Phosphorus Mineralization Dynamics in Acidic Eastern Himalayan Soils: Implications for Sustainable Tribal Agriculture

Abstract

The sustainable livelihood of the indigenous populations residing in the Eastern Himalayas can be maintained through traditional management practices utilizing locally available organic resources. However, knowledge gaps exist regarding nutrient management, particularly phosphorus (P), in acidic hill soils. Additionally, data on the P mineralization (Pmin) rates of various organic sources used in the area are lacking. To address this gap, an incubation study with the aim to determine the kinetics and rate of P mineralization of different local organic sources of North East region of India was conducted with various treatments, including Farm Yard Manure (FYM) (T1), poultry manure (T2), pig manure (T3), and vermi-compost (T4), applied at a rate of 120 kg N/ha equivalent in a Completely Randomized Design replicated four times. Observations were made at 10-days interval over a period of 100 Days Of Incubation (DOI). Results indicated that the highest Pmin rate was observed in T2 (6.66%) > T3 (6.54%) > T4 (6.37%) > T1 (5.74%) compared to the control (T0). Pmin rates positively correlated with soil attributes such as pH (0.86*), EC ( 0.75*), CEC (0.95*) and negatively with SOC ( -0.99*). First-order kinetics revealed the highest Pmin with T2 (R2= 0.96) while second-order kinetics indicated highest for T3 (R2 =0.61). The pattern of Pmin rate showed a gradual increase starting from 20 DOI onwards. Notably, pig manure (T3) exhibited the highest mineralization rate during the initial period, specifically between 10-30 DOI. It is concluded that high Pmin rates were recorded between 50-90 DOI, with the peak occurring recorded at 70 DOI with T2.