Agriculture waste has attracted attention as a potential source to produce raw material silicon dioxide, either crystalline (pyrophyllite) or amorphous form (geothermal sludge). It is an unwanted waste produced as a desired result of agricultural activities. Nanosilicon dioxide has undoubtedly gained eager interest in many vital industries. It is renowned for positively enhancing outstanding performance due to tuneable properties over its bulk counterpart. Silicon dioxide scientifically demonstrates a unique ability to convert efficiently into economic value from silicon-rich agriculture waste. Thus, a noble extraction from silicon-rich waste is undoubtedly gaining enormous attention. However, adequate knowledge on local optimisation of nanosilicon dioxide extraction from silicon-rich agriculture waste is lacking. Specific aims of this comprehensive review mainly highlighted a synthesis method of potential nanostructured silicon dioxide from agriculture waste and their potential applications for plant growth promoters. Reverse microemulsion, chemical vapour condensation, solid gelation, and mechanochemical are preferred methods that were typically specified to focus this comprehensive review critically. Optimisation of nanosilicon dioxide can be achieved precisely via the ideal combination of solid gelation and a high-energy ball mill process. Silicon dioxide is undoubtedly an effective agent as a plant growth promoter to overcome biotic and abiotic factors such as heavy metal uptake and translocation, inhibit pathogenic fungi, improve the antioxidant system, and mitigate various stress factors.

This study was undertaken to investigate the integration effects of pretilachlor, oxadiazon, and dimethenamid with or without glyphosate in stale seedbed method to control weedy rice in wet seeded rice. The study, conducted in 2018 and 2019, comprised two seedbed treatments in main plots: with and without glyphosate (850 g ae ha−1), and four sub plot treatments: pretilachlor, oxadiazon, dimethenamid, and unsprayed check. Fifteen days after glyphosate spray, each sub plot was treated with preemergence herbicides at 500 g ai ha−1, respectively under standing water condition (2 to 3 inches) and the water level was maintained for 7 days. Pre-germinated rice seeds (var. MR297) were hand broadcasted in the moist soil at 120 kg ha−1 of seeding rate. In 2019, the density and dry weight of weedy rice were 30 and 118% higher than those observed in 2018. Stale seedbed with glyphosate reduced weedy rice dry weight 12% as compared to those observed in stale seedbed without glyphosate. Addition of oxadiazon and pretilachlor in stale seedbed drastically reduced weedy rice dry weight by 70 to 88% and 53 to 60%, in both years. Dimethenamid contributed significant reduction of weedy rice dry weight by 19% in 2019 only but failed to provide a positive economic return. Integration of pretilachlor and oxadiazon in stale seedbed with glyphosate gave profitable returns $84 to 311.4 ha−1 and $175.7 to 483.8 ha−1, respectively. Without the presence of glyphosate, pretilachlor or oxadiazon contributed a positive return $318.9 or $469.4, respectively, in 2018, but the economic returns were negative in 2019. These results suggest that integration of pretilachlor or oxadiazon in stale seedbed with glyphosate is more crucial when the weedy rice infestation is high, but glyphosate can be excluded from the management regime when the weedy rice populations are low.

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Field experiments were conducted in the rice fields of the Malaysian Agricultural Research and Development Institute in 2018 and 2019, to determine the efficacy of two commercial premix herbicides consisting of imazapic and imazapyr at 70:30 (formulation 1) and 30:70 (formulation 2) applied singly or in sequence for control of weedy rice and other rice weeds. Formulation 1 was applied as PRE at the 0 to 1-leaf stage of weedy rice while formulation 2 was applied as POST at the 3 to 4-leaf stage of weedy rice. Formulation 1 applied PRE at 150 g ai ha-1 with or without sequential application of formulation 2 applied POST at 75 or 150 g ai ha-1 provided complete inhibition of weedy rice. The same rate of formulation 1 applied PRE highly reduced weed density and dry weight of Monochoria vaginalis (99%) and Fimbristylis quinquangularis (93%) as compared to weedy check plots. Formulation 2 applied POST at 150 g ai ha-1 providing lower weed density and dry weight reduction of weedy rice (59 to 65%), M. vaginalis (80 to 81%), and F. quinquangularis (56 to 64%) as compared to those observed in formulation 1 applied PRE at 150 g ai ha-1. These results suggest that although formulations 1 and 2 share the same active ingredients, excellent control of weedy rice and rice weeds could only be achieved with PRE application of formulation 1 at 150 g ai ha-1.