Field validation of Nutrient Expert for single season rice in China

Nutrient Expert^® (NE) field validation continued for single-season rice in 2017 through 10 on-farm experiments in Jilin and Heilongjiang Provinces of China. The objective was to compare the NE-based fertilizer recommendation method with traditional soil test-based fertilizer recommendations and farmers' practice (FP), in terms of rice grain yield and nutrient use efficiency.

Each individual field site received a site-specific fertilizer application based on the NE tool and soil test results. The average nutrient application rates in the NE-based plots were 171-61-98 kg N-P₂O₅-K₂O/ha, the soil test-based plots received an average of 167-63-84 kg/ha, while the FP plots received 175-63-71 kg/ha in Heilongjiang Province. Average rice grain yield in the NE treatment (9.3 t/ha) was higher than the soil test (8.8 t/ha) and FP treatments (8.1 t/ha), but the values were not significantly different. The average agronomic efficiency (AE) and partial factor productivity (PFP) of nitrogen were 22.9 kg/kg and 54.4 kg/kg in the NE treatment, 20.5 kg/kg and 53.0 kg/kg in the soil test-based treatment, and 15.9 kg/kg and 47.6 kg/kg in the FP treatment, respectively.

For Jilin Province, the average N-P₂O₅-K₂O application rates were 167-65-94 kg/ha in the NE-based plots, 176-69-93 kg/ha in the soil test-based plots, and 182-74-92 kg/ha in the FP plots. There was no significant difference in rice grain yield between the NE (8.8 t/ha), soil test (8.8 t/ha) and FP treatments (8.6 t/ha). Similarly, the AE and PFP values of nitrogen among the treatments were not different.

The NE tool provided fertilizer recommendations that improved yield and nutrient use efficiency in single-season rice and it could be useful when soil testing is not available or timely.