The effect of crop residue cover and soil texture on crusting
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Date
2002-10
Authors
Massingue, Felicidade Isabel
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Free State
Abstract
Large areas of cultivated soils throughout the world develop rainfall-induced soil crusts.
The soil crusts are usually the cause of reduced seedling emergence. To have quantitative
information on the factors influencing the development of surface crusts and on the
influence of ameliorating treatments on crust strength is valuable.
The objectives of this study were firstly, to determine the influence of soil texture on the
susceptibility of different soils for crusting; secondly, to quantify the effect of soil crusts
on the emergence of wheat, sorghum, soybean and sunflower; and thirdly to determine
the optimum level of crop residues that can be used as a mulch to mitigate the effect of
soil crust strength.
Five soils ranging in texture from sand to loam were sampled from the surface (0 - 200
mm). The soil samples were used in four greenhouse pot experiments that were
conducted to examine the effect of crust strength on seedling emergence. Separate pot
experiments in the greenhouse were conducted to determine how particle size distribution
was related to soil crust strength.
Regression analyses showed that silt, silt plus clay and clay contents were related to crust
strength as indicated by modulus of rupture, penetration resistance and emergence force.
All the relationships were of third order polynomial nature. The crust strength increased
initially with increasing silt plus clay contents up to about 35 to 40 %, or clay contents up
to about 25 %, then declined as a result of cracking that occurred upon drying.
The emergence of wheat, soybean and sunflower was little affected at crust strengths less
than 0.7 Mpa or 500 gf when measured as penetration resistance and emergence force
respectively. Above these values seedling emergence decreased linearly with increasing
crust strength.
Large areas of cultivated soils throughout the world develop rainfall-induced soil crusts.
The soil crusts are usually the cause of reduced seedling emergence. To have quantitative
information on the factors influencing the development of surface crusts and on the
influence of ameliorating treatments on crust strength is valuable.
The objectives of this study were firstly, to determine the influence of soil texture on the
susceptibility of different soils for crusting; secondly, to quantify the effect of soil crusts
on the emergence of wheat, sorghum, soybean and sunflower; and thirdly to determine
the optimum level of crop residues that can be used as a mulch to mitigate the effect of
soil crust strength.
Five soils ranging in texture from sand to loam were sampled from the surface (0 - 200
mm). The soil samples were used in four greenhouse pot experiments that were
conducted to examine the effect of crust strength on seedling emergence. Separate pot
experiments in the greenhouse were conducted to determine how particle size distribution
was related to soil crust strength.
Regression analyses showed that silt, silt plus clay and clay contents were related to crust
strength as indicated by modulus of rupture, penetration resistance and emergence force.
All the relationships were of third order polynomial nature. The crust strength increased
initially with increasing silt plus clay contents up to about 35 to 40 %, or clay contents up
to about 25 %, then declined as a result of cracking that occurred upon drying.
The emergence of wheat, soybean and sunflower was little affected at crust strengths less
than 0.7 Mpa or 500 gf when measured as penetration resistance and emergence force
respectively. Above these values seedling emergence decreased linearly with increasing
crust strength.
Description
Keywords
Soil crusting, Crop residues, Dissertation M.Sc.Agric. (Soil, Crop and Climate Sciences))--University of the Free State, 2002