Determining Threshold Values for a Crop Water Stress Index-Based Center Pivot Irrigation with Optimum Grain Yield

Abstract

The temperature-based crop water stress index (CWSI) can accurately reflect the extent of crop water deficit. As an ideal carrier of onboard thermometers to monitor canopy temperature (Tc), center pivot irrigation systems (CPIS) have been widely used in precision irrigation. However, the determination of reliable CWSI thresholds for initiating the CPIS is still a challenge for a winter wheat–summer maize cropping system in the North China Plain (NCP). To address this problem, field experiments were carried out to investigate the effects of CWSI thresholds on grain yield (GY) and water use efficiency (WUE) of winter wheat and summer maize in the NCP. The results show that positive linear functions were fitted to the relationships between CWSI and canopy minus air temperature (Tc − Ta) (r2 > 0.695), and between crop evapotranspiration (ETc) and Tc (r2 > 0.548) for both crops. To make analysis comparable, GY and WUE data were normalized to a range of 0.0 to 1.0, corresponding the range of CWSI. With the increase in CWSI, a positive linear relationship was observed for WUE (r2 = 0.873), while a significant inverse relationship was found for the GY (r2 = 0.915) of winter wheat. Quadratic functions were fitted for both the GY (r2 = 0.856) and WUE (r2 = 0.629) of summer maize. By solving the cross values of the two GY and WUE functions for each crop, CWSI thresholds were proposed as being 0.252 for winter wheat, and 0.229 for summer maize, corresponding to a Tc − Ta threshold value of 0.925 and 0.498 °C, respectively. We conclude that farmers can achieve the dual goals of high GY and high WUE using the optimal thresholds proposed for a winter wheat–summer maize cropping system in the NCP.

Sustainable Water Management for Small Farmers with Center-Pivot Irrigation: A Hydraulic and Structural Design Perspective

“…As hydraulic pressure and energy consumption increase, an enormous amount of horsepower is needed to run the whole system. Leaching will increase and the soil's nitrogen content will decrease due to the change in nozzle discharge and certain leakage issues [44]. Figure 19 depicts the cost estimation from small to large sizes.…”

An Automated Data-Driven Irrigation Scheduling Approach Using Model Simulated Soil Moisture and Evapotranspiration

“…Soil-moisture-based approaches use an Available Water Content threshold (AWC th ), whereas the triggering threshold in the ET-WB-based method is defined using MAD. AWC th = 1 − MAD holds for the same field in the same growing season, as both methods describe a single real value, whether it is determined by site-specific field experiments [24] or a default value drawn from FAO-56 [25].…”

Effect of Border Width and Micro-Sprinkling Hose Irrigation on Soil Moisture Distribution and Irrigation Quality for Wheat Crops

“…The mean annual precipitation (2010-2020) during the growth period of winter wheat was about 150 mm in NCP, and the water deficit during the growth period was about 300 mm [29]. It was necessary to implement multiple supplementary irrigation technology to achieve high and stable grain yield [22].…”

“…It is well-known that plant barriers during the middle to late growth period would significantly reduce the effective spraying radius of micro-spraying irrigation. However, it is still unclear whether the irrigation quality of micro-spraying could be improved by optimizing the design of border widths, which was the low cost of human input and high efficiency of land preparation using mechanized equipment [29]. Previous studies on the effect of border widths on irrigation quality pointed out that the irrigation uniformity coefficient with a 4.0 m border width was significantly lower than that of a 3.0 m border width in the NCP [32].…”