Tillage, Manure, and Biochar Short-Term Effects on Soil Characteristics in Forage Systems

Abstract

Manure, a globally used soil amendment, can contribute to excessive N and P runoff, leading to water pollution. Biochar (BC) shows promise in mitigating nutrient loss by retaining soil nutrients. However, there is limited research exploring the combined effects of tillage practices, biochar, manure, forage crops, and soil types on soil nutrient characteristics in a single field study. Our objectives are to determine if, in North Central Texas, differing soil types, soil amendments, forage crops, and tillage practices affect soil nutrients when applied short term, and whether correlations exist among soil nutrient characteristics as affected by soil amendments, tillage practices, and the presence of forage crops. The study encompasses three field sites with five factors, including soil types, manure rates, biochar rates, tillage practices, and forage crop types. Soil samples were assayed for pH, electrical conductivity (EC), macronutrients, and micronutrients. Data analyses involved variance analysis, Fisher’s tests, and Pearson’s correlations using R in Rstudio (the IDE). Microplots treated with manure (average 2.16 ppm) retained 60% greater average nitrate levels at the end of the growing season than those treated with a synthetic fertilizer (average 1.35 ppm) (p ≤ 0.05). Moderate and strong correlations were observed between EC and S (r (106) = 0.43, p < 0.001 in loamy sand soil; r (106) = 0.80, p < 0.001 in clay loam soil) and between nitrate and Zn, (r (106) = 0.36, p < 0.001 in loamy sand soil; r (106) = 0.44, p < 0.001 in sandy loam soil) across different soil types. Soil type (texture) emerged as the primary influencing factor on plant-available soil nutrients and characteristics, followed by manure application and tillage practices. The impact of BC and forage crop type varied depending on other experimental factors. Understanding the influence of soil type, amendment application, and tillage on soil nutrient characteristics can guide sustainable forage production practices and soil nutrient management strategies.