Soil chemical properties and nutrient status as influenced by different spacings of poplar under agroforestry in Semi-Arid region

A field experiment was carried out during 2018–19 to study the effect of 2¹’² year old poplar based agroforestry system on soil chemical properties and nutrient dynamics. Present study was conducted in an already established two and half-year-old plantation of Populus deltoides with six different spacings viz., 3x3, 4x3, 5x3, 6x3, 7x3 and 8x3m. During rainy season cowpea (var. RC-19) and sorghum (var. HC-171) were sown during first week of July and Oat (var. HJ-8) and Berseem (var. HB-1) were sown in interspaces of poplar spacing's as winter crops and sole crops of both rainy and winter seasons were sown in open condition (devoid of tree) as control. Intercropping of both winter and rainy season crops in poplar spacing's showed better available of macronutrients than sole cropping. Soil pH decreased considerably under different poplar spacing and maximum decrease of 13.60 percent was recorded in 3x3 m spacing over control. However, soil organic carbon (SOC) increased with the decrease in poplar spacing and maximum SOC (0.45%) was observed under 3x3m followed by 4x3m (0.42%), 5x3m (0.40%) and least under sole cropping (0.30%) after harvesting of rainy season fodder crops. The available soil N, P and K increased significantly under different spacings of poplar based cropping system from initial values. The higher available nitrogen (158.5 kg'ha), phosphorous (16.8 kg'ha) and potassium (343.8 kg'ha) was recorded under 3x3 m spacing as compared to other spacings and sole cropping (open environment) after harvesting of both season fodder crops.