth was also restricted at the highest N level. Approximate critical levels for leaf lettuce, radish roots, and spinach are 2000 ppm, 5000 ppm, and 4000 ppm, nitrate‐N respectively, on a dry weight basis.     

Responses of photosynthesis,chlorophyll fluorescence,and grain yield of maize to controlled‐release urea and irrigation after anthesis

Controlled‐release urea (CRU) is a new type of urea, which may increase crop nitrogen (N)‐use efficiency compared with conventional urea (CU), but the conditions where it outperforms urea are not well defined. A field experiment assessing responses of plant growth and grain yield of maize to CRU and irrigation was conducted on a typical agricultural farm in Shandong, China. Five treatments of the two types of urea (75, 150 kg N ha^–1, 0 kg N ha^–1) were applied as basal fertilizer when sowing maize, and two water treatments (W₀ and W₁) were used 23 d after anthesis. Net photosynthetic rate (P_N) and chlorophyll concentration as well as leaf‐area index (LAI) increased significantly by both CRU and CU application, with the increases being larger in CRU‐treated plants than in CU‐treated plants at grain filling and maturing stages. CRU significantly enhanced the maximum photochemical efficiency (F_v / F_m), PSII coefficient of photochemical fluorescence quenching (q_P), and actual quantum yield of PSII electron transformation (Φ_PSII) but decreased the nonphotochemical quenching (NPQ). Cob‐leaf N concentration of CRU‐treated plants was significantly higher than that of CU‐treated plants under no irrigation, but not in the irrigation treatment 30 d after anthesis. Significant positive correlations were found between cob‐leaf N concentration and P_N both with and without irrigation. Grain yield of maize was significantly higher in the CRU treatment than in the CU treatment under both irrigation conditions. In conclusion, CRU as a basal application appeared to increase the N‐use efficiency for maize relative to CU especially by maintaining N supply after anthesis.     

Yield potential of garden pea (Pisum sativum L.) varieties,and soil properties under organic and integrated nutrient management systems

The identification of suitable crop varieties that respond best to organic management is the key to achieving better crop yields. A field experiment was conducted during the winter season of 2005–2006 and 2006–2007 at Almora (Indian Himalayas) to evaluate the performance of five varieties of garden pea (Pisum sativum L.) and changes in the soil properties under organic and integrated nutrient management (INM) systems. The yield reduction under organic management was 14.4% in 2005–2006 and 10.1% in 2006–2007 compared with INM. Among the garden pea varieties ‘Vivek Matar 9’, ‘Vivek Matar 8’ and ‘Azad pea 1’ produced similar but significantly higher pod yield compared to other varieties. The soil pH, organic carbon, and microbial activities in terms of dehydrogenase and phosphatase (acid and alkaline) were higher in the plots under organic management compared to INM. The latter, however, had higher activity of urease, and N, P, and K contents in soil. We conclude that at least 15–20% price premium for organic garden pea may be required to offset the higher cost of cultivation and low yields under organic production system. Among the garden pea varieties, ‘Azad pea 1’, ‘Vivek Matar 8’ and ‘Vivek Matar 9’ were found suitable for organic cultivation.     

Microbiological survey of selected imported spices and associated fecal pellet specimens

A microbiological survey was performed on 4 selected imported spices: black peppercorns, white peppercorns, coriander, and fennel seed. Aerobic plate count values ranged from 10(4) to 10(7) colony-forming units (CFU)/g for black and white peppercorns and from 10(3) to 10(5) CFU/g for coriander and fennel seed. Combined results of the 3-tube most probable number procedure and the API 20E kit indicated the presence of Escherichia coli in 4 test samples of black peppercorns, 1 test sample of white peppercorns, and 1 test sample of coriander. Two test samples of black peppercorns were positive for Salmonella contamination. Among the various Enterobacteriaceae isolated from the spices, Enterobacter cloacae and Klebsiella pneumoniae were found most frequently in all spice types. Of 18 mammalian and avian fecal pellets removed from the spices and analyzed microbiologically, E. coli was found in only 2 pellet specimens. There was no apparent relationship between the enteric microflora found in spices and those found in the fecal pellets.     

