Growth and Nutrient Relations of a Grass-Legume Mixture on Sodic Coal-Mine Spoil as Affected by Some Amendments
1979
Safaya, N. M. | Wali, M. K.
Laboratory and growth chamber investigations were conducted to study the effects of fertilizers, gypsum, H₂SO₄, and leonardite (oxidized lignite) on the growth and nutrient relations of a mixed crop of thickspike wheatgrass [Agropyron dasystachyum (Hook.) Scribn.] and yellow sweetclover [Melilotus officinalis (L.) Lam.] on a calcareous sodic coal-mine spoil. Application of NPK increased the dry matter yield of the two species by 10 and 37 times, respectively. However, sweetclover required P only but wheatgrass yields almost doubled when N was included with P. Inclusion of Zn with NPK decreased the growth of sweetclover, and reduced Mn uptake in both species. Zinc, Mn, Cu, and Fe concentrations in the plants decreased variously with fertilizer applications. P-fertilization decreased the concentration of K in wheatgrass but not in sweetclover. The two species exhibited differential growth response to leonardite, which was correlated with K⁺/Na⁺ ratios in the plants and their Ca-uptake efficiency. Leonardite increased Na concentration in wheatgrass (Ca-inefficient) and decreased its growth, but caused a reverse effect on sweetclover (Ca-efficient). It also decreased K and Zn in wheatgrass, and Cu and Fe in sweetclover. Gypsum tended to alleviate the effects of leonardite on wheatgrass, and increased Zn and Mn content in NPK-supplied plants. The extractability of applied P was higher from leonardite treated spoil. Sulfuric acid proved more effective than gypsum in releasing Na from the exchange sites in the spoil. Moreover, H₂SO₄ improved the P status of plants, and increased the yield of wheatgrass to the same extent as did the application of 75 µg P/g spoil from H₃PO₄ source.
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