Optimizing Price Menus for Duration Discounts: A Subscription Selectivity Field Experiment

The broadcast fertilization method is widely used under basin irrigation in China. A reasonable broadcast fertilization method can effectively improve application performance of fertilization and reduce pollution from non-point agricultural sources. In this study, firstly, a non-uniform broadcast fertilization method and a non-uniform application coefficient were proposed. The value of non-uniform application coefficient is defined in this paper. It represents the ratio of the difference between the maximum and the average fertilization amount of fertilizer applied on the basin surface to the average fertilization amount of fertilizer applied on the basin surface. Secondly, field experiments were conducted to study the movement characteristics of fertilizer under non-uniform broadcast fertilization for basin irrigation. Field experiment results showed that under the condition of basin irrigation, the non-uniform broadcast fertilization method could weaken the non-uniform distribution of fertilizer due to erosion and transport capacity of solid fertilizer by irrigation water flow, which could significantly improve the uniformity of soil solute content. Thirdly, the solute transport model for broadcast fertilization was corroborated by the field experiment results. The variation rule of fertilization performance with non-uniform application coefficient under different basin length and inflow rate was achieved by simulation. The simulation results showed that fertilization uniformity and fertilization storage efficiency increased first and then decreased with the increase of non-uniform application coefficient. In order to be practically applicable, suitable irrigation programs of non-uniform application coefficient under different basin length and inflow rate conditions were proposed by numerical simulation.

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High phosphorus concentrations in seed of wheat and annual medic are related to higher rates of dry matter production of seedlings and plants

Australian Journal of Experimental Agriculture ◽

10.1071/ea9880765 ◽

1988 ◽

Vol 28 (6) ◽

pp. 765 ◽

Cited By ~ 41

Author(s):

MDA Bolland ◽

MJ Baker

Keyword(s):

Triticum Aestivum ◽

Field Experiment ◽

Western Australia ◽

Dry Matter ◽

Field Experiments ◽

Medicago Polymorpha ◽

P Concentration ◽

Pot Experiments ◽

Matter Production ◽

Burr Medic

Seed of 2 cultivars of wheat (Triticum aestivum) and 1 burr medic (Medicago polymorpha) with increasing phosphorus (P) concentrations (wheat 1.4-3.7 g P/kg dry matter, medic 3.3-7.9 g P/kg dry matter) were collected from field experiments with variable levels of applied superphosphate (wheat 0- 577 kg P/ha, medic 0-364 kg P/ha) in south-western Australia. These seeds were used in further experiments to examine the effect of seed P concentration on the subsequent dry matter (DM) production of seedlings and plants in 3 glasshouse pot experiments and 1 field experiment. Seed of the same size (wheat, 35 mg/seed; medic, 3.6 mg/seed) but with increasing P concentration produced substantially higher DM yields in the absence or presence of freshly applied superphosphate P up to 28-35 days after sowing in the pot experiments and 67 days after sowing in the field experiment.

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Growth, freezing tolerance, and yield performance of alfalfa (Medicago sativaL.) cultivars grown under controlled and field conditions in northern latitudes

Canadian Journal of Plant Science ◽

10.1139/cjps-2017-0305 ◽

2018 ◽

Vol 98 (5) ◽

pp. 1109-1118 ◽

Cited By ~ 2

Author(s):

Mervi M. Seppänen ◽

Ville Alitalo ◽

Hanna K. Bäckström ◽

Kirsi Mäkiniemi ◽

Venla Jokela ◽

...

