Impact of Long Term Organic Nutrient Management on Soil Health and Yield of Little Millet (Panicum sumatrense)

Abstract

Aim: To evaluate the long-term effects of complete organic nutrient management in comparison with conventional inorganic fertilization on soil health, yield, nutrient uptake, and economic returns of little millet (Panicum sumatrense). Study Design: A long-term field experiment comparing two nutrient management practices: Complete organic nutrient management and Conventional management with recommended inorganic fertilizers (20–20–20 kg NPK ha⁻¹). The study involved pooled analysis of eight consecutive years of data and t test was conducted to test the significance. Place and Duration of Study: The experiment was conducted at the Acharya N.G. Ranga Agricultural University, Agricultural Research Station, Vizianagaram, Andhra Pradesh, India. The study was carried out for eight consecutive Kharif seasons from 2015 to 2022. Methodology: The experimental soil was sandy loam, neutral in reaction, low in organic carbon (0.43%) and available nitrogen (240 kg ha⁻¹), and medium in available phosphorus (59 kg ha⁻¹) and potassium (315 kg ha⁻¹). Two nutrient management treatments were evaluated: Organic management: In situ incorporation of green manure (sunhemp), application of farmyard manure (FYM), neem cake, and biofertilizers (Azospirillum and phosphorus-solubilising bacteria). Conventional management: Application of recommended dose of inorganic fertilizers (20–20–20 kg NPK ha⁻¹). Soil health parameters, grain yield, nutrient availability, and benefit–cost (B:C) ratio were recorded and analyzed annually. Pooled data were subjected to statistical analysis. Results: Pooled analysis of eight years of experimentation revealed that the yield advantage of organic nutrient management became evident after six years of continuous application. In the sixth year, organic management recorded a grain yield of 833 kg ha⁻¹, which was 9.46% higher than the yield obtained under conventional fertilization (761 kg ha⁻¹), with corresponding benefit–cost (B:C) ratios of 1.34 and 1.81, respectively. In the seventh year, the superiority of organic management became more pronounced, producing a significantly higher grain yield of 941 kg ha⁻¹, representing an 11.2% increase over inorganic fertilization (846 kg ha⁻¹); the B:C ratios were 1.62 under organic and 2.35 under inorganic management. During the eighth year, organic plots registered a further significant increase in grain yield (1017 kg ha⁻¹), showing a 12.2% advantage over inorganic plots (906 kg ha⁻¹), with B:C ratios of 2.39 and 2.60, respectively. In addition to yield improvement, soil health parameters showed marked enhancement under organic management, with significant increases in available nitrogen, phosphorus, zinc, iron, and manganese compared to inorganic fertilization. Soil organic carbon content in organic plots increased from 0.43% to 0.51%, although the improvement was not statistically significant over the conventional treatment. Overall, the results indicate a progressive yield advantage and improvement in soil fertility under sustained organic nutrient management. Conclusions: The long-term study demonstrates that sustained organic nutrient management enhances soil fertility, micronutrient availability, and grain yield of little millet over time. Although conventional fertilization showed relatively higher B:C ratios in earlier years, organic management progressively improved productivity and economic returns. The findings indicate that complete organic nutrient management is a viable and sustainable strategy for maintaining long-term productivity and environmental health in little millet cultivation.