An Apparatus for Application of Nitrogen-15 Fertilizers Through Buried Drip Tubing
- E. A. McGee,
- T. L. Thompson and
- T. W. McCreary
This study evaluated a new apparatus for applying 15N by fertigation to subplots under buried drip irrigation. Leaf lettuce (Lactuca sativa L. cv. Waldmann's Green) was planted in one unfertilized buried-drip-irrigated plot (4.06 by 53.34 m) with four north-south beds. Six subplots (1.02 by 2.00 m) were established by placing a 15N injection apparatus into the drip tubing. Nitrogen-rate treatments (71 and 176 kg ha−1) were replicated three times. Low- and high-N plots received 1.60 and 1.15 atom % 15N urea applied at five times during the season. Plants were harvested at specific positions within and near the subplots. Uniform recovery of 15N by plants within subplots occurred. Uptake of 15N by plants was observed up to 45 cm outside subplots in the north-south directions and in plants on beds immediately adjacent to the subplots. Uptake outside the subplots in the north-south directions (apparent lateral movement) was no more than 21% of total 15N uptake.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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