Uptake of Phosphorus from Modified P-Enriched Douglas Fir Biochar and Its Effects on Crop Growth and P Use Efficiency

Abstract

The potential use of biochar as a sustainable soil amendment has recently gained global recognition. The use of biochar as a soil additive is attributed to its ability to improve soil chemical, physical and biological properties. Studies have shown that biochar amendments can enhance soil nutrient retention and availability, pH, water holding capacity, microbial activity and sequester carbon. In this study using corn (Zea mays L.) as an experimental crop, the influence of P availability from modified P enriched Douglas fir biochar (PEB), triple super phosphate fertilizer (SPF), and modified Douglas fir biochar (MB) on plant growth and P Use Efficiency (PUE) were compared. The rate of P applied (0, 30, 60, 90 and 120 kg·ha-1) was calculated based on % P content of each soil additive. Except for MB treatments, P recovery, crop growth and P Use Efficiency increased with application rates. The maximum above ground dry matter yields corresponding to PEB, SPF and MB treatments were estimated at 3488 kg·ha-1, 2449 kg·ha-1 and 639 kg·ha-1, while their respective agronomic P use efficiency (AGE) rates were 32 kg·kg-1, 17 kg·kg-1, 0.5 kg·kg-1. Also, recovery of K, Mg, Ca, Zn, Fe, Cu, B and Mn improved in both PEB (p value 2 > 0.9) and SPF (p value 2 > 0.9) treatments. More studies at field scale are needed to demonstrate the practicability of using modified P enriched Douglas fir biochar for soil amendments.