A study evaluating the impact of organic soil amendments on canola growth and soil health, conducted by Masooma Hassan and Vladimir Strezov, and published in the journal Scientific Reports, confirmed that using combinations of organic materials can provide superior agricultural outcomes compared to individual applications. The research focused on the combined effect of biochar, manure, and compost on canola cultivation across four distinct soil types: loamy sand (LS), sandy loam (SL), silty clay (SC), and loam. The findings support the use of organic amendments as a cost-effective and environmentally friendly alternative to excessive chemical fertilizers, which can lead to significant environmental contamination.

The experiment revealed that the choice of soil type and the specific organic treatment, as well as their interaction, significantly impacted nearly all measured canola growth, yield, and soil chemical properties. Among the four soil types tested, silty clay (SC) emerged as the most suitable for canola yield parameters, producing the highest flower count and seed weight. This effect was particularly evident when SC soil was treated with biochar (B) alone. The combined treatment of manure + biochar (M+B) was also highly effective in SC, leading to increased germination, chlorophyll content, and number of pods. The optimal performance in SC with biochar suggests that it is the most suitable amendment for promoting yield in this specific soil type.

Analyzing the impact of the organic amendments, biochar alone produced better results for flower count and 100 seeds weight. When amendments were combined, the manure + compost + biochar (M+C+B), manure + biochar (M+B), and compost + biochar (C+B) treatments showed a positive impact on the number of pods and 100 seeds weight. For the loam soil, the combination of manure + compost + biochar (M+C+B) resulted in the highest number of pods. The study’s results support the hypothesis that combining organic materials can provide better outcomes than using individual amendments.

The analysis of soil properties demonstrated that organic treatments profoundly affected the chemical composition across all soil types. Biochar, being rich in carbon and potassium (K), along with manure and compost, significantly improved the levels of total carbon, nitrogen (N), phosphorus (P), and potassium (K). For instance, the manure treatment (M) in loam soil caused the most significant increase in P and K levels. Biochar, compost, and their combinations helped in alleviating soil alkalinity by releasing organic acids, leading to a drop in pH. Conversely, the alkaline nature of biochar can cause an increase in pH in certain soils like silty clay and loam. Wheat straw biochar (WSB) was characterized as having a highly alkaline pH (10.35) and elevated total C (73.01%) and K (310.8 cmol/kg) compared to the other amendments.

A key finding highlighted the influence of soil pH as a limiting factor on canola growth and yield. Changes in pH can either suppress or increase the mobility of nutrients in the soil, which in turn affects nutrient uptake. The overall improvement in canola’s morphological and yield parameters, such as the increase in chlorophyll content and leaf area, is strongly linked to the better uptake of N in the presence of organic amendments.

The results emphasize that organic treatments, soil types, and their synergistic interactions play a critical role in promoting sustainable canola production. Further research is recommended in field settings to test the long-term effects of these combined organic amendments and to determine their optimal application rates.

Source: Hassan, M., & Strezov, V. (2025). Combined effect of biochar, manure and compost on canola growth, yield parameters and soil chemical properties. Scientific Reports, 15(43338).