Effect of Foliar Application of Urea on Reproductive Abscission and Grain Yield of Soybean

Abstract

Soybean (Glycine max L., Merr.) is considered to have relatively high level of reproductive abscission, but research information on how fertilizer use influences this problem is scanty. Field trials were therefore carried out for two seasons (1996 and 1998) to investigate the abscission levels of three soybean cultivars (TGX 536‐02D, TGM 579, and Samsoy 11) as affected by foliar application of urea during the early reproductive stages. Flowering was not significantly increased by urea application, although all fertilized plants had fewer flower abortions than control. Fertilizing twice at full‐flowering and pod‐setting (R2–R3) or thrice at first‐flowering, full‐flowering, and pod setting (R1–R2–R3) stages gave the least flower abortion. In TGX 536‐02D the average flower abortion was 61% in 1996 and 57% in 1998. The abortion rate was about 60% for TGM 579 in 1996 and Samsoy 11 in 1998, respectively. Percentage pod abortion was generally reduced especially at the R1–R2–R3 stage, while the proportion of aborted grains was highest in the unfertilized plants. Fertilizing at R2–R3 and R1–R2–R3 reduced seed abortion by about 8% in TGX 536‐02D. The grain yield of fertilized soybean was between 6 and 68% higher than the control. These increases were attributed to higher number of pods and meaningful reductions in flower and pod abortions. Foliar applied urea at R2–R3 gave satisfactory results but the best stage of application was R1–R2–R3.     

Consequences of ex situ cultivation of plants: Genetic diversity, fitness and adaptation of the monocarpic Cynoglossum officinale L. in botanic gardens

Ex situ collections in botanic gardens have great potential in contributing to the conservation of rare plants. However, little is known about the effects of cultivation on the genetic diversity and fitness of garden populations, about genetic changes due to unconscious selection and potential adaptation to the artificial conditions. We compared the genetic variability and fitness of the rare, short-lived perennial Cynoglossum officinale from 12 botanic gardens and five natural populations in Germany. Genetic variability was assessed with eight nuclear microsatellites. Plants were grown in a common garden and performance was measured over 2 years. Mean genetic diversity was very similar in botanic garden and natural populations. However, four of the garden populations exhibited no genetic variability at all. Moreover, the genetic diversity of garden populations decreased with increasing duration of cultivation, indicating genetic drift. Plant performance from natural and garden populations in terms of growth, flowering and seed production was similar and in garden populations only seed mass was strongly related to genetic diversity. Several lines of evidence indicated genetic changes in garden populations in response to cultivation. Seed dormancy was strongly reduced in garden populations, and in response to nutrient addition garden plants increased the size of their main inflorescence, while wild plants increased the number of inflorescences. These changes could be maladaptive in nature and reduce the suitability of garden populations as a source for reintroductions. We suggest that botanic gardens should pay more attention to the problem of potential genetic changes in their plant collections.     

Interaction of 15N-labelled ammonium nitrate,urea and ammonium sulphate with soil N during growth of wheat (Triticum aestivum L.) under field conditions

The effects of ¹⁵N-labelled ammonium nitrate, urea and ammonium sulphate on yield and uptake of labelled and unlabelled N by wheat (Triticum aestivum L. cv. Mexi-Pak-65) were studied in a field experiment. The dry matter and N yields were significantly increased with fertilizer N application compared to those from unfertilized soil. The wheat crop used 64.0–74.8%, 61.5–64.7% and 61.7–63.4% of the N from ammonium nitrate, urea and ammonium sulphate, respectively. The fertilizer N uptake showed that ammonium nitrate was a more available source of N for wheat than urea and ammonium sulphate. The effective use of fertilizer N (ratio of fertilizer N in grain to fertilizer N in whole plant) was statistically similar for the three N fertilizers. The application of fertilizer N increased the uptake of unlabelled soil N by wheat, a result attributed to a positive added N interaction, which varied with the method of application of fertilizer N. Ammonium nitrate, urea and ammonium sulphate gave 59.3%, 42.8% and 26.3% more added N interaction, respectively, when applied by the broadcast/worked-in method than with band placement. A highly significant correlation between soil N and grain yield, dry matter and added N interaction showed that soil N was more important than fertilizer N in wheat production. A values were not significantly correlated with added N interaction (r=0.719). The observed added N interaction may have been the result of pool substitution, whereby added labelled fertilizer N stood proxy for unlabelled soil N.     

