188-12 Crotalaria Juncea L. Cv. IAC-1 for Livestock Feed and Seed Production in Low-External-Input Mixed Crop/Livestock Production Systems for the Tropics.



Tuesday, October 18, 2011
Henry Gonzalez Convention Center, Hall C, Street Level

Stuart Weiss, Agricultural Experiment Station, University of the Virgin Islands, Kingshill, US Virgin Islands
Crotalaria juncea L. is a tropical warm season legume that is growing in popularity in the United States (U.S.) as a cover crop and green manure crop that can contribute nitrogen and organic matter to the farming system.  It also serves as an important fiber crop, has use as a livestock forage, and may serve as a valuable bioenergy feedstock.  Due to the limited availability of commercial C. juncea seed in the U.S., this preliminary trial investigates C. juncea cv IAC-1 for livestock forage production and commercial seed production under low-external-input farming conditions.  A feasibility study was conducted on St. Croix in the U.S. Virgin Islands to test two seed production systems. Test plots were broadcast seeded and then rolled with a culti-packer.  No inputs were applied for the production of the crop.  The first system (SYS1) measured seed production at 2 harvest dates (160 days after planting (DAP) and 191 DAP).  The second system (SYS2) combined biomass removal through a hay harvest 55 DAP and then seed harvest on the C. juncea  re-growth at 195 DAP or 140 days after forage removal.  SYS2 produced a mean biomass yield of 4,741 kg/ha of forage on a dry matter basis which was dried, bailed for hay, and subsequently fed to sheep in a separate feeding trial.  Preliminary results indicate that SYS2 produced fewer seed pods per plant (21 ±2.8, p<0.05)) and had fewer seeds per pod (4.7 ± 0.2, p<0.0001)) than either harvest 1 (30 ±2.5 and 6.6 ±0.2, respectively) or harvest 2 (29 ±2.5 and 6.4 ±0.2, respectively) from SYS1.  At the time of seed harvest, SYS2 had higher plant density with 67 plants /m2 than harvest 1 (160 DAP) or 2 (191 DAP) from SYS1 with 40 and 41 plants/m2, respectively (p<0.0001).  Total seed yield was highest in harvest 1 of SYS1 producing 3,153 kg/ha ±270 which was statistically similar with harvest 2 that produced 3,115 kg/ha of seed from SYS1, but was greater than the seed harvest in SYS2 with 1,040 kg/ha of seed (p<0.0001).   Results of this study indicate that Crotalaria juncea cv. IAC-1 can be grown in the tropics under low-external-input conditions to produce a robust seed crop, and that farmers can harvest C. juncea  forage for livestock production and still produce and harvest a seed crop for future planting or for sale as a  potential cash crop.  Additional research trials will follow to further investigate the use of C. juncea as a multi-purpose crop in low-external-input mixed crop/livestock systems.
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