Accurate crop yield modeling (CYM) is inherently challenging due to the complex, nonlinear, and temporally dynamic interactions of biotic and abiotic factors. Crop traits, which historically capture the cumulative effect of these factors, exhibit functional relationships critical for optimizing productivity. This underscores the necessity of multi-trait-based CYM approaches. Crop growth models enable trait dynamics with reflectance data and spectral indices as proxies for crop health and traits, respectively, to have real-time, spatially explicit monitoring. The Agricultural Production Systems sIMulator was calibrated to simulate multiple traits across the growth season based on geo-tagged wheat field ground information. Reflectance and spectral indices were processed for the geo-tagged fields across temporal observations to enable real-time, spatially explicit monitoring. Based on these parameters, this study addresses a critical gap in existing CYM frameworks by proposing a machine learning-based model that synergized multiple crop traits with reflectance and spectral indices to generate site-specific yield estimates. The performance evaluation revealed that the Long Short-Term Memory (LSTM) model achieved superior accuracy for the integrated parameters (RMSE = 250.68 kg/ha, MAE = 193.76 kg/ha, and R2 = 0.84), followed by traits alone. The Random Forest model followed the LSTM model, with an RMSE = 293.56 kg/ha, MAE = 230.68 kg/ha, and R2 = 0.78 for integrated parameters, and an RMSE = 291.73 kg/ha, MAE = 223.17 kg/ha, and R2 = 0.78 for crop traits. The superior prediction demonstrated the dominant role of multiple crop traits with satellite-derived reflectance metrics to develop robust CYM frameworks capable of capturing intra- and inter-field yield variability.
21 February 2024 in Environmental Monitoring and Assessment
The integration of the Crop Growth Model (CGM), Radiative Transfer Model (RTM), and Machine Learning Algorithm (MLA) for estimating crop traits represents a cutting-edge area of research. This integration requires in-depth study to address RTM limitations, particularly of similar spectral responses from multiple input combinations. This study proposes the integration of CGM and RTM for crop trait retrieval and evaluates the performance of CGM output-based RTM spectra generation for multiple crop traits estimation without biased sampling using machine learning models. Moreover, PROSAIL spectra as training against Harmonized Landsat Sentinel-2 (HLS) as testing was also compared with HLS data only as an alternative. It was found that satellite data (HLS, 80:20) not only consistently performed better, but PROSAIL (train) and HLS (test) also had satisfactory results for multiple crop traits from uniform training samples in spite of differences in simulated and real data. PROSAIL-HLS has an RMSE of 0.67 for leaf area index (LAI), 5.66 µg/cm2 for chlorophyll ab (Cab), 0.0003 g/cm2 for dry matter content (Cm), and 0.002 g/cm2 for leaf water content (Cw) against the HLS only, with an RMSE of 0.40 for LAI, 3.28 µg/cm2 for Cab, 0.0002 g/cm2 for Cm, and 0.001 g/cm2 for Cw. Optimized machine learning models, namely Extreme Gradient Boost (XGBoost) for LAI, Support Vector Machine (SVM) for Cab, and Random Forest (RF) for Cm and Cw, were deployed for temporal mapping of traits to be used for wheat productivity enhancement.
Agriculture field boundary information is vital in crop health monitoring, food security efforts, and precision agriculture. In countries like Denmark and the Netherlands field parcel information is available whereas Pakistan lacks such datasets.Denmark field boundary data for year 2018 was selected for the training of the model. Satellite imagery of four dates was downloaded and preprocessed to capture crop dynamics on the ground. Semantic segmentation architectures were used to train the models on the imagery, and results were assessed using metrics such as Intersection over Union(IoU) and f1-scores.The results show that UNet architecture with SENet154 backbone performs better than other architecture-backbone combinations. In terms of dates of imagery, data from 27th July achieved a higher IoU score. The method of providing input mask to the model had the most impact on the metrics and resulted in a 35% increase in IoU. Temporal stacking of multi-date satellite imagery proved to be an effective way of increasing information content for boundary delineation and improved the IoU by 6.5% in comparison to a single-date model. The final temporal stacked model had an IoU score of around 0.72.The trained model was able to delineate boundaries and showed good results in comparison to the available ground truth. The results of transfer learning to new areas suggest that there is potential in using such techniques, but further factors need to be considered to improve the metrics.
24 October 2014 in Pakistan Journal of Scientific & Industrial Research Series A: Physical Sciences