SOILS, FERTILIZERS AND IRRIGATION 83 



The straw can be spread in the corral, trampled fine by the stock, and 

 spread with other corral cleanings at the beginning of the rainy sea- 

 son. It may also be piled, wet down and reduced by composting 

 with farm manure. This will make a rich manure for garden use. 

 Sweet peas improve the land for any crop which it is profitable to 

 grow in the locality; so far as we know, everything from grain to 

 vegetables is better when following them. Pea aphis must be killed 

 with a tobacco spray as soon as they appear. They are hard to handle 

 if allowed to get headway. Therefore, the young plants must be 

 closely watched and spraying done as soon as the pest is discovered. 



Fertilizing With Alfalfa. 



Will a six-foot strip of alfalfa in the center of the rows one way 

 furnish sufficient fertiliser in an apricot orchard? I would let it grow 

 continuously. We have no water in August and September, but plenty 

 in the spring. 



Alfalfa does not add all forms of plant food to the soil. Some 

 substances it takes from the soil; and though its growth processes 

 may render them more easily available to other plants, the most it can 

 do in that line does not actually add more of these substances to the 

 soil. If then the alfalfa is grown as a crop and sold away from the 

 land in the form of hay, the supply of these substances is constantly 

 being reduced by growing alfalfa in this way. But alfalfa and other 

 legumes do add nitrogen by their ability to take it from the air 

 through the action of bacteria on their roots. For this reason you 

 cannot count upon alfalfa as restoring to the soil all the plant food 

 which the apricot tree takes from it in its wood growth and fruit 

 crop. All except nitrogen must be made good by other means of 

 fertilization. If alfalfa is grown without cutting, or is cut and the 

 cuttings allowed to remain and decay, the plant will, theoretically, 

 not take anything off the land, but, at the same time, it adds nothing 

 but nitrogen to it. If the soil is naturally richly supplied with all 

 other plant foods, then the addition of nitrogen, by alfalfa growing or 

 otherwise, is a rational proceeding. If only a small addition is needed 

 to the natural supply of nitrogen, then a narrow strip of alfalfa may 

 be enough, but this is probably not often the case. 



A more important consideration for you is whether you have 

 soil-moisture enough to grow the strip, supply the waste by evapora- 

 tion and meet the needs of the trees. You have no water in the 

 autumn, and the probability is that the alfalfa will rob the trees during 

 that period, weaken the next year's fruit buds and perhaps cause die- 

 back of branches if not the death of the trees in extreme cases. 

 Rational enrichment of the soil consists in growing a legume when 

 there is naturally more water in the soil than the tree can use, or 

 when the soil can be kept adequately moist by irrigation. Therefore 

 a winter-growing legume, and not alfalfa, is indicated in your case. 

 However, if you can grow enough alfalfa hay on that strip to spread 

 as a mulch over all the rest of the ground between the trees and thus 

 substitute a mulch for summer cultivation, you may save enough 



