Abstract
Freshwater shortage is becoming one of the major limiting factors for the sustainable development of agriculture in arid and semi-arid areas of north China. A two-year field experiment about mulched drip irrigation on maize was conducted in Hetao Irrigation District with five irrigation water salinity levels (total dissolved solids; 1, 2, 3, 4, and 5 g·L−1). The effects of irrigation water salinity on maize emergence, growth, yield, grain quality, and soil salt were determined. The results indicated that with the soil matric potential of -20 kPa and irrigation quota for each application of 22.5 mm, the irrigation water salinity showed negative influence on maize emergence and maize morphological characteristics (plant height, leaf area index, stem diameter, and dry matter), as irrigation water salt concentrations exceeded 3 g·L−1. The water use efficiency decreased linearly with the irrigation water salinity raised from 1 g·L−1 to 5 g·L−1, while maize grain protein increased and starch content decreased with the increase of irrigation water salt contents. Additionally, both the vertical radius and horizontal radius of salt isoline by mulched drip irrigation reduced with the irrigation water salt concentrations, when the irrigation water salinity was above 3 g·L−1. Summarily, irrigation water salinity of 3 g·L−1 was recommended for maize mulched drip irrigation in this study.
Highlights
The HID (Hetao Irrigation District) is located in the alluvial plain of the middle Yellow River, western Inner Mongolia Autonomous region, China
With the soil matric potential of 20 cm underneath the emitter was controlled at −20 kPa, the relationship between evapotranspiration and irrigation water salinity showed a quadratic polynomial pattern, in which the evapotranspiration amount increased with the increase of irrigation water salinity at first, and reached the maximum value as irrigation water salt concentration reached 3 g·L−1
The high irrigation water salinity usually leads to the low soil matric potential (SMP), which results in a SMP close to the target value (−20 kPa)
Summary
The HID (Hetao Irrigation District) is located in the alluvial plain of the middle Yellow River, western Inner Mongolia Autonomous region, China. Water Conservancy Commission, which has aggravated the shortage of fresh water for agriculture and threatened the health of local agriculture ecological environment. Water 2019, 11, 2095 sustainable development of agriculture in the HID, a series of water-saving irrigation technology and unconventional water resources is urgently needed [4]. As an important unconventional irrigation water, the exploitable amount of shallow groundwater with salinity of 2–5 g·L−1 is 721 million m3 in the HID [5]. The rational utilization of saline water for agricultural irrigation can alleviate the freshwater shortage effectively, and contributes to the refresh of shallow groundwater, which may result in the reduction of accumulated soil salt during dry seasons and soil desalination during humid seasons. The reasonable utilization of saline water is of great significance to improve the local agroecological environment
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