Effect of Nitrogen Fertilizer Application on The Biomass Yield and Nutritive Value of German Grass

Abstract: German grass (Echinochloa polystachya) can be considered as a suitable fodder for ruminants that grow well in low land. Nitrogen is an important fertilizer that may affect to biomass production and nutritive value of German grass. Therefore, it is very important to evaluate the effect of N fertilizer on biomass yield and nutritional quality of German grass. To evaluate effect of N application on biomass yield and nutrient, about 4000 cutting of German grass was planted in Dr. Purnendu Gain Field Laboratory of Agrotechnology Discipline, Khulna University, Khulna. Nitrogen fertilizer was applied in the form of urea. The doses of other fertilizers like gypsum, phosphate etc. were kept constant. The experiment was based on randomized complete block design (RCBD). Number of treatments were five including one control and three replications were for each treatment. Size of each plot was 3×15 m². Four doses of N fertilizer were 130, 140, 150 and 160 kg ha^-1, respectively.  First and second cuttings were done after 60 and 90 days of plantation respectively. Weight of grasses were taken immediately after harvesting to determine the biomass yield. For chemical analysis, grass samples were chopped into small pieces up to 1-2 cm, weighted, and dried for 2-3 days after harvesting whole grasses. Fresh samples were kept in the oven for 24 hours to dry at 105ºC to assess the dry matter. The sundried samples were crushed into fine particles with an electronic grinder and sieved with a 2 mm mesh screen before being stored in dry, well-covered containers until analysis. Proximate analysis of samples was carried out in Animal Husbandry Laboratory of Agrotechnology Discipline, Khulna University, Khulna. Proximate analyses of grasses were performed to determine dry matter (DM), crude protein (CP), ether extract (EE), crude fiber (CF), and total ash (TA) following AOAC (2003) in the laboratory. Same process was done for 2^nd cutting in laboratory to evaluate biomass yield, dry matter, crude protein, crude fiber fat and ash of the sample. The effect of nitrogen fertilizer was significant for biomass yield (p˂0.05) and CP (p˂0.01) at 60 DAP. No significant (p˃0.05) difference was observed among the other nutritive parameters like DM, EE, CF and ash contents of the forage at 60 DAP. Significant effect of N fertilizer on CP (p˂0.05) were found at 90 DAP. No significant effect of N fertilizer was found on yield, DM, CF, EE and ash (p˃0.05) at 90 DAP (2^nd cut). Significantly varied yield (p˂0.05) and CP (p˂0.01) were found at 60 DAP and their highest values were 52.78 tha^-1 and 10.52% respectively. The study also showed that biomass yield, DM, CF and CP content were increased with the doses of N while vice versa in EE and ash content. The highest value of yield, CP and EE were obtained at 60 DAP with the doses of N fertilizer at 160 kg ha^-1. It can be concluded that the total biomass yield and CP content was highest in the doses of 160 kg ha^-1 N fertilizer. Key words: Biomass yield, Fodder, German grass, Nutritive value and Urea

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