关键词: 冬油菜产量, 农民习惯施肥, 推荐施肥, 养分利用效率, 长江流域

Abstract: 【Objective】Reasonable fertilization is critical for improving winter oilseed rape (Brassica napus L.) yield. Rough management of fertilization would cause the nutrient efficiency decline under current intensive planting management mode, thus affecting rapeseed yield. To provide an optimizing management strategy for the rational fertilizer utilization to enhance nutrient use efficiency, yield and nutrient efficiency differences were compared between farmer’s practice (FP) and recommended fertilization (RF) for winter oilseed rapes in the Yangtze River Basin (YRB) in this study. 【Method】Total of 535 field experiments were selected in the YRB during 2005-2016, including Sichuan, Guizhou, Hubei, Hunan, Anhui, Jiangsu and Zhejiang provinces, China. Three fertilization treatments, i.e., no-fertilizer (CK), farmer’s practice (FP) and recommended fertilization (RF), were designed. The differences in yield and its distribution characteristics, as well as differences of yield increase rate, fertilization rates, and partial factor productivity, were compared among the treatments and regions. The differences of fertilizer amounts between RF and FP treatments were calculated, and the reduction space of nitrogen, phosphorus and potassium fertilizer in Yangtze River Basin was evaluated.【Result】The range of winter oilseed rape yield for the CK, FP and RF treatments were 500-1 500 kg·hm^-2, 1 500-3 000 kg·hm^-2 and 2 000-3 000 kg·hm^-2, respectively. For the RF treatment, the contribution rate of the soil indigenous fertility supply was only 45.1%-49.7%. Rapeseed yield showed highest in the lower reach, then the middle reach, and lowest in the upper reach. The average rapeseed yield of FP management in the upper, middle and lower reaches of the Yangtze were 2 033 kg·hm^-2, 2 182 kg·hm^-2 and 2 542 kg·hm^-2, respectively, and the RF management produced more rapeseed (16.7%, 16.5% and 13.9% averagely) than the FP in 77.5%-94.9% of the 535 trails. With the increasing level of soil indigenous fertility supply, yield increase rate showed a decline trend, and RF treatment showed a higher increase rate than FP at different levels. Averaged fertilizer rates of FP were 162.5-239.5 kg N·hm^-2, 58.6-82.0 kg P₂O₅·hm^-2 and 45.5-60.8 kg K₂O·hm^-2, and the values were 162.2-233.6 kg N·hm^-2, 67.2-94.1 kg P₂O₅·hm^-2 and 73.6-108.5 kg K₂O·hm^-2 of RF treatment. There was no significant difference in the amount of N fertilizer used under the two treatments, and the amounts of P and K fertilizer were lower under the FP treatment than the RF treatment. Compared with RF, 45.6% and 25.6% of the 535 experiments could reduce N and P fertilizer rates, respectively. However, only 13.2% of the experiments could lower K fertilizer rates. Meanwhile, 37.8%, 60.0% and 75.9% of the trails needed more N, P and K fertilizers input in the YRB, respectively. Fertilization rates were more appropriate in the lower reaches as compared with the other two regions, in which optimum N, P, and K rates were accounted 25.0%, 22.8%, and 17.1% of the 535 trails, respectively. The average partial factor productivity of nitrogen (PFP_N), phosphorus (PFP_P) and potassium (PFP_K) for FP was 11.1-14.2 kg·kg^-1, 28.6-45.8 kg·kg^-1 and 38.3-47.6 kg·kg^-1, respectively. Although PFP_N in the RF treatment were 12.9%-15.9% higher than that in the FP treatment across the regions, the values were still lower as compared with other developed countries. Meanwhile, the PFP_P and PFP_K of RF were respectively 6.9% and 19.6% lower than the FP treatments, indicating that current recommended fertilization rate also had a potential for fertilizer reducing. 【Conclusion】Recommended fertilizations management could significantly improve rapeseed yield as compared with farmer’s practice, and the fertilizer rates of FP had a larger adjustment space.

Key words: winter rapeseed yield, farmer’s practice, recommended fertilization, nutrient efficiency, the Yangtze River Basin