Improving crop nutrition, soil carbon storage and soil physical fertility using ramial wood chips

Ramial wood chips (RWC) amendment has great potential in sustainable agriculture, however more data is needed to assess its effect on soil fertility and carbon (C) storage. In this study, we investigated the effect of a single application of RWC amendment on a silty clay loam soil. During the 5 year experiment, we measured biomass production, grain yields and crop nutrient uptake. At the end of the experiment, we measured soil micro- and macronutrients, soil organic C (SOC) content and thermal stability, microbial biomass C (Cmic), and organic C and total N contents in soil particle size fractions. Soil physical properties including structural porosity, air and water capacity were also measured. Neither crop biomass production nor grain yields were affected by RWC. However, RWC was found to affect nutrient uptake, with improved N, P and Mg uptakes for the 2nd and 3rd crops after RWC amendment, and decreased Mn, Fe and Zn uptakes in the second half of the study period. The initially low SOC content increased by 10%, mainly in the mineral-associated organic matter fraction, resulting in a higher SOC stability. The increase in SOC following RWC amendment decreased the bulk density and increased the easily available water capacity due to a larger structural porosity. The increased porosity in the 15-30 um diameter range was ascribed to a change in SOC quality. In conclusion, RWC amendment improved macronutrient uptake in the short term, but decreased micronutrient uptake in the medium term. RWC increased SOC content and positively affected SOC quality, thus improving soil physical properties including water capacity and aeration.