Impact of P enriched compost on growth, yield and yield attributes of finger millet (Eleusine coracana L. Gaertn.) French bean (Phaseolus vulgaris L.) cropping sequence in P rich soils

The excessive use of synthetic fertilizers has led to soil degradation and environmental pollution, highlighting the need for sustainable soil management practices. This study examines the impact of phosphorus-enriched compost on the productivity of the finger millet (Eleusine coracana) and French bean (Phaseolus vulgaris) cropping system in phosphorus-rich soils. Field experiments were conducted at two locations in Karnataka, India, Arasana Halli, Chikkaballapur (L₁) and Integrated Farming System (IFS) GKVK, Bengaluru (L₂), during the kharif and summer of 2018-19 and 2023-24. The study involved phosphorus-enriched composts, including urban solid waste compost (USWC), poultry manure (PM), FYM and vermicompost, enriched with rock phosphate (RP) and phosphate-solubilizing bacteria (PSB). The experiment followed a randomized complete block design (RCBD) with 14 treatments to assess the effects of phosphorus-enriched organic amendments on soil fertility and crop productivity. Results showed that T₁₁ recorded higher values in finger millet, including the number of ear heads per hill (4.31 at L₁, 5.10 at L₂), number of fingers per head (6.46 at L₁, 6.66 at L₂), and test weight (3.47 g at L₁, 3.51 g at L₂), followed by T₁₄ (ear heads per hill: 4.26 at L₁, 5.09 at L₂; fingers per head: 6.40 at L₁, 6.59 at L2; test weight: 3.44 g at L₁, 3.51 g at L₂). T₁₁ also achieved significantly higher straw yield (60.62 and 61.83 q ha⁻¹ at L₁ and L₂, respectively) and grain yield (43.57 and 45.83 q ha⁻¹ at L₁ and L₂, respectively), while T₁₄ recorded higher straw yield (57.62 and 58.66 q ha⁻¹ at L₁ and L₂, respectively) and grain yield (41.90 and 43.02 q ha⁻¹ at L₁ and L₂, respectively). Additionally, residual French bean yield attributes in T11, including fresh pod yield (28.25 and 27.10 tons ha⁻¹ at L₁ and L₂, respectively), haulm yield (2867.76 and 2868.88 kg ha⁻¹ at L₁ and L₂, respectively), and pod dry weight (42.06 q ha⁻¹ at L₁, 43.45 q ha⁻¹ at L₂). The study highlights that phosphorus-enriched composts, particularly poultry manure, combined with PSB, improve nutrient availability, soil fertility, and crop productivity, offering a sustainable and eco-friendly alternative to synthetic fertilizers. This approach addresses challenges related to phosphorus scarcity and enhances agricultural sustainability in developing countries.