Influence of varying nitrogen levels on crop productivity, profitability and resource-use efficiency in Bt-cotton (Gossypium hirsutum) in semi-arid region of Afghanistan

Cotton (Gossypium hirsutum L.) is one of the most important commercial crops of Afghanistan mainly grown for fiber production; however, its seeds are used as source of edible oil while cotton cake is used as animal feed. With the collapse of the cotton industry in the last four decades due to war, cotton planting has declined drastically in the country resulting in low cotton production (Noori 2018). There are many production constraints resulting in low cotton productivity in the country like poor irrigation infrastructure, low rainfall, less availability of improved variety seeds, sub-optimal fertilizer use especially nitrogen (N) and poor weed management practices etc. (Ibrahimi et al. 2017; Noorzai et al. 2017; Noorzai and Choudhary 2017). At present, the Afghan government is giving prime emphasis to cotton cultivation keeping in view its quality production and congenial agro-climatic conditions in some parts of the country. However, this crop is grown extensively using conventional local cultivars with sub-optimal or over-doses of fertilizer N which adversely affects the cotton productivity and profitability. Moreover, the optimum N application dose for conventional cotton in general and Bt-cotton in particular has not yet been standardized so for cotton growing areas in Afghanistan. Thus, to promote the cotton cultivation with enhanced productivity in Afghanistan we need to use high yielding cultivars like Bt-cotton with redesigned agronomic practices specifically fertilizer N management (Blaise et al. 2014). Therefore, an attempt was made to assess the optimum N dose for Bt-cotton besides its yield performance visà - vis resource-use efficiency under varying N levels in semi-arid region of Afghanistan.