Jiangxi Institute of Red Soil, National Engineering and Technology Research Center for Red Soil Improvement, Nanchang, 331717, People's Republic of China.
Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China.
Sci Rep. 2021 Nov 18;11(1):22506. doi: 10.1038/s41598-021-02086-5.
Nutrient-deficient red soil found in the southern region of China is increasingly being used for potato crops to meet the demand for this staple food. The application of nitrogen fertilizer is necessary to support the production of higher tuber yields; however, the links between nitrate nitrogen and the nitrogen balance in red soil are unknown. A field experiment was conducted in Jiangxi Province in 2017 and 2018 to determine the effects of different nitrogen application rates, 0 kg ha (N0), 60 kg ha (N60), 120 kg ha (N120), 150 kg ha (N150), 180 kg ha (N180), 210 kg ha (N210), and 240 kg ha (N240, the highest rate used by local farmers), on potatoes growing in red soil. Data on tuber yield, crop nitrogen uptake, and the apparent nitrogen balance from the different treatments were collected when potatoes were harvested. Additionally, the content and stock of nitrate nitrogen at different soil depths were also measured. Nitrogen fertilization increased tuber yield but not significantly at application rates higher than 150 kg ha. We estimated that the threshold rates of nitrogen fertilizer application were 191 kg ha in 2017 and 227 kg ha in 2018, where the respective tuber yields were 19.7 and 20.4 t ha. Nitrogen uptake in potato in all nitrogen fertilization treatments was greater than that in N0 by 61.2-237% and 76.4-284% in 2017 and 2018, respectively. The apparent nitrogen surplus (the amount of nitrogen remaining from any nitrogen input minus nitrogen uptake) increased with increasing nitrogen application rates. The nitrate nitrogen stock at a soil depth of 0-60 cm was higher in the 210 and 240 kg ha nitrogen rate treatments than in the other treatments. Moreover, double linear equations indicated that greater levels of nitrogen surplus increased the nitrate nitrogen content and stock in soils at 0-60 cm depths. Therefore, we estimate that the highest tuber yields of potato can be attained when 191-227 kg ha nitrogen fertilizer is applied to red soil. Thus, the risk of nitrate nitrogen leaching from red soil increases exponentially when the apparent nitrogen balance rises above 94.3-100 kg ha.
在中国南方地区，人们越来越多地利用养分缺乏的红壤来种植土豆，以满足对这种主食的需求。为了提高块茎产量，施用氮肥是必要的；然而，硝酸盐氮与红壤氮素平衡之间的联系尚不清楚。2017 年和 2018 年在江西省进行了田间试验，以确定不同施氮量（0 kg/ha（N0）、60 kg/ha（N60）、120 kg/ha（N120）、150 kg/ha（N150）、180 kg/ha（N180）、210 kg/ha（N210）和 240 kg/ha（N240，当地农民的最高用量）对红壤中土豆生长的影响。当土豆收获时，收集了不同处理的块茎产量、作物氮吸收和表观氮平衡的数据。此外，还测量了不同土壤深度的硝酸盐氮含量和储量。施氮量高于 150 kg/ha 时，块茎产量虽有所增加，但并不显著。我们估计，2017 年和 2018 年氮素肥料的阈值施用量分别为 191 kg/ha 和 227 kg/ha，相应的块茎产量分别为 19.7 和 20.4 t/ha。在所有施氮处理中，马铃薯的氮吸收量比 N0 高出 61.2-237%和 76.4-284%，分别在 2017 年和 2018 年。表观氮盈余（任何氮输入减去氮吸收的剩余氮量）随着氮施用量的增加而增加。0-60 cm 土层的硝态氮储量在 210 和 240 kg/ha 氮处理中高于其他处理。此外，双线性方程表明，较高的氮盈余水平会增加 0-60 cm 土层土壤中的硝态氮含量和储量。因此，我们估计，当红壤施氮量为 191-227 kg/ha 时，马铃薯的最高块茎产量可以达到。因此，当表观氮平衡超过 94.3-100 kg/ha 时，硝态氮从红壤淋失的风险呈指数级增加。
