Effects of pH and Al on the Growth and Chemical Composition of Cicer Milkvetch¹

Abstract

Cicer milkvetch (Astragalus cicer L.) is one of several legume species which has been used for the stabilization of Massachusetts roadsides. In this study the following treatments were combined in soil and water culture experiments: pH levels 4.2, 5.4, and 6.3, and aluminum levels of 0, 2.5, and 5.0 ppm added to soil, 0, 5, and 15 ppm Al in water. The objective was to examine the interactions among soil treatments, factors of acid soil infertility, and the chemical composition and growth of cicer milkvetch (‘Lutana’). Dry weights and root penetration doubled in response to soil pH 5.4. At soil pH 6.3 manganese in the soil and in the plant tissue rose to high levels while dry weights and root penetration declined. On the other hand, dry weight of tops and root elongation were significantly greater at pH 5.4 and 6.3 than at pH 4.2 in water culture. Soil Al treatments were positively related to water soluble soil P and soil Mn availability. Nutrient solution Al additions significantly enhanced Al in tops. Also, the 5 ppm Al level significantly stimulated root elongation, while 15 ppm Al was related to reduced elongation. Dry weights were not significantly affected by Al treatments in soil or water culture. The apparent acid tolerance of cicer milkvetch, plus the buffering capacity of this soil, and the sufficient supply of P at all treatments in water culture apparently diminished the A1 treatment effects. Cicer milkvetch growth is enhanced by CaCO3 application of at least 1,750 ppm to this soil for these reasons: percent Ca and P of tops rose above critical levels, while excess soil Mn and Al levels declined, allowing enhanced root penetration of the soil.

Establishment of perennial species useful for soil conservation and as forages

“…comm.). Growth and nitrogen fixation of some species, including A. cicer (Vickers et al 1977), may have been influenced adversely by the slightly acid trial site. However, pink-centred nodules were found on roots of seedlings of all legume species which suggested that at least Rhizobium growth and nitrogen fixation were not hindered.…”