The status and evaluation of formula fertilization by soil testing technology on maize nutrition management in Tongliao of Inner Mongolia

Objectives It is to clarify the fertilization status of maize in Tongliao City of Inner Mongolia, providing the scientific suggestion in local maize nutrient resource managements.

Methods Comparative and statistical analysis were used based on the survey data of local farmer in 2005–2007 and 2010–2012 in this study.

Results 1) The total amount of chemical fertilizer applied on maize was 333.5–383.5 kg/hm² from 2010 to 2012, in which the rates of nitrogen, phosphorus and potassium fertilizers were 210.0–237.0 kg/hm², 85.5–106.5 kg/hm² and 38.0–40.0 kg/hm², respectively. Compared with the period from 2005 to 2007, there was no significant difference on the total amount and nitrogen fertilizer rate, while the phosphorus rates decreased by 28.5 kg/hm² and 15.0 kg/hm² and the potassium rates increased by 23.0 kg/hm² and 20.0 kg/hm² in rain-fed and irrigated condition, respectively. 2) Compared with the recommended fertilization rate, nitrogen fertilizer application rate was higher, while phosphorus and potassium application rates were lower. 3) In Tongliao, basal application and once top dressing were the main application method of local farmers, which covered all rainfed and 90% irrigated maize. The ratio of basal and top dressing was reasonable, arriving at 1∶2.9 and 1∶3.3 in rainfed and irrigated maize, respectively. 4) Diammonium phosphate and compound fertilizer were generally used as basal fertilizer, urea was as top dressing fertilizer. The formulas of N-P₂O₅-K₂O in compound fertilizer include 15-15-15, 18-18-18, 17-17-17 and 19-19-19, accounting for 77.6% of total fertilizers used in rainfed maize, and 15-15-15, 12-15-8 and 15-20-10 were mainly used in irrigated maize, representing 78.1% of total fertilizer amount. The fertilizer formulas were largely different between rainfed and irrigated conditions. 5) Only small proportion of farmers used organic fertilizers, accounting for 27% of surveyed farmers. 6) The ratio of nitrogen, phosphorus and potassium was 1∶0.45–0.46∶0.10–0.22, the ratio of nitrogen and phosphorus was reasonable but the N/K ratio was inconsistent with maize requirement. In conclusion, nitrogen fertilizer was overused, while phosphate fertilizer, potassium fertilizer and organic manure were much insufficient in Tongliao City, Inner Mongolia Autonomous Region.