Monitoring soil moisture for cereals as adaptation measure of irrigated agriculture to climate change in the Braila County, Romania

Climate change will impact irrigated agriculture by increasing the rainfall variability and average temperatures. Numerical experiments with climate models show that in the future this trend will continue but its evolution will strongly depend on the anthropogenic emission levels of greenhouse gases (IPCC et al., 2021). However, because human-induced warming is superimposed on natural climate variability, the effects of climate change have not been, and will not be, uniform across regions or over time. In some areas of the world, annual precipitation will decline, decreasing river flows and groundwater recharge, while in other places, total precipitation may increase but it will fall over shorter periods with greater intensity so that dry spells are longer (IWMI).

Analysing the projected changes in extreme agro-climatic indicators in the southern part of Romania, Caian et al. (2023) showed that thermal changes are continuous in time with acceleration after 2040 and with higher amplitude in RCP85, reaching up to ~3°C, that is well above the multiannual global average estimated to be critical for climate risk. The precipitation regime changes more slowly in this part of Romania: the number of days with precipitation decreases in all Southern parts of the country. This study reveals that Southern Romania appears as a regional hot-spot of climate change because the projected changes are higher and more accelerated than other regions of the country. In this context, farmers will need to improve crop water allocation for sustainable irrigation as an adaptation measure to climate change.

Irrigation scheduling

Irrigation is the largest consumer in the agriculture sector, and the efficient use of water is of utmost importance (Koech and Langat, 2018). Therefore, the use of modern technologies for irrigation water management is helping to resolve the water scarcity challenges and will bring benefits to farmers (Fouial et al 2020). Monitoring soil moisture will improve water allocation in space and time in irrigated agriculture.

The soil water storage (SWS) is the total amount of water that is stored in the soil within the plant’s root zone and monitoring the changes in SWS allow the farmers to optimise the amount of water to be applied and how long to wait between each irrigation. From the total soil water, only a portion (water holding capacity) is readily available for crops (Fig. 1). Availability coefficients determined experimentally for each crop can be used to calculate the percentage of water that is readily available to the plant. The right moment to apply irrigation can be chosen using the maximum water deficit (MSWD) that corresponds to the amount of water stored in the soil that is readily available to the plant. Once consumed this amount, it must be replaced by irrigation (B.C. Ministry of Agriculture).