Effect of pine needles on inorganic nitrogen pools of soil treated with fertilizers and manure under cabbage crop

Effect of pine needles application on the inorganic nitrogen pools of soil amended with organic and inorganic sources of nutrients was studied in a pot culture experiment using sandy loam soil. Fertilizers NPK (recommended NPK @68:33:33 mg kg⁻¹ soil) and three sources of manures viz. green manure (Sesbania aculeata), farm yard manure (FYM) and vermicompost were applied alone or in combination with pine leaves (9 g kg⁻¹ soil). There was a significant increase in total nitrogen of the soil due to application of manure and pine leaves. Application of different level of green manure, farm yard manure and vermicompost caused 5.4–7.0, 6.7–8.7 and 5.4–12.0 mg kg⁻¹ increase in total extractable inorganic nitrogen (TEIN) and 2.6–4.2, 2.1–5.3 and 2.3–3.0 mg kg⁻¹ increase in total dissolved inorganic nitrogen (TDIN), respectively. Amount of water and 0.5 M K SO extractable NH ⁺ and NO ⁻- N2443 was reduced due to application of pine leaves along with green manure, FYM and vermicompost, whereas, with inorganic fertilizers the amount of 0.5 M K₂SO₄ extractable NH₄⁺ (0.43 mg kg⁻¹) and NO₃⁻(0.47 mg kg⁻¹) and water extractable NO₃⁻ (0.64 mg kg⁻¹) - N at 90 days after application was increased.