MAINTAINING THE ORGANIC MATTER OF SOILS 173 



The following table gives the amount that has heen produced 

 during the two years' growth : 



Investigation of Sweet Clover (Melilotus alba)* 



From the above table it will be seen that the sweet clover pro- 

 duced G.4 tons of total dry matter. Of this 1.2 tons came from 

 the roots. The total weight of sweet clover from a single year's 

 growth in the dry season of 1914 on black clay loam was 4.4 tons 

 per acre. 



QUESTIONS 



1. Would it be advisable to purchase manure for ordinary crops? 



2. What is the first requirement in maintaining organic matter? 



3. Why is it necessary to add limestone? 



4. What is the cost of maintaining it? 



5. What is the effect of phosphorus on growth of clovers? 



(5. What advantage does the livestock farmer have over the grain farmer? 



7. How much organic matter is lost in the process of digestion of pasture 



grasses? Of alfalfa? 



8. What is the remedy for " sod Ixiund " pastures? 

 0. Why is pasturing often of little benefit to soils? 



10. What points should l>e considered in selecting a crop for green manure? 



11. (Jive danger to crop arising from green manure turned tinder in spring. 



12. What are catch crops? For what used? 



13. Explain under what conditions weeds may have some value. 



14. What is the use of cover crops? 



15. In pasturing red clover what per cent of the organic matter is lost? 

 Hi. What proportion of the corn fed is recovered in the manure? 



17. If a farmer keeps 10 horses averaging 1400 pounds each. ."> cows of 



800 pounds and 10 hogs of 100 pounds each, what is the value of the 

 manure produced in a year? 



18. What are the sources of loss of manure? 



10. Give the experiment conducted by the Ontario Station. 



20. Why is there no loss from dry manure? 



21. What is " fire fanging' 1 ? 



22. What is putrefaction? 



23. How may fermentation be prevented? 



24. What parts of manure are affected by fermentation? 



