Erosion of topsoil decreases the yield and nutrient uptake of maize and
soybean grown in Mollisols
Abstract
We established three simulated erosion severities with topsoil depths of
10, 20 and 30 cm in a Mollisol farmland under a maize-soybean rotation
system with no-tillage. After three consecutive years of field
experiment, the decrease in topsoil thickness from 30 to 10 cm resulted
in 9−22% of decrease in maize yield but not soybean. Compared to the 30
and 20-cm topsoil thickness, the 10-cm topsoil significantly lowered
root and shoot biomass of maize at the jointing (V7) and milk stages
(R3) and of soybean at the mid-seed filling stage (R6). Compared to the
30-cm topsoil, the 10-cm topsoil decreased available nitrogen and
phosphorus in soil by 42% and 36% under maize, and by 25% and 19%
under soybean, respectively, while the shallow topsoil also decreased N,
P and K uptake per unit root length with the decreases being less for
maize than soybean. Compared to the 30-cm topsoil, the 10-cm and 20-cm
topsoil significantly increased the activities of urease, phosphatase
and invertase in maize-grown soil, but not in soybean-grown soil except
for the activity of urease in 10-cm topsoil. Maize was more sensitive to
soil erosion than soybean due to the greater decreases in soil nutrient
availability and its capability of nutrient uptake. The greater
stimulation of nutrient mineralization processes in soil did not
alleviate the nutrient constraint to maize yield under severe erosion
conditions.