Submitted to: Nutrient Cycling in Agroecosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2017
Publication Date: 9/27/2017
Citation: Sigua, G.C., Stone, K.C., Bauer, P.J., Szogi, A.A. 2017. Phosphorus dynamics and phosphatase acitivity of soils under corn production with supplemental irrigation in humid coastal plain region, USA. Nutrient Cycling in Agroecosystems. 109(3):249-267. https://doi.org/10.1007/s10705-017-9882-6.
Interpretive Summary: Applications of phosphorus fertilizers to agricultural land have improved soil phosphorus fertility and crop production, but caused environmental damage in the past decades. The rate at which soil phosphorus accumulates in terrestrial ecosystem especially under irrigation systems is still uncertain, as are the mechanisms responsible for the current phosphorus sink and/or sources. It is imperative to have a holistic understanding of phosphorus dynamics from soil to plant by optimizing phosphorus management and improving phosphorus-use efficiency, aiming at reducing consumption of chemical phosphorus fertilizer. Additionally, the dynamics of applied phosphorus in soils and its cycling in agroecosystems are of increased interest due to its contribution to the current environmental, agronomic and economic issues. Our reason for conducting this study was to determine the effect of integrated nutrient management and irrigation scheduling on phosphorus dynamics and phosphatase activity of soils at various growth stages (6 leaves, 16 leaves and silking) of corn production in humid Coastal Plains regions, United States of America (USA). Phosphorus dynamics and phosphatase varied significantly with stages of corn growth and soil types. Phosphorus uptake of corn had an increase of about 1,200 percent from 6 leaves to silking. Both the Melich extractable phosphorus and water soluble phosphorus showed declining trends from 6 leaves to silking. Concentration of phosphorus in pore water was significantly affected by the interaction effects of year, soil types and irrigation scheduling. Concentration of phosphorus in pore water differed significantly with irrigation scheduling in 2014 and 2015, but not in 2013. Concentration of phosphatase among the different soil types was affected by growth stages of corn (6 leaves to silking) and soil depth, but not affected by nutrient management. Our research results suggest that timing the application of nutrients is critical so that they are available before peak crop nutrient demand in soils of the Coastal Plain region of USA. Additionally, our research provides results which can help in optimizing the agroecosystems of Coastal Plain region with respect to both minimizing P inputs and reduce environmental impact on water resources.
Technical Abstract: A three-year (2013-2015) field study was conducted to evaluate the effect of integrated nutrient management (NM) and three irrigation scheduling methods (IS): irrigator pro (IPro); normalized difference vegetative index (NDVI) and soil water potentials (SWP) on phosphorus (P) dynamics and phosphatase activity in four Coastal Plains soil types (ST) at various growth stages (CS: V6, six leaves; V16, sixteen leaves; and R1, silking) of corn (Zea mays, L.). Nitrogen fertilizer was applied at two rates: 157 and 224 kilogram per hectare (kg/ha) through the irrigation system in three applications. Equal amount of P fertilizer was applied on each plot annually at the rate of 118 kg phosphorus pentaoxide (P2O5)/ ha. Phosphorus dynamics and phosphatase activity varied significantly (p=0.0001) with year (Y), CS and ST, but not with NM. Phosphorus uptake of corn had an increase of about 1,200 percent (%) from V6 to R1. Both the Mehlich extractable P (MEP) and water soluble P (WSP) showed declining trends from V6 to R1. Concentration of P in pore water was significantly (p=0.0001) affected by the interaction effects of Y x ST x IS. Concentration of P in pore water differed significantly (p=0.05) with IS in 2014 and 2015, but not in 2013. The order of the concentrations of P in pore water (averaged across ST) as affected by IS is as follows: 2013 (IPro < NDVI < SWP); 2014 (IPro < SWP < NDVI); and 2015 (IPro < NDVI < SWP). Concentration of phosphatase among the different ST was affected by CS, from V6 to R1 and soil depth, but not with NM. The difference in phosphatase concentration between the upper and lower soil horizons (averaged across Y and ST) was about 67.7 microgram per gram per hour (ug/g/hr). Overall, our results have significant implication on P mobility, availability and management in areas under supplemental irrigation like the southeastern Coastal Plains region of United States of America (USA). Results further suggest that timing the application of nutrients is critical so that they are available before peak crop nutrient demand in soils of the Coastal Plain region of USA.