Factors influencing phosphorus losses in agroecosystems dominated by tile drainage

Tile drainage;artificial subsurface drainage;phosphorus;closed depressions;depression index;soil phosphorus;water retention capacity

Andino Galeano, Luis F. ; Arai, Yuji, ; ,Gentry, Lowell E. ; Fraterrigo ; Jennifer M.

关键词: Tile drainage;    artificial subsurface drainage;    phosphorus;    closed depressions;    depression index;    soil phosphorus;    water retention capacity;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/106281/ANDINOGALEANO-THESIS-2019.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Phosphorus is an important macronutrient for crop production but phosphorus surpluses may be conveyed from diffuse sources to streams via surface runoff and artificial subsurface (perforated plastic pipes called tiles) drainage affecting the quality of receiving aquatic ecosystems. However, controls of phosphorus losses at the sub-field and watershed scales are not fully understood. The overall goal of this study is to determine the effect on phosphorus losses of topography, soil phosphorus, management practices, meteorological conditions, and hydrologic characteristics in agricultural fields and watersheds dominated by tile-drainage in central Illinois. First, tile dissolved reactive phosphorus yields and flow-weighted mean concentration were characterized from January 2015 through September 2017 to determine seasonal (growing vs non-growing) patterns from 36 individually monitored plots across a farm under a corn (Zea mays L.) and soybean (Glycine max L.) rotation. Tile dissolved reactive phosphorus yields increased with precipitation and were greatest during the non-growing season in 2016 and 2017. Annual tile dissolved reactive phosphorus yields were positively related to soil test phosphorus. During the non-growing season, there was a positive relationship between depression depth quantified at the plot-scale and tile dissolved reactive phosphorus yields and flow-weighted mean concentrations. Along depression gradients, piecewise regression displayed a threshold at a depression depth of 0.38 m at which soil test phosphorus increased, indicating soil phosphorus accumulation at the bottom of closed depressions. Then, I evaluated how hydrologic drivers (precipitation, water retention capacity, runoff, baseflow) affected phosphorus exports from three agricultural watersheds dominated by tile drainage using long-term datasets (range of 10 – 26 years of records). Water retention capacity expressed as the runoff: precipitation ratio was a better predictor of runoff as well as dissolved reactive phosphorus and particulate phosphorus losses than precipitation. Power law relationships between particulate phosphorus loads and runoff indicated that particulate phosphorus losses increment exponentially during wet years. Additionally, I assessed the performance of the base and modified (including an antecedent flow anomaly term) weighted regressions on time, discharge, and season method to estimate phosphorus exports relative to observed data. The inclusion of the flow anomaly term to the base model did not improve the performance due to the influence of management practices and other physical properties of the watershed. Similarly, the base model needs improvement to estimate phosphorus losses.