科研之友
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摘要
Legumes contribute to pasture sustainability through symbiotic N-2 fixation, which may increase primary productivity and animal performance in low-input systems. Litterfall is the main way of cycling nutrients from tree legumes. We quantified gliricidia [Gliricidia sepium (Jacq.) Kunth ex Walp.] and sabia (Mimosa caesalpiniifolia Benth) litter deposition, along two 336-d cycles, in a signalgrass (Brachiaria decumbens Stapf.) pasture. Litterfall was produced throughout the year but concentrated in the dry season. Sabia produced slightly greater (P < 0.0001) litterfall amounts in the two cycles (10,790 kg ha(-1)) than gliricidia (10,420 kg ha(-1)) but the overall average N concentration of gliricidia (21.5 g kg(-1)) was greater than that of sabia (18.8 g kg(-1)). Nitrogen amounts cycled through the litter were greater for gliricidia in both cycles (105 and 109 kg N ha(-1)) than for sabia (87 and 98 kg N ha(-1)). The proportions of litter N that were derived from the atmosphere by symbiotic fixation were similar (P = 0.05) in both species (55%) and varied little along the two cycles. Lignin concentration, which influences decomposition, was similar in both species, averaging 238 and 214 g kg(-1) in the two cycles for gliricidia and 233 and 246 g kg(-1) for sabia. Greater N concentration, lower C/N ratio and lower lignin concentration indicate that gliricidia litter may have a faster cycling rate than sabia litter. Sabia could be a more promising species for soil cover and protection because of its slower litter decomposition rate.
- 出版日期2016-12
