GIS Based Fertilizer Recommendations for Maize on a County Scale

Regional fertilizer recommendation is urgent needed for the National Soil Testing and Fertilizer Recommendation Program, which started at 2005 and has already covered most counties of agricultural production area in China. This paper took DongChangFu district, LiaoCheng city, Shandong province as an example, established a Geographic Information System (GIS) based fertilizer recommendation system for maize production. The results shown that, through Ordinary Kriging interpolation approach, agricultural soils in this district could be classified into three management zones for phosphorus fertilizer recommendation according to the soil available phosphorus testing (Olsen-P method) value <10, 1030, and >30 mg/kg, respectively. Recommended phosphorus fertilizer rates (P₂O₅) were 143, 95, and 48 kg/hm² respectively. Management zones for potassium fertilizer recommendation were created according to soil available potassium testing (NH₄OAc-K method) value <50, 50-100, and >100 mg/kg, respectively, while recommended potassium fertilizer rates (K₂O) were 90, 60 and 30 kg/ hm², respectively. In conclusion, regional recommendations for phosphorus and potassium fertilizers are practicable on a county scale.