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Nitrogen Relationships of Three Tropical Forage Legumes in Pure Stands and in Grass Mixtures 1
Author(s) -
Whitney A. S.,
Kanehiro Y.,
Sherman G. D.
Publication year - 1967
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1967.00021962005900010014x
Subject(s) - digitaria , desmodium , pennisetum purpureum , agronomy , forage , acre , legume , biology , pasture , zoology , dry matter
The capacities of three tropical forage legumes to fix atmospheric N and to transfer fixed N to two associated grasses were evaluated over a 12‐month period under continuously moist climate in Hawaii. Desmodium canum, Centrosema pubescens and D. intortum were grown alone and in combination with napier grass ( Pennisetum purpureum ) and pangola grass ( Digitaria decumbens ) in polyethylene‐lined plots filled with fresh volcanic cinders. The grasses averaged 4,400 pounds DM/acre, and the legumes yielded on the average as follows: D. canum 3,530, C. pubescens 6,720; and D. intortum 16,710 pounds/acre. Forage N yields plus root N levels indicated that N fixation by D. canum averaged less than 85 pounds N/acre, and that no transfer of N from D. canum to either grass occurred. C. pubescens fixed 240 pounds N/acre in pure stand and about 110 pounds N when grown with grasses. Some transfer of N from centro to the grasses was noted during a long (6‐month) growing period, amounting to 6–11% of the N fixed during that period. Intortum fixed 340 pounds N/acre in 12 months, and 5% or less of this was transferred to the associated grasses. The nitrogen transfer observed apparently involved N released by both the aerial and sub‐aerial portions of the legume plants.