Subsurface drip fertigation estimation tool (SubFerT)

Irrigation and fertilization are essential to increasing crop yield and affect vegetable production and food security. Conventional irrigation and fertilizer application methods often exceed the crop requirements. Moreover, nitrate pollution of groundwater from agriculture is caused by the asynchrony between nutrient availability and crop demand and is an issue of major concern in many regions. As water and nutrients limitations will be more frequent in the coming decades due to climate change along with regulations aiming at protecting water resources, there is a need for innovations in agricultural production to improve water and nutrient use efficiencies. Subsurface drip fertigation (SDF) is the fertigation (irrigation combined with application of dissolved fertilizer) of crops through buried driplines which include built-in emitters to drip water to the surrounding soil. This allows placing the water and fertilizers directly into a small soil volume in the rooting zone at just the rates needed by the plants. SDF systems have a great potential to minimize the movement of water and nutrients below the root zone when effectively managed. Through the combined application of nutrients and water, drought and nutrient stresses can be diminished and yield potentials optimized. SDF systems can therefore make cropping systems not only more environmentally friendly and sustainable, but also more resilient to climatic fluctuations.

The aim of our research is to contribute to the understanding of crop growth under SDF. The work presented here is the Subsurface Drip Fertigation Estimation Tool (SubFerT) which is available for farmers who want to integrate this fertigation system in their production. The tool is based on daily water and nitrogen balances at the field scale by modeling (a) crop growth and nitrogen uptake; (b) crop water requirements though daily ET₀ estimation using the Penman–Monteith equation, separation between evaporation and transpiration (dual Kc approach); (c) dynamics of water (irrigation, precipitation, root uptake, losses) and nitrogen (mineralization, denitrification, leaching) in the soil root zone. SubFerT-tool provides information on when and how much water and fertilizer to apply to crops grown under SDF system. This tool allows farmers to manage the fertigation of the crops under SDF in an efficient way. Additionally, the tool delivers daily time series of different variables involved in the balance: soil moisture, root uptake, deep percolation, total met transpiration, etc.