Potential short-term negative versus positive effects of olive mill-derived biochar on nutrient availability in a calcareous loamy sand soil.

Adel R A Usman,Andrés Rodríguez-Seijo,Mohammad I Al-Wabel,Azzaz Alazzaz,Munir Ahmad,Hesham M Ibrahim,Jamal Elfaki,Mutair A Akanji,Abdelazeem S Sallam

doi:10.1371/journal.pone.0232811

Adel R A Usman, Andrés Rodríguez-Seijo + Show 7 more

Open Access

https://doi.org/10.1371/journal.pone.0232811

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Abstract

In the present work, the olive mill solid waste (OMSW)-derived biochar (BC) was produced at various pyrolytic temperatures (300-700°C) and characterized to investigate its potential negative versus positive application effects on pH, electrical conductivity (EC), and nutrients (P, K, Na, Ca, Mg, Fe, Mn, Zn, and Cu) availability in a calcareous loamy sand soil. Therefore, a greenhouse pot experiment with maize (Zea mays L.) was conducted using treatments consisting of a control (CK), inorganic fertilizer of NPK (INF), and 1% and 3% (w/w) of OMSW-derived BCs. The results showed that BC yield, volatile matter, functional groups, and zeta potential decreased with pyrolytic temperature, whereas BC pH, EC, and its contents of ash and fixed carbon increased with pyrolytic temperature. The changes in the BC properties with increasing pyrolytic temperatures reflected on soil pH, EC and the performance of soil nutrients availability. The BC application, especially with increasing pyrolytic temperature and/or application rate, significantly increased soil pH, EC, NH4OAc-extractable K, Na, Ca, and Mg, and ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA)-extractable Fe and Zn, while AB-DTPA-extractable Mn decreased. The application of 1% and 3% BC, respectively, increased the NH4OAc-extractable K by 2.5 and 5.2-fold for BC300, by 3.2 and 8.0-fold for BC500, and by 3.3 and 8.9-fold for BC700 compared with that of untreated soil. The results also showed significant increase in shoot content of K, Na, and Zn, while there was significant decrease in shoot content of P, Ca, Mg, and Mn. Furthermore, no significant effects were observed for maize growth as a result of BC addition. In conclusion, OMSW-derived BC can potentially have positive effects on the enhancement of soil K availability and its plant content but it reduced shoot nutrients, especially for P, Ca, Mg, and Mn; therefore, application of OMSW-derived BC to calcareous soil might be restricted.

Highlights

Rapid expansion in agriculture to feed the continuously growing world population has increased conventional intensification in farming systems, which has resulted in soil nutrient depletion and various environmental concerns [1]
The solid waste from the olive mill was collected from the Al-Jawf region, Saudi Arabia, and there is no specific permission was required from the company of olive presses to collect the olive mill solid waste (OMSW) samples
BC samples were analyzed with a scanning electron microscope (SEM; FEI, Inspect S50), X-ray diffraction (XRD; XRD-7000; Shimadzu Corp, Kyoto, Japan), surface area analyzer (ASAP 2020, Micromeritics, USA), and the Fourier transformation infrared method (Nicolet 6700 FTIR)

Summary

Introduction

Rapid expansion in agriculture to feed the continuously growing world population has increased conventional intensification in farming systems, which has resulted in soil nutrient depletion and various environmental concerns [1]. Both pyrolysis temperature and application rates of BCs had a significant effect on the increase in the available form of soil K.

Results

Conclusion