Cotton (Gossypium L.) is a main fiber and oil seed crop having global importance, also more importantly a topic of significant scientific interest (Wendel and Grover, 2015; Meng et al., 2023). Cotton is mainly grown for fibre in more than seventy countries of the world of which China, India, USA, Brazil, and Australia are leading one accounting for approximately three-quarters of the cotton production of world during year 2022-23 (ICAC, 2023). Worldwide, cotton is cultivated in an area of 31.43 million ha with a production of 25.18 million tonnes (148.18 million bales) during year 2021–2022 (FAOSTAT, 2022). India has the largest area of 12.47 million ha and highest production of 32.31 million bales (170 kg per bale) among the cotton growing countries followed by China, United States and Pakistan (CCI, 2024; DES, 2024).
High production of cotton is accompanied by generation of tonnes of cotton residues every year (Pandirwar et al., 2023a). About 23–30 million tonnes of cotton residue is produced in India every year at an average rate of 3 tonnes per hectare of area (Ramanjaneyulu et al., 2021). Global cotton residues availability would be estimated between 90.3 and 129 million tonnes annually at a current cotton production rate and is projected to grow consequently (Fawzy et al., 2021). In most part of the world, this invaluable biomass resources are considered as waste and burnt off in the field after the harvest of cotton crop.
Based on recent research, the biomass from cotton crops after the fiber is extracted can be utilized as industrial raw material, source of bioenergy, animal feed, and amendment to the soil. (Pandirwar et al., 2023a). Cotton stalks have a calorific value ranging from 16.4 to 18.26 MJ/kg of dry matter. (Al Afif et al., 2019; Pandirwar et al., 2023b). Unlike other agricultural crop residues, the fiber from cotton stalks is comparable to that of the most widely available species of wood. Therefore, it is better suitable for a range of industrial applications, including the production of particleboard, hardboard, corrugated boxes, paper and pulp, bioenergy and power plant fuel (Silverstein et al., 2007). Cotton stalks are an excellent material to raise edible oyster mushrooms due to their lignocellulosic nature (Sutaria et al., 2016). Among these several applications, the only one widely adopted potential uses of cotton stalks in present scenario is that of fuel. This is mainly due to the unavailability of mechanized facilities required to uproot the stalks along with roots and transfer the stalks from the field to locations where they might be put for other uses.
However, predominantly followed manual uprooting of the deep-rooted cotton stalk by local practices is a costly as well as drudgerous operation and has lower stalk uprooting efficiency with high labour requirement. In another method, mobile cotton stalk shredders cut and shred the plant stems above the ground while leaving the roots beneath soil. Full-size cotton roots do not decay before succeeding planting season which eventually creates disruptions during tillage operations in subsequent season. Cotton crop residues are often ploughed or incinerated into the soil but it may host insects that can invade the subsequent cotton crop (Huang et al., 2012).
Consequently, the complete pulling of cotton stalks along with the roots is economically and environmentally most feasible method for comprehensive disposal of cotton residues and its use as a raw material. Few investigations have been carried out worldwide in past on cotton stalk pullers such as 2-row pull type implement called bobby machine (Pothecarey and Field, 1968), counter-rotating wheel type stalk puller (Sumner et al., 1984a; Sumner et al., 1984b). In recent years some studies have also been conducted specially for uprooting and shredding of deep-rooted cotton crop residues. Khan et al. (2023) reported the cotton stalk puller cum shredder that perform integrated operations such as cutting crop leftovers, mixing plant waste with soil and sowing subsequent crop in single run by conserving input resources. However, no commercially available technology exists for complete uprooting of the cotton stalks along with roots after cotton harvesting. Therefore, in areas where cotton is grown, equipment must be available to harvest and collect the cotton residue to use it as a suitable fuel (Sumner et al., 1984b). Thus, uprooting the cotton residue after cotton harvesting and supply it as a raw material to the biomass-based industries would be a feasible option to overcome the problem of residue management. Therefore, long-term ultimate aim is to develop an uprooting mechanism that can be integrated with the available commercial mobile stalk shredders, so, that an integrated machine can uproot the stalks and simultaneously shred it on the go for its direct use as a raw material.
Operation optimization is a statistical procedure which involves combination of several variables with a purpose of finding finest output. This technique could also be applied in maximising the desired outcome of the machine for example the uprooting efficiency in case of cotton stalk puller. Response surface methodology (RSM) is an advanced mathematical and statistical tool used to evaluate the relationship between multiple independent input variables and output response variables. It optimizes these independent and response variables to get the best responses (Taoufik et al., 2022). Optimization of most of the agricultural machines is often achieved by application of Response surface methodology (RSM). Cai et al. (2024) optimized missing pulling rate and breakage rate of a wheel-belt type cotton stalk puller using a multiple quadratic regression response surface model and found optimal values of operating parameters such as cotton stalk pulling angle, tractor forward speed and clamping speed pulling component. However, RSM has limitations in the range of independent input variables due to its non-linear nature (Raj et al., 2021). On the contrary, the artificial neural network (ANN) is an excellent and highly robust modelling tool commonly used in complex and nonlinear processes, which can effectively overcome the limitations of RSM (Tao et al., 2014).
Numerous researchers have also investigated the use of artificial neural networks (ANNs) to predict the performance metrics of agricultural machineries. ANNs excel at capturing complex non-linear relationships between input and output data, making them invaluable for modelling various agricultural equipment (Anantachar et al., 2010; Pareek et al., 2021). Recently, metaheuristic search algorithms, particularly evolutionary algorithms (EAs) such as genetic algorithms and differential evolution are favoured for their faster convergence rates and cost-effectiveness in optimization tasks. In particular, Particle Swarm Optimization (PSO) has gained attention for its efficacy in modelling the operations of various agricultural machinery (Pareek et al., 2023). PSO has been found to outperform traditional statistical techniques in modelling precision (Kumar et al., 2009; Anantachar et al., 2010). Researchers have employed a range of optimization techniques aimed at identifying the optimal configurations of operating parameters to enhance the efficiency of agricultural machinery operations. By leveraging these advanced methods, significant improvements in the performance and reliability of agricultural equipment can be achieved. At present, RSM and ANN have been widely used in structural design and operation optimization of agricultural machinery (Anantachar et al., 2010; Pareek et al., 2021; Pareek et al., 2023). The integration of these optimization techniques with ANN models represents a promising avenue for further advancements in agricultural machinery technology. Xue et al. (2021) optimized the performance of green forage maize harvester header using a combined Response Surface Methodology (RSM) - Artificial Neural Network (ANN) Approach. Therefore, Response Surface Method (RSM) and combined Artificial Neural Network (ANN)-Particle Swarm Optimization (PSO) approach is proposed in the study for optimizing, modelling and predicting the performance parameters of the cotton stalk puller.
Consequently, the aim of this study was to develop a device that could completely uproot cotton stalks and other alike deep-rooted crops. However, it was necessary to optimise the performance of the developed cotton stalk puller to get maximum uprooting efficiency and to refine the development in future. Therefore, a study was undertaken to find the optimal combination of the operational (counter-rotating drum speed, forward speed) and design parameter (drum inclination) which directly affect the performance of machine in the field.