Is It Possible to Control the Nutrient Regime of Soils with Different Texture through Biochar Substrates?

Understanding nutrient management is essential to ensure healthy and adequate food production, especially in the context of biochar applied to soil with different soil textures. Additionally, farmers are beginning to understand the importance of nutrient management and there are still several knowledge gaps in this area. Several studies on biochar showed its positive effects, especially in sandy and nutrient-poor soils. There is still a lack of information on the impact of biochar on nutrient regimes in texturally different soils with sufficient nutrient supply and favorable soil chemistry. This study investigates the effect of two biochar substrates (a) biochar blended with farmyard manure (BS1), and (b) biochar blended with farmyard manure and digestate (BS2) applied at rates of 10 and 20 t ha⁻¹ alone or in combination with fertilization on the changes in sorption capacity and nutrient regime of two texturally different soils: (a) sandy Arenosol, and (b) loamy Chernozem, (both in western Slovakia) which have a favorable nutrient content. The results showed that in sandy soil, the BS2 at rate of 20 t ha⁻¹ increased the sum of basic cations (by +112%) and CEC (by +93%) compared to the control. In sandy soil, the content of total P increased by +35 and +16% in BS1 20 t ha–¹ and BS2 20 t ha⁻¹, respectively, when compared to the unfertilized control. The content of total P increased by +18% in BS1 20 t ha⁻¹ after fertilization compared to the fertilized control. In loamy soil, the content of total P increased significantly by +53 and +14% in unfertilized treatment BS2 20 t ha⁻¹ and fertilized treatment with BS1 at 20 t ha⁻¹ compared to the respective controls. Available Ca increased in sandy soil by +50 and +53% in fertilized treatments with BS2 at 20 t ha⁻¹ and BS1 at 20 t ha⁻¹, respectively, when compared to fertilized control. In loamy soil, available Mg increased by +13% in fertilized treatment with BS1 applied at 20 t ha⁻¹. In conclusion, BS application at a dose of 20 t ha⁻¹ had a stronger positive effect on soil sorption parameters in sandy soil than the application dose of 10 t ha⁻¹. The same BS application rate significantly increased total P in both soils.