Effect of Sewage Sludge Treatment and Rhizobium Inoculation on Growth, Nodulation Yield Attributes in Lentil (Lens culinaris Medik.) under Field Conditions

Abstract

This study investigated the effects of sewage sludge treatment and Rhizobium inoculation on the growth, yield, and nodulation of lentil (Lens culinaris Medic.) under field conditions. The experiment was conducted at Van Yüzüncü Yıl University over two growing seasons using a randomized complete block design with three replications. Four doses of sewage sludge (0, 10, 20, and 40 t ha-¹) were applied with and without Rhizobium inoculation. The results revealed significant seasonal variations, with biological yield decreasing from 8306 kg ha-¹ in 2003-04 to 3262 kg ha-¹ in 2004-05, and grain yield declining from 2716 kg ha-¹ to 633 kg ha?¹. The application of 20 t ha-¹ sewage sludge resulted in the highest biological yield (6724 kg ha-¹) and grain yield (1854 kg ha-¹), while higher doses (40 t ha-¹) negatively impacted seed yield. The number of plants per square meter significantly varied between years, and reduced from 183 in 2003-04 to 74 in 2004-05, thereby altering growth and yield attributes. Sewage sludge increased plant density, reaching 153 at 40 t ha-¹, while Rhizobium inoculation slightly reduced it. In contrast to grain and biological yields, the number of seeds per plant and seed yield per plant decreased with increasing sewage sludge doses. Overall, the study suggests that 20 ton ha-¹ sewage sludge application optimizes lentil productivity in semi-arid conditions, but higher doses may lead to reduced yield.