Amending Soil with Organic Materials and Clay Minerals to Improve Its Physicochemical Properties and Spinach Growth

Abstract

【Objective】 Increasing and stabilizing carbon in coarse-textured soils is important to improve their stability and fertility. The purpose of this paper is to investigate how soil amendment with organic materials and clay minerals can achieve these goals. 【Method】 We took spinach as a model crop, and compared eight treatments by amending the soil with woody peat (HW), biochar (HB), lignite (HC), humic acid (HH), woody peat + bentonite (HWb), woody peat + illite (HWa) and woody peat + kaolinite (HWg), respectively. Not amending the soil was taken as the control (H0). In each treatment, we measured crop growth as well as the changes in soil physical and chemical properties. 【Result】 Compared with H0, HW, HB, HC and HH improved the growth and yield of the spinach, as well as physical and chemical properties of the soil. In particular, HB increased the net photosynthetic rate, plant height and leaf of the spinach during the harvest period by 21.5%, 23.5%, 69.5% and 70.9%, respectively, and soil organic matter and total nitrogen content by 236.2% and 20.7%, respectively, compared to H0. In comparison, HH reduced soil pH by 16.8% and increased crop yield by 4.7% during the harvest period, compared to H0. Combined with clay mineral amendment, HWb, HWa and HWg increased crop yield by 22.7%, 9.0%, and 9.0%, respectively, and soil organic matter by 33.5%, 2.4%, and 27.0%, respectively, compared with HW without clay mineral amendment. 【Conclusion】 Amending the soil with organic materials alone, biochar was most effective in improving soil fertility and crop yield. For combined amendment with organic materials and clay minerals, amending the soil with woody peat and swelling and shrinking clay mineral bentonite at 2:1 ratio worked best for boosting crop growth while in the meantime improving soil fertility.

Keywords

• soil amendment
• biochar, woody peat
• bentonite
• coarse-textured soil
• spinach