This work investigated the effective doses of biochar (BC) amendment with simulated nitrogen deposition on the stimulation of pecan (Carya illinoinensis) growth. A total of nine conditions combining three levels of BC—BC0, 0 t ha⁻¹ year⁻¹; BC20, 20 t ha⁻¹ year⁻¹; and BC40, 40 t ha⁻¹ year⁻¹—and three levels of simulated nitrogen deposition—N0, 0 kg N ha⁻¹ year⁻¹; N50, 50 kg N ha⁻¹ year⁻¹; and N150, 150 kg N ha⁻¹ year⁻¹—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.

中文翻译：

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生物炭改良剂和模拟氮沉降的相加作用刺激了山核桃（山核桃）幼苗的株高，光合作用和氮磷钾的积累。

这项工作研究了有效剂量的与山核桃（刺激模拟氮沉积生物炭（BC）修正案山核桃illinoinensis）的增长。总共9个条件，结合了BC-BC0的三个级别，0 t ha - ¹年^-1 ; BC20，20吨- ¹年− ^1年; 和BC40，40 t ha - ¹年^-1 –和三个模拟氮沉降水平-N0，0 kg N ha - ¹年^-1；N50，50千克N ha - ¹年^-1 ; 和N150，150 kg N ha - ¹年^-1-在整个一年的山核桃嫁接品种'波尼（Pawnee）'上施用。测定了幼苗的生长，光合作用，叶绿素和养分含量。还测量了土壤容重，pH，氮含量和酶活性。生物炭改良剂降低了土壤容重并提高了土壤pH。同时，借助BC修正，无机氮含量和酶活性随氮剂量的增加而增加。在没有BC修正的情况下，仅通过低水平的模拟氮沉降（N50）来刺激幼苗的高度，光合作用和叶绿素色素，而高水平的模拟氮沉降（N150）会阻碍幼苗的生长。在BC20N150的联合处理下，幼苗的生长最大，其中幼苗的高度，与仅用BC20处理的相比，光合作用和总叶绿素分别提高了22％，70％和40％。BC40进一步增加土壤中的氮保留量并不能进一步改善幼苗的生长，表明可能的机制涉及幼苗中养分的吸收和使用动态。BC修正减轻了模拟氮沉积的拮抗作用，从而抑制了磷，钾和铁的吸收。施用BC修正和模拟氮沉降对幼苗生长的影响在施肥树种上是加性的。表明可能的机制涉及幼苗的养分吸收和使用动态。BC修正减轻了模拟氮沉积的拮抗作用，从而抑制了磷，钾和铁的吸收。施用BC修正和模拟氮沉降对幼苗生长的影响在施肥树种上是加性的。提示可能的机制涉及幼苗的养分吸收和使用动态。BC修正减轻了模拟氮沉积的拮抗作用，从而抑制了磷，钾和铁的吸收。施用BC修正和模拟氮沉降对幼苗生长的影响在施肥树种上是加性的。