Aluminum has long been recognized as a major limiting factor for root growth in acid subsoils, but little has been done to delineate toxic and nontoxic forms of soil‐solution Al. In an effort to determine if the presence of organic acids in soil solutions affected Al phytotoxicity, short‐term, split‐root experiments were conducted with cotton (Gossypium hirsutum L.) taproots as the growth indicator. Based on pure solution experiments, short‐chain, carboxylic acids can be divided into three groups as Al detoxifiers: (i) strong (citric, oxalic, tartaric), (ii) moderate (malic, malonic, salicylic), and (iii) weak (succinic, lactic, formic, acetic, phthalic). The Al detoxifying capacities of these acids were positively correlated with the relative position of OH/COOH groups on their main C chain, positions that favored the formation of stable 5‐ or 6‐bond ring structures with Al. In addition, analyses of soil solutions from several eluviated acid horizons (E, EB, BE) revealed the presence of several organic acids whose concentrations were generally higher in forested than in cultivated soils. Based on these concentrations, total solution Al (as measured by ICAP) was partitioned into monomeric Al (Al3+ + hydroxy‐Al species) and complexed Al (Al‐organic acid complexes). The latter accounted for 93 and 76% of the total solution Al concentrations of the two acid subsoils into which elongation rate of cotton taproot was studied. Root growth was significantly correlated with monomeric Al but not with total Al in soil solutions.

Hypertension as a result of proximal renal artery stenosis has been described in patients with neurofibromatosis, but a review of the English language literature showed no familial incidence of renovascular lesions in association with neurofibromatosis. We report a case of neurofibromatosis in a 24-year-old white woman with renovascular hypertension resulting from a proximal renal artery stenosis and poststenotic aneurysmal degeneration. Her sister, aged 38 years, presented similarly but without clinical evidence of neurofibromatosis. Both sisters had reversed saphenous vein bypass grafting for renal artery stenosis and showed no evidence of pheochromocytoma. Histologic examination of both surgical specimens revealed similar fibrodysplastic changes of the media and adventitia without abnormal neural tissue, findings consistent with those described in patients with neurofibromatosis.

Growth chamber experiments, employing a two‐zone root technique and nutrient solutions, were conducted to study the influence of iron on the growth of Linum usitatissimum L., fiber flax, at various levels of zinc sulfate. Zinc and iron variables were added to one root zone, while all other essential nutrients were added to a second root zone. Plant growth in nutrient solutions containing as much as 1.00 ppm of Zn was increased by the addition of 5.0 ppm of iron as FeCl3. Competition for root absorption sites existed between Zn+2 and Fe+3. Zinc appeared to interfere with iron uptake, whereas iron did not interfere with zinc uptake. FeEDDHA (sodium ferric ethylenediamine di‐[o‐hydroxyphenylacetate]) and Rayplex Fe (iron complexed with modified polyflavonoid copolymers) also increased plant growth in solutions containing 0.50 ppm zinc.

A field experiment was conducted to study the influence of soil pH micronutrient additions and other management practices on soybean yields where peach trees had been grown previously. Decreased soybean yields resulted when either zinc sulfate or superphosphate was added to soil with a pH value below approximately 5.40. FeEDDHA improved plant growth, but did not influence soybean yields. Raising soil pH from 5.40 to approximately 6.40 with 2,602 kg/ha of dolomitic limestone increased plant growth and soybean yields. Zinc content of leaves ranged from a high of 229 ppm in acid soil to 77 ppm in limed soil. Highest soybean yields were obtained from organic matter (snap corn meal) in combination with dolomitic limestone.

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Native phosphate and added water-soluble phosphate are "immobilized" to a high degree by Cecil soil. Addition of high-affinity anions (e.g., citrate and humate ions) which compete with the phosphate anion for cationic soil sites reduces the amount of phosphate immobilized by Cecil soil and increases the amount of phosphate in the soil solution.Quercetin, Gallein, and Mordant Violet 39 (anionic metalizable dyes) are more effective competing agents for Cecil soil sites than either citrate or humate. They are particularly effective phosphate freeing compounds when used at molar concentrations 10 to 20 times that of added phosphate. Under comparable conditions, Quercetin, Gallein, and Mordant Violet 39 appear to have higher affinity than phosphate for Cecil soil. Mordant Violet 39 is sorbed more rapidly than phosphate by Cecil surface soil.The hypothesis which arises from these sorption-desorption experiments is that addition of a high-affinity, metalizable anionic dye to Cecil soil should make soil phosphate more available for plant consumption.

The purpose of this study was to determine if addition of a metalizable anionic dye to a phosphate‐fixing soil would release phosphate for plant consumption. Some evidence of phosphate release was obtained. Addition of Mordant Violet 39 to Cecil surface soil increased flax growth in this soil. In a growth chamber experiment incorporating the dye, plant height increased about 40%, planet weight increased about 60%, and plant phosphorus increased about 100%. The dye‐grown flax was necrotic. It contained more manganese and less calcium and magnesium than control flax.

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