Crotalaria juncea L.: some aspects of its biology, its use as nitrogen fertilizer supplement and for weed suppression in sugarcane
1991
Tapay, R.E.
Crotalaria juncea L. exhibits rapid vegetative growth 21 to 35 days after sowing. The plant started to flower in 21 to 30 days and reached maturity in 63 to 84 days. The reproductive capacity ranged from 428 to 844 seeds per plant. Nitrogen content was highest in the leaves, followed by the whole plant, roots and stems during vegetative growth. At maturity, nitrogen content was greatly concentrated in the seeds and was lowest in the leaves. Biomass yield (fresh and dry matter) of C. juncea significantly increased with plant age. The leaves and roots had greater biomass than the stem in the early stages of growth; but as the plant matured, biomass accumulated more in the stem. The most suitable use of C. juncea intercrop as nitrogen supplement for sugarcane was at a seeding of 20 kg/ha 15 days after planting, incorporated with 4 passes of animal-drawn plow, 30 days after sowing. Higher seeding rates and late sowing and incorporation adversely reduced the tillering of sugarcane and biomass accumulation of crotalaria. The seeding rate of 20 kg/ha (609,600 plants/ha) produced about 5.8 and 1.2 tons fresh and dry matter yields/ha, respectively, and was equivalent to about 34.8 kg nitrogen per hectare. Sugar yield and its components did not significantly respond to green manuring with crotalaria and application of inorganic nitrogen. Tiller height and tiller number gave a positive response only at early stages of growth. The insignificant response of sugar yield to crotalaria green manure could be due to initially high amounts of organic matter and soil nitrogen, which may have negated whatever nutrient contribution crotalaria has added to the soil. Intercropping C. juncea with sugarcane reduced weed weight, but did not alter the density of weeds associated with sugarcane.
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