Temporal variation of water suitability for paddy irrigation needs at karst springs influenced by allogenic recharge in Gunungsewu Karst Area, Indonesia

Irrigation, a critical element in farming, can fulfill crop water needs and increase agricultural productivity during the dry season, provided that the two necessary factors are met, namely water supply and water quality. Water quality is a principal factor in assessing whether or not a water body is usable as a source of irrigation. Excess or lack of elements in irrigation water may affect irrigated crops and soil. For maximum harvests, studies scrutinizing the suitability of water supply for irrigation become necessary. Beton Spring has a large discharge, which the people of Ponjong District, Gunungkidul Regency, rely on for their irrigation and fish farming practices. Uniquely, this karst spring receives allogenic recharges from outside the karst area. This research was intended to assess the suitability of water quality of Beton Spring for temporal irrigation purposes by Sodium analysis (Na), Sodium Adsorption Ratio (SAR), USSL, and Wilcox. The elements observed in the analysis were Ca2+, Na+, Mg2+, K+ and electrical conductivity. Based on the overall analysis results of the water quality series - Sodium analysis (the water samples were classified as Excellent), SAR (Excellent), USSL (moderate to good), and Wilcox (Excellent to Good), Beton Spring produces good-quality water that is suitable for irrigation. © The Authors, published by EDP Sciences, 2020.