PLOWING ORCHARD AND VINEYARD 135 



attains, if this depth can be kept the same for many successive culti- 

 vations. This hardpan, in some soils at least, becomes impervious 

 to water and is otherwise an injury to the growth of the trees. It 

 occurs in irrigated and unirrigated land alike, but is more quickly 

 formed by irrigation. When continuous summer cultivation is prac- 

 tised, the hardpan will be found at whatever depth the teeth uni- 

 formly reach. The remedy is to plow in winter just below this hard- 

 pan layer and thus break it up, and then by the action of the air and 

 rains it is reduced, and cultivation may proceed as before. Where 

 the hardpan is formed by the plow, the ground should be plowed 

 shallow one year and deeply the next, thus alternating from year to 

 year. 



Where compact layers are found below the reach of ordinary 

 plows a subsoil plow is used, and in some cases excellent results have 

 followed the use of powder with the charge fitted to shatter the 

 soil without disturbing the trees. 



Green Manuring. Another advantage in the use of the plow and 

 the disk is, as has already been mentioned, the turning under of the 

 growth of weeds, grass, and clover as a green manure. In recent 

 years growers have learned the great importance of this, and those 

 who had orchards in which winter growth had been killed out by 

 long cultivation, are now growing a quickly-growing crop which 

 they can sow with the first rains and secure enough to turn under 

 with the winter plowing. This consideration will be further pre- 

 sented in the chapter on fertilization. 



Plowing Hillside to Prevent Washing. Where the slope of the 

 land is sharp, there is much danger from washing during the rainy 

 season, if the hillside is not terraced or furnished with ditches care- 

 fully laid out on contour lines to carry the water down on a gentle 

 grade. The old plan of plowing furrows one above another around 

 the hill to check the flow and let the water down easily, is often 

 found treacherous unless one is able to strike good grades, because 

 of the liability to collection of water at certain points and the subse- 

 quent breaking away and washing. Recently some of the foothill 

 growers have adopted the plan of plowing furrows seven or eight 

 feet apart straight down the hill in the direction of its steepest 

 descent. The rainfall is thus distributed over the ground so that not 

 much water is collected at any one place and the harm done by wash- 

 ing will not amount to much. Hillside work differs according to 

 character of soil and of local rainfall and conference with experi- 

 enced men in the region will usually afford the beginner the best 

 suggestions of method. In some localities, the plowing of a few 

 furrows at intervals to assist in penetration and the growth of a 

 cover crop during the winter to assist in binding the soil, will be 

 found better than any attempt at the early plowing, which may work 

 admirably on level lands. 



The Best Plow. For plowing orchards and vineyards many 

 kinds of plows are used, including the ordinary one- and two-horse 

 walking plows, single and double sulky or riding plows, and gang 

 plows of different kinds largely operated by special forms of 



