o34 



Journal of the Department of Agricultcjre. 



Summary of Results : Five-year Rotation. — The following table 

 shows the average yields of maize and also average increases over the 

 average of the control plots for first and second years respectively 

 after cowpeas on the three farms, with the five-year rotation: — 



Figures in l)racke:s indicate the number of yi ars over which the average is taken. 



Since these experiments have only been in progress some four or 

 five years, no conclusions can yet be drawn. The results to date, 

 however, are fairlj^ consistent in indicating the value of cowpeas in 

 increasing the yield of maize over maize grown continuously. In not 

 one plot on the three farms in the five-year rotation is the yield of 

 maize for the first or second year after cowpeas less than thai in 

 either of the control plots where the maize was grown continuously 

 and manured every year. To those who are familiar with the devia- 

 tions to which the yields of plots in agricultural experiment are 

 subject, this result is striking. The averages of the plots of maize for 

 first and second years after cowpeas, compared with the averages of 

 the control plots in each experiment, as shown in the above table, are 

 remarkably good, and indicate very forcibly the value of the cowpea 

 in the rotation. For the first year after the cowpeas, the increase 

 due to this crop on the three farms amounts to 41 per cent, over the 

 yield of 1329 lb. per acre on the plots where the maize is grown 

 continuously and manured every year. Xow, 41 per cent, of 1329 

 lb. is 545 lb. or 2| bags per acre. At 12s. per bag this is worth 33s. 

 per acre. For the second year after cowpeas, the average increase 

 due to the cowpeas on the three farms amounts to 20 per cent, over 

 the vield of L')29 lb. per acre on the control plots; 20 per cent, of 

 1329 lb. is 2(i(; lb., and this at 12s. per bag is worth 16s. Thus the 

 cowpeas have been worth 49s. per acre to the maize. The question 

 now to be determined is whether the total cost of the cowpea crop 

 was less or more than 49s. per acre, plus the value of the cowpea hay. 

 The average yield of cowpea hay, calculating in the " green " 

 weights, appears to have been from 2^ to 3 tons per acre, and this 

 should amply have repaid its cost of cultivation. It is therefore 

 obvious that the introduction of cowpeas into ;i maize I'otation is good, 

 sound practice. 



Summary of Results — Four-year Rotation. — The following table 

 shows the average yields of maize and also average increases over 



* Decrease. 



