Field Crop 2025, Vol.8, No.3, 113-125 http://cropscipublisher.com/index.php/fc 120 resulting in a continuous decline in the groundwater level. If the field corn is generally irrigated by drip irrigation, the amount of water taken per mu per year can be reduced by dozens of cubic meters. In the long run, it is expected to slow down the expansion of the groundwater funnel. 6.2 Control of nutrient loss and non-point source pollution One of the main sources of agricultural non-point source pollution is that excessive fertilizer nutrients in farmland enter water bodies through runoff and leaching. Under the traditional fertilization and irrigation model, excessive fertilizers are often applied at one time. When there is heavy rain or flood irrigation, nutrients such as nitrogen and phosphorus in the soil that are not absorbed by crops are prone to be lost with water, causing pollution to the surface and groundwater. Drip irrigation and integrated water and fertilizer technology has demonstrated unique advantages in reducing nutrient loss and controlling non-point source pollution. On the one hand, drip irrigation and fertilization reduce the occurrence of surface runoff. As drip irrigation is a type of local micro-irrigation, water seeps slowly into the soil and does not form large-scale surface runoff, thus avoiding the problem of nutrient loss along with runoff. Especially in sloping or gully areas, flood irrigation often leads to slope runoff carrying away nutrients, while drip irrigation has a small water supply and almost no runoff, significantly reducing the risk of eutrophication of surface water bodies (Song et al., 2022). On the other hand, drip irrigation reduces the deep leaching of nutrients. Under drip irrigation conditions, the leaching and volatilization of nitrogen in maize fields are much lower than those in traditional irrigation methods, and the apparent utilization rate of nitrogen is correspondingly increased (Liu et al., 2014). This means that through drip irrigation and fertilization, the total amount of nitrogen entering the environment is reduced, effectively controlling nitrogen loss in farmland. For phosphorus, due to its poor mobility in the soil, drip irrigation avoids soil erosion and granular loss of phosphorus caused by flood flow, and also helps to reduce the risk of eutrophication of surface water bodies (Qian et al., 2011). Apart from nitrogen and phosphorus, the significant loss of potassium is generally not severe. However, drip irrigation and fertilization can still reduce the downward migration of potassium in the soil profile, keeping it at the surface layer for crop utilization. 6.3 The ecological and environmental effects of drip irrigation and water and fertilizer integration Drip irrigation and water and fertilizer integration not only achieve increased production and efficiency but also bring about a series of positive ecological and environmental effects, which is of great significance to the sustainable development of agriculture. First, it helps maintain the regional water ecological balance. Traditional agriculture over-extracts groundwater for irrigation, leading to ecological problems such as river drying up and wetland shrinking. Promoting drip irrigation for water conservation can reduce excessive consumption of water resources in agriculture and alleviate the disturbance to the natural hydrological cycle. Take North China as an example. Agricultural water use occupies a large amount of groundwater. After the promotion of drip irrigation, the downward trend of groundwater levels is expected to slow down, which is conducive to protecting the base flow of rivers and the ecological environment of wetlands. The second is to reduce the carbon footprint and greenhouse gas emissions of agricultural production. Drip irrigation of water and fertilizer reduces the excessive use of nitrogen fertilizer, thereby lowering greenhouse gases such as nitrous oxide (N₂O) produced by soil nitrification and denitrification (Zheng et al., 2023). Third, it is conducive to maintaining soil health and biodiversity. Excessive traditional fertilization can cause soil acidification and salinization, and disrupt the balance of the soil microbial community. Drip irrigation water and fertilizer, due to precise fertilization and reduction of surface salt accumulation, can to a certain extent avoid soil acid-base imbalance and salt accumulation, and maintain the stability of soil physical and chemical properties (Figure 2) (Çetin and Akalp, 2019). Fourth, it has promoted the green transformation of agricultural inputs and management methods. Drip irrigation water and fertilizer technology encourages the use of new and highly efficient fertilizers such as water-soluble fertilizers and slow-release fertilizers, reducing the excessive input of traditional large-scale chemical fertilizers. This actually promoted the optimization of the agricultural input structure and reduced environmental risks. In recent years, some innovative technologies such as oxygenated drip irrigation and the application of degradable mulching film under film drip irrigation have also been combined with drip irrigation water and fertilizer, adding the finishing touch to the improvement of ecological benefits (Song et al., 2024).
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