﻿EFFECT OF BORAX ON GROWTH AND YIELD OF CROPS. 27 



assimilation of iron, similar to the action of an excess of calcium, or, as observed, with 

 an excess of manganese compounds. Injurious quantities of borax cause tipburn; 

 in still stronger concentrations wilting ensues, first of the older leaves and then of the 

 entire plant! Borax toxicity is also evidenced in the foliage by a handed bleaching 

 of the chlorophyll of the leaves especially marked at the margins. The extreme tips 

 are often killed, but not the margins. When the injury is less severe the leaves are 

 at first streaked with pale green and may later regain their normal color. 



Beans. — Borax is especially injurious to beans and is harmful at germination and 

 retards development in the early stages of growth. The injury first appears on the 

 margins of the first leaves which unfold, especially the tips. Where injury is severe, 

 the entire leaf soon turns yellow, then white, which is followed by a killing of the 

 tissues, working from the margin inward. It has been observed that the taproot 

 of the bean plant was the most injured portion in the poisoned seedling. The root 

 nodules were markedly reduced in size and number. In all cases of borax injury 

 to beans, a dwarfed plant resulted with a final reduction of both vines and fruit. 



Cotton. — Cotton plants affected by borax both in pots and under field conditions 

 are weak, slender, and frequently die after having made a growth of an inch or two. 

 At the time when the first pair of true leaves should appear, the seedlings show no 

 apparent growth for several weeks, dead sections appearing: alone: the margins of the 

 seed leaves which eventually become dry, and the plant dies. Where injury is less, 

 the plant shows a stunted growth and early maturity. The foliage shows a yellowed 

 effect, and the leaves become dish shaped. The resultant effect is a broken stand, 

 and plants in the field of the same age vary greatly in size. The yield is greatly 

 reduced. 



Tobacco. — Plummer and Wolf (11) describe the effects of borax on tobacco as fol- 

 lows: The roots of borax-affected plants are severely stunted, tend to be densely 

 clustered near the end of the main root, and are all short and fibrous. The lower leaves 

 are pale green, thicker, and less broad. The tissues most distant from the principal 

 veins are palest and may become dead and dry. The leaf margins and tips are rolled 

 downward and become rimbound. The root development of plants which made 

 considerable growth is near the surface of the soil and near the tip of the main root, 

 with few or no roots between these two groups. The stand in borax-treated fields 

 is broken, and the plants lack uniformity in size. 



It would appear from the symptoms described for the various crops 

 that the main characteristics of borax-affected plants are (1) retarded 

 germination ; (2) general dwarfing of the plant including both roots 

 and tops; (3) absence of normal color, which may be characterized 

 by bleached and yellowed foliage, especially leaf tips and margins; 

 and (4) reduced growth and yield. 



SUMMARY. 



The results presented herein show that borax proved to be harmful 

 to plant growth. The experimental work was designed in order to pre- 

 clude any other possible harmful factors. For one thing, practically 

 pure borax was employed to mix with the fertilizers. The fertilizer 

 itself was made from practically borax-free nitrogen, phosphoric acid, 

 and potash salts. Varying quantities of borax, ranging from 1 to 400 

 pounds per acre were mixed with fertilizer and applied to the soil in 

 three different ways. In order to properly compare the effect of the 

 borax, one application of borax-free fertilizer was made in the same 

 way and applied in the same quantity. Finally it was decided 

 essential to carry on the experimental work on a number of soil types 

 and with different crop plants as indicators of borax injury. 



The results show that the potato can tolerate a greater quantity 

 of borax than plants like corn or beans, which were injured by com- 

 paratively small quantities of borax. The degree of injury, however, 

 was modified considerably according to the rainfall. Apparently the 

 depth and distribution of rainfall is the most prominent factor con- 

 cerned. Heavv rainfall in one section caused the borax to leach 



