Over-application of chemical fertilizers to attain optimal crop yields has resulted in an environmental issue of global concern. To mitigate this, reducing nitrogen (N) application and enhancing fertilizer use efficiency is crucial, and nano-fertilizers offer a promising solution. However, there is a paucity of studies examining the use of nano-fertilizers in fields. This study aimed to assess the impact of different dosages of nano calcium carbonate (NCC) mixed with compound fertilizer (CF) on soil N supply, enzyme activity, microbial ecology, as well as photosynthetic characteristics, N accumulation and yield of wheat plants. The effects were examined through a soil column leaching experiment and a two-year field experiment conducted from 2020 to 2022. Five treatment groups were established, namely CK (CF), T1 (CF + 0.15% NCC), T2 (CF + 0.30% NCC), T3 (CF + 0.45% NCC), and T4 (CF + 0.60% NCC), to determine the optimal ratio of NCC to CF. All NCC treatments resulted in reduced leaching of soluble N. Nevertheless, the 0.45% and 0.60% NCC treatments (T3 and T4) posed a risk of migration through water runoff, leading to nutrient losses. The simultaneous application of NCC and CF increased the content of soil nitrate N (NO-N), as well as the activity levels of urease and protease during the anthesis stage. Additionally, it elevated the abundance of various microbial communities, including , , , , and . NCC application reduced the content of Na/K and malondialdehyde (MDA), while elevating the activities of flag leaf superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), nitrate reductase (NR), and glutamine synthetase (GS). Additionally, it increased stomatal conductance (Gs) and net photosynthetic rate (Pn). The 0.30% NCC treatment showed significantly higher N accumulation in the stem, leaf, and spike compared to CK at the maturity stage. Moreover, 0.30% NCC treatment exhibited a significant increase in the number of grains per spike and higher yields compared to CK. In particular, 0.30% and 0.45% NCC treatments accomplished yield boosts of 29.6–34.7% and 19.9–26.0%, respectively. NCC enhanced wheat plant N accumulation and yield through regulation of N release rate and increased soil N content, enzyme activity, and microbial community diversity and abundance. Additionally, NCC boosted flag leaf photosynthesis rate during the anthesis to maturity stage of wheat. This research highlights the potential of NCC to improve wheat crop production. And 0.30% NCC is the optimal application concentration for NCC.

中文翻译：

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纳米碳酸钙通过增强土壤氮供应和剑叶光合特性来提高小麦氮素积累和籽粒产量

为了获得最佳作物产量而过度施用化肥已导致全球关注的环境问题。为了缓解这一问题，减少氮 (N) 施用和提高肥料利用率至关重要，而纳米肥料提供了一个有前景的解决方案。然而，很少有研究检验纳米肥料在田间的使用。本研究旨在评价不同剂量纳米碳酸钙（NCC）与复合肥（CF）混施对土壤氮素供应、酶活性、微生物生态以及小麦植株光合特性、氮素积累和产量的影响。通过土柱淋洗实验和2020-2022年为期两年的田间试验检验效果。设立5个处理组，分别为CK（CF）、T1（CF+0.15%NCC）、T2（CF+0.30%NCC） NCC)、T3 (CF + 0.45% NCC) 和 T4 (CF + 0.60% NCC)，以确定 NCC 与 CF 的最佳比例。所有 NCC 处理都会减少可溶性氮的淋滤。然而，0.45% 和 0.60% NCC 处理（T3 和 T4）存在通过水径流迁移的风险，导致养分损失。同时施用NCC和CF提高了开花期土壤硝态氮(NO-N)含量以及脲酶和蛋白酶活性水平。此外，它还提高了各种微生物群落的丰度，包括、、、、和。 NCC的施用降低了Na/K和丙二醛（MDA）的含量，同时提高了旗叶超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、抗坏血酸过氧化物酶（APX）、硝酸还原酶（NR）和谷氨酰胺合成酶（GS）的活性）。此外，它还增加了气孔导度（Gs）和净光合速​​率（Pn）。成熟阶段，0.30% NCC 处理的茎、叶和穗中的氮积累量显着高于 CK。此外，与 CK 相比，0.30% NCC 处理的每穗粒数显着增加，产量更高。特别是，0.30%和0.45% NCC处理分别实现了产量提高29.6-34.7%和19.9-26.0%。 NCC通过调节氮释放速率、增加土壤氮含量、酶活性以及微生物群落多样性和丰度来增强小麦植株氮积累和产量。此外，NCC还提高了小麦花期至成熟期旗叶的光合作用速率。这项研究凸显了 NCC 提高小麦作物产量的潜力。 0.30%NCC是NCC的最佳使用浓度。