8. Effect of level of effluent from plastic biodigesters loaded with pig manure on the growth of mulberry (Morus alba) trees

Authors: Chiv Phiny, Khieu Borin and Chhay Ty, 2006

Proceeding of Workshop on Forages for Pigs and Rabbots, Phnom Penh, 22-24, August, 2006. pp 197-203

Summary: The research was carried out at the ecological farm of CelAgrid, located in Prah Theat village, Rolous commune, Kandal Stung district, Kandal Province. The center is about 25 km from Phnom Penh City. Previously the field had been used for monoculture rice production. Soil, plot preparation and transplanting of the mulberry seedlings were carried out from March to July 2004 and the trial period was one year. Twenty four plots were prepared with a total area of 918 m² (8.5m x 4.5m each). The planting density was 153 seedlings per plot. Six levels of effluent from biodigester loaded cow manure (0, 100, 250, 400, 550 and 700 kg of N/ha per year) were applied. The 6 treatments had 4 replications divided into 4 blocks according to a Complete Randomized Block Design. During the dry season (December through May) the plots were irrigated by water pumped from underground sources. Effluent was pumped from the effluent tank and stored in 6 earthenware jars (about 500 litres capacity) close to the mulberry plots was applied at weekly intervals in amounts adjusted according to the results of the N analysis . The forages were harvested by cutting the entire plant at 60 cm above ground. The first time of harvesting was 4 months after planting, and subsequently at 2 month intervals. During harvesting, the biomass of mulberry foliage of each treatment was weighed and then separated into leaves and stems. Samples of soil were taken from each plot before planting and after each harvest. Samples of effluent were analyzed for N before application to the mulberry plots. The total biomass yield was recorded and the proportions of leaves, stems and petioles were measured and samples from all treatments taken for analysis. DM was determined by using a microwave oven (Undersander et al 1993). Samples were analyzed for N and Ash (AOAC 1990) and also for water soluble dry matter (WVDM) and water soluble nitrogen (WVN). In each treatment and replicate plot a soil sample of 0.5 kg was taken at approximately 30cm depth and was kept for analysis of pH, N, DM and Ash.

Abstract: An agronomy trial to evaluate the effect of level of effluent from plastic biodigesters loaded with pig manure on the growth of mulberry (Morus alba) trees was conducted for one year (25 August 2004 to 25 August 2005) during both the dry and rainy seasons in the ecological farm of CelAgrid, which is located in Kandal Stung district, Kandal province. The trial included six treatments with four replications, divided into 4 blocks according to Complete Randomized Block Design. The effluent application levels were 0, 100, 250, 400, 550 and 700kg N / ha / year. Effluent was applied every 7days. Mulberry foliage was harvested (cutting height 60 cm above ground level) after 3 months and again at 2 month intervals. The foliage was separated into stem and leaf + petiole and analyzed for dry matter (DM) and nitrogen (N). Dry matter biomass yield of mulberry foliage, and crude protein content of leaves increased linearly with the amount of effluent N applied.