Improvement in precision of agricultural field experiments through design and analysis

The efficiency of Alpha Lattice Design and Randomized Complete Block Design (RCBD) was compared in two research trials conducted at National Agricultural Research Centre (NARC), Islamabad, Pakistan on two different crops to assess the efficiency of each in minimizing experimental error, coefficient of variation and error mean square for yield variable. Alpha designs are used for field trials because they provide better control on experimental variability among the experimental units under field conditions. For this purpose, two research trials on wheat and potato crops using alpha lattice design were conducted at NARC, Islamabad. The results show improvements in the precision level (in terms of decline in the mean square error, coefficient of variation and standard error of difference). The coefficient of variation (CV) calculated for wheat and potato preliminary yield trials are (7.70 and 13.6) for alpha lattice design and (8.54 and 16.39) for RCBD respectively. The error mean squares (EMS) calculated for these trials are (0.95 and 2.07) for alpha lattice design and (1.18 and 3.01) for randomized complete block design (RCBD) respectively. Standard error of difference for alpha lattice design are (218 and 0.8312) and (343and1.41) for RCBD. The relative efficiency of trials shows that alpha lattice design was more efficient than RCBD. The value of relative efficiency (1.24 and 1.46) indicates that the use of alpha lattice design instead of randomized complete block design (RCBD) increased experimental precision by 24 and 46 percent respectively. The gain is considerable in terms of efficiency attained by using Alpha Lattice Design, which favours wider use of these designs under field conditions.