TITLE    (click title to view slides)

Field Plots & Agricultural Research

Dr. Bob Kemerait & Dr. Eric P. Prostko
Cooperative Extension Service
University of Georgia

• Slide Presentation (PowerPoint, 148 KB)

TABLE OF CONTENTS

Field Plots & Agricultural Research Safety First Topics Demonstration Plots Demonstration Plots example: rates of nitrogen on a field crop Replicated Field Plots Replicated Trial example: effect of different rates of nitrogen How many replications are enough? You want how many reps???!!!! Common Types of Experimental Design Completely Randomized Design, 4 reps Randomized Complete Block, 4 reps Field Example Field Example: Block Orientation #1 Field Example: Block Orientation #2 Split-Plot Design Plot Maintenance Data Analysis What’s so significant about "significance"? Getting Started with a Field Trial GOOD LUCK!

SLIDE CONTENTS

Field Plots & Agricultural Research Dr. Bob Kemerait & Dr. Eric Prostko University of Georgia Cooperative Extension Service April 2001 PPT Slide SAFETY FIRST Topics Demonstration plots vs replicated field trials Importance of replications Common experimental designs CRD, RCBD, Split-plot, Factorial Small plots or large plots? Plot maintenance Data analysis & “significance” Steps for a successful trial Demonstration Plots Objectives example/information for growers simple qualitative comparisons Advantages simple to coordinate simple to assess Disadvantages not very useful for quantitative study may oversimplify issue Demonstration Plotsexample: rates of nitrogen on a field crop Replicated Field Plots Objectives desire to statistically compare treatments, varieties, etc. Advantages results recognized by scientific community results suitable for making decisions Disadvantages more complicated to conduct Replicated Trialexample: effect of different rates of nitrogen How many replications are enough? Generally, the more, the better! increased “degrees of freedom” easier to differentiate similar means better assessment of variation within plot area But consider………… land constraints time constraints material constrains (chemical, plants, etc.) You want how many reps???!!!! Minimum number varies with discipline and researcher Absolute minimum: 3 reps Foliar fungicide programs: we like to see at least 4 reps For soilborne diseases, including nematodes- we like 5 and even 6 reps uneven distribution of organisms in the soil Common Types of Experimental Design There is more than one type! all of these designs are replicated completely randomized design appropriate if no variation in plot area randomized complete block design consider ONE source of variation in field!! split-plot design two treatment levels, consider interactions factorial design Completely Randomized Design, 4 reps Randomized Complete Block, 4 reps PPT Slide PPT Slide PPT Slide Split-Plot Design Plot Maintenance Importance cannot be overlooked Uniformity in planting Careful calibration of spray equipment Fertility Weed control Insect control Disease control Field Tours & PRIDE Data Analysis Statistical analysis can be tricky consider specialists as references Statistical Packages/Software SAS--------MSTAT--------ARM Analysis of Variance are treatments significantly different? Mean Separations which means are different? (Fisher’s Protected LSD) What’s so significant about “significance”? Frequent question Confusion over meaning agricultural standard: 95% (usually) “At the 95% confidence level, we can be sure that these means are different at least 95% of the time.” Getting Started with a Field Trial Carefully determine your objectives Decide on (limited) treatments Develop an experimental design & plot plan Secure necessary equipment and materials Identify a conscientious cooperator Choose your field site CAREFULLY Remain safety oriented Keep careful notes Ask for help GOOD LUCK!