Keyword(s):

Field Experiment ◽

Cold Acclimation ◽

Freezing Tolerance ◽

Field Experiments ◽

Starch Content ◽

Day Length ◽

Forage Legume ◽

Northern Latitudes ◽

Medicago Sativa L ◽

Second Year

Alfalfa (Medicago sativa L.) is one of the most popular forage legume crops worldwide. Its cultivation in the boreal and sub-boreal zone is restricted by inadequate winter hardiness, but global warming may increase its adaptability in these latitudes. Here, we examined variation in growth and freezing tolerance of four alfalfa cultivars recommended for the northern temperate climates of Europe (Alexis, Lavo, Live, and Nexus) and two cultivars with adaptation to milder or Mediterranean climates (Rangelander and Hunter River). Two experiments under controlled conditions (growth cessation and cold acclimation experiments) along with a 2-yr field experiment were conducted. Lavo was the most freezing-tolerant cultivar in both the cold acclimation and field experiments. Both Rangelander and Hunter River showed poor freezing tolerance. Lavo responded to decreasing temperatures, unlike the response to shorter day length, by allocating biomass to the roots. In general, better freezing tolerance was associated with high total nonstructural carbohydrate and low starch content. The field experiment results revealed that the more freezing-tolerant cultivars may have some advantages regarding yield, especially in the second year, but the differences between the cultivars were modest.

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Activity of insecticides on coffee berry borer (Hypothenemus hampei) (Coleoptera: curculionidae, scolytinae)

Bioscience Journal ◽

10.14393/bj-v36n4a2020-46735 ◽

2020 ◽

Vol 36 (4) ◽

Author(s):

Dieudilait Metellus ◽

Marcus Vinicius Sampaio ◽

Fernando Juari Celoto

Keyword(s):

Field Experiment ◽

Field Experiments ◽

Residual Effect ◽

Petri Dish ◽

Hypothenemus Hampei ◽

Artificial Infestation ◽

Artificial Breeding ◽

Eggs And Larvae ◽

Residual Control ◽

Green Stage

The objective of this work was to evaluate the topical, residual and agronomic effects of the insecticides Voliam Targo, Benevia, Lorsban 480 BR, Curbix 200 SC, Sperto, Verismo, Polytrin 400/40 CE, Curyom 550 EC, Polo 500 SC and Vertimec 18 EC in the control of the berry borer of coffee (H. hampei). The experimental design was completely randomized and four replicates were used in the trials. In the laboratory, a direct spray was sprayed on the insect (topical effect) and applied to the fruits of the coffee (residual contamination). In both experiments, each plot consisted of a Petri dish lined with filter paper, 10 fruits in the green stage and 10 adult females of the berry borer, originating from artificial breeding. Two field experiments were carried out at Campus Glória Experimental Farm. The first one was carried out with the objective of evaluating the residual effect of the insecticides on artificial infestation of the berry borer after applying the products to fruits at the beginning of maturation. The number of perforated fruits, dead females, number of eggs and larvae were evaluated in laboratory and field experiments. The second field experiment had as objective to evaluate the effectiveness in controlling the natural population of the berry borer. Two applications were performed with a 30-day interval, using a motorized turbocharger. The number of fruits bored in 50 fruits per plot and percentage of seeds bored in a sample of 250 seeds per replicate were evaluated. In the laboratory, all insecticides provided mortality higher than 80% in topical application and greater than 73% by residual contamination, except the insecticide Polo 500 SC, which provided a 55% mortality. In the field experiment with artificial infestation, all the insecticides differed from the control, maintaining residual control until 30 days after application and with mortality higher than 70%, reaching up to 100% of mortality. In the test with natural berry borer females infestation the insecticides differed from the control in all evaluated parameters, showed efficacy higher than 75% at 35 days after the second application. The insecticides Voliam Targo, Lorsban 480 BR, Curbix 200 SC, Sperto, Polytrin 400/40 CE and Verismo presented the best control results, being indicated for use in the management of the berry borer of coffee.

