. Agriculture for southern schools. ir by the workof their root tubercles theygenerally do not need nitro-gen. To add a fertilizercontaining nitrogen istherefore a useless expense. Suiting the fertilizer tothe soil.—What a soilneeds cannot be told bylooking at it. There are,however, some helpful . ■ 1 / ■ll^^^ ^kM Jpr^ m-i- Fig. 68. — Sorghum from Areas On left, no nitrogen in the fertilizer; onrightj fertilized with nitrate of soda. rules. Generally, a soil that is black or very dark con-tains much vegetable matter, which in turn contains muchnitrogen. On the other hand, if the stalks
. Agriculture for southern schools. ir by the workof their root tubercles theygenerally do not need nitro-gen. To add a fertilizercontaining nitrogen istherefore a useless expense. Suiting the fertilizer tothe soil.—What a soilneeds cannot be told bylooking at it. There are,however, some helpful . ■ 1 / ■ll^^^ ^kM Jpr^ m-i- Fig. 68. — Sorghum from Areas On left, no nitrogen in the fertilizer; onrightj fertilized with nitrate of soda. rules. Generally, a soil that is black or very dark con-tains much vegetable matter, which in turn contains muchnitrogen. On the other hand, if the stalks of crops cul- T lO AGRICULTURE tivated on a field are small, there is probably needof nitrogen in the soil. A crop of cowpeas or cloverusually leaves the soil rich in nitrogen. Clay soils gener-ally contain more potash than sandy soils. Whether asoil is rich in phosphoric acid cannot be told by lookingat it. How to find what fertilizer the soil needs. — Even whena chemist analyzes soil and finds out just what it contains,. Fig. 69. — Wheat from Equal AreasOn left, fertilized with nitrate of soda; on right, no nitrogen in the fertilizer. he cannot tell how much of every precious element is in acondition for plants to use. The chemists analysis doesnot, therefore, show what fertihzer to apply. The only way to determine the kind of fertilizer a soilneeds is to make an experiment on that soil with differentfertilizers. It will pay to make this experiment with the principalcrop of any farm. The following diagram shows how tomake such a test. The areas must be of exactly the same SUITING THE FERTILIZERS TO THE SOIL III size, for example, one eighth of an acre. The figures inthe table show the number of pounds of fertilizer for oneacre: 1 2 3 4 5 6 7 B rt rt cS OJ ni rt 13 T3 rt T3 cj -a ^ 0 0 1 ° 0 ft to (A en % 0 0 0 0 0 0 0 Ji 1> u -a 4) .^ OJ ■3 •a S 1 ^ ^H 3 S H 4J ■3 ■3 -y rt ^ 0 0 •■-( u .ti ■3 -M rt c .3 « .2 a 0 ni n ^ tn cn c/l » en *+J M m o5
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Keywords: ., bookcentury1900, bookdecade1900, bookidcu, booksubjectagriculture
