NITROGEN CONTENTS OF COMPOSTS ENRICHED WITH ORGANIC NITROGEN SOURCES
Information is scanty on the potentials of agricultural wastes to enrich composts whose low nitrogen (N) content limits their use in organic farming. This study involved enriching composts - cow dung + sawdust (CDSD) and poultry droppings + sawdust (PDSD) with N at 10, 20, 30 and 50 kg/ha from bone, blood, hoof and horn meals; and neem leaf and tithonia leaf meals and their incubation in soil for 16 weeks. Total N contents monitored at four-week intervals of incubation showed enrichment in 74.0 and 83.0% of CDSD and PDSD compared to the respective controls. N contents were highest in 21, 0, 1 and 28 composts incubated for 4, 8, 12 and 16 weeks respectively. At 4 weeks, CDSD enriched with 50 kg N/ha from blood meal (CDSDBM) and bone meal (CDSDBN) contained 10.5 and 9.2 g/kg total N while PDSD enriched with 50 kg N/ha from bone meal (PDSDBN) and tithonia leaf meal (PDSDTM) contained 9.3 and 8.6 g/kg total N. These are suitable for the cultivation of short-season leaf vegetables. N content reduced at 8 weeks of incubation and increased at 12 and 16 weeks. Only CDSD enriched with neem leaf meal (CDSDNM at all N rates) increased in N content with time of incubation. CDSDNM and PDSDBM at 50 kg N/ha contained the highest total N at 16 weeks of incubation and should be recommended for the cultivation of long-season vegetables.
|Keywords: Composts, agricultural wastes, enrichment, incubation, nitrogen content|
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