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Subject: Soil Science × Author: Janpriya Kaur × Start date: 2018 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Nitrogen, phosphorus and potassium management for wheat in poplar based agroforestry system
    (Punjab Agricultural University, Ludhiana, 2019) Janpriya Kaur; Baljit Singh
    The present studies were conducted to evaluate the influence of different levels of N, P and K on wheat productivity in poplar plantations. Litterfall addition, return and release of nutrients through decomposition of litterfall were also evaluated. Wheat intercropped with different aged (2, 3, 5 and 6 year) poplar plantation and sole wheat was treated with different levels of N (0, 60, 90, 120, 150, 180 kg N/ha and LCC based-115 kg N/ha) and also different levels of nutrients (P and K) i.e. 0:0, 60:0. 60:30, 60:90, 90:0, 90:30 and 90:60 kg P2O5:K2O kg/ha in another experiment. Results indicated that growth, yield parameters, yield and nutrient (N, P and K) uptake by wheat grains and straw decreased significantly with increasing tree age but increased significantly with N fertilization. The best N level for wheat growth, yield, nutrient use efficiency and nutrient uptake under trees was LCC based application followed by 180 kg N/ha. Highest grain yield (44.2 q/ha), nutrient uptake by grains (kg/ha) i.e. N (86.1), P (14.27) and K (33.8) were obtained on fertilization with 180 kg N/ha while agronomic efficiency was maximum (18.4 kg grains/kg N applied) in LCC based treatment. Nutrient content and soil properties (OC, available N, P and K) showed a significant increase with tree age and N fertilization to maximum with 180 kg N/ha. Results of experiment with variable P, K levels indicated that wheat growth, yield, nutrients content, uptake and soil properties (OC, available N, P and K) under trees increased on fertilization with nutrients to maximum in T7 (90:60 kg P2O5:K2O/ha). In another experiment litterfall addition and return of nutrients showed significant increase with advancing tree age (2 to 6 years) and months of litterfall (October to December). The highest litterfall (5.51 t/ha) and among macronutrients maximum return of Ca (104.8 kg/ha) and in micronutrients highest return of Fe (7529 g/ha) was observed in 6 year plantation. Macronutrient return followed trend Ca>N>Mg>K>S>P and micronutrients Fe>Mn>Zn>Cu. Release of nutrients from litter under 2 and 5 year poplar with 120 and 180 kg N/ha increased with increasing N levels and time of decomposition to maximum with 180 kg N/ha 2 year plantation. Order of nutrient release was K>P>N. In incubation study, available N, P and K increased to maximum in soil amended with 0.3 % leaf litter levels treated with 75 mg N/kg soil at 90 days of incubation.