Sustainable and Clean Utilization of Coal Gangue: Activation and Preparation of Citrate-Soluble Silicon Fertilizer

Silicon (Si) fertilizer is of great significance to modern agricultural production; the citrate-soluble silicon fertilizer based on coal gangue is one way to protect the environment and meet the agricultural needs of China. In this study, we produced high-efficiency coal-gangue based silicon fertilizer by calcining a mixture of coal gangue, calcium carbonate (CaCO3) and corn stalk powder at high-temperature (i.e., high-temperature activation technology); the effect of temperature and mixing ratio on the available-Si content of activated coal gangue was studied, followed by an analysis of the mechanism of available- Si formation. The results showed that the layered structure of coal gangue was severely damaged above 600 ℃, and the kaolin began to transform into metakaolin and other substances, where the available-Si content was not high (less than 10%). When CaCO3 alone was added, the peak intensity of quartz and muscovite in coal gangue decreased significantly with the increase of CaCO3. However, CaCO3 mainly played a catalytic role in the entire calcination and activation process, forming only a small amount of calcium silicate on the contact surface with coal gangue; however, the available-Si content was still below 12.60%. When corn stalk powder alone was added, the oxides of the corn stalk ash participated in the chemical reaction involving coal gangue, forming nepheline (K(Na, K)3Al4Si4O16) and other silicates, and the available-Si content was significantly higher than that with CaCO3. When coal gangue, CaCO3, and corn stalk powder were mixed and calcined, the available-Si content was as high as 22.97% under the synergistic effect of CaCO3 and corn stalk powder; the concentration of harmful heavy metals was below 0.025 mg/L. The above is in line with the requirements of silicon fertilizer for use in agriculture, thus confirming the preparation of coal gangue-based silicon fertilizer in an efficient manner.

Siliplant: impact on the intake and degradation of pesticides in potato protection

Представлены результаты исследований влияния кремниевого удобрения Силиплант на поступление и деградацию протравителя Престиж; фунгицидов Акробат МЦ, Пеннкоцеб и инсектицида Шарпей в посадках картофеля. Установлено, что Силиплант активизировал поступление действующих веществ имидаклоприд и пенцикурон в семенные клубни при обработке Престижем, увеличивая их содержание на 20,6 и 6% соответственно. В период бутонизации растений имидаклоприд в основном был обнаружен в ботве картофеля. Его наибольшее количество выявлено при обработке клубней смесью Престиж 0,6 л/т+Силиплант 60 мл/т, оно было на 45% выше, чем при обработке клубней только Престижем в норме 0,75 л/т. Содержание имидаклоприда в столонах было значительно ниже, меньше всего его поступило в молодые клубни. Престиж обеспечивал защиту растений от колорадского жука, тли и других вредителей до фазы бутонизации. Силиплант также активизировал поступление циперметрина при опрыскивании растений инсектицидом Шарпей. Содержание циперметрина в ботве было на 46% выше при опрыскивании смесью Шарпей 0,07 л/га+Силиплант 1 л/га, в сравнении с применением только Шарпея в дозе 0,1 л/га. На содержание действующих веществ фунгицидов (Акробат МЦ и Пеннкоцеб) Силиплант существенно не повлиял. Основное количество диметоморфа обнаружено в надземной части растений, в столоны его поступило меньше, и еще меньше во вновь сформировавшиеся клубни. Снижение нормы расхода препарата Акробат МЦ в два раза привело к значительному сокращению его содержания во всех частях растения. Совместное применение его меньшей дозы в сочетании с препаратом Силиплант не привело к заметному изменению его содержания в растении. Аналогичные результаты получены по содержанию манкоцеба при использовании фунгицидов как Акробат МЦ, так и Пеннкоцеб. На фоне снижения норм расхода препаратов Престиж, Акробат МЦ, Шарпей и Пеннкоцеб в смесях с препаратом Силиплант получен наибольший урожай картофеля. The article presents the results of research on the effect of Siliplant silicon fertilizer on the intake and degradation of Prestige mordant, Acrobat MC fungicides, Penncozeb, and Sharpey insecticide used in potato planting. It was found that Siliplant activated the intake of imidacloprid and pencycuron in seed tubers when treated with Prestige, increasing their content by 20.6 and 6% respectively. During the budding period of plants, imidacloprid is mainly found in the tops of potatoes. Its maximum amount was found when treating tubers with a mixture of Prestige 0.6 l/t+Siliplant 60 ml/t, it was 45 % higher than when treating tubers with Prestige alone in the norm of 0.75 l/t. The content of imidacloprid in stolons was significantly lower and less of it was received in new tubers. Prestige protected the plants from the Colorado potato beetle, aphids, and other pests until the budding phase. Siliplant also activated the intake of cypermethrin when spraying plants with the insecticide Sharpey. The cypermethrin content in the tops was 46% higher when sprayed with a Sharpey mixture of 0.07 l/ha+Siliplant 1 l/ha, in comparison with the use of one Sharpey at a dose of 0.1 l/ha. The content of the active substances of the fungicides: Acrobat MC and Pennkozeb, Sililant did not have a significant effect. The main amount of dimethomorph was found in the aboveground part of the plants, less of it was received in the stolons and even less in the newly formed tubers. Reducing the consumption rate of the MC Acrobat by 2 times led to a significant reduction in its content in all parts of the plant. When combined with a lower dose of the drug with Siliplant, it did not lead to a noticeable change in its content. Similar results were obtained for the content of mankoceb both when using the MC Acrobat and Pennkozeb. Against the background of a decrease in the consumption rates of Prestige, Acrobat MC, Sharpey and Penncozeb in mixtures with Siliplant, the greatest yield of potatoes was obtained.

