Effects of inorganic fertilizers on biological nitrogen fixation and seedling growth of some agroforestry trees in Bangladesh

Abstract

The effects of different inorganic fertilizers (Urea and Triple Super Phosphate (TSP)) on seedling growth and nodulation capabilities of four agroforestry tree species (Albizia chinensis, A. saman, Acacia nilotica and Sesbania sesban) were compared. The nodulation of these seedlings were treated with different fertilizer treatments (at the rate of urea 40 kg·hm−2, urea 80 kg·hm−2, TSP 40 kg·hm−2, TSP 80 kg·hm−2, (urea+TSP) 40 kg·hm−2–and (urea+TSP) 80 kg·hm−2) after one month of seed germination. The results revealed that the seedling growth was enhanced significantly with moderate fertilizer treatment. In some cases, the higher levels of fertilizers reduced the seedling growth. The study also revealed that the nodulation in nodule number and size was significantly inhibited by the application of N fertilizer (Urea), while it was increased significantly with the application of P fertilizer (TSP). This study improved our understanding and provided insights that would be useful to the farmers in their efforts to amend the soil with inorganic fertilizers in order to enhance plant growth and biological nitrogen fixation.