Productivity of Groundnut (Arachis hypogaea L.) under Different Sowing Times, Utrient Supply Levels and Planting Geometry in Sub-Humid Tropical Environment

Groundnut is a vital oilseed and leguminous crop with significant economic and nutritional benefits, offering a promising option for local farmers. However, optimizing sowing dates, fertility levels, and planting geometry remains a challenge, particularly in the context of climate variability. In order to close this gap, a field experiment on clay loam soil in Medziphema was carried out in 2019 and 2020 to assess the effects of these factors on groundnut productivity. The experiment had three planting geometries (30 cm × 10 cm, 40 cm × 10 cm, and 50 cm × 10 cm), three levels of fertility (75%, 100%, and 125% of the prescribed dose of fertilizers), and two sowing dates (20 June and 10 July). Regardless of planting geometry, the results of a two-year pooled analysis indicated that early sowing (20 June) with 125% RDF generated the maximum oil content (43.50%), shoot dry weight (31.59 g plant-¹), and kernel yield (1.57 t ha-¹). The maximum shoot dry weight (31.33 g plant-¹), kernel yield (1.35 t ha-¹), and oil content (42.97%) were observed with a planting geometry of 50 cm × 10 cm. The highest gross (Rs. 57,053.33 ha-¹) and net returns (Rs.34,448.63 ha-¹) were achieved with early sowing, 125% RDF, and 40 cm × 10 cm spacing. The highest benefit-cost ratio (2.08) was noted for early sowing which had 100% RDF and 50 cm × 10 cm spacing, highlighting an optimal balance between input costs and economic returns. These findings provide valuable insights for optimizing groundnut cultivation under varying environmental conditions. The study suggests that adjusting sowing dates and fertility management can significantly enhance yield and profitability, offering practical recommendations for farmers and policymakers to improve groundnut production efficiency.