Subsurface Banding of Poultry Manure Enhances Photosynthetic Efficiency, Yield, and Nutrient Uptake in Buckwheat

Manure application may improve plant growth, yield, and ecological sustainability. This study investigates optimized organic fertilizer application methods for enhancing buckwheat (Fagopyrum esculentum) productivity in semi-arid conditions. Treatments include broadcasting (Br) and subsurface banding (Ba) of poultry (PM) and cattle (CM) manure and foliar spraying (S) of manure extracts (1:5 and 1:10 ratios), urea fertilizer (UF), and a control. Subsurface-banded poultry manure (BaPM) maximized chlorophyll b (4.0 µg/mL), carotenoids (2.30 µmol/mL), anthocyanin (0.02 µmol/mL), leaf area index (2.03), seed nitrogen (3.4%), and spikes per plant (17). BaPM achieved the highest seed yield (646 kg/ha), comparable to BrPM, BaCM, and SPM(1:5). The maximum seed phosphorus content (0.43%) was observed in the BaPM, BrPM, and SCM(1:10) treatments. Dry matter peaked under UF (4870 kg/ha) and BaPM (4641 kg/ha). Banding placement improved nutrient uptake by enhancing root zone retention, while foliar poultry extract (1:5) mitigated phosphorus deficiency. These findings demonstrate that integrating certain manure types with targeted application methods-particularly subsurface banding of poultry manure-optimizes nutrient use efficiency, crop performance, and environmental sustainability in buckwheat cultivation.