Mechanical weeding boosts ecosystem functions and profit in industrial oil palm, study finds

Palms are the most productive olive crop and global demand is increasing. However, their productivity is driven by conventional management practices, including high fertilizer use and herbicide application, resulting in severe environmental damage.

A new study by an international, interdisciplinary research team led by the University of Göttingen shows that a shift to mechanical weeding and reduced fertilizer use leads to significant increases in both ecosystem multifunctionality and profit. The scientists compared different environmental measures and economic indicators in mechanical weeding, herbicide application and combinations of these with high and low fertilizer use. Their study was published in the journal Sustainability of Nature.

Palm oil production has increased in Indonesia, once the world’s largest producer of palm oil, coinciding with the country’s increased rate of deforestation. Although palm oil production has brought socio-economic benefits, it also causes environmental problems such as biodiversity loss, nitrate leaching and greenhouse gas emissions.

The team conducted their research on plantations at least 16 years old, starting in 2016 in Jambi, Indonesia, with the aim of testing reduced management against conventional practices. They looked at the effects of reducing fertilizer use to offset the amount of nutrients removed by harvesting oil palm fruit and mechanical weeding using a brush cutter. For four years, the researchers collected data on palm oil yield, material and labor costs, both on- and above-ground animals, soil vegetation diversity, greenhouse gas emissions, soil fertility and nutrient leaching.

“Despite reduced fertilizer use, oil palm yields are similar to conventional management, but profit increases significantly due to reduced fertilizer costs. Biodiversity is also significantly improved, due to the increase in soil vegetation species with mechanical weeding,” says first author Dr. Najeeb Al-Amin Iddris from the University of Göttingen’s Department of Soil Science for Tropical and Subtropical Ecosystems. As ecosystem functions tend to be interrelated, the analysis was conducted across multiple ecosystem functions, known as ‘polyfunctionality’.

“Mechanical weeding shows significantly higher ecosystem multifunctionality than herbicide application. It promotes rapid recovery of soil vegetation and increases its species diversity, which can enhance nutrient recycling through root uptake and in combination with reduced fertilizer use it reduces leaching and increases nutrient retention in the soil,” explains Iddris.

“The study found no reduction in greenhouse gas emissions with reduced fertilizer use and mechanical weeding over four years of this experiment,” explains lead author Dr. Marife Corre, University of Göttingen.

“The positive effects of mechanical weeding on multifunctionality and ecosystem gain show that such smart practices can bring benefits even in the short term. Using mechanical weeding during the early stage of establishment of an oil palm plantation can reap even greater benefits.” , says Corre.

“These management practices can easily be adopted in the field and should be included as one of the criteria for sustainable palm oil production as defined by the Roundtable for Sustainable Palm Oil, an organization of palm oil producers, processors, manufacturers, investors. , environmental groups and social development stakeholders.”