摘要 : 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... 展开 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 (T_2 to T_(10)) of N and P (as P_2O_5) in addition to an uncropped control (T_1) of poplar plants. Every year, whole of P and 1/3~(rd) N was applied during May after harvesting of wheat, 1/3~(rd)N 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 P_2O_5) @ N_(100)P_(40), N_(150)P_(80), N_(200)P_(120), N_(250)P_(160), N_(300)P_(200) and N_(350)P_(240)g/plant (T_6) 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 T_5 which were Rs. 408791 per acre Soil OC and available N and 6 . P were lowest in uncropped control (T_1) and highest in T_(10) (tenth treatment) i.e., with the application of N and P @ N N_(150)P_(80), N_(200)P_(120), N_(250)P_(160), N_(300)P_(200), N_(350)P_(240) and N_(400)P_(280) 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. 收起