Biochar and Manure Affect Calcareous Soil and Corn Silage Nutrient Concentrations and Uptake

Abstract

Carbon‐rich biochar derived from the pyrolysis of biomass can sequester atmospheric CO2, mitigate climate change, and potentially increase crop productivity. However, research is needed to confirm the suitability and sustainability of biochar application to different soils. To an irrigated calcareous soil, we applied stockpiled dairy manure (42 Mg ha−1 dry wt) and hardwood‐derived biochar (22.4 Mg ha−1), singly and in combination with manure, along with a control, yielding four treatments. Nitrogen fertilizer was applied when needed (based on preseason soil test N and crop requirements) in all plots and years, with N mineralized from added manure included in this determination. Available soil nutrients (NH4–N; NO3–N; Olsen P; and diethylenetriaminepentaacetic acid–extractable K, Mg, Na, Cu, Mn, Zn, and Fe), total C (TC), total N (TN), total organic C (TOC), and pH were evaluated annually, and silage corn nutrient concentration, yield, and uptake were measured over two growing seasons. Biochar treatment resulted in a 1.5‐fold increase in available soil Mn and a 1.4‐fold increase in TC and TOC, whereas manure produced a 1.2‐ to 1.7‐fold increase in available nutrients (except Fe), compared with controls. In 2009 biochar increased corn silage B concentration but produced no yield increase; in 2010 biochar decreased corn silage TN (33%), S (7%) concentrations, and yield (36%) relative to controls. Manure produced a 1.3‐fold increase in corn silage Cu, Mn, S, Mg, K, and TN concentrations and yield compared with the control in 2010. The combined biochar‐manure effects were not synergistic except in the case of available soil Mn. In these calcareous soils, biochar did not alter pH or availability of P and cations, as is typically observed for acidic soils. If the second year results are representative, they suggest that biochar applications to calcareous soils may lead to reduced N availability, requiring additional soil N inputs to maintain yield targets.

Soil Health, Crop Productivity, Microbial Transport, and Mine Spoil Response to Biochars

“…Soil tests were collected over a 2-year period to determine changes in soil fertility, total C, total N, and yield of corn silage in Idaho. Lentz and Ippolito [6] reported the only significant soil fertility increases due to biochar were in soil Mn and total organic carbon, while manure-treated soils had significant increases in extractable K, Mn, Cu, Na, and Zn when compared to the untreated control. Biochars affect on silage yield was mixed, producing a slight increase in year one but a 36 % decrease in year two [6].…”

“…Lentz and Ippolito [6] reported the only significant soil fertility increases due to biochar were in soil Mn and total organic carbon, while manure-treated soils had significant increases in extractable K, Mn, Cu, Na, and Zn when compared to the untreated control. Biochars affect on silage yield was mixed, producing a slight increase in year one but a 36 % decrease in year two [6]. Further investigations of soil fertility showed that the hardwood biochar was unable to adjust the calcareous soil pH to improve nutrient availability and that it did not significantly improve available P, N, or any important plant cationic nutrients [6].…”

“…Variable performance of a hardwood biochar was amply demonstrated after its application to a Haplocalcid soil in Idaho [6]. The hardwood biochar was applied to determine if its addition alone, when mixed with fertilizer and when mixed with animal manure would improve soil nutrient cycling resulting in higher corn stover yields.…”

“…Biochars affect on silage yield was mixed, producing a slight increase in year one but a 36 % decrease in year two [6]. Further investigations of soil fertility showed that the hardwood biochar was unable to adjust the calcareous soil pH to improve nutrient availability and that it did not significantly improve available P, N, or any important plant cationic nutrients [6].…”

“…This result is typical in studies that add biochar to highly weathered soils where biochar improves soil pH and provides nutrients [4]. In contrast, variable improvements in crop grain yields over several growing seasons in Idaho were reported on an Aridisol (i.e., relatively unweathered soils) as compared to those used by Sigua et al [5] suggesting that the specific biochar being evaluated was not always effective [6]. In another report, Spokas et al [7] reviewed the biochar literature and found that 30 % of the studies reported no significant differences, and 20 % reported negative yield or growth effects.…”