Thumbnail Image

The effect of optimum vs deficit irrigation on plant nitrogen uptake and nitrate leaching loss from soil

Carlton, Anna
Cameron, Keith C.
Edwards, Grant
Di, Hong J.
Clough, Timothy J.
Conference Contribution - published
Fields of Research
ANZSRC::079901 Agricultural Hydrology (Drainage, Flooding, Irrigation, Quality, etc.) , ANZSRC::079902 Fertilisers and Agrochemicals (incl. Application) , ANZSRC::0703 Crop and Pasture Production , ANZSRC::0702 Animal Production , ANZSRC::070101 Agricultural Land Management
Nitrate (NO₃⁻) leaching, associated with urine nitrogen (N) deposition during grazing is recognised as a significant environmental problem. In this study it was hypothesised that optimum irrigation could increase plant growth and uptake of urine-N deposited, thereby reducing NO₃⁻ leaching over winter. The objective of this research was therefore to determine the effect of optimum vs. deficit irrigation regimes on N uptake and dry matter yields from diverse and standard pasture species and their effects on annual NO₃⁻ leaching losses from soil. In this study ruminant urine was applied at two rates of N, 500 and 700 kg N ha⁻¹, to soil monolith lysimeters in late spring. Urine was labelled with ¹⁵N stable isotope at 5 atom% prior to application. Irrigation water was applied at optimum vs. deficit rates. Measurements of NO₃⁻ leaching, ¹⁵N abundance and pasture N uptake were undertaken for a 10 month period following urine application.