Nutrient Management Research Database

Nitrous oxide (N2O) emissions were the greatest within hours (24-48) of a fertigation event. There appears to be greater flux of N2O emission from urea ammonium nitrate (UAN) as compared to calcium ammonium nitrate (CAN), however statistical significance has not been confirmed and further analysis will be conducted to confirm or reject this observation. Nitrous oxide emissions appear to be driven by the size of the inorganic pool of N and by temperature. The rate of N2O emissions was different during predawn, morning and late afternoon sampling rounds. Furthermore, faster soil drying rates in June compared to April appear to lead to greater N2O emissions. Our efforts to model spatial N2O emissions indicate emissions from our orchards may be lower than for other agricultural systems.

• Sampling occurred during the spring, summer and fall of 2009 at Paramount Farming Company's Belridge Almond Ranch close to Lost Hills, CA.
• The experiment was a randomized block design with 2 treatments and five blocks for a total of ten field plots.
• Fertilizer treatments of Urea ammonium nitrate (UAN) and Calcium ammonium nitrate (CAN) were applied at a rate of 200lb/acre N, 40lb/acre N in February and October, and 60lb/acre N in April and June.
• N20 samples were collected following fertigation for four and eight days in April and June, with periodic sampling in July, August and September.
• Soil samples to 30 cm depth were collected to determine soil bulk density, volumetric water content NH4 and N03 content.
• Transects were established with flux chambers along the planted row, across the row and into the alley , and parallel and perpendicular to the tree row.

• N20 emissions were greater for UAN treatments when compared to CAN at April and June sampling periods, although differences were not significant.
• Emissions throughout the orchard were more uniform and lower for fanjet micro-sprinklers than for surface drip in the drip zone, although no level of significance was given.

sprinklers were fanjet