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Controlled drainage effectiveness in reducing nutrient outflow in light of climate changes
This modeling study focused on the hydrological and water quality effects of controlled drainage (CD) when operated using a subsurface drainage system in an agricultural field in the Wielkopolska region. The DRAINMOD hydrologic model was well calibrated and validated in an experimental field. This model was used in the performance of CD and free drainage (FD) combinations (108 and 27, respectively) in a near-future climate change scenario. The objective was to understand the potential of CD on the groundwater table (GWT), drainage outflow, surface runoff, and nitrogen and phosphorus reduction under projected climate conditions in Poland during the 21st century with shared socioeconomic pathway SSP370. The results indicated that the earliest start of CD practice is the most effective in increasing GWT. Compared to current climatic conditions, when applying CD on 1 March in the near future, with an initial GWT of 60 and 80 cm b.s.l. in wet years, drainage outflows will increase by 33% and 80% for the GFDL model, by 30% and 40% for the MPI model, and by 17% and 23% for the UKESM model. Comparing the surface runoff values obtained to current climate conditions, the MPI, GFDL, and UKESM models predict a significant increase in surface runoff in the near future, which is due to the predicted increase in precipitation. The annual NO3–N reduction was by 22, 19, and 15 kg per hectare for wet, normal, and dry years, respectively, in the near future. Among the climate scenarios, the UKESM model predicted higher NO3–N and PO4 leaching values compared to the MPI and GFDL models.
Is Controlled Drainage of Agricultural Land a Common Used Practice?—A Bibliographic Analysis
Controlled drainage (CD) is one of the basic techniques used to manage groundwater levels. Farmers can optimize water levels for crop growth at different stages of the growing season. Proper drainage water management can reduce the risk of soil erosion and surface water pollution. By controlling drainage, sediment and nutrient runoff can be minimized, leading to improved water quality in nearby streams and rivers. A mixed methods approach was used, which was based on the bibliometric analysis and content analysis of 462 articles using the bibliometrix R package and VOSviewer software. The article aimed to analyze the Author Keywords and KeyWords Plus to indicate the resulting clusters of complex interdependence that emerge from the main research areas. Continuous research continues to improve drainage techniques and systems to optimize agricultural water use. The results indicated the importance of researching the feasibility of CD for agriculture. The innovation of this study is that it points out the relevance of taking up the possibility of changing the use of unilateral subsurface drainage systems with another method of controlling drainage outflows as a current global challenge, contributing to filling this gap in the literature.