IMPACT OF MULCHING ON POTATO GROWTH IN FLEMISH AGRICULTURAL CONTEXT
The climate is changing
Like in most parts of the world, the climate in Belgium is changing. This is characterized by temperature increase and erratic rainfall (Tun Oo et al., 2023). Moreso, it is projected that winter precipitation will increase while summer precipitation will decrease (Ntegeka & Willems, 2008). As evaporation increases due to temperature increase, there will be less water in the soil for the growth of potatoes in summer.
Increase in temperature and erratic rainfall as effects of climate change; KMI, 2023
Thus, it is needed to engage management practices that can help to conserve water in the soil for plant uptake. Mulching is an age-long technique of covering the soil surface around the plants with living or non-living material to make favorable conditions for plant growth and efficient crop production. And it is essential to know how much of it will be beneficial to crop growth.
Surprisingly, not many farmers in Belgium have adopted this soil management technique due to various reasons. Some of them are aesthetic reasons, lack of technical know-how, cost implication of getting and applying mulch, and uncertainty of a quick return to justify the cost.
Adapting to climate change
Oloyede carried out a field experiment at the Flanders Research Institute of Agriculture, Food and Fisheries (ILVO) in Belgium. He carried out the experiment in the summer (June – September) of 2023. He planted potatoes – some were mulched with 6 cm of air-dried grass-clover, some were mulched by 12 cm air-dried grass-clover, others were grown on the bare soil.
Map showing the experimental field in Melle, East Flanders, Belgium; Oloyede
Using soil sensors, he monitored the amount of water in the soil through the growing season. From a weather station, he obtained the amount of rainfall through the growing season. He was then able to determine how much water was being lost to the atmosphere and the amount the plant was using to grow.
A potato plot mulched with grass-clover, with sensors installed for monitoring soil water; Oloyede
The growing season experienced some periods of drought particularly in June, early in the growing season. There was very little to no rain for the first 16 days when the potatoes needed water to sprout, yet the temperature was high. This made the soil water fall below the maximum allowable depletion threshold. Below this threshold, the crop would start to experience drought stress.
Rainfall and temperature pattern during the growing season (June 1 to September 29, 2023); Data source: KMI, 2023; Oloyede
From the study, Oloyede found that mulching helped to reduce the impact of drought by preventing water loss to the point of stress. The mulched plots have more soil water than the bare ones. And the mulched plots quickly recovered from the impact of drought. Under the mulched plots, water was consistently more available for the potato to grow.
Soil water content under the bare soil and under mulched plots (MAD Maximum Allowable Depletion, PWP Permanent Wilting Point); Oloyede
As the mulching improved soil water conservation, the potato on mulched plots grew better and gave better yield in terms of fresh tuber weight. At harvest, 6 cm and 12 cm mulch produced 43.5 and 44.9 tons per hectare respectively, while bare soil produced 40.5 tons per hectare. This is a 7.4% and 10.9% increase in potato yield due to 6 cm and 12 cm mulch respectively.
Potato yield under bare soil and under mulched plots from different blocks of the field; Oloyede
This means that with the same amount of water available to these plots, the mulched ones produced more yield per unit of water. This is a phenomenon referred to as water use efficiency. The water use efficiency of the bare soil was not significantly different from the mulched ones because the growing season was normal in the amount of rainfall except for the first month that was drier than the long-term average.
But as summer precipitation is expected to decrease, the impact of mulching in improving the water use efficiency of potatoes will be more pronounced. This means that the water conservation effect of mulching would significantly increase yield and water use efficiency under dry conditions. This agrees with the findings of Zhang et al. (2011) for maize in China.
Oloyede concluded from his study that mulching is a cost effective and eco-friendly technique that can enhance potato production and build its resilience to climate change. He therefore recommended that Flemish farmers should use 6 -12 cm thick organic mulch in cultivation of potatoes.
References
Boukhris, O.,Vanneuville,W.,Willems, P.,VanEerdenbrugh,K., 2008.Climate change impact on hydrological extremes in Flanders: regional differences. Technical Report N. 706/13. Waterbouwkundig Laboratorium, Antwerp, pp. 195.
Tun Oo, A., Boughton, D., & Aung, N. (2023). Climate Change Adaptation and the Agriculture–Food System in Myanmar. Climate, 11(6), 124.
Zhang, S., Li, P., Yang, X., Wang, Z., & Chen, X. (2011). Effects of tillage and plastic mulch on soil water, growth and yield of spring-sown maize. Soil and Tillage Research, 112(1), 92-97.