Orchard Groundcover Cultivation: Selected Grasses Proven to Resist Adversity and Sequester Carbon in Taoyuan

Extreme weather is now commonplace, but a new study from Taiwan's Taoyuan Agricultural Research and Extension Station offers a promising solution for orchards. Researchers have confirmed that implementing groundcover cultivation with carefully selected grass species can significantly improve fruit trees' resilience to drought and reduce reliance on herbicides.

The study focused on identifying grasses with specific traits: shade tolerance, drought resistance, high ground coverage, and creeping growth. After a two-year trial, orchards planted with these target grasses showed higher soil organic carbon storage compared to those with naturally mixed grasses or those treated with herbicides. Notably, species such as *Digitaria adscendens*, *Setaria parviflora*, and *Eragrostis curvula* excelled, achieving carbon sink rates exceeding 3.3 metric tons of carbon per hectare annually. This is a substantial improvement over herbicide use, which was found to reduce carbon by approximately 4.2 metric tons per hectare each year.

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The target grass species, due to their creeping growth characteristics, only require 2-3 mows per year during the planting period. This also results in reduced carbon emissions from mower fuel and labor.

Furthermore, the selected grasses, characterized by their creeping growth, require minimal maintenance, typically only 2-3 mows per year. This reduction in mowing not only saves on fuel and labor but also contributes to lower carbon emissions. The research also explored the impact of mowing frequency on soil carbon storage. Intensive mowing (9 times per year) resulted in a negative carbon sink rate, decreasing carbon by 0.4 metric tons per hectare annually. In contrast, a low-frequency mowing strategy (3 times per year) boosted the carbon sink rate to an impressive 6 metric tons per hectare annually, without negatively affecting fruit quality or soil microclimate.

The Taoyuan station plans to further integrate grass selection with low-frequency mowing strategies. By maintaining a low-lying, manageable grass cover, they aim to optimize orchard operations while continuing to assess the soil carbon dynamics of mixed-species plantings. This approach offers a sustainable path for agriculture, enhancing both crop resilience and environmental benefits.

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Reducing mowing frequency has a significant effect on increasing carbon sinks. For example, under intensive management with 9 mows per year, the carbon sink rate was negative, with a reduction of 0.4 metric tons of carbon per hectare annually. In contrast, the low-frequency management model with 3 mows per year achieved a carbon sink rate of 6 metric tons of carbon per hectare annually.