Increased fertilizer input in agricultural systems during the last few decades has resulted in large yield increases, but also in environmental problems. We used data from published papers and a soil testing and fertilization project in Shaanxi province during the years 2005 to 2009 to analyze chemical fertilizer inputs and yields of wheat (Triticum aestivum L.) and maize (Zea mays L.) on the farmers' level, and soil fertility change from the 1970s to the 2000s in the Loess Plateau in China. The results showed that in different regions of the province, chemical fertilizer NPK inputs and yields of wheat and maize increased. With regard to soil nutrient balance, N and P gradually changed from deficit to surplus levels, while K deficiency became more severe. In addition, soil organic matter, total nitrogen, alkali-hydrolysis nitrogen, available phosphorus and available potassium increased during the same period. The PFP of N, NP and NPK on wheat and maize all decreased from the 1970s to the 2000s as a whole. With the increase in N fertilizer inputs, both soil total nitrogen and alkali-hydrolysis nitrogen increased; P fertilizer increased soil available phosphorus and K fertilizer increased soil available potassium. At the same time, soil organic matter, total nitrogen, alkali-hydrolysis nitrogen, available phosphorus and available potassium all had positive impacts on crop yields. In order to promote food safety and environmental protection, fertilizer requirements should be assessed at the farmers' level. In many cases, farmers should be encouraged to reduce nitrogen and phosphate fertilizer inputs significantly, but increase potassium fertilizer and organic manure on cereal crops as a whole.
In order to understand the present situation of rice fertilization and the existing problems in the farmers' nutrient resources input in the Qin-Ba mountainous area of southern Shaanxi, the survey data from 2854 households in 11 counties of this area in the project "soil testing and formulated fertilization in 2006-2009" were analyzed and evaluated, and the countermeasures for the existing problems in the farmers' nutrient resources input were proposed. In the study area, the average rice yield was 7822 kg x hm(-2) per year, and the ratio of the households obtained the medium level yield was up to 50.9%. The input of the total fertilizers N, P2O5, K2O was 169, 68, and 54 kg x hm(-2), and the chemical fertilizer rate was 159, 62, and 45 kg x hm(-2), with the partial factor productivity (PFP) of the N, P2O5, and K2O being 51.52, 135.69, and 158.26 kg x kg(-1), respectively. According to the nutrient fertilization level, the proportion of the households fertilized with rational level of chemical N, P2O5, and K2O occupied 48.0%, 42.4%, and 7.2%, that of the households fertilized with excessive level was 22.6%, 11.2%, and 0.6%, and the proportion of the households fertilized with insufficient level occupied 29.4%, 46.5%, and 92.2%, respectively. The rice yield in the Qin-Ba mountainous area could be increased by 77 thousand tons if the households fertilizing with insufficient level of chemical NPK fertilizers increased the fertilization rate to a rational level. The existing problems in the farmers' nutrient resources input were mainly the coexistence of excessive and insufficient application of nitrogen and phosphate fertilizers and the insufficient input of potassium fertilizer and organic manure. In the rice fertilization in this area, the focus would be the balanced application of nitrogen and phosphate fertilizers, the increase of the fertilization rates of potassium fertilizer and organic manure, and the increase of top dressing, especially potassium.
In this work, Fe 3 O 4 /Cu/CuO (FC) antibacterial nanoagent was synthesized in a “one-pot” approach using copper sulfate and ferric chloride as raw materials, and it was studied using TEM, XRD, XPS, UV-vis, and VSM methods. The antibacterial activity and mechanism of a FC nanocomposite were studied, using a commercially available Bordeaux mixture as a control. The effects of a FC antibacterial nanoagent on mung bean development and its toxicity to human mammary epithelial cells were also investigated. The results revealed that FC antibacterial nanoagent could break the cell walls of E. coli and S. aureus, quadrupling the antibacterial activity of the Bordeaux combination. Furthermore, it was shown that FC antibacterial nanoagent might improve the germination, root development, and chlorophyll content of mung bean seeds while being 1/8 as hazardous to human mammary epithelial cells as the Bordeaux combination. The as-prepared FC antibacterial nanoagent can replace the Bordeaux combination in the management of agroforestry pathogens.
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