Annual Changes in Soil Physicochemical Properties and Kenaf (Hibiscus cannabinus L.) Growth When Returning Grown Kenaf as Organic Matter in Reclaimed Land

Abstract

This experiment was conducted to confirm the efficiency of introducing natural organic matter, crushed kenaf (Hibiscus cannabinus L.), which could lead to soil physicochemical improvement and crop growth improvement in reclaimed land. The plant height of economical crop kenaf after adding crushed kenaf per 3,000 kg 10a-1 as organic matter in 2020 was 219.5 cm. This was 7% less growth than the kenaf grown in standard fertilization, and 13.4% higher than the kenaf grown under in natural non-managed state without fertilization. The kenaf yield in the first year of organic matter treatment in non-developed reclaimed land was 3,215 kg 10a-1 which was 14.7% higher compared to that of under in natural non-managed state without fertilization and 83.9% yield of standard fertilization treatment. However, in the second year of cultivation, the growth and yield of treated with crushed kenaf as an organic matter were increased significantly. The main reason is that enough time was given for the decomposition of the input crushed kenaf, and the effect of kenaf cultivation as a crop on improving the soil environment was clearly appeared. So, the plant height in the second year of kenaf treated with crushed kenaf as an organic matter was 320.9 cm, which was 46.2% higher than that in the first year. In addition, yield also increased significantly, reaching 5,916 kg 10a-1, an 84% higher compared to that of the first year. This rate of yield increase was larger than 15% of in natural non-managed state without fertilization or 33% of standard fertilization treatment, which showed that using kenaf as an organic matter was much more effective in improving the soil environment of reclaimed land and improving crop growth and yield.The annual changes of soil chemical properties when returning of grown kenaf as an organic matter in reclaimed land. Division pH (1:5) EC (dS m-1) OM (g kg-1) Avail. P2O5 (mg kg-1) Exch. cations (cmolc kg-1) K Ca Mg Na 2019 (before input) 7.9 a† 2.04 a 4.6 c 24 c 0.74 c 1.42 b 5.06 a 0.68 a After input 2020 7.2 b 1.22 b 10.4 b 67 b 0.94 b 1.86 a 4.88 b 0.28 b 2021 6.7 c 0.56 c 14.2 a 86 a 1.14 a 1.72 ab 3.81 c 0.19 c †Values within columns having the same letters are not significantly different at the 0.05 as determined by DMRT.