Estimating nutrient uptake requirements for rice in China

Accurate knowledge of the nitrogen (N), phosphorus (P), and potassium (K) requirements for rice (Oryzasativa L.) in China is essential to quantitatively estimate optimal fertilizer application regimes to maximize crop yield and increase nutrient use efficiency. On-farm experiments were collected in China’s major rice-producing regions from 2000 to 2013, to determine the relationship between grain yield and nutrient uptake in the above-ground plant dry matter using the quantitative evaluation of the fertility of tropical soils (QUEFTS) model. The large datasets obtained which covered broader rice growing areas and ecology types (both indica and japonica) in China. The dataset was divided into two groups: single-season riceand early/middle/late rice, according to QUEFTS analysis. The QUEFTS model predicted a linear increase in grain yield if nutrients were taken up in balanced amounts until yield reached about 60–70% of yield potential. To produce 1000 kg of single-season rice grain, 14.8 kg N, 3.8 kg P, and 15.0 kg K were required in the above-ground plant dry matter, and the corresponding internal efficiencies (IEs) were 67.6 kg grain per kg N, 263.2 kg grain per kg P, and 66.7 kg grain per kg K. For early/middle/late rice, the amount of 17.1 kg N, 3.4 kg P, and 18.4 kg K were required in the above-ground plant dry matter to produce 1000 kg of grain, and corresponding IEs were 58.5 kg grain per kg N, 294.1 kg grain per kg P, and 54.3 kg grain perkg K. The QUEFTS model provides a scientific foundation for filtering high-yielding and high-efficiency variety, optimizing fertilizer application rate and developing nutrient management strategies to increase yield and nutrient use efficiency. This is the first report on comparison of the nutrient uptake of different ecology types in rice production area of China using QUEFTS model and test their feasibility through field validation.