Annual average soil loss from a watershed has been measured as $20 \mathrm{Mg} \mathrm{ha}^{-1}$ year $^{-1}$. Watershed has $8 \%$ land slope and $84 \mathrm{~m}$ maximum slope length. Assume all other factors same and dimensionless exponent for slope factor is $0.5 .$ To reduce soil loss from the watershed to $10 \mathrm{Mg} \mathrm{ha}^{-1}$ year $^{-1},$ the maximum slope length in m should be___________________
Annual average soil loss from a watershed has been measured as $20 \mathrm{Mg} \mathrm{ha}^{-1}$ year $^{-1}$. Watershed has $8 \%$ land slope and $84 \mathrm{~m}$ maximum slope length. Assume all other factors same and dimensionless exponent for slope factor is $0.5 .$ To reduce soil loss from the watershed to $10 \mathrm{Mg} \mathrm{ha}^{-1}$ year $^{-1},$ the maximum slope length in m should be___________________