378 SEEDING AND PLANTING 



two or more years following the planting. This is particularly 

 true of plantations made in prairie and semi-arid regions where the 

 trees are likely to suffer from lack of soil moisture because of the 

 competition of grasses and other herbaceous vegetation. Fre- 

 quent cultivation also prevents excessive loss of moisture from 

 the soil through evaporation. Under ^conditions where cultiva- 

 tion is necessary, it is usually continued until the stand closes. 

 Economy demands that as little hand labor as possible be em- 

 ployed in cultivating the plantation, consequently regular spacing 

 should be practiced so that horses may be used. 



24. . METHODS OF REGULAR SPACING 



In all methods of regular spacing the trees are set in straight 

 lines. All methods require the marking of the planting area in 

 order to guide the planters. When the area has been plowed, as 

 is the common practice in prairie planting, it is marked out in 

 straight lines at the required intervals and in both directions. 

 The trees are set at the intersections of the lines. The marking 

 is done oy horses in the same manner that a field is marked in 

 preparing it for a crop of corn. On unplowed areas, planting 

 lines or planting chains are stretched across the area at the re- 

 quired intervals and the plants are set along them at definite 

 points which mark the desired spacing. The trees in regular 

 spacing^ are arranged as follows (Fig. 103) : 



a. Squares, i.e., the plants are set at the 4 corners of squares, 

 the rows crossing each other at right angles and equally spaced 

 in both directions. 



b. Rectangles, i.e., the plants are set at the 4 corners of rec- 

 tangles. The rows cross each other at right angles and are wider 

 spaced in one direction than in the other. 



c. Equilateral triangles, i.e., the plants are set at the 3 corners 

 of the triangle. The rows cross each other obliquely. 



d. Superposed squares, i.e., the. plants are set at the 4 corners 

 of squares. In setting the plants a second crew of planters fol- 

 lows the first crew and sets a plant in the center of each square, 

 judging the distance by the eye. 



In the United States regular spacing as described above is con- 

 fined to plowed areas, chiefly in the prairie regions of the Middle 

 West, agricultural land in the East, and Eucalyptus plantations 

 in California. The trees are usually set in squares or rectangles. 



