| Author(s) | A.A. Leilah* and K. M. Al-Barrak** |
| Affiliation | *Crops & Range Department and ** Soil & Water Department, College of Agriculture and Food Science, King Faisal University, Al-Hassa, Saudi Arabia |
| Title | Estimation of Optimum Field Plot Size and Shape and Number of Replicates in Sorghum Yield Trials |
| Source | Journal of King Saud University. Agricultural Sciences. Volume 17, No 2. (2005/1425) |
| Abstract | Two uniformity trials were conducted to determine the index of soil variability, optimum size and shape of plots and the suitable number of replicates for sorghum fodder yield trials. Optimum plot size was calculated using three methods viz. Smith’s method, modified maximum curvature technique and the comparable variance. Obtained results revealed that index of soil variability was 0.485 and 0.467 in the first and second seasons, respectively. The optimum plot size was estimated to be 4, 5 and 6 times the basic unit, comprising an area of 4.80, 6.00 and 7.20 m2 for Smith’s method, modified maximum curvature technique and the comparable variance, respectively. Plot shape had insignificant effect on variance in this investigation whenever the variability in soil was not clear. Therefore, a rectangular plot (2.0 x 3.6 m) might be most efficiently handled. Increasing number of replications resulted in marked reduction in standard error. The rate of the decrease reached its maximum up to 4-6 replicates. The recommended number of replicates to detect differences at 20 and 15% of the mean were 4 and 6 replicates, respectively. |
