Temperature and Manure Placement in a Snowpack Affect Nutrient Release from Dairy Manure during Snowmelt

Abstract

Agricultural nutrient management is an issue due to N and P losses from fields and water quality degradation. Better information is needed on the risk of nutrient loss in runoff from dairy manure applied in winter. We investigated the effect of temperature on nutrient release from liquid and semisolid manure to water, and of manure quantity and placement within a snowpack on nutrient release to melting snow. Temperature did not affect manure P and NH-N release during water extraction. Manure P release, but not NH-N release, was significantly influenced by the water/manure solids extraction ratio. During snowmelt, manure P release was not significantly affected by manure placement in the snowpack, and the rate of P release decreased as application rate increased. Water extraction data can reliably estimate P release from manure during snowmelt; however, snowmelt water interaction with manure of greater solids content and subsequent P release appears incomplete compared with liquid manures. Manure NH-N released during snowmelt was statistically the same regardless of application rate. For the semisolid manure, NH-N released during snowmelt increased with the depth of snow covering it, most likely due to reduced NH volatilization. For the liquid manure, there was no effect of manure placement within the snowpack on NH-N released during snowmelt. Water extraction data can also reliably estimate manure NH-N release during snowmelt as long as NH volatilization is accounted for with liquid manures for all placements in a snowpack and semisolid manures applied on top of snow.

Dynamics of Measured and Simulated Dissolved Phosphorus in Runoff from Winter‐Applied Dairy Manure

“…This is likely due to a low runoff ratio for this event (0.02, ?26 mm of rain and snowmelt water and 0.4 mm of runoff ) compared with the next three events (runoff ratios of 0.45 to 0.84) (Table 1). It may also be due to a lower than typical rate of manure P release by snowmelt water compared with what we have observed for other manures in our research (see Vadas et al, 2018, and discussion about SurPhos modeling assumptions below). For the December 2016 application on CT plots, runoff did not occur until 10 January, and runoff dissolved P for this and the next two events (average of 0.97 mg L −1 ) was three to four times less than runoff P from the NT plots for the same dates (Fig.…”

“…SurPhos uses the following equation to estimate WEP release from manure during a rain or snowmelt event: where W is the ratio of water volume (rain and/or snowmelt) to manure mass (cm 3 g −1 ). In laboratory experiments using the liquid dairy manure from the same source as used in the field study, Vadas et al (2018) found that Eq. [1] greatly ovepredicted WEP release at lower W values (<150).…”

“…Recent research Abbreviations: CT, chisel tillage; NSE, Nash-Sutcliffe model efficiency; NT, no-till; RSR, the ratio of root mean square error to the standard deviation of observed values; SWE, snow-water equivalent; WEP, water-extractable phosphorus. (Williams et al, 2011(Williams et al, , 2012a(Williams et al, , 2012bVadas et al, 2018) has investigated winter processes and manure P loss at the controlled laboratory scale, but there remains a definite lack of similarly focused data from field studies under natural conditions. This makes it difficult to develop scientifically based winter manure application recommendations that can consistently reduce P loss for a variety of conditions and practices.…”

“…For example, if decreases in measured SWE occurred during days of freezing temperatures, we assumed decreases were due to sublimation or snow drift (and not snowmelt) and decreased estimated SWE to match measured values and not overestimate snowmelt later on. Throughout, we did not consider manure placement in the snowpack as a variable that needed to be accounted for in modeling snowmelt water interaction with manure (Vadas et al, 2018).…”

“…Much research was conducted before 1980 (Converse et al, 1976; Klausner et al, 1976; Young and Mutchler, 1976; Young and Holt, 1977; Phillips et al, 1981; Steenhuis et al, 1981), with some more recently (Hansen et al, 2000; Ulén, 2003; Lewis and Makarewicz, 2009; Komiskey et al, 2011; Owens et al, 2011; Singh et al, 2017). Recent research (Williams et al, 2011, 2012a, 2012b; Vadas et al, 2018) has investigated winter processes and manure P loss at the controlled laboratory scale, but there remains a definite lack of similarly focused data from field studies under natural conditions. This makes it difficult to develop scientifically based winter manure application recommendations that can consistently reduce P loss for a variety of conditions and practices.…”