Pg. Hunt et al., CHANGES IN CARBON CONTENT OF A NORFOLK LOAMY SAND AFTER 14 YEARS OF CONSERVATION OR CONVENTIONAL TILLAGE, Journal of soil and water conservation, 51(3), 1996, pp. 255-258
Citations number
29
Categorie Soggetti
Water Resources",Ecology,"Agriculture Soil Science
Soil carbon (C) management is vital for sandy southeastern Coastal Pla
in (SCP) soils that are naturally low in C. A long-term investigation
began in 1979 to determine if conservation tillage would increase the
C content of a Norfolk loamy sand (Typic Kandiudult) with a cropping s
ystem that included corn (Zea mays L.) cotton (Gossypium hirsutum L.)
soybean [Glycine max (L.) Merr.], and wheat (Triticum aestivum L.). Pl
ots were 60 m (196.8 ft) long and 23 m (75.5 ft) wide with five replic
ations Before modern conservation tillage technology was available, in
creasing soil C was believed to be nearly impossible under row crop pr
oduction, particularly if cotton and soybean were part of the rotation
. Tillage (conventional vs. conservation) war the main plot treatment.
At the beginning of the experiment, C contents were not significantly
different. In years 9 to 14, the mean C content of the 0- to 5-cm (0-
to 2-in) depth for conservation tillage war nearly double that for co
nventional tillage: 12.0 vs 7.2 g kg(-1) (1.2 and 0.72%) (P less than
or equal to 0.05). The r(2) of C content vs time over the 14 years was
0.44 for the 0- to 5-cm layer of the conservation tillage plots. The
slope was 0.61 g kg(-1) yr(-1) (0.06%) and the probability that the sl
ope was zero was < 0.001. A smaller slope increase of 0.17 g kg(-1) yr
(-1) (0.017%) also existed for conservation tillage at the 5- to 10-cm
(2.0- to 3.9-in) depth. The C content was not consistently different
between tillage treatments below the 15-cm (5.9-in) depth. Improved eq
uipment, management and soil quality allowed conservation tillage plot
s to produce greater yields during years 9 to 14. Long-term conservati
on tillage of row crops appears to be a viable method of increasing th
e C content of sandy SCP soil even when soybean and cotton are part of
the rotation.