Long Term Effect of Integrated Nutrient Management on Dynamics of Phosphorous in an Acid Inceptisols of Tropical India

ABSTRACT

The long-term impact of integrated nutrient management (INM) experiment under cereal- vegetables- legume was undertaken to investigate the effect of organic and inorganic sources of nutrients with inclusion of microbial inoculants/biofertilizer and lime on different inorganic fractions of phosphorus (P) in acidic soil. The test crop maize was 17^th crop in the sequence. The INM practices include i) soil test dose (STD) as pure inorganic source ii) Combination of inorganic with organic in the form of either farm yard manure (FYM)@5 t ha⁻¹ or vermicompost @2.5 t ha⁻¹ iii) inclusion of microbial inoculant/biofertilizer (Azotobacter, Azospirillum and PSB (1:1:1) and soil amendment in the form lime @ 0.2lime requirement (LR) compared with iv) absolute control, i.e., without any fertilization. The results showed that integration of organics with STD increased the grain yield by 52% over STD but only 8% yield increment was observed in INM practices compared to organics and inorganics only. Cultivation without any fertilizer caused a decrease in available -P, saloid P(Sal-P), aluminum phosphorus (Al–P), calcium phosphorus (Ca–P) and total P but there is accumulation of iron phosphorous (Fe-P), reductant Phosphorous (Red-P) and occluded Phosphorous (Occ-P) .All the fractions of inorganic P were relatively higher in the treatments receiving full INM package of practices. Integration of organic manure, biofertilizers, lime as soil ameliorant with inorganic fertilizers is a sustainable approach for P mobilization and solubilization from non-labile pool to labile pool of P in soil.

KEYWORDS:

• P dynamics
• INM
• long term experiment
• acid soil
• maize

Acknowledgments

This study was financially supported by the Indian Council of Agricultural Research sponsored All Indian Network Project on Soil Biodiversity and Biofertilizers.