THE FOREST NURSERY 249 



hardwood seedlings grown in rows a foot or more apart or in nar- 

 row beds. Furrows are run between the rows or between the beds 

 and water directed through them until the soil is adequately satu- 

 rated, after which they are closed by cultivation. 



21. SUB-IRRIGATION. Sub-irrigation requires much less water 

 than any method of surface irrigation. This method has been 

 successfully introduced into some of the western nurseries. 1 The 

 water is distributed through a system of concrete tiles open at 

 the joints and laid a few inches under the surface. The water 

 seeps into the soil and is distributed by capillary action. 



22. The Amount of Water Required. The seedbeds should 

 be carefully watched during dry weather. Coniferous species show 

 lack of water by the withering and dying of the lowermost 

 leaves and by all the plants dying in irregular patches through 

 the center of the beds. If water is not applied immediately 

 after the first signs of damage are in evidence, all the plants over 

 extensive areas may be killed within a period of four to seven 

 days. Where an excess of water is applied, particularly on heavy 

 soils and over extended periods, the roots are likely to rot, the tops 

 turn yellow, and the plants finally die in patches. 



Excessive watering results in the production of tender, over- 

 grown, sappy plants that lack resistance when set in the field. 

 On the other hand, the lack of water causes great loss in the seed- 

 beds during the first and second years, and also in the transplant 

 beds where the ground becomes dry soon after the plants are 

 pricked out. 



The amount of water necessary to apply during the growing 

 season is extremely variable, depending upon the climate and the 

 soil. In exceptionally favorable regions, irrigation may not be 

 necessary. Again, it may be necessary to apply water but two or 

 three times during the season. Over most parts of western United 

 States, the frequent application of water throughout the growing 

 season is essential for successful nursery practice. In the forest 

 nursery at Halsey, Nebraska, weekly or bi-weekly irrigation is 

 practiced except during periods of moist weather. In dry, hot 

 weather as much as two inches per week are applied. At this 

 nursery it was the former practice to apply all water with hose 



1 Bates, C. G. and Pierce, R. G. : Forestation of the sand hills of Nebraska 

 and Kansas. (U. S. Forest Service, Bui. 121, p. 24. 1913.) 