不同缓/控释尿素对小麦生长及氮素利用的影响

  【目的】   通过大田试验筛选山东省适宜于小麦生长的缓/控释尿素，并初步研究其氮素高效利用的机制。   【方法】   选用的肥料产品有4种，包括树脂包膜尿素 (PCU)、多肽尿素 (PPU)、脲甲醛尿素 (UF) 和本实验室制备的树脂包膜与脲酶抑制剂结合型控释尿素 (CHQ)，以普通尿素和不施氮肥为对照，分别在山东潍坊和泰安进行田间试验，供试小麦品种为‘济麦22号’，普通尿素按1∶1比例基施和追施，缓/控释肥均一次性基施。分析了小麦不同时期的株高和单株分蘖数、花前花后干物质积累与转运、产量及其构成因素、氮肥利用率以及土壤无机氮含量和脲酶活性的变化。   【结果】   施用4种缓/控释尿素均降低了小麦越冬期的土壤脲酶活性，减缓尿素水解，降低土壤无机氮含量；成熟期，在潍坊试验点仅CHQ处理的土壤无机氮含量高于尿素处理，在泰安试验点4种缓/控释尿素处理的土壤无机氮含量均高于尿素处理，以CHQ处理的无机氮含量最高，CHQ处理的土壤无机氮含量在泰安和潍坊2个试验点较尿素处理分别增加了81.86%和6.20%。与尿素相比，在泰安试验点施用4种缓/控释尿素均可促进小麦生长，提高小麦花前干物质转运与花后干物质生产量，有利于小麦的群体构建和产量形成，增强小麦对氮素的吸收利用能力，提高氮肥利用率，以CHQ表现最优；而在潍坊试验点，仅CHQ肥效优于尿素。CHQ在泰安和潍坊的小麦产量分别为6966.67和10342.22 kg/hm2，较尿素处理分别增加了38.69%和11.07%；氮素生产效率分别为18.83和26.72 kg/kg，较尿素处理分别增加了38.66%和11.06%。潍坊试验点小麦产量和氮素生产效率整体高于泰安，CHQ较尿素的增效幅度低于泰安试验点。   【结论】   土壤肥力影响缓/控释尿素对小麦的增产效果，在高肥力的壤土 (潍坊) 上，只有既控制尿素释放速率又控制其在土壤中的水解速率的树脂包膜与脲酶抑制剂结合型控释尿素可有效促进小麦生长及其对氮素的吸收利用，在低肥力砂壤土 (泰安) 上，4种缓/控释尿素在小麦生长后期均可维持土壤中较高的氮素供应，肥效均好于普通尿素。综合而言，在山东省建议优先选择树脂包膜与脲酶抑制剂结合型控释尿素。     

Influence of water regime on growth,yield, and nitrogen uptake of rice

Abstract

Greenhouse and field experiments were conducted to study the effects of water regime on growth of rice. The greenhouse experiment investigated the effects of two water regimes‐continuous flooding and flooding with soil drying between crops for 2 to 3 weeks on the growth of rice during six cropping (for six week each) on seven soils varying widely in total N contents (0.07 to 0.35%). The results averaged for the 7 soils indicated that the drymatter production or N uptake of rice was not affected by the water regimes during the six croppings.

The field experiment conducted during the dry season for two consecutive years (1976 and 1977) on a near neutral clay soil studied the effects of three water regimes (continuous flooding alternate flooding and soil drying every 2 weeks, and continuous flooding with 2 weeks mid season soil drying after 6 weeks of transplanting) and three levels of fertilizer N (0, 100 and 200 kg N/ha as urea) on grain yield and N uptake of rice. The results confirmed the absence of any significant reduction in grain yield or N uptake as a result of any of the soil drying treatments during the growing season on the unfertilized plots carrying a rice crop. On the plots fertilized with 100 or 200 kg N/na, alternate flooding and drying resulted in a significant depression in both grain yield and N uptake. Soil analysis supported heavy losses of N in the fertilized plots that underwent alternate flooding and soil drying apparently by nitrification and denitrification reactions.

The results of this study suggest that alternate flooding and drying of soils in the presence of established rice plants itiay not cause a significant loss of nitrogen in unfertilized plots although in plots fertilized with high rates of N the losses may be large as indicated by the performance of rice crop.     

Biological Quality of Potting Media Based on MSW Composts: A Comparative Study

Municipal solid waste (MSW) compost from aerobic or anaerobic bioprocesses was evaluated as components of substrates for potted plant production. Experiments were conducted with potted media consisting of MSW compost mixed with other conventional substrates (peat or composted pine bark). Spring barley (Hordeum vulgare L.) and cress (Lepidium sativum L.) were used to evaluate the biological quality of composts. Higher germination rates of spring barley were obtained when MSW compost from aerobic treatment was employed as compared with MSW compost from the anaerobic bioprocess. Improved biological indices were observed when MSW composts were mixed with composted pine bark rather than with peat. Mixtures of 75% aerobic MSW compost and 25% composted pine bark were more favorable for cress growth than peat as sole substrate.     

