Precision application of combined manure, compost and nitrogen fertilizer in potato cultivation using online vis-NIR and remote sensing data fusion

This study evaluates the agronomic, economic and environmental impacts of precision nutrient management through variable rate (VR) application of chicken manure, compost and nitrogen (N) fertilizer compared to the uniform rate (UR) application in potato ( Solanum tuberosum L.) cultivation on two Fluvisol fields (Cayenne, 6.85 ha; Dzhond, 7.15 ha) in Belgium. Soil spectral data were collected at a 20 cm depth using an online visible and near infrared (vis-NIR) spectroscopy multi-sensor platform. Partial least squares regression models were established to predict soil pH, total carbon (TOC), extractable phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca) and cation exchange capacity (CEC). Management zones (MZs) were delineated by integrating Sentinel-2 derived normalized difference vegetation index (NDVI) with the online PLSR predicted soil data using raster and k-means cluster analysis. MZs were classified into high fertile (H), medium-high fertile (MH), medium fertile (M), medium-low fertile (ML) and low fertile (L) zones. A parallel strip trial compared VR application (with nutrient rates adjusted as VR-H: -50 %, VR-MH: -25 %, VR-M: 0 %, VR-ML: +25 %, VR-L: +50 % relative to UR) against UR application of chicken manure, compost, and N fertilizer. Results showed that, in Cayenne, VR-M, VR-ML and VR-L zones exhibited significant ( P ≤ 0.05 ) yield increases of 14.30 %, 9.16 % and 8.89 %, respectively, compared to the UR treatment, whereas crop yield in VR-H and VR-MH zones decreased. In Dzhond, VR-H and VR-ML zones achieved yield increases of 14.85 % and 18.0 %, respectively, whereas VR-M, VR-MH, and VR-L zones showed yield decreases of 5.66 %, 3.00 %, and 11.0 %, respectively. The VR application led to net reductions in nitrogen (ΔN = 17.54 kg/ha for Cayenne, and 4.24 kg/ha for Dzhond) and phosphorus (ΔP = 10.08 kg/ha for Cayenne, and 1.74 kg/ha for Dzhond), which resulted in increased relative gross margins of €142.11/ha for Cayenne and €269.50/ha for Dzhond. This study concludes that site-specific nutrient management improved yields, nutrient use efficiency, and profitability, while reducing N and P inputs, supporting sustainable agriculture. Future research should refine MZ delineation with inclusion of soil nitrate and soil biological data.