Field validation of Nutrient Expert for early and late rice in China

The field validation of the Nutrient Expert® (NE) fertilizer decision support tool, based on the 4R Nutrient Stewardship Principles, continued in 2016 in the early and late rice systems project in Jiangxi and Hunan Provinces. The objective was to compare the NE-based fertilizer recommendation method with soil test-based fertilizer recommendation and farmers' practice (FP). In Jiangxi, on-farm validation experiments were set up in seven early and seven late rice sites , while 10 early and 10 late rice sites were studied in the Hunan Province.

In Hunan Province, 137-47-76 kg N-P₂O₅-K₂O/ha, 141-52-95 kg/ha, and 126-52-75 kg/ha were applied for the NE, soil test and FP treatments in early rice, respectively. The nutrient application in NE, soil test and FP treatments for late rice were 138-42-58 kg/ha, 161-37-95 kg/ha, and 128-53-75 kg/ha, respectively. There was no significant yield difference among the treatments in early or late rice.

In Jiangxi, the NE treatment achieved a significantly higher yield for early rice (10.4 t/ha) with application of 146-80-65 kg/ha than the soil test (8.9 t/ha with 144-66-116 kg/ha) and FP (8.9 t/ha with 201-96-116 kg/ha). The late rice grain yield was also highest in the NE treatment ((9.9 t/ha) with application of 142-55-60 kg/ha, while the soil test-based fertilizer application (176-64-133 kg/ha) and the farmers' practice (216-100-231 kg/ha) yielded 8.9 t/ha.

Results of both early and late rice trials indicated that NE can maintain or improve grain yields with less N or less K fertilizer input and more balanced fertilizer application. Besides changing the rates, NE also recommends a second N application at a later stage than FP for both early and late rice cropping systems. The better results achieved by the NE-based fertilizer recommendation were due to the application of the right fertilizer source at the right rate and time.