Study on Liquid Special Fertilizer for Drip Irrigation of Sugarcane and Its Irrigation Mode in Guangxi Lateritic Red Soil Region

[Objective] Liquid special fertilizer for drip irrigation of sugarcane was de- veloped and the fertilizer patterns were explored in the production to provide techni- cal support for fertigation production of modern agriculture. [Method] ROC22 was selected as experimental material, two formulas of liquid special fertilizer for sugar- cane developed by the cooperation between Guangxi Academy of Agricultural Sci- ences and New Orientation （Guangxi） Chemical Industry Co.,Ltd. were selected, namely, balanced 21-21-21 ~ TE of Xinfangxiang and hyperkalemic 13-6-39-TE of Xinfangxiang. Taking conventional fertilization as the control （CK）, two modes of ap- plying base fertilizer at the earlier stage ＋ fertigation in the tillering stage and ferti- gation in the whole growth period were set. [Result] The two modes of fertilization had not significant effects on the emergence of sugarcane, but applying base fertil- izer at the earlier stage ＋ timely applying water soluble fertilizer in the tillering stage was conducive to the tillering of sugarcane. Harvest results showed that the effects of different treatments on plant height and yield were significant, in which the yield of sugarcane under the treatment of hyperkalemic water-soluble fertilizer increased by 13.04% compared with conventional treatment, and the income increased by 4 500 yuan/hm2, [Conclusion] Liquid special fertilizer for drip irrigation of sugarcane signifi- cantly promoted the growth of sugarcane, moreover, under the same condition, the effect of hyperkalemic water-soluble fertilizer was better.

Effects of Ionic Strength and Sesquioxides on Adsorption of Toxin of Bacillus thuringiensis subsp.kurstaki on Soils

Chemical reactions and fate of the toxins of Bacillus thuringiensis （Bt） in the soil environment are causing increasing concerns due to the large-scale cultivation of transgenic Bt plants. In this study, the effect of ionic strength （0-1 000 mmol kg-1） adjusted by NaCl or CaCl2 on adsorption of Bt toxin by a lateritic red soil, a paddy soil and these soils after chemical removal of organic-bound or free Fe and Al oxides, as well as by pure minerals （goethite, hematite and gibbsite） which are widespread in these soils, were studied. The results indicated that when the supporting electrolyte was NaCl, the adsorption of Bt toxin by the lateritic red soil and paddy soil increased rapidly until the ionic strength reached 250 mmol kg-1 and then gradually slowed down with the increase of ionic strength; while in ease the supporting electrolyte was CaCl2, the adsorption of Bt toxin enhanced significantly at low ionic strength （〈 10 mmol kg-1） and then decreased as the ionic strength increased. The adsorption of Bt toxin by the tested minerals and soils after the removal of organic-bound or free Fe and Al oxides also increased with increasing ionic strength controlled by NaCl. Removing organic-bound Fe and Al oxides obviously increased the adsorption of Bt toxin in the tested soils. Differently, removing free Fe and Al oxides increased the Bt adsorption by the paddy soil, but decreased the adsorption by the lateritic red soil. The study indicated that the varieties of ionic strength and the presence of Ve and Al oxides affected the adsorption of Bt toxin by the soils, which would contribute to the further understanding of the fate of Bt toxin in the soil environment and provide references for the ecological risk assessment of transgenic Bt plants.