Pg. Hunt et al., EFFECTS OF WATER-TABLE DEPTH ON NITROGEN ACCUMULATION AND POD YIELD OF PEANUT, Journal of soil and water conservation, 48(6), 1993, pp. 534-538
Citations number
21
Categorie Soggetti
Water Resources",Ecology,"Agriculture Soil Science
Peanut is an important leguminous row crop in the Coastal Plain of the
southeastern U.S. Its growth and yield are dependent upon dinitrogen
fixation, a biological process that is adversely affected by water def
icits or excesses. Drought and excessive rainfall in the same growing
season present special problems for crop production in this region. A
two-year field experiment was conducted to assess the effects of contr
olled drainage/subirrigation on peanut nitrogen accumulation and pod y
ield. The experiment was located on a lateral of the main channel in a
PL-566 drainage district that was equipped with a water table managem
ent structure. Water table depths (WTD) were obtained from natural var
iations in the surface elevation; four, nonrandomized blocks contained
WTD of 0. 61, 0.76, 0.91, 1.07, and 1.22 m (2, 2.5, 3, 3.5, and 4 ft)
. Plots consisted of eight 15 m (49 ft) rows on 0.91 m (3 ft) spacings
. Peanuts (Arachis hypogaea L., CV Florigiant) were planted during the
second week in May. Shoots and roots were sampled from 0.30 m (1 ft)
of row; shoots uere analyzed for total nitrogen, and roots were assaye
d for dinitrogen fixation by acetylene reduction. Yields were taken fr
om 30 m (98 ft) of row. Rainfall accumulations were 406 and 634 mm (16
and 25 in) in the first and second year, respectively. Pod yields ran
ged from 3.5 to 5.5 Mg ba-1 (1.6 and 2.5 t ac-1) and uere > 4.0 Mg ba-
1 (1.8 t ac-1), if WTD were < 0.91 m. Dry matter accumulation acetylen
e reduction, and peanut pod yield were negatively correlated with WTD
in the first year (R2 values > 0.37), but there uere no meaningful cor
relations between plant characteristics and WTD in the second season b
ecause sufficient rainfall bad eliminated peanut water stress. However
, differences in the partitioning of dry matter between the peanut veg
etation and fruit produced differences in estimated net soil nitrogen
accumulation. When dinitrogen fixation was assumed to provide 45 perce
nt of the total N, estimated net N accumulations were negative and poo
rly correlated to depth (R2 of 0.02) in the drier year. In the wetter
year, estimates of net soil nitrogen accumulation ranged from 64 to 4
kg ha-1 (57 to 3.6 lb ac-1), and the R2 and slope of the linear regres
sion of net N and WTD were 0.40 and -1.05, respectively. Thus, water t
able management and controlled drainage/subirrigation may offer a meth
od that will reduce excess nitrogen and the associated nitrate polluti
on potential as well as stabilize peanut yield.