Nitrogen Uptake Efficiency and Leaching Losses from Lysimeter-grown Citrus Trees Fertilized at Three Nitrogen Rates

Abstract

<jats:p>Four-year-old `Redblush' grapefruit <jats:italic>(Citrus paradisi</jats:italic> Macf.) trees on either the relatively fast-growing rootstock `Volkamer' lemon (VL) (C. <jats:italic>volkameriana</jats:italic> Ten. &amp; Pasq.) or on the slower-growing rootstock sour orange (SO) (C. <jats:italic>aurantium</jats:italic> L.) were transplanted into 7.9-m<jats:sup>3</jats:sup> drainage lysimeter tanks filled with native Candler sand, irrigated similarly, and fertilized at three N rates during 2.5 years. After 6 months, effects of N application rate and rootstock on tree growth, evapotranspiration, fruit yield, N uptake, and leaching were measured during the following 2 years. When trees were 5 years old, low, medium, and high N application rates averaged about 79,180, or 543 g N/tree per year and about 126,455, or 868 g N/tree during the following year. Recommended rates average about 558 g N/tree per year. A lysimeter tank with no tree and additional trees growing outside lysimeters received the medium N treatment. Nitrogen concentration in the drainage water increased with N rate and exceeded 10 mg·liter<jats:sup>-1</jats:sup> for trees receiving the high rates and also for the no tree tank. Leachate N concentration and total N recovered was greater from trees on SO than from those on VL. Average N uptake efficiency of medium N rate trees on VL was 6870 of the applied N and 61 % for trees on SO. Nitrogen uptake efficiency decreased with increased N application rates. Trees outside lysimeters had lower leaf N and fruit yield than lysimeter trees. Overall, canopy volume and leaf N concentration increased with N rate, but there was no effect of N rate on fibrous root dry weight. Fruit yield of trees on SO was not affected by N rate but higher N resulted in greater yield for trees on VL. Rootstock had no effect on leaf N concentration, but trees on VI. developed larger canopies, had greater fibrous root dry weight, used more water, and yielded more fruit than trees on SO. Based on growth, fruit yield and N leaching losses, currently recommended N rates were appropriate for trees on the more vigorous VL rootstock but were 22% to 69 % too high for trees on SO.</jats:p>

Soil Temperature, Nitrogen Concentration, and Residence Time Affect Nitrogen Uptake Efficiency in Citrus

“…Maximum overall NUE values were approximately 83% compared with 71% for reported for another greenhouse study with young seedlings (Maust and Williamson, 1994). The NUE value for lysimeter‐grown trees was on the order of 68% (Syvertsen and Smith, 1996). High maximum NUE observed during this study may be related to the relatively low N supply.…”

“…It is of interest that highest N efficiencies may actually be observed under N‐limiting conditions. However, with good irrigation and fertilizer management practices, NUE values of 60 to 70% for commercial citrus production appears to be realistic (Syvertsen and Smith, 1996) to sustain high yields (Wheaton et al, 1997).…”

“…Studies in Israel showed that, by increasing N rates from 140 to 416 kg N ha −1 yr −1 , NUE was reduced from 57 to 40% (Dasberg, 1987). Reported values of NUE for lysimeter‐grown citrus trees in Florida were on the order of 61 to 68% (Syvertsen and Smith, 1996). Plants grown under N‐limiting conditions may have a greater affinity and capacity for N uptake, resulting in higher NUE (Dasberg, 1987; Jiang and Hull, 1998; Rufty et al, 1990).…”

Effects of Different Nitrogen, Phosphorus, Potassium Rates on the Quality and Quantity of Citrus Plants, Variety Thomson Novel Under Rainfed and Irrigated Conditions

“…The high and significantly effects of N200 treatment indicate that the trees require such amount of N for optimum growth and fruit production (Syvertsen and Smith, 1996;Wang et al, 2006). Nitrogen is a very important nutrient for plant growth and yield production, especially at the vegetative growth stage.…”

Estimating nutrient uptake by mature tree roots under field conditions: challenges and opportunities

“…In the lysimeter method, seedlings or small trees are grown in porous media in containers ranging in size from small pots (Colpaert et al 1999) to large tanks (Weinbaum et al 1994;Syvertsen and Smith 1996). The root systems may be inoculated with mycorrhizal fungi (Colpaert et al 1999).…”