# Phosphate system fertilization in no‐tillage Oxisols: Effects of temporal, horizontal, and vertical distribution of available phosphorus in the soil

## TL;DR

This study explores how different methods and timing of phosphorus fertilization affect crop yields and soil phosphorus levels in high-output farming systems.

## Contribution

The study identifies optimal phosphorus fertilization timing and placement for soybean yield and phosphorus use efficiency in Oxisols.

## Key findings

- Anticipated fertilization at 17 × 5 cm spacing improved soybean yield by 20% and phosphorus balance by 10%.
- Surface soil layers remained phosphorus-rich despite management variations.
- Long-term studies are needed to refine phosphorus management in high-export cropping systems.

## Abstract

System fertilization enhances logistics and phosphorus (P) use efficiency, but its effects in high P‐export systems, particularly regarding fertilization timing, placement, and distribution, remain unclear. This study evaluated P fertilization timing (90, 45, and 0 days before winter crop sowing [DBS]), placement (banded vs. broadcast), and spatial distribution (17 × 5 vs. 40 × 10 cm) in subtropical Oxisols with medium and high soil‐test P. Over 4 years, we assessed crop yields, partial phosphorus balance (PPB), and Mehlich‐1 available soil P (0–10 and 10–20 cm) under rotations of corn (Zea mays L.), soybean (Glycine max L.), and winter crops including black oat (Avena strigosa Schreb.), barley (Hordeum vulgare L.), vetch (Vicia sativa L.), and fodder radish (Raphanus sativus L.). Despite pronounced P stratification, yields and PPB were generally unaffected. In medium P soil, the 40 × 10 cm spacing increased P in the 10–20 cm layer to 61% of the critical value after 4 years. In high P soil, P application at winter sowing raised subsurface P to 4.5 mg dm−3. Soybean yield (5.2 Mg ha−1) and PPB (73%) peaked with 90 DBS banded fertilization. Anticipating fertilization by 90 days with 17 × 5 cm spacing improved soybean yield by 20% and PPB by 10% due to better surface P distribution. The 0–10 cm layer remained P‐rich and sufficient for grain yield. However, the benefits of 90 DBS were limited to two seasons. Long‐term studies are needed to refine system fertilization strategies in high‐output grain systems.

Phosphorus fertilization time and placement minimally affect yields but alter soil P distribution in Oxisols.Anticipated P fertilization at 17 × 5 cm row spacing boosts soybean yield and P balance.Surface soil layers remain P‐rich and sufficient for crop yield despite P management variations.Long‐term studies are critical for optimizing P management in high‐export cropping systems.

Phosphorus fertilization time and placement minimally affect yields but alter soil P distribution in Oxisols.

Anticipated P fertilization at 17 × 5 cm row spacing boosts soybean yield and P balance.

Surface soil layers remain P‐rich and sufficient for crop yield despite P management variations.

Long‐term studies are critical for optimizing P management in high‐export cropping systems.

Plants need phosphorus (P) to grow. Farmers use fertilizer to add P to the soil. In system fertilization, all the P is added during the winter. This study tested different ways and times to do that to see what works best for crops. The researchers wanted to find out the best way to apply P fertilizer in soils that already have medium or high levels of P. They checked how it affected crop production and how much P stayed in the soil. Most of the time, changing how and when the fertilizer was added did not make much difference because the soil already had enough P for plants. But sometimes, adding P 90 days before planting the winter crop and placing it in rows helped soybeans grow better. This way also made better use of the fertilizer. If farmers know the best way to use fertilizer, they can grow more food, spend less money, and take better care of the environment. But we still need more studies to see what works best over many years.