Coal char effects on soil chemical properties and maize yields in semi-arid region

Authors: PANDAY, DINESH - University Of Tennessee; Mikha, Maysoon; SUN, XIAOCUN - University Of Nebraska; MAHARJAN, BIJESH - University Of Nebraska

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2021
Publication Date: 2/24/2021
Publication URL: https://handle.nal.usda.gov/10113/7709485
Citation: Panday, D., Mikha, M.M., Sun, X., Maharjan, B. 2021. Coal char effects on soil chemical properties and maize yields in semi-arid region. Agrosystems, Geosciences & Environment. 4(1). Article e20145. https://doi.org/10.1002/agg2.20145.
DOI: https://doi.org/10.1002/agg2.20145

Interpretive Summary: The addition of high carbon (C) amendments can be effective in enhancing soil C content in semi-arid regions of US where soils are characterized by low C. The objective of this study is to evaluate the effect of char on soil properties and irrigated maize yields in sandy loam fertilized with urea or composted manure. Char was used as soil amendment in a field study conducted at the University of Nebraska-Lincoln Panhandle Research and Extension Center near Scottsbluff, NE from 2016 to 2018. The char used was a product of coal combustion residue from a local factory in Western NE. The experiment was arranged in a split-plot randomized complete block design in four replications with char (0, 6.7, 13.4, 20.1 and 26.8 Mg C per ha) as main plots and N treatment (0, 90, 180, and 270 kg urea-N per ha and composted manure at 33.6 and 67.2 Mg per ha) as subplot. A handheld spectral sensor was used to determine normalized difference red edge (NDRE) at growth stages (V6, V8, V10, and R1) in 2017 and 2018. Char application at a rate of 13.4 Mg C per ha or higher increased SOC compared to the control. In the top 20 cm, Char increased Fe concentration, reduced pH at lower rates, and increased K, and Mg at higher rates. Char did not affect crop yields since it might take several years before benefits of char on soil properties translate into crop yield. There was a strong correlation between NDRE with N rates and grain yields at V8 and V10. This study found no adverse effect of char on soil properties due to one char application. Further site-specific researches are needed to test the broader applicability of char across various agroecosystems to evaluate its potential use as a soil amendment in farmlands.

Technical Abstract: Soil amendments with high carbon (C) content can be effective in semi-arid regions where soils are characterized by low C. A field study was conducted in 2016–2018 to evaluate the effect of char on soil chemical properties and irrigated maize (Zea mays L.) yields in sandy loam fertilized with urea or composted manure. Carbon-rich char used was a product of coal combustion residue from a local factory in western Nebraska. The experiment was arranged in a split-plot randomized complete block design in four replications with char (0, 6.7, 13.4, 20.1, and 26.8Mg C ha-1) as main and N treatment (0, 90, 180, and 270 kg urea-N ha-1 and 33.6 and 67.2 Mg ha-1 of composted manure) as subplot factors. A handheld spectral sensor was used to determine normalized difference red edge (NDRE) at growth stages (V6, V8, V10, and R1) in 2017 and 2018. After 2 yr, char increased Fe, reduced pH at lower rates, and increased K and Mg at higher rates in top 20 cm soil but did not affect crop yields. Char applied at =13.4 Mg C ha-1 increased soil organic C by =8% and composted manure increased soil P and K compared to the control. There was a strong correlation of NDRE with N rates and grain yields at V8 and V10. This study found no adverse effect of char on soil properties. However, more site-specific research is needed before char can be used as a regular soil amendment in semi-arid regions.