Effects of Soil Fertility and Nitrogen Application Rates on Super Rice Yield, Quality, and Nitrogen Use Efficiency

Abstract

Xudao 3 is a japonica super rice cultivar widely used in mid-maturing rice production in the North Huai River area. Using this cultivar, the effects of nitrogen (N) application (0, 148.5, 223.5, 297.0, 372.0, and 445.5 kg ha 1) on yield, yield components, grain quality, and N use efficiency were studied under different soil fertility levels. The yield of Xudao 3 in response to soil basic fertility showed the trend of high fertility medium fertility low fertility. The optimal N application rates for the highest yield were 260.8 kg ha 1 in the high-fertility field, 290.5 kg ha 1 in the medium-fertility field, and 345.5 kg ha 1 in the low-fertility field. There were significant quadratic relationships between apparent N recovery efficiency (ANRE) and N application; and the optimal N application rates for the highest ANRE were 268.6 kg ha 1 in the high-fertility field, 293.4 kg ha 1 in the medium-fertility field, and 335.2 kg ha 1 in the low-fertility field. Optimization of soil fertility was able to improve nutritional, processing, and cooking-eating qualities, and N application rate should vary with the soil basic fertility. In a comprehensive consideration of high-yield, good quality, and high N use efficiency, we suggested that the reasonable N application rates were 240-270 kg ha 1 for soil with high fertility, 285-315 kg ha 1 for soil with medium fertility, and 330-360 kg ha 1 for soil with low fertility in super rice production in the North Huai River area.