典型黑土不同施氮量对马铃薯产量和氮素利用率的影响

  【目的】  我国马铃薯生产中养分不平衡施用问题严重，过量施氮不利于农业可持续发展和生态环境保护。在养分专家系统 (Nutrient Expert，NE) 推荐施肥量基础上，研究不同施氮量对马铃薯产量、养分吸收和氮肥利用率的影响，为马铃薯推荐施肥提供科学依据。  【方法】  于2017―2018年，分别在黑龙江克山县不同地块进行2个田间试验，在NE系统推荐施肥量 (N₁₈₀) 的基础上，设减施推荐施氮量的50% (N₉₀)、25% (N₁₃₅) 和增施25% (N₂₂₅)、50% (N₂₇₀) 4个处理，并以不施氮肥的处理作对照 (N₀)。测定马铃薯产量、养分吸收量、肥料利用率等指标。  【结果】  017和2018年马铃薯产量均以NE系统推荐的N₁₈₀处理最高，较N₀处理两年平均增产40.4%。N₉₀和N₁₃₅处理低施氮水平 (≤ 180 kg/hm2) 下，随着施氮量的增加，马铃薯产量也明显增加，当施氮量超过NE系统推荐的施肥量 (180 kg/hm2) 后，继续增施氮肥对产量增加无明显作用。与N₀处理相比，两年N₁₈₀处理的块茎、秸秆和全株氮素吸收量平均增幅分别为49.8%、58.2%和52.0%，磷素吸收量平均增幅为36.3%、52.2%和39.8%，钾素吸收量平均增幅为26.4%、46.8%和31.3%，生产1 t块茎 (鲜重) 所需要的氮、磷、钾养分分别为4.6、1.1和5.8 kg。N₁₈₀处理的产量和氮磷钾养分吸收量均为最高，氮素农学效率和回收率与N₉₀和N₁₃₅处理差异不显著。  【结论】  在不超过马铃薯氮素需求条件下，增加氮肥投入可显著增加马铃薯产量和氮素吸收量，NE系统能够指导马铃薯科学施肥，保障马铃薯产量，提高氮肥利用效率。

Effects of different nitrogen rates on potato yield and nitrogen use efficiency in a typical black soil

  【Objectives】  The situation of unbalanced nutrient application in potato production in China is serious, and excessive nitrogen application is disadvantagous to agricultural sustainable utilization and ecological environment protection. In this study, the effects of different nitrogen application rates on potato yield, nutrients uptake and nitrogen use efficiency were studied to provide a scientific support for rational fertilization of potatoes based on Nutrient Expert (NE) system.  【Methods】  In this study, two field trials were conducted in different plots in Keshan, Heilongjiang Province during 2017–2018, respectively. Six different nitrogen rates were set up based on the NE system, including no nitrogen fertilizer (N₀), N rate based on NE system decreased by 50% N rate (N₉₀) and 25% N rate (N₁₃₅), NE-recommended N rate (N₁₈₀), N rate based on NE system increased by 25% N rate (N₂₂₅) and 50% N rate (N₂₇₀) . Potato yield, nutrient uptake, and fertilizer utilization efficiencies were measured.  【Results】  In both 2017 and 2018, the potato yield was highest in N₁₈₀ treatment recommended by NE, with an average increase of 40.4% compared with that in N₀ treatment for two years. When N rate was ≤ 180 kg/hm2, the potato yield increased with the nitrogen rate increased; when nitrogen rate was > 180 kg/hm2, potato yield didn't continue increasing with N rate increased. Compared with N₀ treatment, the averaged increase of nitrogen uptake by tuber, straw and whole plants in N₁₈₀ treatment during 2017–2018 were 49.8%, 58.2% and 52.0%, respectively; correspondingly, the averaged increase of the phosphorus uptake were 36.3%, 52.2% and 39.8%, as well as those of the potassium uptake were 26.4%, 46.8% and 31.3%, respectively. The demand of N, P and K was 4.6, 1.1 and 5.8 kg per ton potato fresh weight, respectively. The potato yield and uptake of N, P and K in N₁₈₀ treatment were the highest. And the N agronomic efficiency and recovery efficiency in N₁₈₀ treatment were not significantly different from those in N₉₀ and N₁₃₅ treatments.  【Conclusions】  Rational application of nitrogen fertilizer can significantly increase potato yield and nitrogen uptake, and increase nitrogen use efficiency when N rate does not exceed N demand in potato. NE system can recommended N rate scientificly, ensure potato yield and improve N fertilizer efficiencies.