-6- 



of this fertilizer, about the only thing of ri.ctucl vi'lue is 1-^/^ 

 each of potassium o:':ido and crlcium oxide. ICvideiitly this ma- 

 terial v;s,s about as rich in plant food as th'; dust from a stone 

 crusher. The ad closes v/ith this statement, "Tno n-.;v; mineral 

 fertilizer means healthy and nutritious products whereas manures 

 contain disease producing bacilli fnd debilitating ferment" 

 (vmatever that is) . Modern farmers, with their better under- 

 stcnding of fertilizer analyses i.nC. of plant requirements are 

 in a more favorable position to judge the merits of the available 

 materials. 



Chemistry and Soils 



Speaking on this subject recentl:/-, Ricliard Bradfield of 

 Cornell University said, "It may seem a little far-fetched to see 

 a chemist attacking a fertilizer problem by studying the reactions 

 of fertilizer Y."ith colloidal clay in a test tube. But many prob- 

 lems of fertilizer reaction ere very complex and can be clarified 

 only by breaking them dov,Ti into simpler fragments. We have come 

 to realise that v/hen v/e add fertilizer to the soil v/o do more than 

 fertilize the crop with the ingredients contain'-n,'. in the fertili- 

 zer b?c. By fertilizing the soil v/e set in operation a compli- 

 cated series of reactions w'nich often require months, and even 

 years, for their completion. In fact, it is doubtful if the soil 

 is ever the same after a fertilizer cpplicrtion. The growth of 

 the crops v/hich follow is influenced b--'' the Indirect as well as 

 the direct reaction of the fertilizer." 



One Lesson from a Dry Season 



The severe drouth of 1939 whicii extended up to the har- 

 vest season in the Mid-West has prompted some pointed comments 

 from F. S. Hewlett of Ohio State University, ho sa^'s, "Evidence 

 has been obtained from growers ul:o have irrigated, and tiierefore 

 have paid close attention to penetration of v.-at:;r, concerning the 

 effect of orchard tools ?nd equipment upon soil structure. One 

 grower informed the v/ritnr that in no place in the orchard is 

 satisfactory penetrcition of water observed except beneath the 

 trees where the soil hcd not been trod upon or recently disturbed. 

 The physical structure of the soil between th3 trees has become 

 distinctly'- unfavorable -.s time h^as passed not only for v/ater pene- 

 tration but also for root penetration. This might not be of great 

 importance in a soil ^.'here rooting is comparatively deep, but in 

 soil where aeration is naturally' shallov; it is of rather serious 

 consequence. In suci: orchards irrigc.tion is almost essential 

 and good v/ater penetration is obviously desirable. This fact 

 emphasizes the importance of limiting the use of heavy equipment 

 in the orchard. It rc.lso ccli: for ci\e adoption of a system of 

 soil management vaiich maintains a structure of the soil favoring 

 high water permeability, better aeration, and more extended root 

 grov/th. The drouth has given some indication of those portions 

 of existing orchards wliere mulching should be (.;arried out. It 

 has brought out the advantages as well as tlie limitations of 

 mulching. V'.T:iere trees have been mulched, loss severe effectsr 



