Effect of fortified pine needle biochar on green fodder yield, nutrient uptake of oat and soil properties

In the Himalayan region, the low green fodder supply to livestock necessitates agronomic interventions, including the use of fortified pine needle biochar, a viable option for slow-release nutrients, to enhance fodder oat production, improve soil health, and safely manage the abundant pine needles that pose a fire risk. In a greenhouse study, the effect of different levels of pine needle biochar (0, 0.02, 0.04, 0.11 and 0.22 % of soil weight) fortified with 0, 75 and 100 % of the recommended dose of fertiliser (RDF, 80 kg N: 60 kg P 2 O 5 : 40 kg K 2 O ha −1 ) was examined on the green fodder yield, nutrient concentration and uptake of oat, and general soil properties and extractable nutrients. Application of 0.02 % biochar fortified with 75 % RDF gave a fodder yield (56.9 g pot −1 ) which was 46.6 percent higher than the control (38.8 g pot −1 ) but statistically similar to the yield with 100 % RDF alone (54.9 g pot −1 ). The highest fodder yield (72.0 g pot −1 ) was recorded with 0.22 % biochar fortified with 100 % RDF. Higher doses of biochar without fortification decreased the N concentration but increased the K concentration and brought no significant change in P concentration in the fodder oat. Biochar fortified with 75 and 100 % RDF enhanced the uptake of N, P, and K by fodder oat. The moderate levels of biochar (0.02 and 0.04 %) fortified with 75 % RDF and all levels of biochar fortified with 100 % RDF decreased soil pH while higher levels of biochar fortified with 100 % RDF increased soil EC and organic C. The treatments receiving the highest level of biochar addition (0.22 %) with 0 % RDF, 0.11 and 0.22 % biochar fortified with 75 % RDF and all levels of biochar fortified with 100 % RDF significantly increased soil extractable N, P and K after crop harvest except for K under 0.22 % biochar fortified with 100 % RDF. Pine needle biochar fortified with RDF helped to achieve higher oat fodder production and maintain soil fertility than solo application of biochar or chemical fertilisers.