Impact of planting geometry on Ailanthus excelsa L. based silvoarable systems for food and biomass production.

The increasing demand for biomass for biofuel production is facing challenges due to shortage of feedstock. Growing a variety of different short rotation tree species as well as oil seeds on marginal lands, as an inter crop, may contribute to energy security, climate change mitigation, apart from creating new employment opportunities in a sustainable way. Ailanthus excelsa Roxb. (Mahaneem) is one of the promising fast-growing and multipurpose trees of dry areas and used in various plantation programmes due to its ability to grow well with less rainfall. Therefore, in this study, Ailanthus excelsa based agroforestry systems (growing of trees and food crops simultaneously on the same piece of land) with different plant geometry, i.e. 10 × 20, 10 × 10, 10 × 6.5 and 10 × 5 m (50, 100, 150 and 200 trees ha⁻¹) were assessed for food and biomass production. Among all the plant geometries, the plant geometry of 10 × 20 m exhibited higher yield components and yield viz. number of effective tillers and siliquae per plant (306.7 m⁻² and 268.42), number of grains per spike and per siliqua (44.83 and 12.5), test weight (40.21 and 5.89 g), grain and seed yield (3.93 and 1.90 t ha⁻¹), straw and stover yield (5.0 and 2.70 t ha⁻¹); and root weight (2.11 and 0.76 t ha⁻¹) and total biomass (11.04 and 5.36 t ha⁻¹) of wheat and Indian mustard, respectively. Biomass of 28.6 t ha⁻¹ from trees and 5.9 t ha⁻¹ from wheat (only straw and underground) under 5 × 4 m tree geometry can be potential feedstock for biofuel production on sustainable basis. [ABSTRACT FROM AUTHOR]