No. 7. DEPARTMENT OF AGRICULTURE. 601 



Theory of Tillafre. — What I have been giving are facts. The 

 tigilies are the yields actually secured by farmers. There can be uo 

 question about them. When we try to explain why these figures are 

 as thev are, we enter the Held of theorv. We often fail to distin- 

 guish between theorj' and fact. Very often we hear a man start 

 to give his ''experience'' in fruit growing bnt spend all his time on 

 theories. Evidently the average sod orchard in Western New York 

 does not yield as many apples nor as valuable apples as the tilled 

 one. This is the proved fact. >A'hy this is the case no one can posi- 

 tively say. 



Grass may harm the trees in one of four or more ways: 1, by ex- 

 hausting the plant food; 2, by exhausting the water; 3, by unfavor- 

 ably influencing the living organisms of the soil; 4, the grass roots 

 may give off some substance that is harmful to trees. 



It is probable that the injurious effects are sometimes due to one, 

 and sometimes due to a combination of several or all of these causes. 

 If plant-food is the chief factor, then the soil that is rich in plant- 

 food may be able to produce an excellent crop of apples and also 

 grow grass. So the water factor may be eliminated on some soils 

 that naturallv have too much water. Such orchards mav be better 

 if left in sod. Other orchards may be on land that is too stony for 

 tillage or on hillsides that are too steep for tillage. By pasturing 

 an orchard the plant-food is mostly retained and the moisture is 

 probably less exhausted. Barnyard manure may sometimes coun- 

 teract all four of the suggested ways in which grass may injure 

 an orchard. Whether an individual orchard should be tilled or not 

 depends on many questions. But there is little doubt but that most 

 orchards should be tilled. 



The time to till an orchard is as early as the ground is fit. If 

 tillage is begun early and stopped early many of the undesirable 

 effects of tillage may be lessened. At New Brunswick, N. J., last 

 summer we measured the growth of twigs about every two weeks. 

 Half of the growth of twigs, of trees was completed by the middle 

 of May and four-fifths by the middle of June. The best time for 

 tillage seems to be to begin as early as the ground is fit and stop 

 early in July. Then seed to some cover crop or let the weeds grow. 

 The condition of the weather and of the crop will of course have to 

 be considered. 



Some men fear that tilling too early will start the fruit buds 

 so that they are likely to be injured by frost. Last winter we tried 

 this at the New Jersey Station in the following manner. A peach 

 tree was so arranged that its roots were in a greenhouse that was 

 growing tomatoes while its tops were outdoors in January weather. 

 At the end of a month the top was brought into the house. It 

 blossomed in a short time. The warming of the soil had no harm- 

 ful effect on the buds. 



Effect of Tillage on Quality of the Fruit. — Apples from sod or- 

 chards are frequently more highly colored than are those from 

 tilled orchards, but are not necessarily so. Tillage may make it a 

 little more difficult to secure good color, but there wore many sod 

 orchards that gave highly colored fruit. The trees in a tilled or- 

 chard must be pruned more openly and fertilized with less nitrogen 

 than is given to orchards in sod. 



Many farmers think that apples from sod orchards have the bet- 



