A Lysimeter Study to Investigate the Effect of Dairy Effluent and Urea on Cattle Urine n Losses, Plant Uptake and Soil Retention

Abstract

Loss of nitrate (NO − 3 ) from grazing land is a major cause of surface and groundwater contamination. These losses increase when N sources such as fertilizer are applied to grazing land. The objectives of this work were to (1) study the impact of dairy effluent (DE) or urea on N losses and plant uptake when DE or urea was applied with and without cattle urine and; (2) determine the effect of organic C rich DE on the fate of urine N. The experiment was conducted using lysimeters that contained Templeton sandy loam soil extracted from a pasture in New Zealand. Application of DE resulted in significantly less ( p < 0.05) NO − 3 leaching compared with urea in the first year, but not in the second year. Differences between years could be attributed to the comparatively lower C:N ratio of applied DE in the second year, causing relatively greater N mineralization and greater NO − 3 leaching. Differences could also be due to cumulative effects of DE (first year applied) on second year NO − 3 leaching. Total annual pasture N uptake was similar for DE and urea treatments. During the first year, the average NO − 3 concentration was lower when DE was combined with urine compared to urine alone, but not in the second year. The combination of DE with urine resulted in significantly greater ( p < 0.01) annual pasture N uptake compared with the urine alone treatment in both years. Urine plus urea resulted in the greatest leaching losses in both years, but its impact on pasture N uptake was mixed. The total leaching loss of N from urine plus DE (90 kg N ha −1 ) was similar to urine alone (77 kg N ha −1 ) in the second year. Likewise, the annual percentage of 15 N recovered in the leachate from urine plus DE (9%) was not significantly different from urine alone (6%). However, 15 N recoveries revealed that the contribution of urine N to NO − 3 leaching was greater when urine was combined with DE (98.8%) compared to urine alone (83%). The greater NO − 3 leaching from urine when combined with DE could be a result of greater nitrification due to the low C:N ratio of DE. Additionally, the annual percentage of urine N uptake by the pasture from urine plus DE (29%) was significantly less than from urine alone (39%) ( p < 0.01). The application of organic C rich DE had no significant effect on soil N retention or denitrification when combined with urine.

Urine patch and fertiliser N interaction: Effects of fertiliser rate and season of urine application on nitrate leaching and pasture N uptake

“…Previous studies on urine-N fate in temperate environments have recorded similar lag periods of 1-3 months (Clough et al, 1996;Silva et al, 1999;Di and Cameron, 2007). The peak concentration of NO 3 À -N under autumn applied urine in other pasture based lysimeter studies has ranged from 50 to 225 mg N L À1 (Di et al, 2002;Decau et al, 2003;Silva et al, 2005;Di and Cameron, 2007) and the peak NO 3 À -N concentrations observed under autumn urine treatments in the current study are of a similar magnitude. Table 6 Percentage fertiliser recovered as 15 N from pasture, leachate, roots, stubble and soil fractions in lysimeters at the end of the study (28 August Significance of variation presented as: *P < 0.05; **P < 0.01; ***P < 0.001, n.s: not significant P > 0.05).…”

“…Decau et al (2004), Silva et al (2005), Leterme et al (2003) and Silva et al (1999)), this is one of the first studies to specifically partition the fertiliser component of the urine patchfertiliser combination to determine its effect on NO 3 À -N leaching. There was little variation in drainage between the lysimeters until spring 2011.…”

“…grazed pasture) will lead to an increased risk of N leaching and decreased fertiliser N use efficiency (Silva et al, 1999;de Klein et al, 2001;Silva et al, 2005;Mackenzie et al, 2011;Cameron et al, 2013), few studies have quantitatively investigated the interaction between concurrent mineral fertiliser-N application and urine-N deposition with respect to N leaching (Silva et al, 1999;Leterme et al, 2003;Decau et al, 2004;Silva et al, 2005). Furthermore, no studies have partitioned the fertiliser contribution to N leaching under concurrently applied urine and fertiliser.…”

The Challenge of the Urine Patch for Managing Nitrogen in Grazed Pasture Systems

“…Silva et al (2005) measured more N leaching from a urine patch that received 400 kg N ha À1 as fertilizer over a year than from urine alone. Using 15 N-labeled fertilizer, Buckthought (2014) suggested that additional N leaching was not necessarily fertilizer N, but a substitution in drainage by urinary N for the added fertilizer.…”

Influence of nutrient input on the trophic state of a tropical brackish water lagoon

“…During the dry season, DON could explain 58% variability of Chl-a concentration in the lagoon, which showed the relative importance of regenerated DON over anthropogenic DON to the primary producer when DIN:DIP was <16. Our present understanding of the linkages between nitrate, ammonium and urea fertilization and their transport to downstream aquatic systems is limited (Silva et al 2005;Di and Cameron 2008). The influence of in situ biogeochemical processes like DNRA, denitrification, mineralization, etc.…”