Soils and Fertilizers for Pecans 91 



terial if his soil is of a different type or geological formation 

 from those on which tests have been conducted. 



The influence of cover-crops on the effect of fertilizer mix- 

 tures deserves close observation. Orchards in which legu- 

 minous cover-crops have been grown and turned under will 

 require a fertilizer with less nitrogen than one with no cover- 

 crop. 



Fertilizer experiments with pecans conducted by J. J. 

 Skinner of the United States Department of Agriculture show 

 the influence of phosphates, ammonia, and potash when used 

 singly and in combination of two and three. He employed 

 the triangular system of experimentation which included 

 twenty-one fertilizers or combinations, covering the field of 

 ratios or formulas. Four years' work on various soil types 

 and with different ages and varieties of pecan trees shows in- 

 creased yields of nuts and improvement in vigor of the trees 

 by certain of the fertilizers. Summaries of the results on two 

 soil types for 1921 are representative of the effect of the 

 fertilizer on the yield and the quality of the nuts as reported 

 by Skinner.^ 



The Greenville sandy loam is one of the strongest pecan 

 soils. It has a brown to red surface soil which is underlain 

 by a deep red subsoil. Four-year-old Stuart, Pabst, and 

 Schley pecan trees were given five pounds of fertilizer each in 

 1918 and in 1919 ; in 1920 and 1921, ten pounds ; and in 1922, 

 twenty pounds. In addition to the use of phosphoric acid, 

 nitrogen, and potash singly and of three complete fertilizers, 

 namely a 9-3-3, a 3-9-3, and a 3-3-9 mixture, there were in the 

 experiment six fertilizers with a high proportion of phosphate 

 and a low proportion of ammonia and potash; six mixtures 



^Proceedings Ga.-Fla. Pecan Growers' Assoc, 1922. 