Characteristics and Influencing Factors of Microbial Community in Heavy Metal Contaminated Soil under Silicon Fertilizer and Biochar Remediation

Silicon fertilizer and biochar have been widely used to remediate soil contaminated by heavy metals. The effects and mechanism of silicon fertilizer and biochar addition on the heavy metal availability, soil biological properties, and microbial community characteristics need further study in soils contaminated by heavy metals. Therefore, this research determined how silicon fertilizer, biochar, and their combined using affected microbial communities related with nitrogen and phosphorus cycling. The abundance and composition of the microbial community were evaluated by quantitative PCR and phospholipid fatty acid analysis, respectively. Results showed that silicon fertilizer and biochar addition significantly changed soil properties, including pH, total organic carbon, ammonium, nitrate. The Cd and Zn speciation were significantly reduced by silicon fertilizer, biochar, and their integrated application. Microbial community abundance and structure were also significantly changed. Principal component analysis shows that the difference in soil microbial community structure is the most obvious under the combined addition of biochar, silicon fertilizer and biochar. In addition, the results of fluorescence quantitative PCR showed that with biological addition, the number of soil bacteria was significantly reduced. This study reveals the influence of silicon fertilizer and biochar on bacterial and fungal communities in heavy metal soils and the effect of soil heavy metal availability.

Synergistic effects of bast fiber seedling film and nano-silicon fertilizer to increase the lodging resistance and yield of rice

The use of bast fiber film can improve rice seedling quality, and nano-silicon fertilizer can increase rice yields. This study aimed to compare the effects of using bast fiber film, nano-silicon fertilizer, and both treatments on rice yield and lodging resistance. A 2-year field experiment was conducted in 2017 and 2018, in Liaoning, China. The experiment comprised a control (no-bast fiber film, no nano-silicon fertilizer; CK), and three treatments: seedlings cultivated with bast film (FM), single nano-silicon fertilization (SF), and bast fiber film seedlings + nano-silicon fertilization (FM + SF). The japonica rice (Oryza sativa L.) cultivar Liaojing 371 was used. Compared with the plants in CK, those in the FM treatment showed greater average root diameter, root volume and root dry weight. The SF treatment increased the single stem flexural strength, increased the contents of silicon, lignin, and cellulose in the rice plant stalk, and reduced the lodging index, thereby increasing lodging resistance. The SF treatment resulted in increased leaf chlorophyll content at late growth stage and a higher net photosynthetic rate, which increased plant dry matter accumulation. In the FM + SF treatment, plant growth was enhanced during the whole growth period, which resulted in an increased number of effective panicles and an increased grain yield. The results show that the combination of FM and SF synergistically improves rice lodging resistance and grain yield. This low-cost, high-efficiency system is of great significance for improving the stability and lodging resistance of rice plants, thereby increasing yields.

Role of Silicon in Sustainable Fruit Production under Stress Conditions: A Review

Silicon is a beneficial element as it can significantly improve the growth, yield and quality of fruit crops through silicon-enhanced resistance to biotic and abiotic stress. Mechanisms involved in alleviation of abiotic and biotic stresses are stimulation of antioxidant system in plants, complexation or co-precipitation of toxic metal ions with Si, immobilization of toxic metal ions, exclude uptake of toxic metal ions and vacuolar compartmentation of metal ions. The ignorance of plant physiologists is because of the visible symptoms of either Si deficiency or toxicity are not apparent and because of the abundance of the element in nature. Whereas, repeated cropping and the constant application of chemical fertilizers such as nitrogen, phosphorus and potassium have depleted the amount of Si that is available to plants in the soil. Awareness of Si deficiency in soil is now being recognized as a limiting factor for crop production and application of silicon fertilizer is practised worldwide, however there is limited case study regarding use of silicon fertilizer in our country despite its many advantages.