Effect of Soil pH and Liming on Growth and Nodulation of Soybeans in Histosols1
- D. B. Mengel and
- E. J. Kamprath2
Soil acidity severely limits the growth of soybeans [Glycine max. (L.) Merr.] on Histosols in North Carolina. Laboratory and greenhouse studies were conducted to determine the critical soil pH levels for soybean growth and the chemical factors influencing growth. Soybeans were grown on eight organic soils which had been limed with dolomitic limestone to give a pH range from 4 to 5. Lime rates were based on the CaCl2 exchangeable acidity of each soil. Measurements were made of exchangeable soil acidity, exchangeable AI and Ca, and water soluble AI and Ca. Plant variables measured were shoot, root and nodule dry weight, nodule number and concentration of N, P, K, Ca, Mg, and AI in shoots and roots. These measurements were made at 28 and 40 days after planting in order to calculate growth rates and nutrient uptake rates. Growth responses to liming were obtained on all soils. Shoot growth was significantly related to soil pH and water soluble AI and Ca. Nodule number and weight increased significantly as soil pH increased. Both N con. centration and uptake increased markedly as soil pH increased. Critical soil pH for shoot, root, and nodule growth was in the range of 4.6 to 4.8 for most of the soils. The growth responses to liming are attributed to decreasing the exchangeable and water soluble AI, increasing the water soluble Ca and providing a favorable soil pH for rhizobium activity.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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