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Publication Date
1981
Description
Grazing ruminants aggregate large quantities of forage nitrogen (N) into urine patches. Pasture plots treated with urine N were studied to assess its fate under contrasting seasonal conditions: cool-moist (representing winter-spring); warm-moist (late spring-early summer), and warm-dry (late summer-autumn). A permanent ryegrass (Lolium perenne L.)-white clover (Trifolium repens L.) sward on free-draining alluvial soil was studied. 'freatments were replicated in randomized blocks. Urine N was applied at 30 or 60 g N/m2• Relevant measurements were then continued until treatment differences disappeared. Apparent N balances for urine treatments were compiled. Fixation by white clover was always greatly reduced in urine-treated swards. Urine N increased herbage N yield only when moist conditions favored plant growth. Overall, apparent recovery of urine N by pasture averaged 32 % and ranged from 55 % under cool-moist to 11 % under warm-dry conditions. Soil total N was unaffected by treatments. Some two-thirds of urine N was lost from the soil-plant system during these studies. Extremes in average loss were 45 % and 80% under cool-moist and warm-dry conditions, respectively. Nutrient recycling in the excreta of grazing animals is generally considered beneficial to pasture production and the major pathway for transfer of clover-fixed N to grass associates. The authors dispute those views with respect to N. Rather, they contend that grazing ruminants cause substantial N losses from developed pastoral ecosystems. Sheep or cattle grazing well-managed grass-clover pastures in New Zealand excrete several hundred kg urine N/ha/yr. The more intensively utilized systems may be in negative N balance, largely because of N escape from urine patches.
Citation
Ball, P R. and Keeney, D R., "Nitrogen Losses from Urine-Affected Areas of a New Zealand Pasture, Under Contrasting Seasonal Conditions" (1981). IGC Proceedings (1981-2023). 6.
(URL: https://uknowledge.uky.edu/igc/1981/seection4/6)
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Nitrogen Losses from Urine-Affected Areas of a New Zealand Pasture, Under Contrasting Seasonal Conditions
Grazing ruminants aggregate large quantities of forage nitrogen (N) into urine patches. Pasture plots treated with urine N were studied to assess its fate under contrasting seasonal conditions: cool-moist (representing winter-spring); warm-moist (late spring-early summer), and warm-dry (late summer-autumn). A permanent ryegrass (Lolium perenne L.)-white clover (Trifolium repens L.) sward on free-draining alluvial soil was studied. 'freatments were replicated in randomized blocks. Urine N was applied at 30 or 60 g N/m2• Relevant measurements were then continued until treatment differences disappeared. Apparent N balances for urine treatments were compiled. Fixation by white clover was always greatly reduced in urine-treated swards. Urine N increased herbage N yield only when moist conditions favored plant growth. Overall, apparent recovery of urine N by pasture averaged 32 % and ranged from 55 % under cool-moist to 11 % under warm-dry conditions. Soil total N was unaffected by treatments. Some two-thirds of urine N was lost from the soil-plant system during these studies. Extremes in average loss were 45 % and 80% under cool-moist and warm-dry conditions, respectively. Nutrient recycling in the excreta of grazing animals is generally considered beneficial to pasture production and the major pathway for transfer of clover-fixed N to grass associates. The authors dispute those views with respect to N. Rather, they contend that grazing ruminants cause substantial N losses from developed pastoral ecosystems. Sheep or cattle grazing well-managed grass-clover pastures in New Zealand excrete several hundred kg urine N/ha/yr. The more intensively utilized systems may be in negative N balance, largely because of N escape from urine patches.
