Chromium additions [0–5 ppm Cr(VI)] to soybeans, Glycine max (L) Merrill, grown in nutrient culture resulted in decreased concentrations and total uptake of Ca, K, P, Fe, and Mn in tops and of K, Mg, P, Fe, and Mn in roots. These effects were often apparent at Cr treatments as low as 0.5 ppm.In soil culture Cr additions [0–60 ppm Cr(VI)] appeared to interfere with the accumulation of Ca, K, Mg, P, B, and Cu by soybean tops, with little or no effect on Fe, Mn, or Zn uptake. These effects were generally first observed at the 5‐ppm Cr treatment.The initial symptoms of Cr toxicity appeared as severe wilting of tops of treated plants.It could not be concluded from the results of these experiments that Cr, as the hexavalent anion, specifically interfered with uptake of Fe or P by plants, as earlier reported.

The 2:1 layer silicate mineralogy of a Vertic Haplaquoll of north‐western Minnesota was studied using x‐ray diffraction and determination of cation exchange capacity (CEC). The x‐ray diffraction behavior of Li‐ and K‐saturated samples demonstrated that a highcharge smectite with tetrahedral charge dominates the mineralogy of both the coarse and the fine clay fractions. The high CEC and the large difference between Li‐CEC and K‐CEC confirmed the x‐ray results. Alkylammonium‐clay complex basal spacings show two phases of 2:1 clays; a high charge (about 0.9 molc per ½ unit cell formula) phase concentrated in the coarse clay and an Fe‐rich beidellite with a charge of 0.4 to 0.5 molc per ½ unit cell formula. The high charge phase largely represents K+ ‐depleted mica formed during the analytical procedure. This phase may also contain some soil vermiculite. The results presented in this study suggest that beidellite is a product of mica weathering, and that during weathering soil mica is transformed first to a vermiculite then to a beidellite, preserving the tetrahedral character of the charge.

Phosphorus losses from natural systems are the background levels against which losses from managed systems should be measured. In Minnesota many recreational lakes are surrounded by deciduous and mixed deciduous‐coniferous forests. The P losses from the forests contribute to the natural nutrient levels of the lakes. Phosphorus losses in leaching water are small. Thus, a logical mechanism for the loss of P from forests is surface runoff (overland flow). This research was conducted to study surface runoff amounts and P content.On a 16% slope, 0.09 kg ha−1 year−1 P of which 0.03 kg was bound to sediment and 0.06 kg was soluble was measured in surface runoff. The major period of runoff was during spring snowmelt when the soil was frozen. The source of P is the litter layer which undergoes freezing and thawing in fall and early winter.

The content of opal phytoliths was measured in selected horizons of six soils from Goodhue County, Minn. The highest amount of opal phytoliths occurred in a Typic Hapludoll (Kenyon series) suggesting a soil developed under dominant grass vegetation because most of the opal is derived from big bluestem (Andropogon gerardi L.) and little bluestem (A. scoparius L.). Opal phytoliths isolated from some horizons were similar in morphology to reference slides made of opal from burr oak (Quercus macrocarpa Michx.), ironwood (Ostrya virginiana (Mill.) K. Koch), and a shrub, hazel (Corylus americana Walt.).Opal phytoliths in two associated Aquollic Hapludalfs (Kasson and Taopi series) were derived primarily from big and little bluestem and with minor amounts from trees. This suggested at least a period of forest vegetation. A striking feature of Kasson, Kenyon, and Taopi soils is the higher content of opal phytoliths in till material II which begins in the B2 horizon at depths of about 50 inches. Possibly at one time the top of material II might have been prairie covered landscape and the overlying silty material was deposited later.

HIS is the third in a series of reports on leaching losses, T r u n o f f , and percolate produced by natural precipitation on eight Illinois soils. Measurements were made on triplicate profiles of each of the eight soils in erosion-type lysim