Nitrogen leaching losses from lysimeters containing winter kale: the effects of urinary N rate and DCD application

Abstract

Nitrogen (N) leached from the plant-soil system is an environmental concern. The objective of this study was to quantify N leaching losses from cow urine deposited during grazing of a winter forage crop (kale), and determine the effect of using the nitrification inhibitor dicyandiamide (DCD) to reduce N leaching losses. Fresh cow urine was applied to the surface of large soil monolith lysimeters in late June 2011 at two urinary N deposition rates; 500 and 700 kg N ha −1 (with and without DCD), and compared with losses from lysimeters receiving no urine. Most of the N leaching loss was in the form of nitrate-N (NO 3 --N), with an average of 25% leached as ammonium-N (NH 4 + -N). Nitrate-N leaching losses were significantly higher under urine-treated lysimeters (213 and 380 kg NO 3 --N ha −1 at the 500 and 700 kg N ha −1 rates, respectively) than those without urine (c. 33 kg NO 3 --N ha −1 ). The application of DCD reduced NO 3 --N leaching losses by up to 54%. The results indicate that N leaching losses from winter forage crop systems are high and that the application of DCD can reduce these losses.

Effect of nitrification inhibitors on the content of available nitrogen forms in the soil under maize (Zea mays, L.) growing

“…Liu et al (2013) observed that the application of dicyandiamide and 3,4-dimethylpyrazol phosphate slightly decreased the soil N-NO3 -contents and significantly increased the soil N-NH4 + contents in the study. Malcolm et al (2015) state that, the application of dicyandiamide reduced N-NO3 -leaching losses by up to 54%. However, some previous studies have shown a shorter longevity and lower mobility of dicyandiamide compared with other nitrification inhibitors (Zerulla et al, 2001).…”

Nitrate leaching losses from lysimeters simulating winter grazing of fodder beet by dairy cows

“…Further, as a proportion of the amount of N applied to the lysimeters in the urine, an equivalent of 21%-32% was leached as NO 3 − -N. In the study of Malcolm et al (2014) where N leaching losses beneath winter kale were reported, there was a higher proportional leaching loss, equivalent to 43% and 54%, when urine was applied at the higher rates of 500 and 700 kg N ha −1 , respectively. This is similar to trends observed in grazed pasture systems (Cameron et al 2013), suggesting an exponential relationship between urine-N loading rate and N leaching losses under winter forage crop systems.…”

“…The soil surface inside the lysimeters was then heavily trampled using a manually operated trampling device as described in Malcolm et al (2014).…”

“…Following simulated grazing on both 26 June 2012 and 14 June 2013 as described above, 2 L of the urine collected and standardised the previous day were uniformly applied to each lysimeter to simulate urine deposition during winter grazing (Hogg 1981;Malcolm et al 2014). This represented urinary N loading rates equivalent to 300 and 250 kg N ha −1 , respectively.…”

“…Shepherd et al 2012;Smith et al 2012;Hill et al 2014;Malcolm et al 2014), until now little attention has been given to winter-grazed fodder beet. The objective of this study was therefore to quantify NO 3 − -N leaching losses from urine and non-urine areas of a fodder beet winter-grazing system using large intact soil monolith lysimeters.…”