Acquisition of rock phosphate by combined application of ammonium fertilizers and Bacillus amyloliquefaciens FZB42 in maize as affected by soil pH

Abstract

Aims The use of plant growth‐promoting micro‐organisms (PGPMs) to improve plant‐nutrient acquisition has a long history but reproducibility remains a challenge. Recent findings suggest an important role of suitable inoculant‐fertilizer combinations for the expression of PGPM‐effects, particularly with respect to nitrogen (N) supply. In face of the well‐documented N form effects on rhizosphere pH, this study addressed the impact of ammonium‐assisted PGPM‐interactions on the acquisition of sparingly soluble calcium‐phosphates as affected by soil pH. Methods and Results The effects of stabilized ammonium fertilization combined with the PGPM inoculant Bacillus amyloliquefaciens FZB42 on the acquisition of rock phosphate in maize were examined on two soils (moderately acidic‐pH 5·6 and alkaline‐pH 7·8). On the two contrasting soils, FZB42 improved the P status and promoted plant growth by different mechanisms. On the acidic soil, a combination of ammonium‐fertilization with FZB42 increased P‐acquisition by Rock P solubilization via rhizosphere acidification but P‐supply in the noninoculated control was already sufficient to meet the plant demands. By contrast, on the alkaline soil, plant growth‐promotion was associated with FZB42‐induced root growth stimulation. Conclusion The results suggest a significant impact of soil pH on performance and the mode of action of PGPM inoculants, to be considered for practical applications. Significance and Impact of the Study The study advanced existing knowledge on PGPM‐assisted P solubilization as affected by different soil properties. The results suggest perspectives for management options to be considered for efficient use of PGPMs in terms of selecting application strategies with compatible PGPM‐fertilizer combinations, depending on soil pH conditions.

Isolation and Molecular Characterization of Plant-Growth-Promoting Bacteria and Their Effect on Eggplant (Solanum melongena) Growth

“…On the other hand, this result also confirmed our hypothesis that bacteria obtained from mountain soil have good growth-promoting effect. Consistent with our results, many other studies also found that phosphorus solubilizing bacteria isolated from acidic soil could promote plant growth [31,39].…”

“…Due to the fact most immature soil from newly reclaimed land is usually very acidic, this result showed that the five strains have great potential in improving soil quality and promoting plant growth. In agreement with the result of this study, previous reports also indicated that the inoculation of phosphate solubilizing bacteria in soils can restore the overall balance of nutrients and health of the soil to sustain it for plant growth and agricultural production [30,31]. This may be due to the secretion of organic acids and phosphatases, which convert insoluble phosphates into soluble phosphate that plants can utilize.…”

Long-Term Chili Monoculture Alters Environmental Variables Affecting the Dominant Microbial Community in Rhizosphere Soil

“…Moreover, based on ABT, VPA, and Mantel tests, Bacillus was positively correlated with >2 mm water-stable aggregates, alkaline phosphatase activity, moisture, salt, OM, and AP, but negatively correlated with pH, polyphenol oxidase activity and catalase activity. In a previous study, Bacillus amyloliquefaciens FZB42 improved the P status ( Mpanga et al, 2020 ), and the inoculation of Bacillus isolates significantly increased the activity of alkaline phosphatase ( Ramesh et al, 2011 ). Correlation studies of other dominant microbes and the environmental variables in this study have not been reported.…”

Grape pomace's potential on semi‐arid soil health enhances performance of maize, wheat, and grape crops

“…Reducing alkaline soil pH remains a challenging task, especially for certified organic production systems that are not allowed to use synthetic chemicals in their fields. To date, the most prominent methods for reducing the pH in alkaline soils for immediate effects include the application of urea and ammonium‐based nitrogen fertilizers frequently stabilized with urease or nitrification inhibitors (Fageria et al., 2010; Malhi et al., 1995; Mpanga, Nkebiwe, et al., 2019; Mpanga, Gomez‐Genao, et al., 2019; Mpanga et al., 2020; Mpanga, 2020) and the use of elemental sulfur (Horneck et al., 2007; Obreza et al., 2015; USDA, 2018). These approaches are not always desirable due to their cost and potentially negative environmental effects such as greenhouse gas emissions from their productions and transportation; hence, alternative local materials such as GP that are inexpensive and environmentally friendly may be the solution for many areas.…”

“…Soil organic matter is frequently deficient in semi-arid soils due to higher temperatures, insufficient moisture, and low availability of organic feedstock, limiting the diversity and functions of the soil microbiota. High pH soils particularly limit the availability of phosphate and micronutrients to most plants, and the practice of using synthetic nitrogen fertilizers and plant growth-promoting microorganisms as well as foliar application of micronutrients has been used to mitigate these problems (Brady & Weil, 1999;Mpanga et al, 2018;Mpanga, Gomez-Genao, et al, 2019;Mpanga, 2020;Mpanga et al, 2020;Mpanga, Nkebiwe, et al, 2019;Neina, 2019;Nkebiwe et al, 2016;USDA, 2018). There is an ongoing search for alternative organic amendments for alkaline soil pH management, with additional benefits such as soil health, and GP may be suitable for addressing these issues.…”