Santos-Vargas, Ana D.

Profile Picture

Filters

20101
Reset filters

Settings

Citations

Publication Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    Publication
    Potencial productivo de Crotalaria Juncea CV. Tropic Suns en agroecosistemas de Puerto Rico
    (2010) Santos-Vargas, Ana D.; Valencia-Chin, Elide; College of Agricultural Sciences; Ramos Santana, Rafael; Román Paoli, Elvin; O'Farrill, Hipolito; Department of Crops and Agro-Environmental Sciences; Alfaro Lozano, Mónica
    Sunn hemp (Crotalaria juncea L.) is a multipurpose legume of fast growth and high N2 fixation ability, thus justifying its use on degraded soils in the tropic to improve their fertility. However, there is limited information about the time of planting as well as the date of harvest to maximize biomass production and nitrogen (N) accumulation in Puerto Rico. The objective of this study was to assess two planting dates of cv. Tropic Sun and three harvest dates effects on biomass and nitrogen accumulation in two agroecosystems of Puerto Rico. In the first experiment, Tropic Sun was seeded at 7 kg ha¯¹ on a Mollisol (San Antón series) at the Agricultural Experimental Sub-station of Lajas, University of Puerto Rico. At 84, 121 and 177 days after planting (DAP), biomass was estimated for May and October planting dates. Although there was no significant harvest date effect, there was planting date effect on biomass production (p<0.05). Sunn hemp produced 5,384 to 9,111 kg ha¯¹ dry matter in a 84 to 121 days period when planted on May, surpassing the biomass produced when planting on October. Mean values for N accumulation were 123 to 127 kg N ha¯¹ from 84 to 121 DAP for the first planting season. Significant differences were found (p<0.05) in N concentration when upper and lower plant canopy was compared. Mean values were 2.12% and 1.00% for upper and lower canopy, respectively. Nitrogen content in upper and lower canopy was also expressed as crude protein (CP) percentage. Maximum values were obtained when harvesting the upper plant canopy (16.05% CP) when planting in May. For the second experiment, Tropic Sun was seeded (10 kg ha-1) on an Oxisol (Cotito series) at the Agricultural Sub-station of Isabela, University of Puerto Rico. At 71, 92 and 121 DAP, biomass was estimated for June and November planting dates. There was time of planting and harvest date effects (p<0.05) on biomass production. Maximum biomass was produced at the June planting at the 121-DAP harvest (20,734 kg ha-1) and was three times higher than the November planting (6,062 kg ha-1). When comparing date of harvest, biomass at 71-DAP in June exceeded the 71-DAP in the November harvest by 6,363 kg ha-1. Because of the higher yield for the June planting, maximum N accumulation (471 kg ha-1) was obtained at 121 DAP and was significantly different (p<0.05) when compared to the 121 DAP harvest for the November planting (134 kg ha-1). N concentration differed (p<0.05) when canopy position was compared. Mean values were 2.67% and 0.64% for upper and lower canopy, respectively. There was a significant effect (p<0.05) of canopy position, planting and harvest date on CP content. Maximum values were obtained when harvesting the upper plant canopy at 92 DAP for the November planting (19.00% CP), and was significantly higher when compared to lower canopy content during the same period (4.72%). In summary, Sunn hemp was more productive when planted in June. Although Sunn hemp has good protein content, further research on nutritional value can be helpful to determine its potential as a forage crop. Depending on the date of planting and harvest, various benefits can be obtained from this legume when included in short rotation sustainable production systems because of its good biomass production and N accumulation. The data suggested that when planted on summer, Sunn hemp has good potential as a cover crop and green manure in two agroecosystems of Puerto Rico.