142 Appendix. 



One man is sure clean culture is Ijest. another srows a crop of hay and figures 

 he is so many dollars ahead of the first, another has unbounded faitli in cover 

 crops, a fourth uses the grass mulch, while perhaps a fifth finds it more satis- 

 factory to combine two or more of them. Here is considerable diversity, and 

 if my discussion shall enable you to choose more discriminatingly among tliem, 

 I shall not feel that I owe any apologies for taking up your time. 



All management of orchard soils has two chief ends in view, to maintain 

 moisture and fertility. It would be convenient, if practicable, to consider 

 separately the means of attaining each, l)ut such separation could be carried 

 only a little ways before the two would liegin to overlap. Thus adding com- 

 mercial fertilizer to the ground will not lielp the moisture, but barnyard manure 

 will: and on the otlier hand shallow cultivation will not only conserve moisture, 

 but actually enrich the soil by allowing more air to enter and break up the 

 mineral particles which contain potash and phosphates. So let us remember 

 in what follows that most of the things we do to secure moisture increase 

 fertility, and vice versa. 



We should remember at the outset tliat fertility means more than mere 

 richness in the elements necessary to plant growth ; much more than tliis, it 

 means suitable physical condition cf the soil. Tlie cliemist's analysis may 

 sliow a certain soil to contain plenty of nitrates, phosphates and potash, or 

 you may add them liberally in the form of commercial fertilizers, yet if the 

 soil happens to be a clay, puddled and caked so that notliing will grow on it. 

 it is really not fertile at all. In perhaps nine cases out of ten infertility is due 

 to poor mechanical conditions rather than lack of any chemical elements. 



If any of these elements are deficient, nitrogen is most apt to be the one, 

 iis its salts are most soluble in water, and hence leacli away most readily. Tlie 

 only otlier elements at all apt to be lacking are potasli and phosphorus, but 

 these are much more (irmly held by the soil, so it is far less often necessary to 

 supply them than nitrogen. ITnfortunately for us, the latter is tlie most 

 expensive of the three, costing in the form of nitrates about 12 cents a pound 

 wholesale, while potash costs 8 cents and phosphorus only 3 cents. When I 

 s;)eak of nitrogen I do not of course refer to the gas, but to its solid salts called 

 nitrates (whicli much resemble impure rock salt in appearance) ; the relation 

 between tlie two forms of it being in some respects similar to tliat between 

 steam and ice, wliere the same substance appears in one case as a gas and in 

 tlie otlier as a solid. Nitrogen in tlie gaseous form is exceedingly abundant in 

 the air, forming over four-fifths of it, but in this form is not useful to plants. 

 If you find it necessary to supply nitrogen (where trees lack it their leaves 

 are a paler green, and the wood growth is less tlian it sliould be) tliere is a 

 cheaper and better way of getting it than to buy nitrate of soda, dried blood, 

 or tanliage. and that is by growing cover crops of legumes. Tlie term cover 

 crop is sometimes misunderstood, so I may say in passing that it is a crop 

 grown exclusively for tlie benefit of tlie soil, allowed to I'emain on or in the 

 ground instead of being liarvested. Tlie legumes, such as clover, vetcli, alfalfa, 

 peas and beans, serve, as you well know, as liosts for certain bacteria which 

 live on their roots, causing little swellings or nudules wliich often reacli tlie 

 size of a bucksliot. Now these minute organisms, while tliey doubtless do some 

 injury to tlie plant by causing these abnormal bunches and feeding on tlie 

 plant juices, much more than offset it by furnishing nitrogen, which they give 

 off as a waste product, to the plant, for tliey have the power denied to the 

 plant of appropriating atmospheric nitrogen. Tlius this group of plants is able 

 through indirect means to take advantage of tlie great stores of nitrogen in 

 the air, and by growing crops of them and turning them under we can add their 

 ■•iccumulation to tlie soil. It must not be supposed, however, that all the nitrogen 

 they contain represents a clear gain from tlie atmosphere, for crops other than 

 the legumes or "nitrogen-gatherers," such as oats, show in analysis very con- 

 siderable quantities of nitrogen, which was of course derived entirely from the 

 soil. 



