Organic amendments, such as compost and biochar, mitigate the environmental burdens associated with wasting organic resources and close nutrient loops by capturing, transforming, and resupplying nutrients to soils. While compost or biochar application to soil can enhance an agroecosystem’s capacity to store carbon and produce food, there have been few field studies investigating the agroecological impacts of amending soil with biochar co-compost, produced through the composting of nitrogen-rich organic material, such as manure, with carbon-rich biochar. Here, we examine the impact of biochar co-compost on soil properties and processes by conducting a field study in which we compare the environmental and agronomic impacts associated with the amendment of either dairy manure co-composted with biochar, dairy manure compost, or biochar to soils in a winter wheat cropping system. Organic amendments were applied at equivalent C rates (8 Mg C ha^-1). We found that all three treatments significantly increased soil water holding capacity and total plant biomass relative to the no-amendment control. Soils amended with biochar or biochar co-compost resulted in significantly less greenhouse gas emissions than the compost or control soils. Biochar co-compost also resulted in a significant reduction in nutrient leaching relative to the application of biochar alone or compost alone. Our results suggest that biochar co-composting could optimize organic resource recycling for climate change mitigation and agricultural productivity while minimizing nutrient losses from agroecosystems.

This data file includes five datasets:

• The first dataset describes soil available nitrogen content (average and 1x standard error, n = 4) across different soil depths in different treatment plots at the mid- and end-growing seasons.
• The second dataset describes the concentration of available nitrogen and phosphorus (average and 1x standard error, n = 4) in leachate samples collected monthly at the treatment plots.
• The third dataset describes the cumulative soil greenhouse gas emissions (average, 1x standard error, n = 4, and 95% confidence interval) at different sampling days throughout the field experiment.
• The fourth dataset describes the soil greenhouse gas fluxes and soil volumetric water content measured at each sampling day in all treatment plots throughout the field experiment.
• The fifth dataset describes the soil greenhouse gas emissions, plant total biomass, and soil greenhouse gas emissions per unit of plant total biomass at all field treatment plots at the end of the growing season.