Trash management and Trichoderma harzianum influencing photosynthesis, soil carbon sequestration, and growth and yield of sugarcane ratoon in subtropical India

Soil organic carbon management is a key component for crop growth and provides sustainability in the cropping system. In subtropical India, soil organic carbon in agricultural soils continuously decreases, and most soils have very low organic carbon content. Trash management in the sugarcane ratoon crop improves soil quality parameters and supports crop growth favourably. Further inoculation of Trichoderma has also shown a synergistic response with trash application on nutrient availability in the ratoon crop. Improving soil quality also influences physiological activity, net photosynthesis, and crop yield. The present investigation aimed to determine the effect of trash management and Trichoderma application on changes in soil chemical and biological properties besides net photosynthetic rate, dry matter accumulation, and nutrient uptake by sugarcane ratoon crop to assess the sustainability of the system. Thus a field experiment was conducted with four treatments viz., (i) sugarcane trash mulching without Trichoderma harzianum, (ii) trash removal without Trichoderma, (iii) trash mulching +  Trichoderma and (iv) trash incorporation +  Trichoderma in a randomized block design (RBD) and five replications. Trash incorporation and inoculation of Trichoderma influenced net photosynthetic rate (NPR) positively. The lowest NPR (19.14 µmol/m 2 /s) was recorded under trash removal without Trichoderma. An increment of 16.15 % in total dry matter accumulation was recorded under trash incorporation + Trichoderma compared to trash removal without Trichoderma. Trash incorporation and Trichoderma accumulated the highest N in leaf, cane, and roots. Thus NPK uptake could be improved by the application of trash and Trichoderma application. The mean available K content in soil was significantly improved by 12.48 % compared to the initial level. An improvement of 33.6 kg K/ha was recorded after the harvest of the ratoon crop. The highest soil organic carbon (15.28 Mg/ha) was recorded with mulching of sugarcane trash under Trichoderma inoculation. The highest bacterial population was recorded under trash incorporation with Trichoderma. Soil microbial biomass carbon (SMBC) could be improved by 1.82 times under trash mulching +  Trichoderma as compared to the initial status. Trash incorporation and Trichoderma application recorded the highest mean cane weight (1053 g) in ratoon crop. Trash incorporation+  Trichoderma registered an increase of 16.19 % increase in sugarcane yield as compared to trash removal without Trichoderma. However, sugar yield in a similar treatment was improved by 27.8 %. Thus trash application along with Trichoderma harzianum holds great promise in sustaining soil health and sugarcane and sugar yields in subtropical India.