Quantitative multifactor analysis of planter settings and row unit design for corn stand establishment in precision agriculture

Abstract

Achieving a uniform stand of corn (Zea mays L.) is paramount for maximizing yield potential and enhancing resource use efficiency. Despite considerable advancements in planting technologies, challenges associated with variability in seed placement accuracy, seed depth, and overall population uniformity persist. This variability is attributed to intricate interactions among planter operational parameters, soil heterogeneity, and the design of mechanical components. Critical factors, including planting speed, hydraulic downforce application, and row unit arrangement, significantly influence the quality of seed-to-soil contact and the integrity of furrow closure, which in turn affects early seedling emergence and final stand uniformity. Nonetheless, there exists a gap in the comprehensive understanding of optimal combinations of these factors, particularly in the context of varying environmental conditions and emerging adaptive hydraulic technologies. This doctoral research aims to address these challenges through a multifactorial analysis encompassing planter settings, hydraulic dual force control, and row unit component design. The study systematically evaluates the combined effects of these variables on seed placement precision, emergence dynamics, and population uniformity under diverse field conditions in North-central Kansas, USA. Utilizing John Deere ExactEmerge™ planters equipped with standard unidirectional and experimental dual hydraulic force control systems, the research varied planter speeds (ranging from 8 to 16 km h⁻¹), implemented discrete hydraulic downforce margins, and assessed multiple furrow-closing device types, including rounded and spiked rubber closing wheels, as well as more sophisticated devices incorporating discs and hydraulic pressure augmentation. The experimental design employed a rigorous split-split plot with randomized design methodologies to robustly capture treatment interactions. State-of-the-art instrumentation facilitated real-time acquisition of hydraulic pressures, mechanical load data, and spatial seed placement metrics, thereby enhancing data resolution. A comprehensive statistical analysis integrated spatial statistics, logistic regression modeling, and multivariate data integration to quantify the effects of planter and component configurations on critical performance metrics: singulation error rates, seed depth uniformity, in-row plant spacing variability, seedling emergence probability, and achieved population percentages. The results indicated that increased planting speeds generally correlated with decreased early emergence probability, particularly when utilized with specific closing devices such as spiked rubber wheels. Conversely, the adaptive dual hydraulic force control system exhibited significant potential in dynamically modulating force application in response to soil spatial variability, thereby markedly improving the consistency of seedling emergence and corn population uniformity. The integrated findings elucidate several key insights: (1) the synergistic interplay between planter speed, hydraulic downforce, and row unit location on seed placement accuracy and seedling emergence uniformity; (2) the modulation of seedling emergence rates by environmental factors and planting speed, in conjunction with closing wheel design; (3) the critical influence of closing wheel design on seed placement precision and in-row plant spacing uniformity; and (4) the promising efficacy of prototype dual hydraulic force control systems in enhancing plant stand uniformity through real-time adjustments based on prevailing soil conditions. Collectively, this research advances the understanding of how integrated mechanical configurations and operational strategies of planters can be optimized to ensure consistent corn stand establishment, ultimately leading to improved yield stability and sustainability in precision agriculture. The outcomes provide valuable guidance for the development of precision planting technologies and agronomic best practices, emphasizing the significance of engineering innovation in bolstering efficient and resilient crop production.