Short‐term effect of biochar and compost on soil fertility and water status of a Dystric Cambisol in NE Germany under field conditions

TLDR

Sandy soils limit crop growth due to low plant‑available nutrients and water. The study aimed to assess whether compost and biochar could alleviate these nutrient and water limitations. A 1‑ha maize field trial on a Dystric Cambisol tested a control, compost, and three biochar‑compost mixtures (32.5 Mg ha⁻¹ compost plus 5–20 Mg ha⁻¹ biochar), measuring TOC, TN, nutrient availability, and soil water content over four months and lab water‑retention. The mixtures doubled organic‑matter and nutrient availability, raised pH by up to 0.6, and doubled soil water retention, demonstrating a synergistic benefit of compost and biochar.

Abstract

Abstract Crop growth in sandy soils is usually limited by plant‐available nutrients and water contents. This study was conducted to determine whether these limiting factors could be improved through applications of compost and biochar. For this purpose, a maize ( Zea mays L.) field trial was established at 1 ha area of a Dystric Cambisol in Brandenburg, NE Germany. Five treatments (control, compost, and three biochar‐compost mixtures with constant compost amount (32.5 Mg ha –1 ) and increasing biochar amount, ranging from 5–20 Mg ha –1 ) were compared. Analyses comprised total organic C (TOC), total N (TN), plant‐available nutrients, and volumetric soil water content for 4 months under field conditions during the growing season 2009. In addition, soil water‐retention characteristics were analyzed on undisturbed soil columns in the laboratory. Total organic‐C content could be increased by a factor of 2.5 from 0.8 to 2% ( p < 0.01) at the highest biochar‐compost level compared with control while TN content only slightly increased. Plant‐available Ca, K, P, and Na contents increased by a factor of 2.2, 2.5, 1.2, and 2.8, respectively. With compost addition, the soil pH value significantly increased by up to 0.6 ( p < 0.05) and plant‐available soil water retention increased by a factor of 2. Our results clearly demonstrated a synergistic positive effect of compost and biochar mixtures on soil organic‐matter content, nutrients levels, and water‐storage capacity of a sandy soil under field conditions.