Assessing soil water balance to optimize irrigation schedules of flood-irrigated maize fields with different cultivation histories in the arid region

Abstract

Water availability is the most critical restriction for sustainable crop plantation in the arid region; consequently, it is essential to quantify the soil water balance and optimize the irrigation schedules in the farmland. However, the effects of cultivation history on crop field water balance and optimized irrigation design were rarely studied. In this study, three typical maize (Zea mays L.) fields with different cultivation histories (i.e., old oasis maize field, OF; new maize field developed from a wetland, NFW; new maize field developed from the desert, NFD) in arid regions of Northwest China were selected, which had major differences in soil textures and GWLs. Based on one growth season (i.e., from April 30th to September 30th) in situ field monitoring (e.g., soil water content, maize growth index, meteorological data) and numerical model (HYDRUS-1D) simulation, the water balance and root water uptake deficit in these fields were quantified, and optimized irrigation schedules were proposed. During the maize growth period under the current irrigation schedule, the highest percolation was observed in OF (364 mm), followed by NFD (231 mm) and NFW (−52 mm). The soil water in NFW was obviously recharged by the capillary rise from groundwater, while the OF and NFD were not. Also, the most severe water deficit was identified in NFD, followed by NFW and OF. Compared with the current irrigation schedule, the irrigation was reduced by 65%, 45%, and 13% under the optimized irrigation amount in NFW, OF, and NFD, respectively. Furthermore, it was reduced by 84%, 61%, and 23% under both irrigation time and amount optimized in NFW, OF, and NFD, respectively. Under either optimized irrigation, the water deficit was relieved, deep percolation was reduced during the maize growth period, and less soil water was stored after maize was harvested. Especially under irrigation time and amount optimizing, the least irrigation times (4) and amount (90 mm) were applied in NFW among three fields, ascribing to a large amount of water recharge from shallow groundwater by capillary rise. Due to the soil texture differences, fewer irrigation times (6) with considerable single irrigation amount (30–70 mm) was recommended for OF with loamy soil, whereas more irrigation times (12) with less single irrigation (25–50 mm) were appropriated for NFD with sandy soil. It concluded that the effects of soil texture and GWL should be well considered for optimizing irrigation schedules.