Performance of Poplar Plantation under different levels of Nutrients in an Agroforestry System

Abstract

Poplar (Populus deltoides Bartr.) has been adopted in agroforestry systems by farmers of north-western India owing to its fast growth. An experiment was conducted to standardize the nutrient requirement of poplar plantation during 6 years of growth for getting its better productivity. The treatments consisted of nine combinations (T₂to T₁₀) of N and P (as P₂O₅) in addition to an uncropped control (T₁) of poplar plants. Every year, whole of P and 1/3^rd N was applied during May after harvesting of wheat, 1/3^rdN in July and the remaining 1/3^rd N in September. The height and diameter at breast height (DBH) of plants were measured every year in the month of January and timber weight was calculated from these parameters. The DBH, height and timber weight of poplar plantation were lowest in uncropped control (19.01 cm, 17.56 m and 310 q/acre, respectively) and highest (21.46 cm, 20.10 m and 449 q/acre, respectively) with the application of N and P (as P₂O₅) @ N₁₀₀P₄₀, N₁₅₀P₈₀, N₂₀₀P_120, N₂₅₀P_160, N₃₀₀P₂₀₀ and N₃₅₀P₂₄₀g/plant (T₆) during 1^st, 2^nd, 3^rd, 4^th, 5^th and 6^th year, respectively. However, the application of P during 4^th, 5^th and 6^th year did not increase the timber weight over N application alone. The grain yield of wheat and fodder yield of pearlmillet decreased with increase in age of plantation. Net returns from the agroforestry system (crops and trees) were highest in T₅ which were Rs. 408791 per acre Soil OC and available N and 6 . P were lowest in uncropped control (T₁) and highest in T₁₀ (tenth treatment) i.e., with the application of N and P @ N N₁₅₀P₈₀, N₂₀₀P₁₂₀, N₂₅₀P_160, N₃₀₀P_200,N₃₅₀P₂₄₀ and N₄₀₀P₂₈₀ g/plant during 1^st, 2^nd, 3^rd, 4^th, 5^th and 6^th year, respectively. Therefore, treatment T was better than other treatments for getting higher productivity 6 and better returns from poplar plantation.