Potassium and phosphate were extracted at low temperature by acid hydrolysis process to decompose a new type of associated phosphorus and potassium ore. The main factors affecting the dissolution rate were investigate...Potassium and phosphate were extracted at low temperature by acid hydrolysis process to decompose a new type of associated phosphorus and potassium ore. The main factors affecting the dissolution rate were investigated, such as grinding fineness, the amount of sulfuric acid and fluoride salt, reaction time and temperature, etc. Meanwhile, the effects of various factors on the formation of soluble potassium and phosphate were also discussed. The reaction products and residues were determined by X-ray diffraction(XRD), scanning electron microscopic(SEM) analysis and other means. The results showed that the dissolution rates of potassium and phosphorus were 70wt% and 93.7wt%, respectively, under the conditions of a grain size of 95.64wt% lessthan 0.074 mm, 9.78 g·g^(-1) sulfuric acid, 0.5 g·g^(-1) ammonium fluoride, 160 ℃ and a reaction time of 2h. The thermodynamic and chemical reaction mechanism was revealed that the primary reaction could be completed spontaneously in a temperature range of 298-433 K. The increase of reaction temperature had an important influence on ion exchange reaction, which was more conducive to the spontaneous process. The research will open up a new way for efficient use of potassium ore resources.展开更多
Erratic rainfall and temperature regimes, strongly affect agricultural productivity. To address the reduction in production, this study assessed the effect of Zai pit depths on selected soil properties and cowpea grow...Erratic rainfall and temperature regimes, strongly affect agricultural productivity. To address the reduction in production, this study assessed the effect of Zai pit depths on selected soil properties and cowpea growth and grain yield. “Zai” pit technology was tested in two locations falling under Agroecological Zone IV (relatively dry areas) <i>i.e.</i> Katumani in Machakos County and Naivasha in Nakuru County, Kenya, aiming to determine the combined effect of four “Zai” pit depths and two levels of manure (plots with manure and plots without manure) on selected soil properties, growth and yield of cowpea. Experiment was laid out in split plot arrangement, with manure levels as the main plot factor and “Zai” pit depths (Flat: Z<sub>0</sub>, 30 cm: Z<sub>30</sub>, 45 cm: Z<sub>45</sub> and 60 cm: Z<sub>60</sub>) as subplot factor, replicated four times. Cowpea (M66 variety) was used as the test crop. Inorganic N and extractable P were significantly (P < 0.05) higher, at 1.37 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>kg<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup> for N<sub>in</sub> and 80.4 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>kg<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup> for P<sub>ex</sub> in Zai pits compared to flat plots which were at 0.91 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>kg<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup> for N<sub>in</sub> and 47.1 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>kg<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup> for P<sub>ex</sub>. The values of N<sub>in</sub> and P<sub>ex</sub> also varied depending on depths, with Z<sub>45</sub> having highest N<sub>in</sub> at 1.17 against the least, at 0.89 in the Z<sub>0</sub>, while Pex was highest in Z<sub>30</sub> at 102.3 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>kg<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup> while Z<sub>0</sub> having the least P<sub>ex</sub> of 89.7 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>kg<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup>. Generally, crops in “Zai” pitted plots were larger in diameter at 0.46 cm than crops in flat plots at 0.42 cm. Better performance was observed in yield, with Z<sub>30</sub> yielding 30.5% against 18.2% Flat plots in Machakos while 27.9% in Z<sub>30</sub> against 22.5% from Flat plots in Naivasha. This study demonstrated great potential of “Zai” pit technology on crop production, as reflected on improved growth and yield of cowpeas. Combining “Zai” pits with manure increases soil N<sub>in</sub>, P<sub>ex</sub> and is a guarantee of great crop performance in terms of high final yields.展开更多
基金Funded by the National Natural Science Fundation of China(51274158)the National Twelfth Five-Year Plan for Scientific and Technological Support(2013BAE04B03)the Scientific and Technological Support Project of Hubei Province(2015BCA251)
文摘Potassium and phosphate were extracted at low temperature by acid hydrolysis process to decompose a new type of associated phosphorus and potassium ore. The main factors affecting the dissolution rate were investigated, such as grinding fineness, the amount of sulfuric acid and fluoride salt, reaction time and temperature, etc. Meanwhile, the effects of various factors on the formation of soluble potassium and phosphate were also discussed. The reaction products and residues were determined by X-ray diffraction(XRD), scanning electron microscopic(SEM) analysis and other means. The results showed that the dissolution rates of potassium and phosphorus were 70wt% and 93.7wt%, respectively, under the conditions of a grain size of 95.64wt% lessthan 0.074 mm, 9.78 g·g^(-1) sulfuric acid, 0.5 g·g^(-1) ammonium fluoride, 160 ℃ and a reaction time of 2h. The thermodynamic and chemical reaction mechanism was revealed that the primary reaction could be completed spontaneously in a temperature range of 298-433 K. The increase of reaction temperature had an important influence on ion exchange reaction, which was more conducive to the spontaneous process. The research will open up a new way for efficient use of potassium ore resources.
文摘Erratic rainfall and temperature regimes, strongly affect agricultural productivity. To address the reduction in production, this study assessed the effect of Zai pit depths on selected soil properties and cowpea growth and grain yield. “Zai” pit technology was tested in two locations falling under Agroecological Zone IV (relatively dry areas) <i>i.e.</i> Katumani in Machakos County and Naivasha in Nakuru County, Kenya, aiming to determine the combined effect of four “Zai” pit depths and two levels of manure (plots with manure and plots without manure) on selected soil properties, growth and yield of cowpea. Experiment was laid out in split plot arrangement, with manure levels as the main plot factor and “Zai” pit depths (Flat: Z<sub>0</sub>, 30 cm: Z<sub>30</sub>, 45 cm: Z<sub>45</sub> and 60 cm: Z<sub>60</sub>) as subplot factor, replicated four times. Cowpea (M66 variety) was used as the test crop. Inorganic N and extractable P were significantly (P < 0.05) higher, at 1.37 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>kg<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup> for N<sub>in</sub> and 80.4 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>kg<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup> for P<sub>ex</sub> in Zai pits compared to flat plots which were at 0.91 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>kg<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup> for N<sub>in</sub> and 47.1 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>kg<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup> for P<sub>ex</sub>. The values of N<sub>in</sub> and P<sub>ex</sub> also varied depending on depths, with Z<sub>45</sub> having highest N<sub>in</sub> at 1.17 against the least, at 0.89 in the Z<sub>0</sub>, while Pex was highest in Z<sub>30</sub> at 102.3 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>kg<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup> while Z<sub>0</sub> having the least P<sub>ex</sub> of 89.7 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>kg<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup>. Generally, crops in “Zai” pitted plots were larger in diameter at 0.46 cm than crops in flat plots at 0.42 cm. Better performance was observed in yield, with Z<sub>30</sub> yielding 30.5% against 18.2% Flat plots in Machakos while 27.9% in Z<sub>30</sub> against 22.5% from Flat plots in Naivasha. This study demonstrated great potential of “Zai” pit technology on crop production, as reflected on improved growth and yield of cowpeas. Combining “Zai” pits with manure increases soil N<sub>in</sub>, P<sub>ex</sub> and is a guarantee of great crop performance in terms of high final yields.