Finding more sustainable ways to cultivate rice crops

Finding more sustainable ways to cultivate rice crops
Iron speciation measured soft X-ray NEXAFS at the surface of soil particles showing changes of P binding affected by ASi addition. Four individual soil aggregates were visualized in average OD images (695–760 eV) of 4 × 6 µm2 regions of paddy soil samples with (a, g) and without (m, s) ASi addition. RGB composite maps of Fe(III)-rich (red), Fe(II)-rich (blue), and non-Fe phases (green) visualize the spatial distribution of the Fe redox states in the soil aggregates of Si-treated (b, h), and of untreated control samples (n, t). Specific maps of the Fe(II)-rich phase for Si-treated paddy soil samples (c, i) and non-treated control samples (o, u) show the distribution of reduced Fe species (equal to the blue channel in the prior RGB composites). Average OD masks (d, j, p, v) based on the entire average OD images (a, g, m, s) and OD masks (e, k, q, w) based on Fe(II)-rich regions (c, i, o, u) were used to extract spectra of regions of increasing thickness. Spectra were extracted using these masks for Si-treated samples (f, l) and untreated control samples (r, x), where gray lines represent spectra extracted from the respective entire dataset (a, g, m, s), whereas blue lines represent spectra extracted from the Fe(II)-rich regions (c, I, o, u) only. Spectra of pure reference compounds ferrihydrite (fh), goethite (goe), siderite (sid), and vivianite (viv) are plotted for comparison. The best linear decomposition fit between the sample and various combinations of reference spectra was achieved with vivanite as the Fe(II) species, suggesting that P is bound to Fe(II) in these soil particles. Credit: Scientific Reports (2022). DOI: 10.1038/s41598-022-20805-4

Rice farmers depend on phosphorous fertilizers to maximize their yields of this major staple food, which helps nourish more than half of the world's population. However, there is a finite supply of the nutrient available to be mined.

Using the ultrabright light of the Canadian Light Source at the University of Saskatchewan, German researchers examined soil samples from paddies in China in the hopes of learning how can reduce the need for -based fertilizers and make farming more sustainable.

Dr. Joerg Schaller and colleagues discovered that silicon, which is also known to play a key role in growing rice, can replace phosphorus in soil and mobilize it to be available for absorption by the plants that need it. Phosphorus binds to iron in soil, rendering it unavailable to plants.

"If all the building places are occupied with silicon, there is no space for phosphate to bind (in the soil). It means you need only half of the fertilizer," said Schaller, who is with the Leibniz Centre for Agricultural Landscape Research (ZALF).

By taking multiple from that have been used to cultivate rice for between 50 and 2,000 years and examining them using scanning transmission X-ray microscopy at the CLS, Schaller and his colleagues were able to better understand how and why silicon and phosphorus bond to the soil.

The wide range of paddy soil gave Schaller's team a precise look at how long it takes soil to be depleted of silicon and saturated with phosphorus.

"It's really valuable (to be able to study so many samples)," said Schaller. "Rice cultivation, they've done it for a really long time…it's really interesting, to use such samples."

Because phosphorus is critical to the growth of rice and so many other crops, finding a more sustainable solution to promoting rice growth—like using cheaper and more available silicon-based fertilizers to prevent phosphorus saturation—is critical for the world's food supply.

"This is really important for humankind," Schaller said. "If we could decrease the need for phosphorus fertilization, this is a really important thing."

The research is published in Scientific Reports.

More information: Jörg Schaller et al, Silicon as a potential limiting factor for phosphorus availability in paddy soils, Scientific Reports (2022). DOI: 10.1038/s41598-022-20805-4

Journal information: Scientific Reports

Citation: Finding more sustainable ways to cultivate rice crops (2022, November 16) retrieved 29 January 2023 from https://phys.org/news/2022-11-sustainable-ways-cultivate-rice-crops.html
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