The changes in the soil physical properties due to soil
deformation and mulching were mediated by different weather
conditions during the three soybean growing seasons (2006–
2008), growth phase and soil layer.
Straw mulch generally improved soil water status, reduced the
hydraulic gradients and soil temperature during growing seasons
by providing an insulation layer, mostly in the period until canopy
was established. In periods of limited water availability, soil
deformation resulted in grater hydraulic gradients, likely as a result
of poor root penetration and reduced water uptake from deeper
depth.
The effects of soil deformation and mulching on soybean shoot
growth and yield parameters were linked with inter-annual
weather fluctuations during growing season. The mean shoot
biomass and leaf area during the beginning pod stage (R3) and
yields of seeds, straw, proteins, and oil were the largest in 2007
(with good water supply throughout growing season), and they
successively decreased in 2008 (with alternative periods with high
and low rainfalls) and 2006 (with drought at bloom-full seed
stages).
Irrespective of the experimental year, most of the yield
components and water productivity increased from non-compacted
(NC) to moderately compacted (MC) and decreased from
MC to strongly compacted soil (SC). Mulching improved the seed,
protein and oil yields as well as water productivity in growing
seasons with adequate water supply (2007–2008), particularly in
2007 when these characteristics reached maxima at all comparable
soil deformation levels. However, in the warmer 2006 growing
season with extended period without or scarce rainfalls mulching
affected negatively soybean growth and yield. This was attributed
to the rainfall interception by mulch that did not recharge soil
water and limited root growth due to excessive mechanical
impedance, particularly in compacted soil.
The results supported hypothesis that straw mulching and
weather conditions mediate soil deformation effects on soybean
performance.
The changes in the soil physical properties due to soildeformation and mulching were mediated by different weatherconditions during the three soybean growing seasons (2006–2008), growth phase and soil layer.Straw mulch generally improved soil water status, reduced thehydraulic gradients and soil temperature during growing seasonsby providing an insulation layer, mostly in the period until canopywas established. In periods of limited water availability, soildeformation resulted in grater hydraulic gradients, likely as a resultof poor root penetration and reduced water uptake from deeperdepth.The effects of soil deformation and mulching on soybean shootgrowth and yield parameters were linked with inter-annualweather fluctuations during growing season. The mean shootbiomass and leaf area during the beginning pod stage (R3) andyields of seeds, straw, proteins, and oil were the largest in 2007(with good water supply throughout growing season), and theysuccessively decreased in 2008 (with alternative periods with highand low rainfalls) and 2006 (with drought at bloom-full seedstages).Irrespective of the experimental year, most of the yieldcomponents and water productivity increased from non-compacted(NC) to moderately compacted (MC) and decreased fromMC to strongly compacted soil (SC). Mulching improved the seed,protein and oil yields as well as water productivity in growingseasons with adequate water supply (2007–2008), particularly in2007 when these characteristics reached maxima at all comparable
soil deformation levels. However, in the warmer 2006 growing
season with extended period without or scarce rainfalls mulching
affected negatively soybean growth and yield. This was attributed
to the rainfall interception by mulch that did not recharge soil
water and limited root growth due to excessive mechanical
impedance, particularly in compacted soil.
The results supported hypothesis that straw mulching and
weather conditions mediate soil deformation effects on soybean
performance.
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