60 



SOIL AN IMPORTANT FACTOR 



Tem'perature 



Treatment 



Start 



20 min. 



40 min. 



60 min. 



80 mm 



100 mm 



120 min 



Water only 



etc 



Questions. — (a) Why does dry soil heat quicker than wet soil? 

 (6) Why does sand heat quicker than silt loam? 



(c) Why are northern slopes preferable for orchards? 



(d) Give four reasons why a water-logged soil will not warm up so readily 

 as a well-drained soil. 



(e) How can a farmer aid a low, wet field to warm up quicker in the spring? 

 (J) Name the factors that influence soil temperature. 



Field studies. — Become famihar with the meaning of tilth and seed bed 

 by observing soil condition in several selected fields. 



Note the temperature of certain well-drained soils, sandy soils, heavy 

 soils, peat and muck, poorly drained soils, and soil on south and north slopes. 



QtmSTIONS 



1. Name the periods in the life history of a plant. Through what periods does 



it pass in contact with the SQil? 



2. Why is it important to have favorable conditions surrounding a planted 



seed? What are these favorable conditions? 

 Can a farmer ever help to create more favorable temperature conditions 



for seed germination and plant growth? How? 

 What is meant by tilth? Good tilth? Poor tilth? Illustrate. 

 Does good tilth imply a rich soil? 

 What is the relation between the absorption of water by seeds 



and germination? 

 Name factors influencing rate of water absorption by seeds. Discuss each 

 Which is the period of greatest activity in the life history of a plant? 



Name these activities. 

 How may a plant be compared to a factory? 

 Name the requirements and conditions necessary during the growing 



period of a plant. How do these requirements compare with those of 



the germinating period? 

 Discuss temperature in relation to crop growth. 



12. What is the importance of permeable soil in relation to the growth and 



vigor of young plants? 



13. What is the importance of good tilth as regards the seed and the 



young plant? 



14. Explain how texture, structure and moisture content of soils affect the 

 development of good ti,lth through cultivation. 



Why is it good to plow a hard, lumpy soil or a heavy clay in the fall? 



What is meant by availability of the plant-food elements? 



What becomes of the carbon taken in by plants? Of the nitrogen? 



Of the sulfur? 

 What seems to be the function of calcium in plants? Of magnesium? 



Why do plants need iron? 

 Give three reasons why it is important to have a good supply of available 



phosphorus in the soil. 



20. Explain why corn, sugar beets and potatoes require much potassium. Do 



alfalfa and clover crops need much potassium? 'Why? 



21. What are the requirements of a plant in the fruition period? 



22. For summary of Chapter V se^ the table of contents. 



3. 



4. 

 5. 

 6. 



8*. 



9. 

 10. 





15. 

 16. 

 17. 



18. 



19. 