Influence of Azolla (Azolla microphylla Kaulf.) compost on biogenic gas production,inorganic nitrogen and growth of upland kangkong (Ipomoea aquatica Forsk.) in a silt loam soil

Azolla microphylla Kaulf. (Azolla) biomass was composted to create a high nitrogen (N) organic matter amendment (Azolla compost). We examined the effect of this Azolla compost on carbon (C) and N mineralization and the production of biogenic gases, nitrous oxide (N₂O) and carbon dioxide (CO₂), in a soil incubation experiment. A pot experiment with upland kangkong (Ipomoea aquatica Forsk.) examined plant growth in silt loam soil treated with three levels of Azolla compost. The results showed that N₂O production from soil increased with urea amendment, but not with Azolla compost treatments. The Azolla-amended soil showed enhanced CO₂ production throughout the 4-week incubation. The Azolla-treated soils showed a 98% lower global warming potential compared to urea treatment over the 4-week incubation. However, Azolla-amended soil had higher nitrate (NO₃^–) levels compared to urea-fertilized soil at 1 week of incubation, and these were maintained until the fourth week. Soils amended with Azolla compost showed lower ammonium nitrogen (NH₄-N) levels than those in the urea-fertilized soils. The height and dry weight of upland kangkong fertilized with Azolla compost were similar to plants receiving urea fertilization. Therefore, the use of Azolla compost as a substitute for urea fertilizer would be beneficial for reducing the production of N₂O while maintaining plant growth.     

Evaluation of Indian coriander accessions for resistance against stem gall disease

Seventy accessions of coriander (Coriandrum sativum L.) were screened for resistance against stem gall, a severe disease caused by Protomyces macrosporus Unger., with the goal to select the resistant cultivars. The accessions PH-7, Pant Haritima, COR-17 and COR-2 were highly resistant. These may be used as the parents to breed high yielding accessions resistant to stem gall disease.     

Effects of deep placement of controlled-release nitrogen fertilizer on soybean growth and yield under sulfur deficiency

Sulfur (S) and Nitrogen (N) metabolisms in plants are interacted and it is known that S deficiency decrease N absorption and metabolism. In leguminous plants S deficiency also decreases N₂ fixation by rhizobia in the nodules. Deep placement of a controlled-release N fertilizer is a good method to provide nitrogen to soybean without inhibiting N₂ fixation; thus, it was hypothesized that this method is able to provide nitrogen effectively to sulfur-deficient soybean plants. In this study effects of deep placement of coated urea on S-N physicological interaction, growth and productivity in soybean plants were examined using pot experiments. Soybean plants were grown with sulfate concentrations of 30, 100, or 1000 μM, with or without deep placement of coated urea. Shoot weights at the developing stage were not affected by S deficiency. SPAD values of leaves during the flowering stage decreased with S deficiency and increased with the deep placement of coated urea. S deficiency decreased seed weight per plant at the harvesting stage, but this decrease was attenuated by the deep placement of coated urea. N and S content in shoots at the developing stage increased with the deep placement of coated urea, whereas in seeds, only the N content increased. N₂ fixation activity based on the relative ureide-N content in xylem sap indicated that the deep placement of coated urea did not inhibit N₂ fixation activity at the early flowering stage. Without deep placement of coated urea, the relative ureide-N content decreased under S deficiency at the seed filling stage. These results suggest that the deep placement of coated urea is an efficient method to supply N to support soybean yield under S deficiency.

Abbreviations: Deep+: with deep placement of coated urea; Deep–: without deep placement of coated urea     

Critical nitrate levels for squash,cucumber and melon plants

Abstract

Squash (Cucurbita pepo), cucumber (Cucumis sativus) and sweet melon (Cucumis dudain) plants were grown in sand culture with N as the variable and were harvested at the early flowering stage. The plants at this time showed a definite gradation of symptoms from severe to no deficiency of N. The tops were separated into leaves and stems. Leaves were separated into young, mature and old and then subdivided respectively into petioles and blades. The petioles were analyzed for NO₃‐N. The critical NO₃‐N concentration for squash, cucumber and melon on a dry basis was 1000, 2000 and 3000 ppm, respectively. A relatively high concentration of NO₃‐N in the nutrient solution decreased the growth of squash and cucumber plants significantly, but had no effect on melon plants. Melon plants can tolerate relatively high concentrations of N0,‐N in the plant tissues, while squash and cucumber cannot.