| Abstract: |
Drought has a signifcant impact on ecosystem functions, especially on the biogeochemical cycling of phosphorus
(P), which is a crucial nutrient for plant growth and productivity. Despite its importance, the effects of different
drought scenarios on soil P cycling and availability remain poorly understood in previous studies. This study
simulated drought conditions in tropical soils using maize as a test crop under varying feld capacity (FC) levels
(100%, 80%, 60%, 40%, and 20%) over a 60-day pot experiment. P uptake and plant biomass decreased signifcantly
lower FC level. P uptake was highest at FC100 (5 g kg−¹) and lowest at FC20 (3.5 g kg−¹). Similarly, biomass was
greatest at FC100 (70 g plant−¹) and declined to 35 g plant−¹ at FC20, underscoring the adverse effects of drought
on P availability and growth. The results showed a substantial increase in calcium-associated P (HClD-Pi), reaching
45% at FC20. Conversely, labile inorganic P fractions (NaHCO₃-Pi and NaOH-Pi) decreased signifcantly, from 14.73
to 6.2 mg kg−¹ and 29.4 to 17.7 mg kg−¹, respectively, in FC20 compared to FC100. Organic P fractions (NaHCO₃-
Po, NaOH-Po) increased by 6 and 2.4 times, respectively, under lower FC treatments, while HClc-Po was also
elevated under drier conditions. These transformations were attributed to changes in soil pH and calcium content,
favoring the stabilization of P as HClD-Pi. Drought disrupted the replenishment of inorganic P in the soil solution,
reducing bioavailability, though phosphatase activity enhanced organic P release. Pearson’s correlation analysis
revealed positive associations between labile and moderately labile P fractions (NaHCO₃-Pi, NaOH-Pi, HClD-Pi)
and soil elements (Ca, Al, Fe). RDA highlighted a positive link between phosphatase activity and reduced labile P,
while P uptake and biomass were strongly associated with labile and moderately labile P fractions. These fndings
demonstrate drought’s signifcant impact on P bioavailability, soil P cycling, and nutrient dynamics.
|
|
|