. Journal of agricultural research . ressed as the nitrate (NO3) equivalent and computed to parts per million of soil. In order to bring out more clearly certain apparent relations betweenthe water extracts and the amounts of soil solutes taken up by the plant,we have computed the plant constituents in terms of the correspondingions of the soil and expressed these in terms of parts per million of themass of soil upon which the plants were grown and in which the variousconstituents must have originated. The data from the soils are expressedin similar terms (fig. 9-13). It should be pointed out
. Journal of agricultural research . ressed as the nitrate (NO3) equivalent and computed to parts per million of soil. In order to bring out more clearly certain apparent relations betweenthe water extracts and the amounts of soil solutes taken up by the plant,we have computed the plant constituents in terms of the correspondingions of the soil and expressed these in terms of parts per million of themass of soil upon which the plants were grown and in which the variousconstituents must have originated. The data from the soils are expressedin similar terms (fig. 9-13). It should be pointed out at once thatthe soil data are not to be too literally interpreted. For instance, it isclear that we can not expect that the gains and losses of a given con- Oct. 15. I9I9 Rate of Absorption of Soil Constituents 67 stitu^ut by the plant will be accompanied by exactly equal losses or gainsin the soil extract. The more obvious reasons for this are that the waterextract is to be regarded only as an indicator of the general magnitudes of. Fig. 10.—Absorption of potassium by barley, computed to parts per million of soil. the solutes present and not as the equivalent of the soil solution, that ionsabsorbed by the plants may be partially or entirely replaced in the waterextract by solution from the soil minerals, and that solutes lost from theplants may not reappear in the form determined in the soil extract. .55 r j»- -% ^•^/Hc %>p •X y / ? CALCIUM (Ca) \ \ / ^-%. %>, / £LANr
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectagricul, bookyear1913
