[ 96 ] 



roots 3ft. long. A loose soil is of great help in developing 

 roots of agricultural crops. (2) Roots penetrating deep, 

 a crop can resist drought better as the soil is, as a rule, more 

 and more moist the deeper one goes. (3) By deep plough- 

 ing the distances between plants can be shortened and as 

 roots can then, instead of spreading out, sink deep in search 

 of food. The disadvantage of deep cultivation lies in the 

 fact of a great deal more of plant-food being made soluble 

 and available than can be utilised by the crop, and the liability 

 of this plant food so let free, being washed out. That most 

 Indian soils have gone on yielding some return for years with- 

 out manure, is to be accounted for by the fact of shallow cul- 

 tivation being practised. Shallow cultivation is better than 

 deep cultivation if no manuring is done. It results in a better 

 conservation of food materials in the soil for future use, 

 though the immediate return is poorer. 



121. Spacing, One object of tillage operations is to allow 

 just sufficient space to each class of crops. A rice plant should 

 have at its disposal one-third cubic foot of earth (about 20 Ibs.). 

 A bean plant should have at its disposal i cub. ft. of earth (about 

 60 Ibs.; ; a potato plant 3 cub. ft. (about 190 Ibs.) and a tobacco 

 plant as much as 7 cub. ft. (470 Ibs.). In an experiment con- 

 ducted by Hellriegel with barley plants grown on jars, it was 

 found out that a plant grown on a large jar containing 28 Ibs. 

 of earth weighed when ripe and perfectly dry 33,000 milli- 

 grams and bore 636 seeds ; while 24 plants grown in a jar 

 containing u Ibs. of earth, weighed when dry 21,600 milli- 

 grams and bore only 384 seeds of a smaller size. The mini- 

 mum space consistent with good yield should be allowed to 

 each plant. For instance, though one potato plant will give 

 the highest yield if it is given 3 cub. ft. of space it is more 

 economical to have 2 plants in this space though these two 

 will yield only a little more than the one plant. Potatoes 

 planted in double rows 4 inches apart have been found at the 

 Sibpur farm to yield more than those planted ,in single rows, 



