Background and aims

Diversifying grassland sward composition and application of microbial inoculants are potential alternative routes to facilitate enhanced nutrient acquisition by plants, but their relative effects have been rarely tested in grasslands. In a two-year field experiment, we investigated the impact of inoculants and sward types on forage yield, nutrient uptake, and the soil microbiome.

Methods

We implemented a fully factorial experiment with inoculants (eight levels; arbuscular mycorrhizal fungi (AMF), Paraburkholderia phytofirmans PsJN and Bacillus sp. P5 (P5), applied singly and in combination), and sward types (three levels: grass-only, grass and legume, mixture of grass, legume, and herb) as the two factors.

Results

In both years, there was a very strong effect of sward type, with the grass + legume and grass + legume + herb swards having much higher yields and nutrient uptake (N, P, K, S, Ca, Mg, Zn, Cu) than grass-only. Generally, there was no effect of the inoculants on yield and nutrient uptake, with limited exceptions involving AMF + P5. The best-performing microbial inoculant increased forage yield by 597 kg/ha/year, while switching from grass-only to one of the other sward types increased forage yield by 3932 kg/ha/year (grass + legume) and 4693 kg/ha/year (grass + legume + herb). The inoculants persisted in plots for > 1 year after application. Inoculants and sward type significantly affected the overall prokaryotic and fungal community structures.

Conclusion

Overall, under controlled field plot conditions, including legumes and herbs in a grass sward proved to be a far better farm-scale management strategy for increasing grassland forage yield and nutrient uptake than the application of microbial inoculants.

中文翻译：

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在集约化管理的草地中，操纵草地多样性是比添加微生物接种剂更有效的管理策略

 背景和目标

草原草地组成多样化和微生物接种剂的应用是促进植物增强养分获取的潜在替代途径，但它们的相对效果很少在草原上进行测试。在一项为期两年的田间实验中，我们研究了接种剂和草坪类型对饲料产量、养分吸收和土壤微生物组的影响。

 方法

我们对接种剂（八个级别；丛枝菌根真菌 (AMF)、Paraburkholderia phytofirmans PsJN 和芽孢杆菌属 sp. P5 (P5)，单独应用和组合应用）和草地类型（三个级别：纯草、草和豆类，草、豆类和草本植物的混合物）作为两个因素。

 结果

在这两年中，草丛类型的影响非常强烈，草“+”豆科植物和草“+”豆科植物“+”草本草丛的产量和养分吸收（N、P、K、S、Ca、Mg、Zn、Cu）要高得多。比仅草。一般来说，接种剂对产量和养分吸收没有影响，AMF + P5 除外。性能最佳的微生物接种剂使牧草产量增加了 597 公斤/公顷/年，而从纯草切换到其他草坪类型之一则使牧草产量增加了 3932 公斤/公顷/年（草+豆科植物）和 4693 公斤/公顷/年（草 + 豆类 + 草本植物）。施用后接种剂在地块中持续存在> 1年。接种剂和草坪类型显着影响整体原核和真菌群落结构。

 结论

总体而言，在受控的田块条件下，在草丛中种植豆类和草本植物被证明是比施用微生物接种剂更好的农场规模管理策略，可以提高草地饲料产量和养分吸收。