Yu Jing-Lin, Liu Feng, He Yue-Lin, Zhu Wei, Xi Ben-Ye, Jia Li-Ming
Ministry of Education Key Laboratory of Silviculture and Conservation, Beijing Forestry University, Beijing 100083, China.
Ying Yong Sheng Tai Xue Bao. 2020 Jul;31(7):2314-2322. doi: 10.13287/j.1001-9332.202007.007.
We explored the coupling effects of water and nitrogen in furrow irrigation on the growth and absorption and utilization of water and nitrogen in young poplar trees (triploid ), under three irrigation levels (W, W, W; when the soil water potential of 40 cm under the ditch reaches -20, -33 and -45 kPa respectively, irrigate), four N application levels (N, N, N and N; the fertilization amount was 120, 190, 260 and 0 kg·hm·a), and natural conditions (CK). Based on the growth status of trees, the optimal combination of irrigation level and nitrogen application rate under furrow irrigation conditions was determined. The results showed that WN (high water and low fertilizer; soil water potential threshold for initiating irrigation was -20 kPa and N application rate was 120 kg·hm·a) had the strongest effect on the stand productivity, with a value of 33.37 m·hm·a. The significant coupling effect of water and N was detected only for tree height and total individual biomass. The increase of both irrigation amount and N application rate could increase the amount of N uptake, being mainly affected by the latter. The total amount of N uptake was the highest in the WN treatment and reached 112.17 kg·hm·a, being 74.0% higher than that in CK. Among all the treatments, N uptake efficiency and N fertilizer partial productivity of WN were the highest and significantly higher than those of the other treatments. The N uptake efficiency of the whole plant, aboveground part, and belowground part reached 36.8%, 28.5% and 6.4% in the WN treatment, and its total N partial productivity reached 221.4 kg·kg. The effect of irrigation amount under different water-nitrogen coupling treatments on the irrigation water use efficiency was significant. Among them, irrigation water use efficiency in WN was the highest and reached 13.66 g·kg. WN had the highest water uptake amount and efficiency, which were 13268.28 t·hm and 129.4%, respectively. To achieve great benefits, adequate irrigation (-20 kPa) and relatively low N application rate (120 kg·hm·a) should be selected during the young growth of the triploid .
我们研究了沟灌条件下水分与氮素耦合对三倍体毛白杨幼树生长及水分和氮素吸收利用的影响，设置了3个灌溉水平（W₁、W₂、W₃，分别在沟下40 cm土壤水势达到-20、-33和-45 kPa时灌溉）、4个施氮水平（N₁、N₂、N₃和N₄，施肥量分别为120、190、260和0 kg·hm⁻²·a）以及自然条件（CK）。基于树木生长状况，确定了沟灌条件下灌溉水平与施氮量的最优组合。结果表明，W₁N₁（高水低肥，起始灌溉土壤水势阈值为-20 kPa，施氮量为120 kg·hm⁻²·a）对林分生产力影响最强，值为33.37 m³·hm⁻²·a。仅在树高和单株总生物量上检测到水分与氮素的显著耦合效应。灌溉量和施氮量的增加均能提高氮素吸收量，主要受施氮量影响。W₁N₁处理的氮素吸收总量最高，达112.17 kg·hm⁻²，比CK高74.0%。在所有处理中，W₁N₁的氮素吸收效率和氮肥偏生产力最高，且显著高于其他处理。W₁N₁处理全株、地上部分和地下部分的氮素吸收效率分别达到36.8%、28.5%和6.4%，其总氮偏生产力达221.4 kg·kg⁻¹。不同水氮耦合处理下灌溉量对灌溉水利用效率影响显著。其中，W₁N₁的灌溉水利用效率最高，达13.66 g·kg⁻¹。W₁N₁的吸水量和吸水效率最高，分别为13268.28 t·hm⁻²和129.4%。在三倍体毛白杨幼林生长期间，为获得良好效益，应选择充足灌溉（-20 kPa）和相对较低的施氮量（120 kg·hm⁻²·a）。
