raUIT liOT-JS - Decer.ibei', 1939 



V/. H. TaiGS 

 2;:ceiisian Morticulburist 



PJ!SZ,®-1 ^PPyJT-^. S'f.^S^jrJx. ArF. -PjlP""'^^, I";L^'Ortant 



The erratic aaid di3ap_30inting behavior of orchards on waterlogged 

 or otherv/ise poorly aerated soils is partially e;:pla:.ned by recent investi- 

 gations in Llev/ York State. D. Boynton aiid V/. Reuther have measured the 

 seasonal variation of oxygen and carbon dio;;ide in three orchard soils of 

 varying productive capacity. Measurenents were r.iad.e at depths of one to 

 six feet over a period of twelve laonths . The results have been suirx-arized 

 in the 1938 Report of the Ai.:erican Society for Horticultural Science. 



Previous studies have ehovrn that apple tree roots fail to function 

 normally as regards intake of rdneral elc;_ients a;id water if the o;:ygen con- 

 tent of the soil air is loss than lO.o. A^ia if it falls as low as 5/0, roots 

 are quite inactive. It appears fro:.: these studies th£.t nonial behavior of 

 roots at any given level is lii.ited by the o::yge:-: content of the air in tlie 

 soil spaces at that lovol. Furthermore, the efficiency of these roots is 

 also i:if luenccd by the nu:''ber of r.ionths of favorable soil aeration. 



In any soil type the spaces or pores bet\/ee:i the soil particles /nay 

 be classified as capillary poi'esj which ere s:.:all enough to serve in holding 

 r.ioisture, aiid non capillari'', or larger pores j v,d:ich fs.cilitate the uovemeiit 

 of gases in the soil. In a sandy loa;-.i soil tliis non capillary porosity was 

 fou:id to be about lo/i, while in a silty clay it was only ifo. These dif- 

 fereiices are strikingly reflected in the o;:ygen content. For exai-vple, at 

 a 6 foot depth in a sandy loa:.i soil the o:.:ygen content varied fron about 

 14-g-/i to 20/0 during the year, while in a silty clay loa;'.i belov/ a depth of 

 3 feet it was less than 5/o for a period of at least & months and was less 

 than 10/i for a:i additional 2 moiiths . In the silty clay where the orchard 

 has been relatively unproductive the o;:ygen conte:it at a depth of 4 feet 

 was above 5,i for a period of only about 3 months during the su:.-j::er. There 

 are roots below that level but they ::ust be in "gas storage" during the 

 dorv.iant season and part of the growi:ig season even though rainfall is nor- 

 :.ial. Fro;u these studies it is believed that tiie critical ra.:ige of non 

 capillary porositj'-, from the standpoint of soil aeration, lies soraewhere 

 between l^a and l/c. These studios suggest that a waterlogged soil or an 

 impervious soil r.ay bo u:afavorable not alone bocause of faulty v/ater rela- 

 tions bu'G because the roots can't get cnov.gh oxygen. 



S uppl yin.;; t_he jtit i" o^en_ iC e_e_d 3_ o_f the_ Agp le_ Tr_e_e 



Speaking before ci:e of the sessions of the ;!.F.'r.A« in \7orcester, 

 J. Re Liagness of the U.S.^.A- presented a cleai'-cut analysis of the nitrogen 

 needs of an a-yjle tree and r.iade so::e recom.iendations for su-v, lying thcr.i. A 



Issued by the 3:;tension Service, Y/illard A^ IJunson, director, in fuz'ther- 

 aiice of Acts of l.ky 8 and June 30, 1914, llassachusotts State CollOf^/e, United 

 States Departv.:ent of Agriculture, and County K-.tension Services cooperating. 



