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United States Department of Agriculture

Agricultural Research Service

Title: Effects of Lime and CA on Root Growth and Nodulation of Clovers

Authors
item Brauer, David
item Ritchey, Kenneth
item Belesky, David

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 1, 2001
Publication Date: March 1, 2002
Citation: BRAUER, D.K., RITCHEY, K.D., BELESKY, D.P. 2002. EFFECTS OF LIME AND CA ON ROOT GROWTH AND NODULATION OF CLOVERS. Crop Science. 42(5)1640-1646.

Interpretive Summary: It is well known that liming acidic soils increases nodulation of red and white clover. The effects of liming may be due to increases in soil pH or soil Ca or both. Greenhouse, growth chamber and field studies were conducted to ascribe the effects of liming on nodulation to either changes in soil Ca or pH. Soil Ca and pH were manipulated independently by amending soils with either Ca sulfate or Ca carbonate There was a strong curvilinear relationship between the number of nodules per plant 28 days after planting and soil pH. There was no relationship between nodualtion and soil Ca. These results indicate that changes in nodulation were more closely associated with changes in soil pH than changes in soil Ca. These results are of interest to agronomists and soil scientists for refining soil test recommendations for growing clovers.

Technical Abstract: Liming acidic soils tends to increase root growth and nodulation of clovers. Greenhouse, growth chamber and field studies were conducted to determine the effects of lime on root growth and development, and to ascribe the effects of liming on nodulation to either changes in soil Ca or pH. A Gilpin series silt loam soil (fine loamy, mixed mesic, Typic Hapludult) from Bragg, WV was used in these studies. Addition of lime to increase soil pH from 4.8 to 5.3 increased nodulation and root growth of white clover (Trifolium repens L., cultivar Huia) the first 28 days after planting in a growth chamber experiment. White clover seedlings from the unlimed soil formed fewer indeterminate and determinate types of roots as plants from the limed soil. A greenhouse study was conducted to determine the effects of soil Ca and pH on nodulation of white clover seedlings. Soils were amended with either CaSO4, CaCO3 or a mixture of the 2 Ca sources to increase soil Ca by 300 and 600 mg Ca kg-1 soil (dry weight). There was a strong curvilinear relationship between the number of nodules per plant 28 days after planting and soil pH. A field experiment was conducted to confirm these results. Field plots were amended with either lime or a coal combustion by-product that supplied CaSO4 in 1993 and seeded to either red (Trifolium pratense, L.) or white clover in spring of 1998. Nodules were counted in May and August of 1998, and May of 1999. At all three sampling dates, the number of nodules per primary root was more closely associated with soil pH than soil Ca. These results indicate that changes in nodulation were more closely associated with changes in soil pH than changes in soil Ca.

Last Modified: 7/22/2014
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