Abstract
Long-term surface application of lime (L) and/or phosphogypsum (PG) in no-till (NT) systems can improve plant growth and physiological and biochemical processes. Although numerous studies have examined the effects of L on biomass and plant growth, comprehensive evaluations of the effects of this practice on net CO2 assimilation, antioxidant enzyme activities and sucrose synthesis are lacking. Accordingly, this study examined the effects of long-term surface applications of L and PG on soil fertility and the resulting impacts on root growth, plant nutrition, photosynthesis, carbon and antioxidant metabolism, and grain yield (GY) of maize established in a dry winter region. At the study site, the last soil amendment occurred in 2016, with the following four treatments: control (no soil amendments), L (13 Mg ha–1), PG (10 Mg ha–1), and L and PG combined (LPG). The long-term effects of surface liming included reduced soil acidity and increased the availability of P, Ca2+, and Mg2+ throughout the soil profile. Combining L with PG strengthened these effects and also increased SO42–-S. Amendment with LPG increased root development at greater depths and improved maize plant nutrition. These combined effects increased the concentrations of photosynthetic pigments and gas exchange even under low water availability. Furthermore, the activities of Rubisco, sucrose synthase and antioxidative enzymes were improved, thereby reducing oxidative stress. These improvements in the physiological performance of maize plants led to higher GY. Overall, the findings support combining soil amendments as an important strategy to increase soil fertility and ensure crop yield in regions where periods of drought occur during the cultivation cycle.
Highlights
Soil degradation is a serious threat to food security worldwide (Bindraban et al, 2012; FAO, 2015; Gibbs and Salmon, 2015)
While advances in plant biotechnology have aided the development of plants that are more resistant to abiotic stresses (Gupta et al, 2020), soil management practices that enable crop development even under unfavorable conditions remain fundamental to food production (Gibbons et al, 2014; Holland et al, 2018)
PG increased the levels of Ca2+ in topsoil in relation to the control, resulting in high base saturation (BS) values (Figure 2D), but BS remained lower in the PG treatment than in the L and L and PG (LPG) treatments
Summary
Soil degradation is a serious threat to food security worldwide (Bindraban et al, 2012; FAO, 2015; Gibbs and Salmon, 2015). ∼2.0 billion hectares (ha) of arable soil in the tropics is affected by high acidity (Bian et al, 2013), which is the most important factor limiting crop development and food production capacity in tropical crop systems (Costa and Crusciol, 2016). Acidic and weathered soils are naturally less fertile due to the limited availability of calcium (Ca2+), magnesium (Mg2+), phosphorus (P), and high aluminum (Al3+) availability, especially in the deepest soil layers (Nora et al, 2017; Costa et al, 2018). The combination of low soil fertility and limited root development with prolonged periods of water limitation contributes strongly to lower yields, especially since the vast majority of the cultivated area is in upland conditions (Carmeis Filho et al, 2017). While advances in plant biotechnology have aided the development of plants that are more resistant to abiotic stresses (Gupta et al, 2020), soil management practices that enable crop development even under unfavorable conditions remain fundamental to food production (Gibbons et al, 2014; Holland et al, 2018)
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