124 CONSERVATION AND IMPROVEMENT OF SOIL 



determine the depth of the surface soil. If the surface soil is not all being turned 

 up, find if possible why the plowing is not made deeper. 



2. Have one part of the field plowed extra deep and the remainder plowed 

 as usual. Then compare the yield after the crop is grown. Young people not 

 having an opportunity to carry out this exercise on their own places may induce 

 some farmer or gardener to conduct the experiment under their guidance. 



3. Fall or Spring Plowing. Compare the yields of crops, or fields plowed 

 in the fall, and those not plowed until the following spring. 



4. Study the effects of rolling by having one part of a grain field rolled 

 after seeding, and the other part not rolled. In which plot does the grain 

 sprout first? Which has the more rapid growth later on? 



5. Effect of Green Manure. Compare the yield of grain or corn on two 

 plots, one of which has been supplied with green manure turned under and 

 the other having no green manure. This exercise is more valuable if the green 

 manure consists of the crimson clover or other legume crops. A comparison 

 may also be made between crimson clover and rye as green manures. 



6. Testing Barnyard Manures. On two plots test the value of spreading 

 manure fresh from the barn on the field instead of allowing it to remain in a 

 heap in the yard for some time. Test one plot with fresh manure from the stalls 

 and the other plot with a like amount of manure which has stood under the 

 eaves of the barn for six months or so. Corn may be grown on these plots, and 

 yields recorded. 



7. The value of rock phosphate as an absorbent in stables may be shown 

 by manuring two plots. On one use manure in which the rock phosphate has 

 been used as an absorbent, and on the other use the manure without this. 

 The result should show the first season on corn or cotton. 



8. Forms of Lime. -Test the caustic effects of the three main forms of 

 lime: freshly burned lime, hydrated or slacked lime, and ground limestone. 

 Use litmus paper in the test. Also wash a small quantity of each of these ma- 

 terials and determine the alkalinity of the water resulting therefrom. Which 

 would be more quickly available in the soil? Which is the most caustic? 

 Which would remain in the soil a longer time? 



9. Slack some fresh lime in a pile after having determined its volume in 

 advance. After the air slacking is entirely finished, determine the volume 

 again. How much increase do you find? 



10. Take a pound of freshly burned lime. Let it gradually air slack, and 

 then again determine its weight. How do you account for the change in weight? 



11. Potash from Ashes. Put a few pounds of wood ashes in a tin can pro- 

 vided with holes in the bottom. Fill with water and allow it to leach through. 

 Catch the teachings and test for alkalinity. Feel of the liquid and see if it 

 feels slippery to the fingers. 



12. Fertilizer Samples. Make collection of samples of fertilizers in glass 

 bottles. Obtain all kinds in the market, including materials from which mixed 

 fertilizers are made, and also the mixtures themselves. Label each with the 

 name and composition. 



13. Solubility of Certain Fertilizers. Test the solubility of sulfate of 

 ammonia, nitrate of soda, and the several potash salts. 



14. Study Phosphorus as suggested in a high school chemistry. Care- 

 fully handle the material, as it is very combustible. If a piece of phosphorus 

 is exposed to the air for a few minutes,the white fumes produced when dissolved 

 in water, are the same as pure phosphoric acid in fertilizers. 



15. Availability of Phosphoric Acid. Put samples of rock phosphate, 

 phosphoric acid and ground bone each in separate test tubes or bottles to de- 

 termine their solubility. Whether any of the material is dissolved or not may 

 be determined by pouring in a little clear lime water. If there be any soluble 

 phosphate present there will be a white cloudy appearance. Which one of 



