Effect of AMF Inoculation on Reducing Excessive Fertilizer Use

Abstract

Excessive use of chemical fertilizer is a global concern. Arbuscular mycorrhizal fungi (AMF) are considered a potential solution due to their symbiotic association with crops. This study assessed AMF's effects on maize yield, fertilizer efficiency, plant traits, and soil nutrients under different reduced-fertilizer regimes in medium-low fertility fields. We found that phosphorus supplementation after a 30% fertilizer reduction enhanced AMF's positive impact on grain yield, increasing it by 3.47% with pure chemical fertilizers and 6.65% with mixed fertilizers. The AMF inoculation did not significantly affect the nitrogen and phosphorus fertilizer use efficiency, but significantly increased root colonization and soil mycelium density. Mixed fertilizer treatments with phosphorus supplementation after fertilizer reduction showed greater mycorrhizal effects on plant traits and soil nutrient contents compared to chemical fertilizer treatments. This study highlights that AMF inoculation, closely linked to fertilization regimes, can effectively reduce fertilizer use while sustaining or enhancing maize yields.

Keywords: low-phosphorus soils; mycorrhizal effect; phosphorus supplementation; plant trait; soil mycelium density.

Figure 1

The frequency of mycorrhiza (a), colonization intensity (b), and arbuscule abundance (c) of maize roots in different fertilization treatments (Chem, Mix: local traditional application with chemical fertilizer or mixed fertilizer. RedChem, RedMix: 30% reduced application with chemical fertilizer or mixed fertilizer. RedChemP, RedMixP: phosphorus supplementation after 30% reduction of chemical fertilizer or mixed fertilizer) and inoculation treatments (Blank bars: without AMF inoculation. Solid bars: with AMF inoculation). Different uppercase letters above the bars represent significant differences among different fertilization treatments, while different lowercase letters on the bars represent significant differences between different inoculation treatments (p < 0.05).

Figure 2

The maize grain yield (a) and 100 kernel weight (b) in different fertilization (Chem, Mix: local traditional application with chemical fertilizer or mixed fertilizer. RedChem, RedMix: 30% reduced application with chemical fertilizer or mixed fertilizer. RedChemP, RedMixP: phosphorus supplementation after 30% reduction of chemical fertilizer or mixed fertilizer) and inoculation treatments (Blank bars: without AMF inoculation. Solid bars: with AMF inoculation). The numbers above the bars represent the difference in yield compared to the yield of Chem treatment (CK, traditional fertilizer application).

Figure 3

The nitrogen agronomic efficiency (AUEn, (a)) and phosphorus agronomic efficiency (AUEp, (b)), nitrogen partial factor productivity (PFPn, (c)) and phosphorus partial factor productivity (PFPp, (d)) in different fertilization (Chem, Mix: local traditional application with chemical fertilizer or mixed fertilizer. RedChem, RedMix: 30% reduced application with chemical fertilizer or mixed fertilizer. RedChemP, RedMixP: phosphorus supplementation after 30% reduction of chemical fertilizer or mixed fertilizer) and inoculation treatments (Blank bars: without AMF inoculation. Solid bars: with AMF inoculation). Different uppercase letters above the bars represent significant differences among different fertilization treatments.

Figure 4

The mycelium density (a) and spore density (b) in different fertilization (Chem, Mix: local traditional application with chemical fertilizer or mixed fertilizer. RedChem, RedMix: 30% reduced application with chemical fertilizer or mixed fertilizer. RedChemP, RedMixP: phosphorus supplementation after 30% reduction of chemical fertilizer or mixed fertilizer) and inoculation treatments (Blank bars: without AMF inoculation. Solid bars: with AMF inoculation). Different uppercase letters above the bars represent significant differences among different fertilization treatments, while different lowercase letters on the bars represent significant differences between different inoculation treatments (p < 0.05).

Figure 5

The mycorrhizal effects on plant morphological and nutrient traits, and soil nutrient contents in different fertilization treatments (Chem, Mix: local traditional application with chemical fertilizer (a) or mixed fertilizer (d). RedChem, RedMix: 30% reduced application with chemical fertilizer (b) or mixed fertilizer (e). RedChemP, RedMixP: phosphorus supplementation after 30% reduction of chemical fertilizer (c) or mixed fertilizer (f)). The asterisk represents significant mycorrhizal effect at p < 0.05.

Figure 6

The correlation of nitrogen and phosphorus input with various variables under inoculated and non-inoculated treatments. *, **, and *** represents significant correlations at p < 0.05, p < 0.01, and p < 0.001.