Effects of Incorporation of Nano-carbon into Slow-released Fertilizer on Rice Yield and Nitrogen Loss in Surface Water of Paddy Soil

Abstract

The use of slow-released fertilizer has become a new trend to save fertilizer consumption and to minimize environmental pollution. Duo to its high surface energy and chemical activity, the application domain of nanomaterials has significantly expanded with the development of nanotechnology in conjunction with biotechnology in various fields, such as water purification, wastewater treatment, environmental remediation, food processing and packaging, industrial and household purposes, medicine and in smart sensor development. However, use in agriculture, especially for plant production, is an under-explored area in the research community. In this work, nano-carbon was incorporated into slow-released fertilizer and the influence on rice yield and nitrogen loss in surface water of paddy soil was conducted by field experiment. The experiment was a randomized block design with five treatments and three replications, the control (CK), Jingzhengda slow-released fertilizer (JSCU, N 42%), Jingzhengda slow-released fertilizer and nano-carbon (JSCU+C), Stanley slow-released compound fertilizer (SSRF, N-P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> -K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O=20:9:11), Stanley slow-released compound fertilizer and nano-carbon (SSRF+C), respectively. The results indicated that the total nitrogen concentration in surface water of paddy soil increased rapidly at the 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> day after fertilization and decreased gradually after that in all treatments. Compare to JSCU, sampling at different times after fertilization, the total nitrogen concentration in surface water of paddy soil under JSCU+C treatment was declined in the range of 19.1%-46.8%, the average was 31.0%, and the time of nitrogen runoff loss due to rainfall was shorten 2.2 day. For SSCU+C treatment, the average total nitrogen concentration was decreased by 29.8% and the time of nitrogen runoff loss was shorten 1.8 day. The rice grain yield and nitrogen use efficiency were increased significantly after applying slow-released fertilizer added nano-carbon. The rice grain yield and nitrogen use efficiency under JSRU+C and SSRF+C treatments were 11650.5 kg/hm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 21.4 kg/kg N and 11201.0 kg/hm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 18.4 kg/kg N, respectively, increased by 11.3%, 7.9 kg/kg N compared with JSRU and 5.6% and 4.4 kg/kg N compared with SSRF. The rate of saving nitrogen was 10.1% and 5.1% for JSCU+C and SSRF+C, respectively. These results suggest that it is possible that the nano-carbon is used as coating material for slow-released fertilizer and incorporation of nano-carbon into slow-released fertilizer is benefit for reducing water pollution, especially JSCU+C.