Precision farming and production optimization depend on accurate nutrient deficit (ND) diagnosis. In order to diagnose various problems in okra leaves, this study proposes a repeatable and comprehensible deep-learning pipeline that combines segmentation, adaptive picture improvement, handcrafted deep feature fusion, and a lightweight convolutional neural network (CNN) classifier. By simultaneously adjusting Gaussian and Poisson noise weights, a Dual Adaptive Weighted Kalman Filter (DAWKF) reduces noise in input images. Segmentation is carried out via an Adaptive Weighted Optimizer with Otsu Thresholding (AWO-AOT) using bio-inspired adaptive migration methods that improve local thresholds. Local Binary Patterns (LBP), FAST, and SIFT descriptors are used in Adaptive Fused Features (AFF), which feed a SIFT-guided CNN to learn spatial-texture representations. 2,030 agronomist-verified okra-leaf photos from various field sources make up the extended dataset. They are divided into 70/15/15 sections for training, validation, and testing, and they are assessed using five-fold cross-validation. The suggested framework outperformed BM3D and PSO-Otsu baselines with 98.6 ± 0.3% accuracy and statistically significant gains (p < 0.05) in PSNR (+1.8 dB) and SSIM (+0.014). Grad-CAM explainability studies revealed important symptom regions associated with necrosis and leaf chlorosis. The technique provides a repeatable mechanism for real-field agronomic decision assistance and is generalizable across lighting, camera, and field conditions.