About Us
Member Directory
Update Member Information
or Register as New Member
2003 Conference
Related WWWs
Announcements
Newsletter
Abstracts
Proceedings
FATE OF NITROGEN IN RYEGRASS SEED CROPS - CAN WE ALTER DESTINY?
J.S. Rowarth1, W.R. Cookson1, P.H. Williams2 and K.C. Cameron1
1Soil, Plant and Ecological Sciences, PO Box 84, Lincoln University, Canterbury, New Zealand.
2 Crop and Food Research, PO Box 4704, Christchurch, Canterbury, New Zealand
There is increasing onus on users of fertilizer nitrogen (N) to show that it is used efficiently. This research was established to investigate whether the fate of applied N and efficiency of use of N was altered by changing the amount and time when N was applied. Uptake by plants was greatest, and losses from leaching and volatilization were least, when N was applied in late winter and early spring. Applying N at these times influenced herbage uptake and chlorophyll concentration in early spring. The latter was related to seed yield. Winter N at 100 kg ha-1 had a large effect on uptake by seed, which may be important when considering vigour.
Ryegrass seed crops (with 180 kg ha-1 N) were found to increase soil N by 90 kg ha-1 and contributed 8250 kg ha-1 root material to the soil, which is important for maintaining good soil structure in arable soils. The data show that by timing N for maximum efficiency of use, ryegrass seed yield and quality can be increased without causing environmental degradation.
Keywords: 15N; efficiency; leaching; recovery; SPAD; uptake; volatilization; vigour.