# Integrated Application of Cattle Manure or Microbial Inoculants with Chemical Fertilizers Improves Nutrient Cycling in Albic Soils and Enhances Nutrient Use Efficiency and Yield in a Maize–Soybean Rotation System

## TL;DR

Combining chemical fertilizers with cattle manure or specific microbes improves soil health and crop yields in a maize-soybean rotation in China.

## Contribution

The study introduces a crop-specific strategy for integrating chemical fertilizers with organic amendments or microbial inoculants to optimize nutrient cycling and yield.

## Key findings

- CF+CRB increased maize grain yield by 28.6% compared to chemical fertilizer alone.
- CF+CRB improved soybean yield by 15.8% and enhanced soil available phosphorus during critical growth stages.
- Integrating chemical fertilizer with CRB or cattle manure improved nutrient use efficiency and crop-specific nutrient translocation.

## Abstract

Soil quality degradation and low nutrient use efficiency constrain sustainable maize–soybean rotation in the Albic soil region of Northeast China. A field experiment was conducted in 2023–2024 at Qixing Farm (Jiansanjiang, Heilongjiang, China) to evaluate chemical fertilizer combined with cattle manure or microbial inoculants. Five treatments were established: no fertilization (CK), chemical fertilizer alone (CF), chemical fertilizer combined with cattle manure (CF+CM), chemical fertilizer combined with a Bacillus subtilis inoculant (CF+CRA), and chemical fertilizer combined with a Bacillus megaterium inoculant (CF+CRB). Soil available nutrient dynamics, crop nutrient accumulation and translocation, fertilizer use efficiency, and yield were assessed. In maize, CF+CRB significantly enhanced pre-anthesis N translocation and post-anthesis P accumulation, increasing grain yield to 14,533 kg ha−1 (+28.6% vs. CF). In soybean, CF+CRB produced 3328.15 kg ha−1, 15.8% higher than CF. CF+CRA significantly increased soil available P during the soybean flowering-pod stage and improved K allocation at later stages. Overall, integrating chemical fertilizer with CRB improved yield and nutrient use efficiency. Based on crop-specific nutrient requirements, CRB is recommended for the maize season to strengthen nutrient translocation, whereas cattle manure or CRA can be applied in the soybean season to sustain K supply.