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Susceptibility of Myzus persicae, Brevicoryne brassicae and Nasonovia ribisnigri to Fungal Biopesticides in Laboratory and Field Experiments

Insects ◽

10.3390/insects11010055 ◽

2020 ◽

Vol 11 (1) ◽

pp. 55

Author(s):

Gill Prince ◽

Dave Chandler

Keyword(s):

Field Experiment ◽

Myzus Persicae ◽

Field Experiments ◽

Brevicoryne Brassicae ◽

Vegetable Crops ◽

Potato Aphid ◽

Cabbage Aphid ◽

Nasonovia Ribisnigri ◽

Fungal Biopesticides ◽

Peach Potato Aphid

The aim of this study was to evaluate the potential of entomopathogenic fungi (EPF) for the control of aphid pests of field vegetable crops. Four biopesticides based on the EPF Beauveria bassiana (Botanigard ES and Naturalis L), Cordyceps fumosorosea s.l. (Preferal WG), and Akanthomyces dipterigenus (Vertalec) were evaluated in a laboratory bioassay against peach-potato aphid Myzus persicae, cabbage aphid Brevicoryne brassicae, and currant-lettuce aphid Nasonovia ribisnigri. There was significant variation in the spore dose provided by the products, with Botanigard ES producing the highest dose (639 viable spores per mm2). Botanigard ES also caused more mortality than the other products. Combining Vertalec with the vegetable oil-based adjuvant Addit had an additive effect on the mortality of B. brassicae. All fungal products reduced the number of progeny produced by M. persicae but there was no effect with B. brassicae or N. ribisnigri. When aphid nymphs were treated with Botanigard ES and Preferal WG, both products reduced population development, with up to 86% reduction occurring for Botanigard ES against M. persicae. In a field experiment, Botanigard ES sprayed twice, at seven-day intervals, against B. brassicae on cabbage plants, reduced aphid numbers by 73%. In a second field experiment with B. brassicae, M. persicae, and N. ribisnigri, Botanigard ES reduced populations of B. brassicae and N. ribisnigri but there was no significant effect on M. persicae.

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Field Experiments and Behavioral Theories: Science and Ethics

Political Science and Politics ◽

10.1017/s1049096519001112 ◽

2019 ◽

Vol 53 (1) ◽

pp. 89-93 ◽

Cited By ~ 1

Author(s):

Elizabeth Carlson

Keyword(s):

Field Experiment ◽

Real World ◽

Field Experiments ◽

Experimental Treatment ◽

Constant Field ◽

Relevant Factor ◽

Multiple Factors ◽

Behavioral Theories ◽

Political Theories

ABSTRACTThe design of field experiments makes them inappropriate for testing many common political theories. These theories propose that certain factors—for example, income or information—affect how individuals make choices. To test these theories, researchers typically investigate the correlation between the relevant factor and individuals’ choices, holding other factors constant. Field experiments, in contrast, allow multiple factors to vary at once: they create real-world disruption and do not control how actors behave in response. Subjects’ choices will be affected by the experimental treatment as well as by other changes that occur as the larger system reacts. It will be difficult to isolate the effect of any one factor, particularly without a good preexisting model of the system and how it is likely to respond. If a field experiment will not tell us what we need to know, the benefit of the study cannot outweigh harm, and it also will be unethical.

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Studying Abroad as a Sorting Criterion in the Recruitment Process: A Field Experiment Among German Employers

Journal of Studies in International Education ◽

10.1177/1028315317697543 ◽

2017 ◽

Vol 21 (5) ◽

pp. 412-430 ◽

Cited By ~ 8

Author(s):

Knut Petzold

Keyword(s):

Human Capital ◽

Experimental Design ◽

Field Experiment ◽

Social Desirability ◽

Recruitment Process ◽

Job Interviews ◽

Studying Abroad ◽

Professional Careers ◽

Self Selection ◽

Available Information

As the experience of studying abroad can signal general and transnational human capital, it is considered to be increasingly important for professional careers, particularly in the context of economies’ internationalization. However, studies using graduate surveys face problems of self-selection and studies on employers’ opinions face problems of social desirability. To overcome endogeneity problems and to investigate the employers’ decisions directly, a particular field experimental design of a correspondence test was applied. Two hundred thirty-one applications of a real student with systematically varied studying abroad and professional working experience were randomly sent out for true internship offers of German employers. The time provided for the response and invitations for job interviews was measured, and additional publicly available information on the employers were collected. Results show that studying abroad decreases the days required until response and slightly increases the probability of invitation. However, at least in this field experiment, studying abroad is considered to be more of a sorting criterion by the employers with foreign branches than by those without.

