Zinc (Zn) deficiency affects 17% of the world’s population, particularly those consuming large cereal grains with low Zn concentration and poor bioavailability. Here, we synthesize data from four field trials along with 139 studies from the literature, to evaluate the impact of management practices and soil properties on improving grain Zn concentration in wheat through applying Zn fertilizers. Soil application of Zn fertilizer improves grain Zn concentration by only 29.1%, below the biofortification target of 40 mg kg⁻¹ required for human nutrition. Foliar Zn application and soil+foliar applications increase grain Zn concentration by 55.2% and 62.3%, respectively, surpassing the 40 mg kg⁻¹ threshold. Factors such as the rate of Zn application, initial grain Zn concentration (prior to Zn application), and timing of Zn spraying are identified as principal factors influencing the response of grain Zn concentration to Zn fertilization. In search of desirable grain Zn concentration in wheat while minimizing potential environmental risks, our study proposes a method for assessing rates of Zn fertilizer application based on the Zn biofortification target, the Zn agronomic biofortification index, and the contribution of principal factors influencing the improvement in grain Zn concentration.

Irrational phosphorus (P) nutrient management practices often fail to match of P fertilizer type, soil P transformation and crop P demand, lead to increased accumulation of legacy P, reduced PUE, and pollution, affecting crop production. A pot experiment incorporating soil types and P fertilizer types (SSP, simple superphosphate; CMP, calcium magnesium phosphate; DAP, diammonium phosphate; TSP, triple superphosphate; APP, ammonium polyphosphate; CK, no P application) to establish coupling of the soil and P fertilizer types, soil P pool characteristics, crop P uptake. In calcareous soil, the available P concentrations in rhizosphere soil were higher under TSP and DAP, with the increase in NaHCO₃-Pi concentration the most. In non-calcareous soil, the NaHCO₃-Pi and NaOH-Pi increased the most under SSP, DAP, and TSP at anthesis. Shoot P accumulation at maturity was highest under TSP and APP, TSP and DAP, respectively, in the two soil. TSP and APP significantly increased yield and PUE in the calcareous soil, while TSP and DAP performed better in the non-calcareous soil. NaHCO₃-Pi and NaOH-Po are potentially available P sources in calcareous and non-calcareous soil, which remarkably affect shoot P uptake through H₂O-P. Comprehensive assessment of the relationship between soil P pool characteristics, yield and PUE, TSP and APP are recommended for application in calcareous soils and TSP and DAP for application in non-calcareous soils in wheat cropping systems.

Overuse of mineral fertilizer has become common at the North China Plain. Simultaneously, more organic manure resources are available for smallholder farmers. In order to increase the use of organic manure and reduce mineral fertilizer applications, a 10-year fertilization experiment with maize took place between 2008 and 2017. We assessed the long-term effects of cattle manure (CM) application and a complete nutrient substitution with mineral fertilizer (MF) at four application levels (3, 6, 9 and 12 t ha⁻¹ CM) on yield, macronutrients (N, P and K) use efficiencies and soil conditions. Results showed that maize yields from CM and MF treatments differed across time and were significantly different in the first year of the experiment to no significant differences with increasing experimental time. In addition, increased MF levels did not result in increased maize yields; this response was different with CM applications. The highest 10-year maize average yield was 7.7 t ha⁻¹ obtained with 9 t ha⁻¹ of CM. Our results also showed that at the lowest application level (3 t ha⁻¹ CM), the partial factor productivity (PFP) and the agronomic efficiency (AE) of all macronutrients were significantly higher with MF than with CM applications. Nevertheless, these differences narrowed with increased fertilizer input levels. The MF and CM recovery efficiency (RE) of N, P and K performed differently. Generally, MF exhibited significantly higher N-RE than CM treatments. CM treatments had significantly higher P-RE, but no K-RE differences were found between CM and MF. Soil available N, P and K significantly increased when fertilizer levels raised. MF treatments exhibited similar levels of soil available N, but lower soil available P and K compared with CM treatments.

Although phosphorus (P) fertilizer application is widely used to improve production, irrational P application has a negative impact on the zinc (Zn) nutrition of cereal crops. Previous researchers observed and confirmed that P application decreases grain Zn concentrations and bioavailability in cereal crops. However, it remains unclear whether different P fertilizer types can alleviate the antagonism of P and Zn in the soil and grain and, thus, enhance the Zn nutritional level of cereal crops while maintaining production. Thus, a completely randomized pot experiment was conducted on winter wheat grown in two calcareous soils (lime concretion black soil and fluvo-aquic soil). Five P fertilizer types (single superphosphate, diammonium phosphate, fused calcium–magnesium phosphate, triple superphosphate, and ammonium polyphosphate, abbreviated, respectively, as SSP, DAP, FMP, TSP, and APP) were applied to each soil compared to no P fertilizer (CK). Plant and topsoil samples were collected during the flowering and maturity stages of winter wheat, and biomass, Zn concentrations in each organ, and grain phytic acid concentrations were analyzed. Grain yield was not affected by the application of different P fertilizer types to lime concretion black soil, while it was significantly increased by the application of TSP and APP to fluvo-aquic soil. The application of DAP and APP effectively promoted soil available Zn concentrations in both calcareous soils. In lime concretion black soil, the application of FMP significantly increased Zn remobilization to grains, while the application of DAP increased post-anthesis Zn uptake, thereby increasing grain Zn concentrations and its bioavailability. In fluvo-aquic soil, post-anthesis Zn remobilization and uptake were significantly increased by the application of TSP and APP, finally achieving higher grain Zn concentrations and Zn harvest index and effectively promoting grain Zn bioavailability. In conclusion, the rational application of DAP to wheat grown in lime concretion black soil and of TSP or APP to fluvo-aquic soil can achieve superior grain Zn nutrition quality while concurrently retaining high production and high P use efficiency, reducing micronutrient deficiency and further contributing to green agricultural development and human health.

Inefficient phosphorus (P) fertilizer application often accumulates soil P, wasting valuable phosphate resources and contributing to environmental pollution. Given the suboptimal P fertilizer use efficiency (PUE), understanding soil P dynamics and selecting appropriate fertilizers is crucial. Fluvo-aquic soil and yellow-cinnamon soils were used in a rice pot trial to compare five P fertilizer types: single superphosphate (SSP), diammonium phosphate (DAP), calcium magnesium phosphate (CMP), triple superphosphate (TSP), and ammonium polyphosphate (APP), alongside a no P, control (CK). In fluvo-aquic soil, TSP and APP significantly increased rhizosphere P availability at anthesis, while SSP increased yield and shoot P accumulation at maturity. In yellow-cinnamon soil, DAP had the highest rhizosphere P availability at anthesis, while APP significantly increased shoot P accumulation at anthesis and shoot P accumulation and grain yield at maturity. Moreover, PUE was highest with SSP and CMP in fluvo-aquic soil and APP and TSP in yellow-cinnamon soil. Throughout the experiment, increased soil alkaline phosphatase activity promoted NaOH-Po conversion to NaHCO₃-Pi, increasing rice shoot P uptake, yield, and PUE in both soils. Based on the above findings, it is recommended to apply SSP and TSP to fluvo-aquic soil and APP and TSP to yellow-cinnamon soil to achieve higher yield and PUE, which can be further confirmed by subsequent field-scale studies.