Field Crop 2025, Vol.8, No.4, 176-186 http://cropscipublisher.com/index.php/fc 178 Figure 1 Water-use efficiency in soybean under different foliar-applied nutrients (2015-2017). WS: water spray, Urea2%: 2% urea solution, DAP2%: 2% di-ammonium phosphate solution, MOP0.5%: 0.5% muriate of potash solution, NPK2%: 2% solution of 19:19:19 NPK, Mo0.5%: 0.5% molybdenum solution, B0.5%: 0.5% boron solution, Zn 0.5%: 0.5% chelated-Zn solution, and NFN: no-foliar nutrition (Adopted from Dass et al., 2022) 3 Fertilization Strategies for Optimal Yield in Soybean Cultivation 3.1 Integrated nutrient management: combining organic and inorganic sources Not all fertilizers are effective for whoever uses them. An increasing number of experiments have shown that the combined use of organic and inorganic fertilizers brings more practical benefits than using either one alone (Amiri et al., 2021; Iqbal et al., 2022). For instance, some people have tried to halve the recommended dose of NP fertilizer and add an equal amount of vermicompost, or combine broiler bedding with diammonium phosphate. As a result, both seed yield and biological yield have significantly increased, and the harvest index is also higher. Moreover, in some cases, these alone are not enough. Especially in areas with poor soil nutrition, adding some biological inoculants, such as slow-growing rhizobia, can further promote plant growth and help it fix more fixed nitrogen. This approach, called "Integrated Nutrient Management (INM)", not only boosts yields but also helps reduce reliance on chemical fertilizers, making it an attempt towards sustainability (Turabi et al., 2024). 3.2 Site-specific nutrient management: tailoring applications using soil testing and sensors Not every plot of land is the same. What to apply and how much to apply depend on the "foundation" of the soil. Site Nutrition Management (SSNM) is precisely based on this, using soil testing, nutrition maps, and even sensors to "tailor" fertilization plans. Compared with the approach of "one formula for the entire field", this method can ensure that every plot of land and every row of crops get just the right amount of food. The experimental data are quite convincing. Combinations like N43P43K50 are based on soil test results. The number of pods, seed yield and economic benefits after fertilization with it are basically superior to those of traditional schemes (Kaur et al., 2020). However, conversely, if these "local differences" are ignored or certain key nutrients are omitted, the yield and income may be directly "discounted". This has been verified in some plots (Almeida et al., 2023). 3.3 Controlled-release and foliar fertilizers: innovations for increased efficiency The emergence of controlled-release fertilizers and foliar fertilizers has somewhat changed some old concepts. For instance, controlled-release urea, wrapped with a layer of polymer on the outside, can allow nutrients to "come slowly" and keep up with the rhythm of crop demands. During the critical period of soybeans, such as the R3 period, using controlled-release urea is much more stable than applying it all at once. The yield can be increased by 5% to 9% without affecting the nitrogen fixation of rhizobia (Pierozan et al., 2023). Sometimes, the "form" of fertilizer also affects its effect. For example, the compound phosphate fertilizer such as struvite-polysulfide not only releases slowly, but also promotes better root development, and the overall biomass also increases accordingly (Valle et al., 2022). For instance, spraying a little zinc during the podding stage is indeed helpful in improving seed quality and yield, especially in soils with insufficient nitrogen (Cuesta et al., 2023). In addition to enhancing efficiency, these strategies also have a potential advantage-reducing emissions. Whether it is
RkJQdWJsaXNoZXIy MjQ4ODYzNA==