Triticeae Genomics and Genetics, 2025, Vol.16, No.5, 220-229 http://cropscipublisher.com/index.php/tgg 222 3 Field Experiment Methodologies for Fertilization Studies 3.1 Site selection and soil condition assessment To conduct a field fertilization experiment, you must first select a good test site and carefully evaluate the soil conditions. Researchers generally select some more representative plots, and the soil type must also be related to agricultural production. Before starting the experiment, you must first understand the basic conditions of the soil, such as soil texture, organic matter content, and nutrient levels. Because these factors will directly affect the crop's response to fertilizers, and the yield is also closely related to them (Buczko et al., 2017). If you are doing a long-term experiment, you can also select some plots with different soil pH and nutrient levels, so that you can observe the effects and patterns under time changes (Pedersen et al., 2025). 3.2 Plot design, treatment levels, and replication principles When conducting an experiment, the land should be divided into small plots and different treatments should be arranged. The common method is to use factorial design or composite design to arrange the experiment, so that different fertilizer types, dosages and application methods can be compared at the same time. The use of full factorial design or composite design allows us to more accurately see the effects of each treatment and their mutual influence. In order to reduce experimental errors, the method of repetition and random distribution is generally used, which is fairer and more scientific (Inkson, 1966). The size of each plot and how to arrange it should also consider the statistical effect and the convenience of practical operation. Generally, several repeated plots are arranged for each treatment, so that the results are more reliable. 3.3 Data collection on yield components and statistical evaluation Data collection focuses on key indicators such as grain yield, biomass, nutrient use efficiency, and some environmental indicators such as greenhouse gas emissions and changes in soil nutrients (Chen et al., 2022; Wu et al., 2024). When analyzing these data, commonly used methods include analysis of variance (ANOVA), analysis of covariance (ANCOVA), regression analysis, and response surface models. These methods can help us determine the effects of different treatments, see how much the changes in the soil itself affect the results, and find the most appropriate amount of fertilizer (Heil and Schmidhalter, 2017). Sometimes some spatial information and data from specific locations are combined for analysis, so that the results are more accurate and easier to interpret. 4 Optimization of Nitrogen Application 4.1 Split application strategies to reduce nitrogen loss Applying nitrogen fertilizer in several times, especially arranging the ratio of base fertilizer and topdressing reasonably, is a good way to reduce nitrogen loss and improve utilization efficiency. Many field test results show that, for example, using base fertilizer and topdressing in a ratio of 5:5 can make the leaves have more chlorophyll, stronger photosynthesis, and more protein accumulation. Doing so can also reduce the accumulation of nitrates in the soil and improve the utilization efficiency of water and nitrogen (Yao et al., 2023). Some topdressing methods are now determined by data. These methods combine crop growth and environmental information, which can greatly reduce the amount of nitrogen fertilizer used, sometimes saving up to 48%. At the same time, it can also effectively reduce the loss of active nitrogen and reduce greenhouse gas emissions (Ruan et al., 2024). 4.2 Synchronization with wheat growth stages for maximal uptake Timely application of nitrogen fertilizer during some key periods of wheat growth, such as tillering and grain filling, can allow crops to better absorb and utilize these nutrients. In particular, topdressing during these periods can not only make wheat grow better, have higher yields, and contain more protein in the grains, but also make carbon and nitrogen metabolism after flowering smoother. Some simulation models and actual experiments have shown that applying nitrogen according to wheat needs can effectively increase yields and make better use of resources, especially when combined with modern irrigation systems (Si et al., 2021). 4.3 Nitrogen-use efficiency under different soil-climate scenarios Nitrogen fertilizer utilization efficiency (NUE) is affected by soil type and climatic conditions, so different regions need different application plans. Taking the North China Plain as an example, the high-yield and high-efficiency nitrogen fertilizer application rate is generally between 180 and 210 kg per hectare. If too much is applied, not
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