Developing a nitrogen fertilizer management model for wheat in calcareous soils using the critical nitrogen dilution curve

Abstract

The critical nitrogen (N) dilution curve, which expresses whole-plant critical N concentration as a function of shoot biomass, can be used as a N management diagnostic tool for cereals. The objectives of this research were to develop a critical N dilution curve for wheat grown in calcareous soils and to formulate a model for estimating N fertilizer requirement of wheat crop at different growth stages. Six N fertilization rates (0–250 kg N ha−1) were used to induce variability in plant growth throughout six site-years (three locations at West Delta of Egypt and two seasons [2020/21-2021/22]). Aboveground shoot biomass (W; Mg DM [dry matter] ha−1) and N concentration (Nc; g kg−1 DM) were determined on five sampling dates during the growing season. A critical N dilution curve was developed as: $${N}_{\mathrm{c}}=50.141 {\mathrm{W}}^{-0.424}$$ N c = 50.141 W - 0.424 . The Nc dilution curve was then used to develop a N fertilizer topdressing strategy. The study relied on N nutrition index inferred from the Nc based on N uptake, and instead of relying on a single N recovery efficiency coefficient, a variable N recovery efficiency was developed. This approach increased the hypothetical N requirements at low N application rates while decreased requirements at high N application rates, implying that the Nc dilution curve can be used successfully to estimate the rates of supplemental N application. The developed strategy will provide a solid basis for precisely managing N fertilizer, though challenge ahead at the farm level will be in determining the actual shoot biomass and N concentration.

Combined Effect of Biochar and Mycorrhizal Fungi on Wheat (Triticum aestivum L.) Growth and Performance in Calcareous Soil

“…Since soil pH is presumed to be a key factor influencing the sorption of P, poultry manure may have lower P adsorption in calcareous soils. In calcareous soils, Ca build-up can result in CaCO3 precipitating surrounding roots (Ali, Saudi, & El-Sadek, 2023), which can stunt plant growth by causing chlorosis due to lime. In contrast with poultry manure, the findings of this study have also shown that the combination of biochar and mycorrhiza, particularly Cattle1 t.h.…”

“…Biochar and its impact on soils can lessen the requirement for synthetic fertilizers. It has been demonstrated that biochar, which depends on its porosity and surface charge, enhances the soil's ability to retain nutrients in calcareous soil (Ali, Saudi, & El-Sadek, 2023). Biochar improves soil nitrogen and phosphorus retention by minimizing leaching and gaseous loss, depending on the pyrolysis and feedstock conditions.…”