Measuring the environmental impacts of Rice-Wheat and Cotton-Wheat Cropping System in Pakistan using Life Cycle Assessment Approach

Abstract

The rice-wheat (RW) and cotton-wheat (CW) cropping system holds 60% of the cropped area of Pakistan in the form of rice, wheat, and cotton production. These are the major crops in Pakistan, but the research information on the environmental impacts associated with their production phases is merely available. Identification of major contributing factors towards the environmental impacts of both systems can help to improve agronomic practices, and policy development. Therefore, this study aimed at the development of inventory to perform life cycle assessment of both systems to identify the major contributing factors/processes increasing their environmental impacts. A study was designed to gather the data of all aspects/process of RW or CW cropping systems for the year 2022 in south of Punjab Pakistan. The data inventory was used to quantify the environmental impacts of RW and CW cropping systems using a cradle-to-gate (distribution center) life cycle assessment (LCA) approach. The system boundary of the study was set to the impacts of seedbed preparation, fertilization, pesticides application, fuel usage, and transportation of produce to the farm gate. The functional unit of the study was set to 1 hectare for both RW and CW cropping systems. The surveys and meetings with farmers provided primary data to meet system boundary, while the secondary data was gathered from literature. The primary data were combined with secondary database information and modeled using recipe 2016 (H) midpoint methodology in the OpenLCA software. The analysis of this study was based on four predominant harm categories: i) climate change, ii) human health, iii) ecosystem quality, and iv) resources. For the agricultural phase, we sourced inventory data from farmer interviews. Our system boundaries spanned from cradle to farm gate, with (kg ha-1 ) designated as the functional unit. Our results highlighted that RW production cause more environmental impacts in all harm categories (apart from water consumption) than CW cropping system. The RW cropping system showed higher carbon footprints (12.82% more CO2 eq) than CW cropping system. However, the CW cropping system produced a slightly higher (0.45%) economic return. It is therefore recommended to improve the environmental impact by reducing the use of machinery and transportation in RW cropping system. Overall, to achieve low carbon footprints of RW and CW cropping systems, the agricultural sector needs to identify the major regional hotspots to develop policy. The study serves as a benchmark for formulating comprehensive plans to reduce emissions from different cropping systems