ule formulation are similar to those of secondary root formation (Gresshoff, 1993). Improvements in image Acidic soils can reduce the nodulation of forage legumes. Studies analysis technology allow researchers to assess the efwith a Gilpin series silt loam (fine loamy, mixed mesic, Typic Hapludult) from New, WV, were conducted to determine the effects of lime fects of soil conditions on specific root types, rather on root development, and to assess effects of soil Ca and pH on than just total root length or growth. Recent results innodulation. Liming increased soil pH from 4.8 to 5.3, nodulation, and dicate that different root types respond to environmenroot growth of white clover (Trifolium repens L., cultivar Huia) 28 d tal conditions differently (Zobel, 1992). after planting. Seedlings from unlimed soil formed fewer indetermi-It is still not clear whether the effects of liming on nate and determinate roots. Next, soils were amended with either nodulation are due to changes in soil pH, soil Al, or CaCO 3 or a mixture of CaCO 3 and CaSO 4 to achieve a soil pH of 4.7 soil Ca. In mineral soils, plant available Al is most often to 6.1 and soil Ca of 170 to 680 mg kg Ϫ1 soil. There was a strong controlled by soil pH (Thomas and Hargrove, 1984). quadratic relationship between number of nodules per white clover Therefore the effects of soil pH may be due to changes seedling 28 d after planting and soil pH. Another experiment was conducted to determine if these trends were expressed under field in plant available Al. At this time there is no adequate conditions. In 1993, field plots were amended with lime or a coal way of varying soil pH and plant available Al indepencombustion by-product that supplied Ca as CaSO 4 and seeded in 1994 dently with the Gilpin series soils. Experiments examinto cool-season grasses. In spring of 1998, plots were drilled with either ing the effects of pH and Al on root growth have been red (Trifolium pratense, L.) or white clover. The nodules per primary conducted using non-soil rooting media (Brauer, 1998, root were determined in May (1998, 1999) and August (1998). Number and references therein).of nodules per primary root was more closely associated with soil pH A series of papers (Lynd and Ansman, 1989a, b; Purthan soil Ca. These results indicate that changes in nodulation were cino and Lynd, 1986) examined the effects of changes more closely associated with changes in soil pH than soil Ca.