The Apple in Oregon : Part II, 13 



o 



<'lianges constantly going on in ordinary agricultural soils Independent of tillage 

 operations, but both of whicli may be greatly augmented by judicious tillage, 

 {'hemical changes in the soil result more or less directly in the release of 

 mineral substances needed by the plant. These changes are hastened and 

 increased by the presence in the soil of water, heat and air in suflScient quan- 

 tities and by i.ie stirring and consequent changing of position of the soil 

 particles. Tnese requirements, or rather desirable conditions, are fully induced 

 by proper tillage operations. By pulverizing the soil, air is admitted ; this 

 warms the soil : the water of the soil during the dryer part of the season, by this 

 same operation, is kept from passing off in the form of vapor as readily as 

 it oherwise would, and while the position of the soil particles is greatly 

 changed, their size is also reduced. 



The biological changes taking place in the soil and which are likewise 

 greatly facilitated by good tillage, are various and quite imperfectly understood. 

 A few of the more important ones like nitrification, have received much atten- 

 tion in recent years and results of much moment to the soil tiller are being 

 reached through the biological investigations of the soil now being carried on 

 in nearly every scientific center. 



CULTIVATION. 



Tillage operations generally discussed as cultivation are as variable as the 

 individuals that are engaged in orcharding. Some rely chiefly upon the old- 

 time plow, but more count the modern disc-harrow the staple tool. These latter 

 followed by clod-crushers, acme harrows, and scarifiers do most effective work 

 under the usual soil conditions to be found in Oregon orchards. 



One plowing in alternate years is held to be suflBcient for all the mellow 

 soils, though some find that disking alone is all sufficient. Upon the clayey 

 soils most cultivators deem one plowing a year desirable and in this practice 

 the two operations of contiguous years are at right angles, 4. c, one year 

 l)low east and west : next year, north and south. Plowing or disking are usually 

 followed by clod crusher or pulverizing harrow. The first operation is usually 

 just after the blossoms fall.* Then at intervals of two or three weeks the 



♦Recently some discussion has been provoked by the statement that the 

 first plowing should precede blossoming. The reason assigned for this is that 

 the stirring of the soil at that time induces a more vigorous root activity thus 

 enabling the tree through this stimulus to set more fruit than it otherwise 

 would. The issue is debatable at least, and the position, probably erroneous. 

 No experimental evidence of unquestioned character has been produced ; and 

 it is not yet credited by the known principles of vegetable physiology : Sap 

 pressure does not indicate the extent to which elaborated food is present, such 

 as young buds or blossoms require. What a bud needs at the time of opening is 

 a good supply of digestible food material. This food material is prepared the year 

 before. It would seem that if a bud is low in vitality it could hardly be ex- 

 pected that the overcharging of it with water and crude "mineral matter would 

 increase its vitality, i. e. make it do more work by way of fertilization of 

 flowers. 



It is a generally accepted view that the pollen grain is normally rich in 

 proteid matters, i. c. substances rich in nitrogen, sulphur and phosphorus, and 

 that for the growth that takes place at the time of fertilization elaborated 

 carbon foods are chiefly required. This carbon food material is only developed 

 in the presence of green leaves, ;". c. the year preceding. Thus it appears that 

 early tillage operations have no direct bearing upon the fertilization of the blos- 

 soms. Tillage indirectly, however, might be beneficial to tlie tree at this early 

 period through the aeration of the soil whereby it would become warmer and 

 thus more suitable for root activity. This induced root activity would cause an 

 increased sap pressure and this in its turn would have a measurable influence 

 upon the jjeriod of cell activity in the region of the blossoms, but it is very 

 doubtful if it could add anthing to the vitality or vigor of the blossoms and 

 especially the organs of fertilization, stamens and pistils. 



If a crop of fruit is wanted next year preparation for it must be made this 

 year while the tree is growing and particularly while it is storing food during 

 the latter part of the vegetable period. Feed the tree well this year ; keep it 

 clean and free from pests, and other conditions, as climatic, being afvorable next 

 year, the tree will yield a crop in return for your judicious care. 



