Lv Jinling, Liu Hua, Wang Xihe, Li Kaihui, Tian Changyan, Liu Xuejun
Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China.
Institute of Plant Nutrition, Resources and Environmental Sciences, Henan Academy of Agricultural Sciences, Zhengzhou, China.
PLoS One. 2016 Oct 31;11(10):e0165404. doi: 10.1371/journal.pone.0165404. eCollection 2016.
Few systematic studies have been carried out on integrated N balance in extremely arid oasis agricultural areas. A two-year field experiment was conducted to evaluate the N input and output balances under long-term fertilization conditions. Five treatments were chosen, namely CK (no fertilizer), NPK, NPKS (10% straw return N and 90% chemical N), NPKM (one third urea-N, two thirds sheep manure) and NPKM+ (1.5 times NPKM). The results show an abundance of dry and wet N deposition (33 kg N ha-1 yr-1) in this area. All treatments (excluding CK) showed no significant difference in wheat production (P>0.05). NPKM gave higher cotton yields (P<0.05). In both crops, NPKM and NPKS treatments had a relatively higher N harvest index (NHI). 15N-labeled results reveal that the fertilizer N in all N treatments leached to<1 m depth and a high proportion of fertilizer-N remained in the top 60 cm of the soil profile. The NPKM+ treatment had the highest residual soil mineral N (Nmin, 558 kg Nd ha-1), and NPKM and NPKS treatments had relatively low soil Nmin values (275 and 293 kg N ha-1, respectively). Most of the treatments exhibited very high apparent N losses, especially the NPKM+ treatment (369kg N ha-1). Our arid research area had a strikingly high N loss compared to less arid agricultural areas. Nitrogen inputs therefore need careful reconsideration, especially the initial soil Nmin, fertilizer N inputs, dry and wet deposition, and appropriate organic and straw inputs which are all factors that must be taken into account under very arid conditions.
在极端干旱的绿洲农业区，很少有关于综合氮平衡的系统研究。开展了一项为期两年的田间试验，以评估长期施肥条件下的氮输入和输出平衡。选择了五种处理方式，即CK（不施肥）、NPK、NPKS（10%秸秆还田氮和90%化学氮）、NPKM（三分之一尿素氮，三分之二羊粪）和NPKM+（1.5倍NPKM）。结果表明，该地区干湿氮沉降量丰富（33千克氮·公顷⁻¹·年⁻¹）。所有处理方式（不包括CK）的小麦产量均无显著差异（P>0.05）。NPKM处理的棉花产量较高（P<0.05）。在两种作物中，NPKM和NPKS处理的氮收获指数（NHI）相对较高。¹⁵N标记结果显示，所有氮处理中的肥料氮均淋溶至<1米深度，且大部分肥料氮保留在土壤剖面的顶部60厘米处。NPKM+处理的土壤矿质氮残留量最高（Nmin，558千克氮·公顷⁻¹），NPKM和NPKS处理的土壤Nmin值相对较低（分别为275和293千克氮·公顷⁻¹）。大多数处理方式的表观氮损失都非常高，尤其是NPKM+处理（369千克氮·公顷⁻¹）。与干旱程度较低的农业区相比，我们的干旱研究区氮损失极高。因此，需要仔细重新考虑氮输入，特别是初始土壤Nmin、肥料氮输入、干湿沉降以及适当的有机和秸秆输入，这些都是在极端干旱条件下必须考虑的因素。
