126 A YEAR IN AGRICULTURE 



end of each tube and fill with soil. Fasten the tubes with 

 one end lowered in a vessel of water. Note from hour to 

 hour the first day, and for twenty-four-hour periods after- 

 wards, the rate and height of the rise of water in each type 

 of soil. 



7. Water-holding capacity of different soils. Fill tubes 

 similar to the ones given in the preceding exercise with the 

 same types of soil, and weigh the soil in each tube. Sup- 

 port the tubes so that water may be poured at the top and 

 be permitted to percolate through the soil. As soon as the 

 water begins to drip through the soils, cease pouring water 

 upon them and after the dripping has stopped weigh the 

 tubes to determine the amount of water held in the soils. 

 This exercise will also show variations in the rate of per- 

 colation of water through the different types of soil. These 

 facts should be noted, also, in recording the results of this 

 exercise. 



8. Effect of the soil mulch. Fill two vessels with equal 

 weights of the same kind of moist soil. Stir the surface of 

 one, and leave the other with the surface the same. Continue 

 stirring the surface from day to day and note the difference 

 in the weights of the two vessels. Explain the result of this 

 exercise. 



9. Effects of lime on physical condition. Make up a clay 

 mud-ball mixed with ordinary rain water, and a second ball 

 mixed with saturated limewater. Place the two balls aside 

 for two days. Note the difference with which the two balls 

 may be crumbled. Explain. 



10. Effect of manures on physical condition of soil. Put 

 some finely-screened clay in each of two pans. Pour the same 

 amount of water into each pan and stir each until you have 

 a thick, well-mixed mass. Into one pan mix thoroughly a 

 handful of well-rotted manure or leaf -mould. Set both pans 

 aside for the soil to dry. Which dries first? Why? When 



