FERTILITY 



FERTILIZATION 



1221 



in a hole about 1 inch in diameter and 2 feet deep at 

 each plae:e> where :i tree is to he set. Sueli t rent rnent 

 tends to promote filtration, to set, free plant-food by 

 aeration and to improve! the physical condition of 

 the adjacent soil, while at the same time it lessens 

 the labor necessary to prepare the ground for tree- 

 setting. 



Hani manures, when properly oared for and intelli- 

 gently applied, not only furnish acceptable plant-food 

 but iunnus as well. Fertility and high productivity 

 usually may be maintained many years by means of 

 superior tillage, leguminous harvest, and cover-crops, 

 and the manures of the farm. In some cases a high 

 slate of fertility can be maintained only by occasional 

 applications of commercial mineral fertilizers, such as 



Khosphates and potash, but too often expensive ferti- 

 /ers have been substituted for tillage, leguminous 

 plants and barn manures. 



Fertility may frequently be promoted by light 

 applications (ten to twenty bushels to the acre) of 

 quicklime. Lime serves to make plant-food more 

 available, to improve soil texture and to correct acidity. 

 It may also be applied beneficially to a green-manure 

 fallow. Lime tends to sink into the soil, therefore 

 it should be applied after the last plowing preceding 

 the seeding, and should be covered and mixed with the 

 soil by tillage. Hydrated, or biting lime, not only tends 

 to set free plant-food but to flocculate the soil, thereby 

 improving its physical condition. Its use is especially 

 recommended on clay and moist lands and in orchards 

 where the ground is much shaded. Applications of 

 gypsum and salt are sometimes beneficial in main- 

 taining fertility, but they, as well as lime, usually act 

 indirectly, as the soil is seldom deficient in these con- 

 st it nt cuts so far as they are required as plant-food. On 

 high-priced lands, especially those; devoted to horti- 

 culture, the soil should be made and kept fertile well 

 up to its highest productive power. 



A bare summer fallow of one to three plowings and 

 suitable surface tillage will not only destroy weeds, but 

 liberate plant-food as well, while storing moisture in 

 the soil for the immediate use of young plants. Hut a 

 bare fallow, if not accompanied by the addition of some 

 plant-food, may hasten the depletion of the soil. It 

 is a mat I er of judgment, then, as to whether the particu- 

 lar soil contains such abundant supplies of plant-food 

 that some; of them may be removed; or whether it is 

 very deficient. In the latter case a green fallow would 

 be i'ar preferable to a bare one. In many cases a bare 

 fallow is merely a method of mining-farming which 

 hastens the time when the land must be turned out 

 to pasture for economic reasons. Often productivity 

 is increased more satisfactorily by means of green- 

 manuring than by bringing plant-food to the land 

 from outside sources. In most of the humid districts 

 early sowed pe;is (which withstand late frosts) followed 

 by buckwheat, and both plowed under some time 

 before they mature, can be grown in time to fit the 

 land for seeding in September to wheat, rye or timothy, 

 the nurse crop being omitted. When the land might, 

 be made too porous by this method, rye sowed in the 

 fall, plowed under before coming to head and followed 

 by peas, would greatly improve; the light and sandy 

 soils by bringing stores of nitrogen and humus. 



Nature, in producing and storing fertility, provides 

 a great variety of plants and an infinite number of 

 ways of multiplying them so that the land is fully 

 covered with vegetation except in desert regions. 

 Upon the best of these Jands a vast animal life is main- 

 tained while the remainder produces other plants to 

 feed other animals. In the densely settled agricul- 

 tural districts of China, for the last two thousand 

 years the farmers have been returning as much to the 

 land as they have taken from it; and the soil is now 

 more productive than it was when first brought into 

 cultivation. The problem of conservation and resto- 



ration erf se>ils is nenv in America the most, serious one 

 the; agriculturist has te) solve. 



