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

The Nutrient Expert^(R) (NE) for rice decision support system was first validated in early and late rice system in Guangdong, Jiangxi and Hunan in 2014. The objective was to test the NE-based fertilizer recommendation method as compared to soil testing and farmer’s practice (FP).

There were 14 field validation experiments on early (7 sites) and late rice (7 sites) in Guangdong. For early and late rice respectively, the NE treatment supplied 160-71-62 kg N-P₂O₅-K₂O/ha and 160-70-61 kg N-P₂O₅-K₂O/ha, while the soil test-based treatment supplied 156-48-126 kg N-P₂O₅-K₂O/ha and 159-50-126 kg N-P₂O₅-K₂O/ha, and the FP treatment provided 192-46-101 kg N-P₂O₅-K₂O/ha and 191-50-102 kg N-P₂O₅-K₂O/ha. Higher grain yield was obtained under NE (7.9 t/ha) than with soil test (7.7 t/ha) and FP (7.6 t/ha) treatments for early rice. In late rice, NE also improved grain yield (7.1 t/ha) compared to the soil test (6.9 t/ha) and FP (6.9 t/ha) treatments.

There were 16 field validation experiments on early (8 sites) and late rice (8 sites) in Jiangxi. In early rice, NE (143-60-56 kg N-P₂O₅-K₂O/ha) produced a similar grain yield (6.0 t/ha) compared to the soil test (150-66-109 kg N-P₂O₅-K₂O/ha) and FP (150-68-88 kg N-P₂O₅-K₂O/ha) treatments. For late rice, NE produced a higher grain yield (8.0 t/ha) with 154-64-64 kg N-P₂O₅-K₂O/ha compared to the soil test (7.7 t/ha with 150-66-109 kg N-P₂O₅-K₂O/ha) and FP (7.6 t/ha with 142-66-89 kg N-P₂O₅-K₂O/ha).

Ten field validation experiments on early (5 sites) and late rice (5 sites) were conducted in Hunan. The NE treatment improved grain yield for both early rice (7.1 t/ha) and late rice (7.6 t/ha) with 143-56-49 kg N-P₂O₅-K₂O/ha and 153-59-52 kg N-P₂O₅-K₂O/ha, respectively. While lower than NE, no differences in grain yield were found between the soil test-based treatments (6.9 t/ha with 141-68-68 kg N-P₂O₅-K₂O/ha for early rice, and 7.3 t/ha with 160-62-109 kg N-P₂O₅-K₂O/ha for late rice), and FP treatments (6.9 t/ha with 104-45-49 kg N-P₂O₅-K₂O/ha for early, and 7.2 t/ha with 154-58-81 kg N-P₂O₅-K₂O/ha for late rice).

Results from early and rice grown in three provinces indicated that NE can maintain the grain yield with less N or less K fertilizer input. The key points learned from NE is the importance of applying fertilizer at the right rate and right time. The NE recommendation of applying the second N application at a later stage than FP for both early and late rice systems is significant.