Hou Zhiying, Tang Yiquan, Li Caiyun, Lim Kean-Jin, Wang Zhengjia
State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, Zhejiang, China.
AoB Plants. 2020 Jul 26;12(4):plaa035. doi: 10.1093/aobpla/plaa035. eCollection 2020 Aug.
This work investigated the effective doses of biochar (BC) amendment with simulated nitrogen deposition on the stimulation of pecan () growth. A total of nine conditions combining three levels of BC-BC0, 0 t ha year; BC20, 20 t ha year; and BC40, 40 t ha year-and three levels of simulated nitrogen deposition-N0, 0 kg N ha year; N50, 50 kg N ha year; and N150, 150 kg N ha year-were applied throughout 1 year on the pecan-grafted seedlings of cultivar 'Pawnee'. The growth, photosynthesis, chlorophyll and nutrient content in the seedlings were measured. The soil bulk density, pH, nitrogen content and enzymatic activities were also measured. Biochar amendment reduced soil bulk density and elevated soil pH. Meanwhile, aided by BC amendment, the inorganic nitrogen content and enzyme activities increased with increasing doses of nitrogen. In the absence of BC amendment, the seedlings' height, photosynthesis and chlorophyll pigments were only stimulated by a low level of simulated nitrogen deposition (N50), whereas a high level of simulated nitrogen deposition (N150) impeded the growth. The seedlings improved the most under the combined treatment of BC20N150, wherein the seedling heights, photosynthesis and total chlorophyll improved by 22 %, 70 % and 40 %, respectively, compared to those treated solely with BC20. Further increase of nitrogen retention in the soil by the BC40 did not further improve the growth of the seedlings, suggesting the possible mechanisms involve nutrient uptake and usage dynamic in the seedlings. The BC amendment alleviated the antagonist effect from simulated nitrogen deposition that suppressed the absorption of phosphorus, potassium and iron. The effect of applying both BC amendment and simulated nitrogen deposition to the growth of seedlings was additive at fertilizing tree species.
本研究通过模拟氮沉降，探讨了生物炭（BC）改良对山核桃（）生长的促进作用及其有效剂量。在山核桃品种‘波尼’的嫁接幼苗上，设置了9种处理组合，包括3个生物炭水平（BC0，0 t·ha⁻¹·年⁻¹；BC20，20 t·ha⁻¹·年⁻¹；BC40，40 t·ha⁻¹·年⁻¹）和3个模拟氮沉降水平（N0，0 kg·N·ha⁻¹·年⁻¹；N50，50 kg·N·ha⁻¹·年⁻¹；N150，150 kg·N·ha⁻¹·年⁻¹），为期1年。测定了幼苗的生长、光合作用、叶绿素和养分含量，同时测定了土壤容重、pH值、氮含量和酶活性。生物炭改良降低了土壤容重，提高了土壤pH值。同时，在生物炭改良的辅助下，无机氮含量和酶活性随氮剂量的增加而增加。在没有生物炭改良的情况下，幼苗的高度、光合作用和叶绿素色素仅在低水平模拟氮沉降（N50）下受到刺激，而高水平模拟氮沉降（N150）则抑制了生长。在BC20N150组合处理下，幼苗生长改善最为明显，与单独使用BC20处理相比，幼苗高度、光合作用和总叶绿素分别提高了22%、70%和40%。BC40进一步增加土壤氮保留量并未进一步改善幼苗生长，表明可能机制涉及幼苗养分吸收和利用动态。生物炭改良减轻了模拟氮沉降对磷、钾和铁吸收的拮抗作用。在施肥树种中，生物炭改良和模拟氮沉降对幼苗生长的影响具有累加效应。