Sometimes soils are; re;nele;re;el unfruitful by the 

 presence of delete-riems substances, as e>rganic aciels or 

 alkaline salts, or a superabundance of se>me one or 

 more of its usually useful ingredients, as water or 

 nitre>ge;nous compemnels. An e>xce>ss of nitrogen stimu- 

 lates the growth erf stalk anel straw at the e-xpe-nse of 

 grain, or in the orchard it tends to the; fetrmatiem of 

 wood rathe'r than to fruitfulness. The ae;ielity shoulei 

 be corrected by lime 1 , as noted abe)ve, the surplus water 

 removed by elrainagc, the nitre)ge;ne)iis matter reduced 

 by the production of such crops as are; not harmfully 

 aifect,e;el by its superabundance, such as forage crops 

 which are; prized for their foliage; rather than for their 

 seeds, while; the alkalinity may sometimes be overcome 

 by deep tillage*, irrigation or application of gypsum in 

 suitable amounts. J. p. ROHKKTB. 



FERTILIZATION is the: fusion of sexually differ- 

 entiated cells, anel with spe;cial reference to the seed 

 plants it me;ans that a cell (a fertilized egg, or zygote) 

 is thus formed which is capable of developing into the 

 e-mbryonic plant later recognized in the plantlct of 

 the; se;ed. The fusing cells, or gametes, are (1) the; egg 

 (female cell), which is organized in the ovule, as 

 describee! below, and (2) a sperm-cell, or nucleus (male 

 cell), devele)pe;e! in the germi- 

 nating pollen-tube. Fertiliza- 

 tion is a process which may not 

 be reaelily observed in the se;eel- 

 plants except through the; use 

 of careful histological methods. 

 both m the fixation of material 

 and in the subsequent pro- 

 cesses of imbedding anel stain- 

 ing. The phenomena are illus- 

 trated in Figs. 1496-1497. 



The term "fertilization" has 

 always implied the union of 

 male and female cells; but 

 formerly, when less was known 

 regarding the details erf the 

 phenomenon, " fertilization " 

 included the mere mechanical 

 process whereby pollen from 

 1495. A pollen-grain of tnc an ther was transferreel by 

 Lilium philadelphicum . t to thc gti of thc 



Section of a single gram a o ' _ y nr *u: s ro ,,Bon "fer- 

 before the anther opena; t, nowc r: J 

 the tube-cell; g. the genera- tllization by insects Or fer- 



nv. ...|i. The large Bpheri- tilization by wind" meaning 



oul Ixxly in each cell in the ^i +___(,. n c nnttan u v thoao 

 nucleus: ( Magnified 500 tnc transl l)v U " ' 



agencies arc freouent expres- 

 sions in the work of Darwin 

 and Wallace. In this last-mentioned sense, the wore! 

 pollination is appropriate, and now commonly em- 

 ployesd. If the silks of corn are pollinated with corn 

 ix)llen, fertilization normally ensues and seeds are 

 produced; but if the corn-silks are pollinated by the 

 pollen e>f the lily, no seeds will be formed. It is obvious 

 that cross-pollination has no limits; but cross-fertiliza- 

 tion is limited to those cases in which the sexual cells 

 unite and a new organism develops. 



The development of some structures essential in 

 fertilization are of interest in this connection. The 

 mature; pollen-grain consists of a large tube-cell and 

 nucleus and a small generative cell and nucleus. When 

 lodgeel upon a suitable stigma the pollen-grain germi- 

 nates by the development of a tube which enters the 

 loose; tissue of the stigma and grows further into the 

 conducting parts of the style. In some cases, definite 

 stylar canals are present, but usually the tube we;elge>s 

 itself between the yielding e;e:lls, absorbs nutrient in 

 its course, anel force;s or dissolves its way to the ovule; 

 or sceel-case, where, as a rule, it enters the micropyle 

 anel approaches the embryo-sac and egg-cell. In its 