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The Biochar challenge in Mediterranean viticulture: results from 10 years of field experiment

10.5194/egusphere-egu2020-20731 ◽

2020 ◽

Author(s):

Silvia Baronti ◽

Anita Maienza ◽

Fabrizio Ungaro ◽

Antonio,Antonello Montagnoli ◽

Lorenzo Genesio ◽

...

Keyword(s):

Climate Change ◽

Field Experiment ◽

Water Relations ◽

Soil Amendment ◽

Field Experiments ◽

Central Italy ◽

Plant Water ◽

Grape Quality ◽

Mediterranean Countries

<p>There are extensive reports and scientific articles in literature on the applicability of biochar as soil amendment in agriculture and on the benefits that this practice can bring in terms of soil improvement and optimization of water resources. The use of biochar as a soil amendment in agriculture is a suitable option that helps to mitigate the effects of climate change. Biochar has an approximate mean residence time in the soil over 1,000 years and this long-term stability is a fundamental prerequisite for considering biochar as a suitable method for carbon sequestration. Unfortunately, most literature provides results based on one-year trials. Not enough for a soil amendment to be able to claim effectiveness for many decades and not enough for a soil treatment to be considered irreversible. An effective option to fill this knowledge gap is represented by long-term field experiments. In this study, we investigated the effect of biochar application on plant water relations and soil properties during 10 years in a field experiment in Central Italy on Vitis vinifera. Biochar was applied at a rate of 22 t ha-1 in two consecutive growing seasons: 2009 and 2010. The results obtained during these years on biochar treatment compared to the control treatment are exciting: we demonstrated an increase in grape production, up to 66%, without a decrease of the grape quality, an increase in plant-soil water relations, no effects on the concentrations of soil PAHs, no eco-toxicity soil effect and a positive effect on soil chemical and biological parameters. Surprisingly, after 10 years the biochar effect continued to demonstrate significant differences among treatments, in particular: a significant increase of soil biological quality, decrease in soil bulk density coupled with a corresponding increase in saturated hydraulic conductivity, an enhance in soil available water content and a significant improvement of plant water status. The modification of plant water availability induced by biochar application increase the resilience of vineyards to droughts, as demonstrated by the lower leaf potential and higher stomatal conductance. This effect has a significant impact on quantity and quality of grape production after 10 years. Moreover, in the long-term perspective the biochar demonstrates to have an effect on soil biological communities that resulted sensitive to biochar with positive increase of abundance of species related to soil moisture content and enhance of biodiversity index. According to these results, the viticulture is now in the position to provide an effective contribution to mitigate climate change and we expect that this will be an example for other Mediterranean countries.</p>

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L'importance des interactions dans une population de l'araignée Lepthyphantes flavipes (Blackwall) (Araneida: Linyphiidae)

Canadian Journal of Zoology ◽

10.1139/z91-314 ◽

1991 ◽

Vol 69 (8) ◽

pp. 2246-2249 ◽

Cited By ~ 1

Author(s):

Jacques Leclerc ◽

Patrick Blandin

Keyword(s):

Field Experiment ◽

Web Sites ◽

Web Site ◽

Field Experiments ◽

Deciduous Forest ◽

Interference Competition ◽

Forest Litter

The significance of interactions between spiders was evaluated in a population of Lepthyphantes flavipes (Blackwall) that occurs on a deciduous forest litter. Three hypotheses are presented: (i) H0, interactions, mainly interference competition for web sites, are not important in structuring the population; (ii) H1, spiders tend to use silk from deserted webs; (iii) H2, dominant spiders tend to displace resident subordinate spiders from their web sites. Because spinning a new web is costly in Lepthyphantes, substantial gain may be obtained when moving to a new web site under hypotheses H1, and H2. These hypotheses were tested in a field experiment by means of plastic rings introduced on litter as web sites. Results confirm hypothesis H0. Hypothesis H1 is not rejected for small-sized spiders and needs to be explored through more field experiments. Hypothesis H2 is rejected.

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