Field Crop 2025, Vol.8, No.3, 113-125 http://cropscipublisher.com/index.php/fc 117 irrigation can achieve "the same or even higher yield with less water consumption" by optimizing the water-consuming process, that is, the efficiency of the so-called "water-for-production" has been greatly improved. Of course, the specific water consumption pattern of corn under drip irrigation conditions is also influenced by climatic conditions and management methods. 3.3 Method for determination and evaluation of water use efficiency The water use efficiency (WUE) of corn is usually expressed by the yield obtained per unit of water consumption, that is, WUE = grain yield/total water consumption of crop transpiration-evaporation. In field experiments, the determination of WUE generally requires monitoring the soil moisture changes, precipitation and irrigation volume throughout the growth period, and calculating the crop evapotranspiration (ET). Common methods include soil moisture balance method and water balance calculation model, etc. Among them, the soil moisture balance method calculates the total water consumption ET of crops by measuring the changes in soil water storage during sowing and harvesting, and by estimating precipitation, irrigation and runoff seepage, and then combines the yield to calculate WUE. Under drip irrigation conditions, since deep seepage and surface runoff are usually small, it can be approximately considered that ET = rainfall + irrigation-increase in soil water storage (Liu et al., 2023). It should be noted that WUE evaluation can not only calculate the total water consumption (referred to as the WUE throughout the entire growth period), but also calculate the irrigation water utilization efficiency (IWUE) for the irrigation water portion, that is, IWUE = yield/irrigation water volume, to measure the utilization efficiency of the irrigation water itself. When rainfall is uncontrollable, IWUE can better demonstrate the effectiveness of irrigation measures. In drip irrigation experiments, the IWUE of different irrigation treatments is often compared to evaluate the water-saving effect. For instance, a certain study compared the IWUE of fully irrigated and under-irrigated corn. The result showed that the IWUE of under-irrigated corn was significantly higher than that of fully irrigated corn (El-Hendawy et al., 2014). 4 Influencing Mechanism of Nutrient Utilization Efficiency in Corn Fields 4.1 Nutrient migration and distribution under integrated water and fertilizer conditions Under traditional fertilization methods, fertilizers are usually applied to the soil at one time, and the migration and distribution of nutrients in the soil are affected by processes such as rainfall, irrigation, and soil adsorption and fixation. A large number of studies have shown that after conventional field nitrogen application, only 30% to 40% of the nitrogen is absorbed and utilized by crops, and the remaining considerable part is leachate to the deep layer in the form of nitrate nitrogen or lost in gaseous form (Bi et al., 2021). The integration of water and fertilizer management effectively alters the migration patterns and spatio-temporal distribution of nutrients in the soil profile through multiple applications of small doses. On the one hand, the nutrients evenly applied with the drip irrigation water are mainly concentrated in the moist area around the dripper, and the nutrient concentration decreases as the distance from the dripper increases. Since the root system of corn is also mainly distributed in the soil near the plant boundary, the integration of water and fertilizer can keep the soil nutrient concentration in the root zone at a relatively high level and increase the nutrient supply around the root system (Li et al., 2008). On the other hand, the high-frequency nature of drip irrigation results in a relatively small amount of nutrients being applied each time, making it difficult to achieve deep breakthroughs in the cross-section of nutrients. Most of the nutrients remain within the active layer of the root system. Especially when nitrogen exists in the form of nitrate, it is prone to be leached to the deep layers with water and even enter groundwater. Under drip irrigation conditions, due to the small amount of water applied in a single irrigation, nitrate nitrogen mainly accumulates within the soil layer of 30 to 60 cm and is promptly absorbed by the root system. 4.2 Influence of drip irrigation mode on the absorption efficiency of nitrogen, phosphorus and potassium Different drip irrigation and fertilization modes (such as fertilization frequency, fertilization amount, and drip irrigation methods, etc.) will have a significant impact on the efficiency of corn in absorbing nutrients such as nitrogen, phosphorus, and potassium. In terms of nitrogen, an appropriate level of nitrogen supply is particularly crucial for the high yield and efficiency of drip irrigation corn. Studies have shown that under drip irrigation conditions, the amount of nitrogen fertilizer required by corn can be lower than that of traditional fertilization, while crops can still obtain sufficient nitrogen to achieve high yields (Fanish and Muthukrishnan, 2013). This
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