March, 1938] 



Agricultural Research in N. H. 



23 



make recommendatious therefor. Since August first the agents have 

 been handling the recommendations, although the tests are still being 

 run at the Station. 



During the year it seemed advisable to summarize a large number 

 of tests to find out in a general way how these were running and to 

 assist those who are to suggest lime and fertilizer treatment for the soils 

 that are to be tested. It is impossible in this report to cover all the de- 

 tails of how soil test recommendations are made, but this general sum- 

 mary is presented here to indicate how the soils tested and why a rela- 

 tively high fertilizer schedule is necessary : 



* Marked "extra low" on test. 



To interpret properly and make recommendations for these tests one 

 has to take into consideration the fertility requirements of the crop to be 

 grown, the soil type and organic content, the probable fixation power 

 of the soil for phosphorus and its acidity. For example, soils testing 

 "none," "trace," or "very low" nitrates and ammonia nitrogen should 

 have an application of nitrogen for all crops. Soils testing ' ' low ' ' would 

 probably be satisfactory for legumes but should be topdressed with nitro- 

 gen for grass hay, or if corn or potatoes are to be grown, manure or 

 nitrogenous fertilizers should be applied. Soils testing medium should 

 be satisfactory for hay or corn, but would need more nitrogen for 

 potatoes. 



A soil testing "very low" or lower for phosphorous should have 

 phosphorus for any crop. One at "low" is suitable for grass hay but 

 for no other, and then only in case the field is an established sod where 

 the fertilizer is intended for topdressing. It can thus be seen that 935 

 samples, or 93.5%, of these soils should have a phosphorus application 

 for full yields of all crops save grass hay and 58.1% should be treated 

 with phosphorus even for grass hay increases. 



Likewise 83.6% of the samples fall below the requirements of all 

 crops for potash. If legumes are to be seeded and the soil tests "trace" 

 or "none" for potash, an application of potash in fertilizer should be 

 used even though manure is applied. 



Soils showing "extra low" or "no" magnesium should have this ele- 

 ment supplied in fertilizers except in cases where manure is to be used 

 for the crop. 



