A VISIT TO BELTSVILLE 



A few weeks ago the writer visited the USDA Plant Industry Station at Beltsville, 

 I'arvland, and looked over some of the important fruit research v;ork now under way. 

 In this issue v/e include a brief summary of a rather outstanding mulching 

 experiment which has a direct application to orchards in Massachusetts. 



Comparison of High Nitrogen Kay and Straw I.Iulch On the light soil in the 

 experimental orchani, a block of York Imperial trees have sho^/m everj^ evidence of 

 faulty nutrition. They were typically "sick trees." Some of the limbs were 

 dying and others vrere on the way. Here seemed to be an ideal chance to compare the 

 nutritive effects of mulch materials, a test which would show very little on a 

 good soil. Previously, mulching experiments have been conducted mainly to 

 determine the effects on yields and growth without going into the chemical and 

 nutritive effects. 



The two mulch materials selected were straw, a low nitrogen high carbon 

 jnaterial, and high nitrogen hay, obtained by fertilizing an orchard grass meadow 

 with 300 pounds per acre of ammonium nitrate. The grass v;as cut at the heading 

 stage and the vield amovmted to as much as <, tons per acre. A chemical test 

 showed slightly more than 2',\ actual nitrogen. This hay, as the reader _ can well 

 imagine, was dark green in color, the kind any dairyman would welcome in his 

 haj-mow. It was applied to half of the "sick trees" in June at the rate of 

 100 pounds of air dried hay per tree, the other trees receiving a similar amount of 

 straw. A year later, 200 pounds of these materials were added to the same trees. 



:;ithin a year of the time the hay was applied, the trees receiving the hay 

 were definitely on the v;ay back v*ile the trees receiving straw plus as much nitrogen 

 as the hay contained had sho'/m much less response. The latter looked better than 

 unmulched trees, but in no case v;ere they as vigorous as the trees mulched vdth hay. 

 The trees mulched vdth high nitrogen hay were thriving, and the set of fruit ^vas 

 heavy. Analyses of the leaves shovred a somev/hat higher content of all the 

 essential mineral elements, including the so-called minor ones. Evidently, the 

 decaying hay mulch was yielding these mineral elements in available form or v;as 

 helping to make them available in the soil. And as might be expected, root develop- 

 ment just beneath the hay mulch was very hoticeable. 



As a preliminary to this test, a laboratory study of the rate of decay of high 

 and lo;v- nitrogen hay had been made. Some elements, notably potassium, may leach 

 from mulches vdthout the benefit of decomposition, while other ions, combined in 

 the more complex molecules apparently require micro-biological action for their 

 release. This laboratory study substantiated the claim that nutrients are released 

 more readily from a high nitrogen material. 



From a practical standpoint the test at Beltsville points the way toward the 

 nutrition of trees on a light soil by the application of mulch material grown 

 outside the orchard under a fairly liberal supply of nitrogen instead of trying to 

 nourish the tree directly from the fertilizer bag. It also suggests the value of 

 broadcasting a nitrogenous fertilizer over the orchard floor to grow more high 

 nitrogen hay in the orchard and then cutting the hay for use around the trees. 

 Fertilizer used in this way may return more profit than if used in a ring applica- 

 tion. This method assumes, of course, that ample high magnesium lime has been 

 applied in the orchard to bring the pH up to at least 5.5. It takes about 3 pounds 

 of dolomitic lime to counteract the acidifying effect of one pound of sulfur used in 

 the dusting program. 



